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Philly_Weather1

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Philly_Weather1 last won the day on June 17

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    Philly, PA

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    Long Range, Severe Weather, Tropics
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    Inside the CCB of a snowstorm

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  1. For those wondering when the heat may subside, look no further than Monday. Currently have GoA low (pink) that will shear apart and push east. We will also see low pressure in Canada (purple) drop south. Shortwave activity over the Rockies and S. Canada will merge with vort max dropping south over the Lakes. The existing shortwave in the merged location (3rd purple circle in SE Canada) will push northeastward over the next day and will help pump a -NAO pattern for a couple days, long enough to drop a trough. The result is stronger vort lobe over the Lakes/SE Canada, high pressure building behind it, some of which is connected between Alaska and the desert SW. As high pressure builds out west, especially in W. Canada, it'll help the remnants of the low pressure (pink) link up with the phased low over SE Canada and drop a trough into the E US. A legit cold front with some relief from Canada. What you see in the Gulf of Alaska is a new cut-off low.
  2. Lots of activity, expecting some cells to become warned
  3. Thank you! I originally started writing with my phone where the images appeared normal and when I went to add the finishing touches on desktop computer I noticed how large some of the images were. I appreciate the help!
  4. A little bit of everything today. Decided to write up a post about it. Also, a bit Philly-centric but I can't help myself sometimes Sorry for the varying size of the pictures. Not sure how to format them better. Currently we are seeing a cold front dropping down into the Great Lakes and meeting up with post-tropical cyclone Barry in the Ohio Valley. The former tropical cyclone will enhance frontal activity including thunderstorms and rain. The tropical moisture train will be a heavy influence in our weather starting later this afternoon as we increase the flood potential. Current radar showing some showers and storms in Northern PA and NY. The models favor the heavy rainfall and thunderstorm axis north of the Philly Area. Even as the front drags south, the enhanced activity for severe weather coupled with the remnants of Barry are to the north of the region. That being said, with the warmest temperatures of the year and instability throughout the region, severe storms cannot be ruled out for Philly and even SNJ down to the shore points. The remnants of Barry can be seen spinning away on the latest satellite imagery as the counter-clockwise low pressure swirl entering Ohio. The trajectory of Barry takes it pretty close to the Philadelphia area. So most of the enhanced rainfall will occur of N. Pa and NY throughout the day. However, there remains significant risk for severe weather as the upper level remnant of Barry tracks east. Should be a fair amount of sunshine this afternoon mixed with clouds to increase instability. NAM 500mb look at initialization shows the mid-level remnants well This afternoon those remnants track east along with the sinking cold front to the north, enhances precip in N. PA and NY. The timing of the interaction is key because all of the instability and enhancement of rain will maximize during the afternoon for those areas. Temperatures and Excessive Heat Risk NWS high temperature forecast for the day includes mid-90s for much of the area. From Allentown to Atlantic City, expect uncomfortable conditions. Closer to the southwest near Baltimore and D.C, temps may approach 100. NAM heat index for this afternoon shows widespread 100s and areas approaching 105 degrees as well. The NWS has issued an excessive heat warning for the immediate Philadelphia area. Heat indices are expected to be over 100 degrees. Again, there remains a significant excessive heat risk for this afternoon right along I-95. The rest of the area is mostly in an elevated heat risk with temps in the low 90s and real feel of upper 90s. Severe Thunderstorms As stated above, with Barry's trajectory expected to be near Philly, the enhanced area of severe weather will be to the north of the region. Below is the NWS/SPC forecast for severe weather which includes a slight risk for severe storm in Allentown, Trenton, and up into Long Island and SNE. That doesn't mean severe weather isn't possible for Philly down to the shore. There is more than enough instability to increase severe weather thresholds this afternoon. NAM appears to want to bring a bow echo like segment later this evening. Plenty of storms over in PA during the day that will coalesce into this line as the instability parameters remain high in PA during the late evening. Presently we have CAPE values already exceeding 3000 J/kg in some locations. The more sun we get, the most unstable the airmass becomes to help support stronger storms later on with remnants of Barry's approach. We can see in the wide view a fairly decent low level jet associated with Barry's remnants extending into W PA and WVA. This will slide east and aid in thunderstorm development. Flash Flooding NAM forecast brings over 3"+ of rainfall in some spots with the heavy thunderstorms this afternoon. That seems to be a possibility with the cold front being enhanced by Barry's remnants. There is also about 1" of rain in the Philly area and that has to do with thunderstorms. You can see the flash flood risk and why the NWS has issued a flash flood watch. Below is an image of low/mid-level moisture transport which is currently most enhanced ahead of the front into W. PA and W NY. There is a thumb of increased theta-e beginning in the Gulf Of Mexico (look at yellow shadings), jumping up into North Carolina, and then up into S. NY. This parameter tells us that there is warm air with moisture moving into the vicinity that will increase instability. Theta-e tells us where some of the convective areas of interest may set-up during the day. We have a lot to keep an eye on today, so stay weather aware and keep an eye to the sky! Be conscious of flash flooding potential if you see storm clouds approaching. Also, stay hydrated and limit outdoor activities. It is one of those days where you can quickly become susceptible to the conditions without even noticing it. So we have a deep moisture feed in an unstable environment aided with remnant tropical features. Hot, humid, tropical, and if you were missing summer for the last few months, you probably aren't missing it as much today.
