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  1. Quite the super soaker coming up. NAM 3k. I would disregard the hyper-localization at this point - this model does not get specifics down well, especially at this range. I would say 1"+ is fairly likely in most areas. HRDPS. I like the "flatness" of the precipitation this model produces, always seems to paint a good picture, at least in my mind. Here's a GIF of its simulated radar. Couple of tidbits out of OKX. Area Forecast Discussion National Weather Service New York NY 331 PM EDT Thu Apr 25 2019 Considering the high amount of rain the region has received recently, and the forecasted rainfall amounts, I would say the flooding threat is quite likely. Especially in areas where thunderstorms decide to deluge on.
  2. ...a series of late season (for California) storms are likely to cause widespread rain and perhaps isolated thundershowers from mid-week into this weekend...this may(May!) be the start of an unusual pattern for California for May into June...a rather impressive late season storm is eyeing the West Coast, and California should see rain spread south into parts of Southern California as first a front, then the associated low pressure system move into the west coast region... ...these two NOAA GOES WEST ir satellite views on Monday afternoon show the large LP system to our northwest...this system is unusually moist and well south for this time of the year off the West Coast...quite often a ridge of HP has already 'bridged' across the Great Basin, which keeps storminess away from California until September into October...could it be that a late season tropical connection is influencing the pattern...could the warm tropical waters in the Equatorial eastern Pacific Ocean be finally sending El Nino(like) moisture into the CONUS? ...the local forecast for SF Bay Area/Monterey/San Jose area from the local NWS office agrees... ...and not only does the OPC 48hr map shows the first of several perturbations sitting off the coast by Wed. morning...the 'parent' low to the north is forecast to push south, bringing unstable air into the region, and spreading the trough of LP over the entire region... ...and the 96 hr OPC 500mb shows the Pacific Jet 'roaring' across the entire Pacific Ocean...setting up a 'Zonal Flow' almost looking like a February or March pattern (to the eyes of 'rain greedy' Californians) ...perhaps a little QPF's anyone? .awaiting next weeks set-up before 'confirming' a continued rainy pattern in the West... lots of moisture will be heading East into the CONUS for at least the next week starting Wednesday.. idee...
  3. April 14-15, 2019 Possible Severe Weather Event Disco Is there a rumble of thunder on the way? Or perhaps the sound of hail hitting the roof? Strong winds blowing stuff around? Maybe darkness takes over and the lightning for a couple of seconds interrupts it. Ah, and there´s also the good old heavy rain. Well, posters and readers, it looks like severe weather is on the way for the Mid-Atlantic and portions of Southern New England. There appears to be enough instability and energy available to work with the FROPA that will be pushing eastward through the region on April 14th, as the storm center (the recent enraged blizzard that paralyzed the Midwest) responsible for the cold front, will track over the western Great Lakes and push the cold front through the region, causing the cold front dynamics and lift to clash with the available instability and CAPE energy out ahead. All that will be supported by a decently robust southwest flow flooding the region with higher heat energy and air moisture content in the form of higher dew point temperature values. Let´s check some important severe weather parameters to see how the potential stacks: First off the main ones; CAPE and shear-related parameters: Bulk Shear Threshold values Storm Relative Helicity 0-1 km Storm Relative Helicity 0-3 km Threshold values Threshold values Most Unstable and Surface-Based CAPE Threshold values Please go to the next page to see the other severe weather parameters and their values for this potential event. After checking the main parameters, we need to analyze the complementary and supportive ones. Please see them below: Lapse Rate: 700-500 mb Surface Based Lifted Index Threshold values Threshold values Surface-Based LCL Energy Helicity Index 0-1 km K Index Overall, I would say that as of April 12th, 2019, the odds for a stronger severe weather event for the Mid-Atlantic especially, are pretty decent. The close to the Ohio Valley one goes or is, the better the chances for stronger severe weather. The post following this one will display SPC´s Day 3 outlook, which would indicate an enhanced chance of severe weather closer and over the Ohio Valley and a slight risk for areas to the east. Let´s see how this one will unfold.
  4. SEVERE WEATHER ALERT - DAY 1 OUTLOOK *** MODERATE & ENHANCED RISKS *** Given the possible severity of the severe weather event forecasted for today, Good Friday, April 19th, this thread is created exclusively to allow for posters and readers to be able to only discuss and read about the possibilities, outcome and observations of the progged MODERATE and ENHANCED risks for a big chunk of the Mid Atlantic. The NAM shows supercell composite values ranging from 10 to 18 for parts of Virginia and North Carolina, while SigTor values range from 1.8 to 2.3 for areas over central and eastern VA and NC. As per the NAM bulk shear values could be ranging from 50 to 75 knots. RADAR Imagery: SPC DAY 1 Outlook: Categorical Wind Hail Tornado Given that this may turn out to be a rough situation later on this morning and into the early afternoon for the people in central and eastern areas of VA and the Carolinas, please make sure, if you live in those locations, you are prepared and pay attention to the latest information and forecasts concerning this severe weather event,
  5. Quick thread opener here to allow for a place for the discussion of the threat of a possible coastal storm affecting the Mid-Atlantic as a whole and possibly southern New England, and also to avoid the off-topic contamination of @MaineJay´s April Fools storm thread. And yeah, also because no one volunteered to start this one. Below, please see some recent model images for this possible coastal mischief. March 28th 12Z GFS March 28th 12Z FV3: March 28th 12Z ECMWF: Let´s see if there will be any frozen precipitation surprises or if it will be a complete big soaker for many folks.
