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Found 8 results

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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!
  7. 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].
  8. 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.
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