  5. Looking like another chance of flooding rains for the Philly area. Actually two weak surface boundaries, one in south central PA bringing some rain to the east and a stronger boundary in W. PA. This stronger one has a more potent shortwave extending into NY as well. I think there is a chance for isolated tornado in C. Pa or perhaps a little further south in MD. Mid-level lapse rates are poor but the surface should have excellent CAPE, lift, and significant veering of winds. Once the shortwave enters the area later on this afternoon, something to keep an eye on. NAM wants to create two lines later today. One out by Ohio and one into MD/DE/SNJ. We will see how that goes. Before that, plenty of rain and thundershowers and elevated flood potential as storms generally will occur over the same area, at least through the afternoon. Some spots by late tonight may even reach 3" of rain.
  6. It is not unusual for to see ENSO evolution become unclear during summer. The upwelling KW is expected to last into at least September. OKW have temporal/spacial scales differ drastically from the atmospheric kelvin waves we see that help initiate tropical convection (such as the one that helped ignite Barbara). For what it's worth, I agree with your assessment @idecline. Too soon to rule out Nino for the fall/winter. Next two weeks MJO/200 VP anomalies will be centered over the E. Pac and Americas, which will reduce trades and may stimey the cooling. I look forward to seeing what the updated MEI shows as well as it takes more into consideration than simply SSTA. In a holding pattern for now, but weakening flag is "on" so to speak
  7. It's usually not so easy to switch out of ENSO states. The atmosphere is reluctant, clinging on to the familiar phase it has been in, trying to keep things the way they were. The MJO is simply a piece of the larger puzzle and may only return out of its weak amplitude phase by mid-July. Right now SSTAs are neutral and subsurface is trying to squeeze out the warmer waters to the surface. CFS over next 2 weeks wants to weaken trade winds and in time with monsoonal flow in E.Pac, create more robust 850mb westerlies. So for now just watching and waiting to see where things go from here.
  8. Guys, El-Nino is in trouble Tropical convection expected to increase in the IO. If it fails to propagate east, the warm waters that it upwells, won't move. Whatever warming is needed to sustain El-Nino won't happen. Furthermore, such continued activity in the IO without movement would support subsidence in the W/C tropical Pac, possibly enhancing easterlies. We ccould see a flip to the other side if it happens again. We shall see
  9. Man, the HRRR was so off this morning regarding that line. Parameters were in place if you looked at the big picture. That's why models are to be used as guidance and not gospel. Impressive MUCAPE and DCAPE values. Also some storms firing with the greatest instability in DE and SNJ. You can see a well developed cold pool behind the storms in PA. You know it's going to get breezy with that gradient. SBCAPE supportive of continued development. Some storms firing ahead of the line as well.
  10. Very true Main 500 lobe will swing through tomorrow and touch up some more showers and storms, mostly in northern regions. Early morning rain in Hudson Valley and perhaps a few tumblers in NH/VT associated with strong PVA axis
  11. Already have some good bit of instability showing up with MUCAPE >2000 in a wide area. Localized 3000 and should spread with more sun.
  12. NAM actually shows almost 4000 j/kg of CAPE in some areas, particularly S PA and SNJ. Plenty of jet fuel but also some CIN nearby. Plenty of bulk shear too. Strong storms for sure but main severe threat will be winds as storm formation appears linear. Cannot rule out some hail either. One limiting factor for severe weather outbreak is lapse rates, which will be modest. Concern also for flash flooding. Tomorrow looks nice for much of the region.
  13. The El-Nino is on tilt right now. Both SSTA and subsurface anomalies have trended colder. The westward propagating rossby wave with upwelling kelvin wave did not produce a downwelling wave to compensate. Trade winds will likely subside next week or two with subsidence reigning in the E. Pac following the tropical activity and that will put a halt to some of those strong easterlies in July. But it appears the oceanic-atmosphere dynamic is increasingly neutral. And in general there appears to be a regime shift in the N. Pac with HP building into Alaska, the EAJ could undercut it in the 7+ day range to enhance W US activity. But the Pacific is changing. Not unexpected for summertime, so it remains to be seen long term. But we are most certainly heading into neutral territory.
  14. So hot, I get people like the seasons and the heat but unless I'm at the beach and can get unto the water its a hard pass. Looking over some of the model runs, have trough dropping in from Canada and plenty of CAPE with Lape Rates >7 in some spots. Northwest flow, so cannot rule out isolated tornado either. Looks like a modest cold front in general, so not likely a large outbreak. Just some pop up storms and then perhaps a line ahead of the front as it drops south. Best parameters in NEPA through SNE. But definitely can't rule out something strong further south. Might see some iso strong storms later this evening in the region. Again, some instability and a little PVA moving through.
  15. MJO hit a brick wall trying to move eastward against the enhanced trade winds. Currently occupying the COD and likely remaining there for the foreseeable future. Some of the hovmollers have picked up a westward propagating Rossby Wave associated with the blowup of easterlies. Still, a kelvin wave is forecasted to make it's way into the EPac/Atlantic over the next 10 days, perhaps enhancing tropical activity. But for us in the mid-latitudes, there has been significant momentum transport out of the tropics into the high latitudes, and as a result, continued blocking showing up. But also impacting things is the kelvin wave, which could force up a ridge. I like the idea of a strong high pressure area in the U.S, but models will struggle with placement and intensity. When there is a tropic~midlatitude influence, they usually do. I think the eastern 2/3 of the country will see higher pressure overall, but limited in reach with the wavenumber pattern 5/6 showing up. Unlikely to see prolonged heat unless in the deep south.
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