  6. Some members have been alluding to the potential for a rather wound up storm during this time frame. It is pure fantasy currently, but tele's look favorable.
  7. Don't see a thread for this, so might as well make it. Nice coverage over the Northeast right now. 18z NAM 3k - I do think this model "overlocalizes" some cells, just look for lines of pop-up thunderstorms. 18z HRDPS - I do favor this model for general placement as well as QPF. 0z HRRR "action time" for NYC and the surroundings. GOES-EAST Band 8 "Upper-Level Water Vapor". Look at that moisture plume. Efficient rain-producer. OKX mentions two concerns - high PWAT and snowmelt from VT/NH. Area Forecast Discussion National Weather Service New York NY 716 PM EDT Fri Apr 12 2019
  8. March 26-28, 2019 | Spring Storm | Snowfall Possible? Well, I thought the March 18th thread was going to be the last thread to discuss a snow potential that I opened. But given what I have been observing for the last 3 days using many different operational and ensemble guidance and continued decent teleconnection signals, I was dragged back to open yet another thread to discuss the possibility of snowfall for the region. General Set up and Idea Low pressure developing in and around the Tennessee Valley, may be infused by incoming strong arctic air courtesy of a north to south dropping cold front from the SE Canada (Quebec area) as high pressure builds in over the region behind the cold front. Such setup may result in a blocking mechanism, which may force the low-pressure system to track in a more slow-paced fashion to the south and around of the frontal boundary where the baroclinic zone sets up. There also the possibility that given the setup, that the storm may get cut off somewhere over the Mid-Atlantic or to the south of Long Island over the Atlantic Ocean. Descriptive Set up Illustration Guidance Output March 17th 12Z EPS Control OUTCOME In short, if the building high pressure is very strong heavy with cold arctic air, the magnitude of the cold air would push and block the main part of the storminess, namely the storm center (the low-pressure system itself) to the southeast, which would prevent the northern Mid-Atlantic and perhaps southern New England from being directly affected by the low pressure system as an ENE sliding coastal storm or in a more amplified case a Nor´easter. In this case, the region aforementioned would most likely be affected by moisture being lifted by the cold front as it pushes southeastward and by warm air advection out ahead of the low-pressure system due to southwesterly flow. However, if the building high pressure is not as strong and heavy, and therefore the cold air magnitude is not as intense, then the Mid-Atlantic and southern New England could very well be affected by ENE an ENE sliding coastal storm or in a more amplified case a Nor´easter. In both cases though, unless the modeled arctic cold front with its attending cold air is totally misinterpreted and its forecast is very wrong, there is a pretty good possibility that this time frame features snowfall for the Mid-Atlantic and/or southern New England just as spring is saying hello.
  9. Hello, folks! Opening up this thread here in the Southeast sub-forum to allow for a possible pretty strong and fascinating cyclogenesis that could take place deep over the central GOMEX and affect Florida with lots of rain and even wind possibly. Different models have shown different solutions and varying intensity degrees, but there´s a possibility that this storm could go through some pretty amazing deepening cycle as it hits the southeast CONUS Atlantic coast after leaving Florida. Depending on how this progresses and the track it takes, the Southeast CONUS coast could deal with a pretty potent early spring coast storm along its coast where heavy rain, flooding, wind and perhaps thunderstorms could affect the region pretty substantially. I think it should be a cool event to track and see how it evolves and if something decent comes out of it. Below, please see today´s 12Z ECMWF model image: I hope there´s interest in this one and a nice discussion and tracking take place. Will be updating the thread through the next coming days.
  10. Hello folks! One more thread, but a with a short opener and probably the last one related to a winter potential concerning the 2018/19 winter season. Possibility Description This one is brought to you in order to allow for the discussion of a possible clipper system that may interact with a piece of southern branch energy that could track far enough NE´ward as it reaches the southeast CONUS or just offshore to be able to interact with the clipper, hence the Clipper Miller Tale title. If there´s no interaction, then we are left with a clipper probably impacting the region before a possible bigger storm affects the area on the March 22-23rd time frame. The time frame for this is now in the 10-day out range, and guidance like the GFS and FV3 has been showing this possible storm potential on different runs, although with no solid continuity so far. Additionally, recently as we got into the 10-day out time frame, the CMC hints at something in the time frame talked about and the operational ECMWF shows a clipper trying to interact with weak southern stream energy as moisture affects the region. Moreover, EPS control has shown on some different runs this possibility as well. Aspects to look for that may hamper a good storm outcome: Clipper and southern branch energy interaction or lack thereof; Messy interaction for the lower latitudes south of eastern southern New England; Clipper only storm; Lack of deeper cold air layer on the surface level, Off timing. Track Scenarios Under construction - 2 more scenarios and model images will be added still.
