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Northeast Severe/Convective/Thunder thread IV


NJwinter23

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Finally have had a chance to look at things. Haven't gone into great detail yet and I have read the past 2 pages of this thread and I certainly agree with the issues mentioned for SNE. One other thing is soundings at least across northern CT show another capping inversion just above 500mb...it's not overly strong and given how strong the cap is with the EML-like feature if we get lift strong enough to bust through that it certainly will be strong enough to bust through the cap just above 500mb but it's just another wrench in this mess.

I certainly could see the bulk of the activity staying to our north.

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Well the 0z NAM has all sorts of interest for Friday.

First off, we are very unlikely too see widespread convection on Friday (and this will actually be considered a good thing for the sake of this setup). So a widespread severe weather event is extremely unlikely, however, significant severe weather is quite possible.

The 0z NAM actually looks pretty decent with timing of the s/w as it moves multiple s/w energies through northern New England after 18z. While the energy is confined to northern New England the height falls associated with the mid-level s/w trough are quite decent even down into southern New England. While 500mb temps do slightly warm during the afternoon we actually see 700mb temps cool during the afternoon with the approaching s/w trough. This will certainly help to erode the strong cap (EML) that will be in place and despite the slight warming at 500mb if the lift is strong enough to punch through this baby it will certainly be good enough to break through any weak cap around 500mb.

Below the EML surface temperatures should be well into the upper 80's (immediate coast/Pete land) to mid 90's across inland areas along with dewpoints into the mid to perhaps even upper 60's...however, there could be a little pickle here...if surface winds are more westerly this is going to allow much more vertical mixing of the atmosphere and the dry air associated with the EML will actually be able to work down towards the surface and we could see dewpoints mix back into the 50's and this would cut back on the instability quite a bit, although thanks to the EML/steep mid-level lapse rates we'd still have a good amount.

With the approach of the s/w trough we also see a major increase in the wind fields aloft with 500mb winds increasing to around 60 knots, 700mb winds to around 40 knots and 250mb winds increasing to around 90-100 knots!!! Winds at 925/850mb also around 20-30 knots. There also happens to be a decent amount of helicity between about 1-3km as winds from 925mb to 250mb turn from a more westerly to northwesterly direction. If winds at the surface can become more southerly with winds at 925/850mb becoming more southwesterly not only will this keep the low-level moisture locked in place but it would significantly increase the level of helicity across the region...for this to happen though we would want to see some s/w energy dig into southern New England more instead of traversing northern New England zonally and we would like to see trough in the lower levels (925/850) dig more from New York State to western southern New England as opposed to southern Canada to northern New England/Maine...this would bring those lower level winds more from the southwest.

So what to expect...

Well at this point you really can't expect anything, however, conditions are going to be prime ripe for severe so any cell that develops would likely quickly become severe and given how there will be no other storms to compete with one storm could really take off and quickly become a supercell posing a threat for extremely large hail and perhaps even a threat for a tornado.

One note of interest is the NAM has developed light QPF across the same general area for a few runs in a row now.

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Besides weathergeek pro 2 some other incredible iphone apps are

weatherwall mobile $9.99

Has your reflectivity/base velocity radar data as well as dual pole! It also has GPS enabled so you can check where your locaiton is relative to the storm, it also has topography underlay so you can see where valleys/hills/mountains are in relation to the storm and you can do the same thing with cities and where the highest population is in relation to the storm!

weather 4d is also pretty sick! I believe that is $9.99 as well.

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SPC SREF really starting to pick up on the potential that exists tomorrow and even has someone of a tornado threat across ME.

Had some discussion yesterday about the possibility of some super cell development that could spawn a possible tornado in this Nam setup

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This pattern is just not quite right for southern New England even if for 1 day a classic EML sounding is realized. Given the large scale players this summer, a true EML - significant severe threat will be more likely mid-July as the ridge continues to build north and eastward. There is a tendency in El Nino years (or relative peaks in AAM) to do this in July as many have pointed out already. Consider yourself lucky to get a thunderstorm out of this. With that expectation, you'll be fine.