  11. Introduction The winter 2018/19 is coming to an end as we approach its official last 30 days. But the question remains, can the region as a whole, or at least the snow-starved I-95 corridor from Philadelphia to Boston and areas about 50 miles inland from I95, get the storm they have been waiting for? Well, as of the time this thread is launched, that answer will be as slippery as the I95 covered with an ice accretion of 0.75 inch itself. But do not let that bring you down for next on the list of the noticeably legitimate storm threats, is the March 2nd through March 5th time frame. Within this time frame, the region (Mid-Atlantic & Northeast) should expect to be affected by a winter storm of possibly decent proportion. as it's well known, it´s obviously too difficult to determine 10 to 12 days out, which areas of the whole region will be most affected and with what kind of inclement weather. So please, analyze the data provided by model guidance, NWS offices, and the WPC, each day that passes. This way you will surely be prepared and eventually be aware of the kind of impacts this potential storm would have and where the impacts will be most felt. As a starting guide and attempt at shedding some light on the possible storm potential for this time frame, this thread will provide relevant different data outputs from the ESRL/PSD Map Room site as well as varied EPS outputs, so you, the reader, the lurker and even the posters, may start to think up different scenarios and possible outcomes for this time frame, and this way enrich the thread and the community with a plethora of unlikely, likely and even viable end game solutions. To kick start this discussion, let it be known that model guidance such as the GFS, which will be retired in 30 days on March 20th 2019, the FV3 GFS, which will be promoted to the main NCEP operational global model on March 20th, 2019, have been showing on and off on different runs the idea of a interesting storm for this time frame. on different runs for a while now. Furthermore, the EPS and it´s control have hinted at a storm affecting the region as well albeit all the mentioned guidance still do not present a coherent and continuing run to run consistency. That consistency is quite elusive as we well know, especially during this winter season given how the pattern has run the show. Storm Track Scenarios So, what to expect? Well, the usual suspects. Rain, snow, wind, wintry mix and lots of guidance variability in search of fine-tuning the eventual outcome. We should expect a storm, perhaps, tracking from Texas to central NY state as the northern track boundary and as the southern track boundary a storm coming from Florida, either from the panhandle or from its NE coast, being possibly exciting enough to trigger the so wondrous JAX rule. On the next page, EPS and ESRL/PSD data can be found as to allow you to judge whether or not this time frame holds any hope, or potential, if you will. ESRL/PSD Map Room Data First off, the H5 Northern Hemisphere view data from NCEP and PSD for the time frame in analysis. It gives this time frame some good support given what is shown; a possible ridge out west and a robust trough over the eastern CONUS connected to the arctic cold source. As we continue, the next data piece of evidence is the PSD 4 teleconnection indices panel. On it, we see that around this time frame the PNA should be positive, the NAO should be switching from negative to positive and the EPO should be decently negative. These signals, although not 100% awesome, would indeed give support to a colder storm on the eastern 1/3 of the CONUS for the time frame under the microscope. And to finalize the ESRL/PSD Map Room contribution, we see below the deterministic precipitation from analogs for the time frame from February 27th through March 6th, which obviously encompasses this thread´s time frame. Now, let´s switch sources and look at the EPS data. EPS Data Looking higher up away from the surface, we see below, the H5 North America view data from the EPS for the relevant time frame. Notice that it is hinting at a pretty strong and amplified trough over the eastern CONUS while a rather pronounced ridge is located over the western CONUS and Alaska. That makes me think of that rather strong negative EPO aforementioned in this thread. This setup hinted by the EPS, in case it verifies, may be pretty fruitful. Now coming back down to the surface, the EPS continues to hint at the good potential that the H5 setup above suggests. Surface analysis shows lower pressures developing over Florida and then continuing to evolve NNE´ward towards northern New England and into the Canadian Maritimes. Both the MSLP and MSLP anomaly products display the same idea. And to complement, below one can see how the moisture plume associated with the lower pressure shown above evolves and behaves over the region. Bundling all what as shown in the thread opener together, one may come to the conclusion that the March 2nd - 5th time frame, does indeed show a legitimate good potential. So, as always, discuss, discover, participate, read and enrich the thread and the community with your theories, ideas, and conclusions. Perhaps this one will be the one for you...
  12. Nor´easter always deserves its own thread. So, let´s then, discuss here how this one went from a weak disorganized almost completely out to sea mess to a mature and well-versed Nor´easter by the time it reaches eastern southern New England. Here we will tell the history of the 2019 Nor´easter that went from Fledgling to Full-fledged before our very eyes. The NAM is showing this little Nor´easter strength-wise, to look quite well structured. Perhaps it will strengthen a bit fast. February 28, 2019 00Z NAM looks very nice.
  13. While many are getting excited about the bigger storms ahead of this date, some forum members @MaineJay @PlanetMaster have mentioned that this storm deserves some love. It might continue to become more robust as the NAM has been showing. Certainly this one is a job for the mesoscale models. With the low placement, I have my suspicions that this may overproduce in some places. 2-4 is quite possible for many, perhaps a little more if the QPF is not being depicted accurately.