There is a bit of surface convergence in far SE NE tomorrow but the models obviously keep it capped. At least you guys have that for a fighting chance. Down my way, I have deep W-NW flow at most layers.

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This pattern is just not quite right for southern New England even if for 1 day a classic EML sounding is realized. Given the large scale players this summer, a true EML - significant severe threat will be more likely mid-July as the ridge continues to build north and eastward. There is a tendency in El Nino years (or relative peaks in AAM) to do this in July as many have pointed out already. Consider yourself lucky to get a thunderstorm out of this. With that expectation, you'll be fine.

There is a bit of surface convergence in far SE NE tomorrow but the models obviously keep it capped. At least you guys have that for a fighting chance. Down my way, I have deep W-NW flow at most layers.

Yeah this threat is ultimately not materializing. I'll probably be awakened tomorow at 4am to a clap of thunder as a decaying MCS moves through (can't wait! :axe: ), but thats about it. Looks like the Mid-Atlantic is still in the game especially DC/VA as we move through the day Friday, but even they are strongly capped. If any amount of forcing available can penetrate that, then there could be a nasty storm down that way.

July definitely has the looks of AN for just about the entire country HM, ala 2002 I suppose. With the drought in the Midwest/Plains, the greatest warm anomalies should continue to try and reside there and give a feedback to enhanced ridging.. though I'm guessing there will be a tendency to try and shift the mean ridge a little further west with time (Intermountain region, where its also been very hot as well) due to more of an el nino tendency. The last 2 runs of the euro ensembles trended cooler on the East coast next week (negative SOI repsonse maybe??), and have trended to well above normal for the Pacifc Northwest interestingly with more ridging out west in days 11-15. It is still well above normal into the Midwest for that period, but I would have to think some cooler/troughing risks would reside in the Northeast in that pattern. That takes us through the 2nd week of July.

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Yeah this threat is ultimately not materializing. I'll probably be awakened tomorow at 4am to a clap of thunder as a decaying MCS moves through (can't wait! :axe: ), but thats about it. Looks like the Mid-Atlantic is still in the game especially DC/VA as we move through the day Friday, but even they are strongly capped. If any amount of forcing available can penetrate that, then there could be a nasty storm down that way.

July definitely has the looks of AN for just about the entire country HM, ala 2002 I suppose. With the drought in the Midwest/Plains, the greatest warm anomalies should continue to try and reside there and give a feedback to enhanced ridging.. though I'm guessing there will be a tendency to try and shift the mean ridge a little further west with time (Intermountain region, where its also been very hot as well) due to more of an el nino tendency. The last 2 runs of the euro ensembles trended cooler on the East coast next week (negative SOI repsonse maybe??), and have trended to well above normal for the Pacifc Northwest interestingly with more ridging out west in days 11-15. It is still well above normal into the Midwest for that period, but I would have to think some cooler/troughing risks would reside in the Northeast in that pattern. That takes us through the 2nd week of July.

I mentioned in the other thread that a boundary shows signs of setting up south of SNE after the 11th or so in response to a trough digging into New England.

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Yeah this threat is ultimately not materializing. I'll probably be awakened tomorow at 4am to a clap of thunder as a decaying MCS moves through (can't wait! :axe: ), but thats about it. Looks like the Mid-Atlantic is still in the game especially DC/VA as we move through the day Friday, but even they are strongly capped. If any amount of forcing available can penetrate that, then there could be a nasty storm down that way.

July definitely has the looks of AN for just about the entire country HM, ala 2002 I suppose. With the drought in the Midwest/Plains, the greatest warm anomalies should continue to try and reside there and give a feedback to enhanced ridging.. though I'm guessing there will be a tendency to try and shift the mean ridge a little further west with time (Intermountain region, where its also been very hot as well) due to more of an el nino tendency. The last 2 runs of the euro ensembles trended cooler on the East coast next week (negative SOI repsonse maybe??), and have trended to well above normal for the Pacifc Northwest interestingly with more ridging out west in days 11-15. It is still well above normal into the Midwest for that period, but I would have to think some cooler/troughing risks would reside in the Northeast in that pattern. That takes us through the 2nd week of July.