  14. Hello everyone! As we continue our journey through the 2018-19 winter season and endure disappointment when it comes to the snow aspect of winter, our next storm chance comes around the President´s Day holiday time frame, which I then took the opportunity to dub this one the Commander-in-Chief winter storm. Let´s just hope it does come with all the splendor that the title brings with it. This storm could be an overrunning type of storm that comes from the central Rockies region and tracks eastward across the country. As with any storms 10 days out, a few outcomes are on the table. Let´s talk about them. A flatter storm crossing the Southern Plains which may amplify enough after crossing the Appalachian mountains as it emerges over the Atlantic Ocean somewhere near or south of Long Island; A more amplified storm that could track ENE/NE and pass by south of the Great lakes and when possibly cut tracking over Michigan or western NY, Option 1 but with a coastal redevelopment over the offshore waters near VA, which would then track to the ENE or NE. A primary low track the could take it over Minnesota and then cyclogenesis occurs far south over South or North Carolina or just offshore near either one of those two states. Given the conflicting teleconnections signals, it´s perfectly fine to expect the possibility of different outcomes at the 10 days out range. Please take a look at the teleconnections outputs from the ESRL/PSD map room and the EPS ones: Ensemble guidance support has been so far not too clear, which is not alarming. Some EPS control runs have hinted at this storm affecting the region. However, what is interesting is that the GFS, FV3, and ECMWF have been showing a storm during this time impacting the region. The GFS and its successor FV3 are more on then overrunning bandwagon while the ECMWF is playing with the idea of a coastal redevelopment near the VA offshore waters. The images will not be posted because they are readily available on well-known sites sources. Track Scenario Maps Perhaps a more simplistic thread opener, but still respecting the need to content addition and textual descriptions, may work to make this storm potential a candidate to take over the Commander-in-Chief title.
  15. Okay, I'll start a thread since I promised, and I know @Mike W IN ALTMAR is patiently waiting for it. Let's not beat around the bush, no one in this sub-forum is excited about a 978mb low in the great Lakes. It's also not often that one can open a thread with NAM images, but here we are. To the surprise of no one, the NAM12 is colder than the GFS family, as it more aggressively pops a coastal low reflection, as well as picking up on the CAD signal ECMWF might be the most aggressive, keeping me all snow miraculously. Subtract about 0.4" from this, and it's still borderline warning level snows. So feel free to post those rainfall totals, and may they be light! GYX disco, interesting that in a winter of many CAD events, this one stands out for some reason.
  16. Synopsis A low pressure system tracking over the Lakes will weaken as a secondary low pressure develops near the Gulf of Maine tracking into the The Bay of Fundy to cross just north of the shoreline in Southern New Brunswick. Current indications suggest with a cold artic high to the north will keep much of the warm air to the south of the warm front which will be squeezed out of the low drying the precipitation out over Nova Scotia. This will result in much of Nova Scotia's first significant snowfall of the season despite the secondary development tracking to the north of that province which at this time this will still result in a changeover from snow to ice pellets and maybe freezing rain to a brief period of rain or a taper to showers. The deep south of Nova Scotia will have the most rain with Northwestern Nova Scotia having the most near the New Brunswick Border. As a result Environment Canada has issued Winter Storm Warnings over all of New Brunswick and Prince Edward Island with much of Nova Scotia with the exception of Halifax County, Annapolis County, Guysbourough County, and Lunenburg County which have blowing snow warnings where 10cm with locally upto 15 is possible. Meanwhile Yarmouth, Shelburne, and Digby can expect 5-10cm and 10+mm of rain where wind warnings are posted. All areas in Nova Scotia can genrally expect 15 to locally 25cm of snow with some ice and freezing rain and maybe some tail end rain. New Brunswick has 15-30cm respectfully. https://weather.gc.ca/warnings/index_e.html The Setup Teleconnection Indices The PNA is super negative which aids the primary low in the Great Lakes to be a Cutter however there is a secondary low which will aid along with a slight negative NAO to suppress too much of the warm air from trending as it has usually into the southern maritimes especially Nova Scotia which at this time except extreme southern Nova Scotia from being a primary rain story. Taken the 6pm time as Kings County and Halifax County are in the mix or freezing rain zone at this time with all areas north and west as snow and areas south as light rain. The centre of the low is trending towards the northern shore of the Bay of Fundy. But despite this the cold air is much to strong to overcome in the extremity so this makes this low a cold core storm. Winds will still be strong from the south east, blowing snow is expected prior to the changeover. Looking over the other models most of them are in agreement over this track, though there are slight differences as the Canadian ones seem to be slightly warmer with a little more rain and perhaps a little less snow overall. However as we know when there is ice pellets involved and rain final snow totals will tend to be on the lower side of the spectrum, so snow mobiling season in Nova Scotia will largely still be a no go after this event. Compared to the snow hole in New England the snow hole or snow deprived areas of Nova Scotia will do better in this one as much of the province should have a net positive gain for the next few days before mother nature which has played take away this year unlike keep away further south will bring more rain washing it all away.
  17. PREFACE NOVEL - Perfume & Blizzard, a war of seasons The time has come for winter to take revenge on those who have dismissed it, laughed at it and wanted to replace it with Spring. Winter intends to show those that mocked it, who roars in February is still the lord of ice and snow, the lord of blizzards; Lord Winter Solstice. To make that roar loud and clear, a Nor´easter shall humble those who intended to start a coup in favor of the lord of fragrance and flowers; Lord Spring Equinox. Taken by rage, Lord Spring Equinox warns Lord Winter Solstice that it has the ability to deploy one of its Atlantic Ocean´s soldiers, the SE Ridge to flood the eastern seaboard with its warm air to offset one of Lord Winter Solstice´s most beloved weapon, the snow. Keeping that in mind, all those beings being kept hostage to this power struggle, the people of the Mid-Atlantic and Northeast CONUS, become aware that the SE ridge is a force to be reckoned with and that it should not be neglected or forgotten. It needs to be watched every step of the way to see if it will be able to further Lord Spring Equinox´s influence over the region and keep Lord Winter Solstice´s loyal subjects in the Mid-Atlantic and Northeast apprehended under the most severe punishment of all, warm air in winter with no snow. But we all know that Lord Winter Solstice, although beaten down since December by a hostile rogue split flow pattern, not being able to count on one of its most loyal soldiers, the -NAO, which has been kidnapped by its evil twin the +NAO for many months now, will strive to make a come back and avenge all those involved with this Lord Spring Equinox led coup, as well as in the process, be able to count on the Greenland blocking, another of Lord Winter Solstice´s loyal member, the royal guard gatekeeper which has been unable to manifest itself due to the poisoning of the atmospheric flow over North America by many masked unrevealed Lord Spring Equinox supports. Acting out of deep fear and staunch resolution that there should not be Spring during Winter´s reign time, Lord Winter Solstice´s bountiful supports in and around the frontline, resort to consulting and interpreting while trying to trust the world most famous group of seers; weather prophets called: Weather Guidance Model Operational & Ensemble Association aka WGMOEA. Lord Winter Solstice´s supporter hopes rest on the shoulders of the WGMOEA as they yearn for most needed support and good news from the weather seers that Lord Winter Solstice and its loyal soldiers will be able to fight back and squash the ongoing coup by releasing the frontline from Lord Spring Equinox´s oppressive untimely rule using Lord Winter Solstice´s most powerful weapon, the Blizzard. They hope, they say, that the Blizzard with its frostbiting winds, heavy wind-driven snows, thunderous snowfall, and deep low surface pressure, can prevail and hence the frontline finally rejoice with a celebration at Lord Winter Solstice´s, whose nickname is P. Master, headquarters located in Long Island, NY. Please see the next page for some images provided by the WGMOEA of the future of this battle. Possible Battle Outcomes WGMOEA Depictions A different take on this thread starter post. Hopefully, a good outcome is the final result from this battle.
  18. Current Hazards. As you can see it is very elevation dependent. Current Radar. Lots of moisture. Snow Forecast. URGENT - WINTER WEATHER MESSAGE National Weather Service Denver CO 636 PM MST Thu Feb 14 2019 BULLETIN - IMMEDIATE BROADCAST REQUESTED AVALANCHE WATCH COLORADO AVALANCHE INFORMATION CENTER RELAYED BY NATIONAL WEATHER SERVICE DENVER/BOULDER CO 737 AM MST THU FEB 14 2019 URGENT - WINTER WEATHER MESSAGE National Weather Service Grand Junction CO 201 PM MST Thu Feb 14 2019
  19. PREFACE Well, the discussion and discovery must continue. It cannot stop. So, even though we have been getting burned by big ghost storms, or if you prefer big snowstorms fairy tales on the models, we must keep the conversation about storms going and this way hopefully we are graced with a good winter storm for most of the region. Having gotten that out of the way, the time frame in question is at least almost entering the medium range, as this time we will use this thread, to tackle the February 7th-8th time frame which is about 8 to 9 days out. Hopefully this time, with a shorter lead time, we avoid the drastic and volatile model swings we have been dealing with this winter with model depictions beyond 10 days out. SET UP DESCRIPTION The time frame in question appears to present a possible overrunning type storm originating from Texas and tracking towards the Mid-Atlantic on an ENE motion. Along its way towards the Mid-Atlantic coast and then off the coast over the Atlantic, moisture from the GOMEX should be introduced and lifted and thrown over a colder air mass to the north of the storm´s low-pressure track; overrunning. Additionally, it´s possible that some northern stream vort energy gets introduced into the dominant southern stream flow, which may cause an increase in strength and consequently a bigger storm. That though, as we all know, can bring to the table farther north track outcomes resulting in mixing and rain issues for the areas close to the storm´s low-pressure center. Furthermore, as the storm approaches the Mid-Atlantic region, there is a decent possibility that an off the coast redevelopment farther to the SE may occur and thus, some areas may experience snow or a wintry mix to rain to snow scenario as the redeveloping low-pressure takes over, if that kind of coastal cyclogenesis occurs at all. Things to watch for: How far south the storm originates in Texas Possible northern stream vort getting enthused into the dominant southern stream low-pressure system Southcentral and southeast Canada High pressures Cold air strength and location Cold air damming (CAD) Baroclinic zone Coastal redevelopment Southeast ridge Suppression SIMPLE OVERALL ILLUSTRATION Please find data relevant to this time frame on the next page. RELEVANT SUPPORTIVE DATA Teleconnections ESRL/PSD The ESRL/PSD teleconnection package looks pretty beneficial for a storm over the eastern US that may be a somewhat amplified and allow for possible redevelopment off the coast. EPS 46-days AO EPO AO and EPO combo looks supportive for cold air availability. NAO PNA Negative NAO and negative PNA send a conflicting signal. Suggests a possible overruning type outcome. ENSEMBLE GUIDANCE Jan 29th, 2019 00Z Jan 29th, 2019 12Z Jan 29th, 2019 EPS All in all, this time frame looks active and is another shot for the region to get a storm that depending on how the players present themselves, could deliver wintry precipitation for areas to the north of the low-pressure system. The track may be far enough south that areas from Philadelphia to Boston may be affected by wintry precipitation. Let it evolve! Let it do what it gotta do!
  20. PREFACE Hello, posters and lurkers! This thread opener will not be a very laborious one. Perhaps because the weather has been so ingrate, it does not deserve a traditional thread opener. This time frame may give the region some kind of storm to entertain us courtesy of the same usually players; an active southern stream with its moisture riches and the northern stream. But this time, we have a very illustrious player; the polar vortex. There are some indications that since the polar vortex will from time to time relax its grip over the region, a storm could take the opportunity to affect the region, using the polar vortex as some kind of blocking mechanism to spare us a Great Lakes cutter. From the observations I have been making for the last two days, it seems that the first period that the polar vortex will relax some over the region will be during the time frame for this thread. With so much energy crossing the continental US and that unrelenting southern stream branch, perhaps the presence of the polar vortex during a reloading period is what is needed to make a storm come together for the region in a way most could benefit. Now, talking guidance wise, there are some hints here and there both on the operational and ensemble sides. Please see them below, most should be subtle, though. EPS CONTROL 12Z Jan 23rd 00Z Jan 24th 12Z Jan 24th 00Z Jan 25th 00Z FV3 06Z FV3 [Given the chaotic state of the atmosphere over the CONUS, the thread dates will likely need to be adjusted later on closer to whatever event comes].
  21. PREFACE Getting past the January 20th time frame and storm, there are indications that a cold air invasion is becoming more and more apparent for the eastern CONUS as we fast approach the last 10 days of January. With that in mind and considering that the southern stream over the CONUS should continue to be actively keeping the GOMEX rich moisture content available to be lifted and gathered for storm formation, I see a rather good opportunity for a storm to impact the region, which would include the Mid-Atlantic and even New England depending on how amplified the storm becomes. For a more amplified storm to come to be, we need a solid set of teleconnections (AO, EPO, NAO, and PNA) and the development of Greenland into North Pole blocking, or at least a Greenland block. Given the actual data available from the EPS 46 days and EPS products, the January 24-26 time frame, would benefit from a mostly solid teleconnection package and perhaps the advent of a Greenland into North Pole blocking. The blocking though, may not be totally established yet during this time frame, but by the end of January, it could be the big boss in town. Long range operational model signals do exist for a storm in this time frame, but as I usually do, I try to avoid using the operational model storm signals for possibilities that are in the 12 to 16 days in the future time frame for the thread openers, instead relying on the ensemble guidance signals or other longer range weekly or monthly models. Given that some operational models present "forecasts" or outputs for 15 to 16 days out, I use that range as my limit to consider opening a storm thread, to avoid turning the thread into a long-range pattern discussion thread. Overall Set up Continued southern stream activity with ample GOMEX moisture to be tapped and lifted along with deeper cold air presence perhaps with a high-pressure presence and CAD development. Teleconnection robust package, possible initial developing stages of Greenland blocking, aiding in a more teemed northwestern Atlantic Ocean. Track-wise, we could have one of the 3 most traditional tracks, the western/central PA cutter track, the northern Mid-Atlantic tucked to the coast track and the beloved benchmark track. Which track would be the verified one come the time frame, would be determined in good part by the depth of the cold air in place, blocking high-pressure placement, possible phasing time, if one ever comes to be, and interestingly enough, whatever influence the initial development stages of the Greenland block would have on this time frame, if any at all. Most of these mentioned can certainly be a result of how strong the teleconnection package for this time frame is. Below, an image showing the 3 possible storm tracks can be seen. Storm Track Visual Aid Before we move on the next page, on which you will be able to see the forecasted EPS North American and Northern Hemisphere setup, the EPS 46-days teleconnections and EPS precipitation output for this time frame, I would like to finish this page, with a couple of EPS control runs images and an very interesting, perhaps surprising to some, seasonal CFS MSLP output for this time frame. CFS Surface Pressure It´s very intriguing or interesting to me at least, that very robust storm would be shown on the CFS at such a time range, near the time frame that this thread discusses. It´s a neat piece of information or perhaps, let´s say evidence. Jan 9th, 2019 12Z EPS CONTROL (tucked and benchmark track hybrid) Jan 10th, 2019 00Z EPS CONTROL (western PA track hybrid) On the next page, you will see additional data related to this time frame. To start off this page, please see the Northern Hemisphere and North America set up for the time frame in discussion. January 7th, 2019, 00Z EPS 46 day Northern Hemisphere North America There´s no way to look at this setup and be indifferent to it. That argues for a real winter over the eastern CONUS. We can see the lower heights over northern Canada connect to the lower heights over the SE CONUS, setting up a deep negatively oriented trough over eastern North America, and the developing Greenland block. All that if were to verify, would translate to a much colder eastern United States and a much more promising storm track from the southeast to northeast CONUS with the less progressive component courtesy of the Greenland blocking. As we continue, you can see below the EPS 24-hour precipitation for the time frame in discussion. Jan 9th, 2019 12Z Jan 10th, 2019 00Z And now the EPS 46-days teleconnections (AO, EPO, NAO, and PNA) AO EPO There is not much to argue concerning this EPS AO/EPO combo as it relates to the time frame. Both teleconnections are in their negative state, which is primordial for the availability of a strong and more sustained cold air presence over the eastern CONUS. The -AO is around -1.5 to -1.7 while the -EPO is around -1.3 to -1.5, which is the most negative it has been in recent weeks. We like this. NAO PNA This combo, the way I interpret it, looks very promising and supportive of a storm track that could deliver the wintry goods and be more amplified, and perhaps not so quick to exit the region. The -NAO can lay a hand in allowing blocking conditions over the eastern areas of North America while the +PNA would argue for a ridge over the western US and depending on how it interacts with the -EPO aforementioned, a deeper colder trough could pass through the eastern US. Notice that the -PNA is in positive to negative trajectory during the time frame in discussion, and flips to negative sometime around January 28th. That changing magnitude could play a positive role in the flow pattern. Given the data, this time frame looks like it has more robust aspects to it to allow the region to at least have a better shot at a wintry storm that may impact areas that are snowless since November, What do you guys think? Does this one have a standing chance? Or is it another dream only reality? Later! UPDATES: Jan 11th, 2018 January 10th, 2019, 00Z EPS 46 day Northern Hemisphere North America January 10th, 2019, 00Z EPS 46 day AO EPO This combo has suffered a blow and is weaker now as compared to the January 7th run. The -AO continues pretty solid. However, the EPO has changed to neutral to slightly negative. Before on the 7th of January, it was decently in a negative state. NAO PNA This combo also has suffered from changes. Although the NAO continues to be negative, it is not as negative as compared to the output from the January 7th run. As for the PNA, it went from a more solid positive state to a slightly positive state, basically neutral and flat. We will see how this evolves on the next update scheduled to occur on January 14th, 2019.
  22. There looks to be a good chance at seeing a decent system around this time frame. It’s on all the models. Lots of shifts in expected track for the next few days but it’s no doubt one that needs tracking. 18z GFS 12z CMC 12z euro
  23. Overall Setup Continued active southern stream branch, with conflicting teleconnections signals and active robust BSR signal. Northern stream still sending energy impulses eastward. As always timing between the northern and southern branches can greatly influence the outcome of this possibility but does not necessarily mean that only a phased solution is required as depending on the track of the southern stream energy, in case it´s more eastward, this time frame seems colder. BSR Depiction A low-pressure system developing over the northeastern GOMEX and southern SE CONUS, tracks ENE'ward towards the southeast coastal waters and the northeastward towards the Mid -Atlantic coastal waters. Once it´s offshore near the coast of Virginia, the storm tracks either to the ENE affecting only the Mid-Atlantic including near coastal areas of the northern Mid Atlantic and southern New England or actually continues on towards the Gulf of Maine and also impacts northern New England. Now, the BSR is showing what it seems to be two different potential storms in the time frame between Jan 13th and 15th. However, so far it does not seem that there are signals for two storms in this time frame on the models. It may take a bit more time for us to identify exactly which one would be the storm that comes to reality in this time frame for the region, the one that occurs on the 13th or the one on the 15th. Both take similar tracks from the southern southeast CONUS to Virginia and the off the coast. From there, the tracks diverge, as one tracks offshore to the ENE and the other tracks NE towards southern New England. Please see below the possibilities depicted by the BSR. 13th: 15th: 500mb Flow (Jan13th through 15th) The 500mb flow is pretty interesting and does indicate that a storm is possible, although not a too powerful one, especially because we do have conflicting teleconnections during this time frame. On the next page, more relevant and related data can be found, including the teleconnection readings for this time frame. Northern Hemisphere and North American views EPS 500mb height and MSLP: EPS North America flow 500mb height EPS North America Normalized MSLP Overall, not a classic flow, but also not a terrible one. There´s room for a decent storm, while also one cannot disregard the possibility of a farther offshore outcome, in which no one north of eastern Virginia would be impacted. Teleconnections EPS: AO is negative, around -1 while the EPO is in a weak positive state near neutral. This is not a terrible combo as it is, but it´s not ideal as well, given the positive EPO even though is almost in a neutral state. The NAO is transitioning from a near weak positive neutral state to a weak negative one, while the PNA looks to looks to be positive around 1. This combo, although not ideal because of the weak magnitude of the negative NAO flip, nevertheless still have the flipping NAO which is beneficial as well as the positive PNA. As we go on and take a look at the GEFS teleconnections forecast, we see a bit of a different look. GEFS This GEFS AO/EPO combo does look pretty decent, as we have a negative AO around -2 and a negative EPO around -0.5. In case the EPO was in a strong negative state, this would basically be a good one. As we take a look at the NAO/PNA combo, we can argue that this one is pretty decent. The NAO is negative around -0.5 and the PNA is positive around 0.7. The magnitude of the readings is not ideal as both are in weak states, but the signs of polarities for each are good. In short, this one looks to have a good potential to bring wintry precipitation for the thread´s region, also keeping in mind that this does not mean that the whole region will see wintry precipitation. The exact track and storm strength will be determined later. The other aspect to keep in mind is that there´s a chance that whatever storm comes, it could take a further offshore track and not affect areas north of Virginia. Let´s see how it goes folks. Hopefully, it´s time to be rewarded for the snowless December. Have fun!
  24. Introduction Hello, posters and lurkers! Quick opener here. I have been observing that the Mid-Atlantic has a good chance of getting an interesting storm around the January 3-4th time frame. There has been off an on operational model support, and EPS support as well as EPS Control support for some runs. And after the Jan 1-2 storm, which looks to be 85% rain, cold air should be invading the region, which may force this wave of low-pressure to take a more eastward path tracking along the cold and warm air boundary. This setup is at least a decent one for areas of Virginia to get snow, maybe even North Carolina. However, given how the supporting energy behind the developing storm behaves there a chance that the storm may deepen more and track more to the northeast and impact the northern Mid -Atlantic and southern New England. So, please stay on the lookout for the possibility of snow in Virginia and North Carolina. but be aware that this is a very volatile situation as changes over North America, may be in the works to bring in a colder period to the north of where the mean zonal flow establishes itself. Expect some model mayhem. On the next page, we can see some supportive EPS output data. Supportive Data December 25th 12Z EPS Control: December 26th 00Z EPS Control: December 26th 00Z EPS: Please let´s know what you all think!
  25. Preface Hello, posters and lurkers! Perhaps this thread will inject some optimism in us all and cheer your souls up a bit as I believe we have a decent shot at getting the first real winter storm of the now, official winter season 2018/19. What has intrigued me and helped me make up my mind was the impressive BSR data for this time frame, as so far there has been no operational model support for this time frame which is about 18 days away. Overall Setup Simply put, as we have seen so far this season many times, the southern stream should be continuing to do its dirty and beneficial work, keeping energy running near the GOMEX to be tapped or let´s say, excited. Meanwhile, the northern stream may be doing some work across the US central plains, and as a result, may be attractive enough to excite the southern stream to perhaps accept to dance a very classical tango. In addition to that, I expect some sort of high-pressure complex to be floating around from north of the central Great Lakes to northeast of Maine, perhaps bridging with the north-central Atlantic ridge and considering that this will be early January, this high-pressure complex should be more robust millibars wise. In short, these players would need to form a smooth orchestra, to translate the BSR depiction into a cold wintry storm. But in case the orchestra fails to be fine-tuned, then the BSR can still verify, but deliver liquid H20 instead. Moving along, please see below the BSR depiction for this time frame; both 500 mb and surface. It´s pretty impressive and should serve as a real good test of this marvelous forecasting tool. Bearing Sea Rule Surface 500mb This BSR depiction is highly impressive by itself. And if it did not depend on anything else, especially the teleconnections, one could say that a big and powerful storm is coming. But since the weather does not work like this, we will need to take a look at the teleconnections and see if this BSR depiction has an even better chance of actually coming to fruition. Next, let´s go check on some teleconnections. Below, we can take a look at the Dec 17, 20018 00Z EPS 46 days AO, EPO, NAO, and PNA. AO EPO NAO PNA As one interprets the data above, we see: AO = ~ 0.3 negative (supportive) EPO = ~ 0.7 positive (not supportive) [However, not as positive as many instances during the last few weeks] NAO = ~ 0.3-0.2 negative, approaching neutrality (supportive) PNA = ~ 0.3 positive, having just flipped from negative to positive (supportive) All in all, there is teleconnection support for the BSR. The weakened state of the positive EPO should technically prevent a flood of warmer air. Therefore, allow for the presence of cold air to some degree. The highlight then is the flipping negative PNA to a positive PNA and the weaker positive EPO. Let´s see how this one turns out to be. As the days passe, and more data becomes available, I will be updating this thread opener with more information to give support to the BSR for this time frame, and enrich the depth of the thread. Hope to see some good ideas and discussions in here from all of you.
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