Yeah this is a classic case of using 700mb anomalies and pattern recognition to determine the level of caution with medium ranged severe weather forecasting. Despite how impressive the EML is and how unusually displaced it is, the ultimate track of the 700mb warmth and general pattern supported a suppressed solution. This doesn't mean severe weather can't happen this weekend up our way, but we will not see a classic EML - sig severe event. Oh and LOL at the morning thunder tomorrow waking us up. At least on Monday I was up well before it hit.

July is a funny month. You have two things always pulling at you and it makes for a tricky long range forecast. Despite the general signals in retrogression you're seeing, the month also sees a significant wave shortening as the barotropic atmosphere becomes firmly entrenched. The widespread drought will have a significant feedback on the warm anomaly for sure, as you have alluded too. I see a period of progression after the holiday as the Aleutian High advances eastward BEFORE waves begin to shorten to a point where that doesn't matter. I think the ridge will try to make a run eastward before retracting West. Having a trough dive Southeast after that only increases my confidence for a good severe weather episode. Take my word with a grain; I don't have access to data anymore and I don't look everyday now. :)

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I mentioned in the other thread that a boundary shows signs of setting up south of SNE after the 11th or so in response to a trough digging into New England.

Yeah I hope not though. Was thinking 2nd week in July would be the next best chance for widespread warmth in the northeast since last week's widespread heat event.

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Yeah I hope not though. Was thinking 2nd week in July would be the next best chance for widespread warmth in the northeast since last week's widespread heat event.

Well it looks like the 8-11th or so will feature another warmth surge east?

Okay it looks like I misunderstood you guys. I think we are all on the same page about another surge of warmth coming.

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Okay it looks like I misunderstood you guys. I think we are all on the same page about another surge of warmth coming.

I may not have been clear either. It was during that time and after, where the anomaly went west into the Rockies. At least as currently modeled.

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Well to stay on topic of the thread, I think July 8-10 has a higher than normal risk for an EML induced severe weather outbreak. I would also urge caution about any lengthy cool period afterwards despite the shifting warm anomaly west. As the waves shorten, that could actually mean a western Atlantic ridge could pop too. What a ridiculous time of year in pinpointing anomalies.

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The lapse rates are not quite amazing yet near the Appalachians but check out DTX:

http://www.spc.noaa....812_OBS/DTX.gif

Impressive mid level lapse rates!

I wonder if we could get a decent MCS out of this farther west. The Euro has pretty explosive thunderstorm development this evening/overnight. Not a terrible pattern for a derecho but the lack of good LLJ winds/convergence is probably an issue.

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Well to stay on topic of the thread, I think July 8-10 has a higher than normal risk for an EML induced severe weather outbreak. I would also urge caution about any lengthy cool period afterwards despite the shifting warm anomaly west. As the waves shorten, that could actually mean a western Atlantic ridge could pop too. What a ridiculous time of year in pinpointing anomalies.

I know this is extrapolating, but I could see the heat building east again for a time in the second half of the month as the ridge flattens again. You almost can see those signs on the euro ensembles.

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Well it looks like the 8-11th or so will feature another warmth surge east?

It does appear on the latest euro ensembles that after the cooler troughing scenario plays out next week along the New England coast (cooler versus previous data), another round of heat comes in for the next weekend timeframe and hopefully (for my sake) into the beginning of the following work week (pretty much the 8~10th/11th like coastalwx was saying). This is ahead of another trough moving into SE canada that looks to drop into New England near the end of the 11-15 (which is middle July 2nd week pretty much, and what I was alluding to in the first post with bigger warmth building in the Northwest/cooler risks new england).

That also means verbatim a WNW flow signal and hence HM's next potential EML event beyond the 8th.

Okay it looks like I misunderstood you guys. I think we are all on the same page about another surge of warmth coming.

I don't think you mis-understood, I wasn't too specific with the exact days and this is all confusing speculation anyways. And between the data overload we deal with in this field, I'm not sure I know what day it is most of the time lol.

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Yeah this is a classic case of using 700mb anomalies and pattern recognition to determine the level of caution with medium ranged severe weather forecasting. Despite how impressive the EML is and how unusually displaced it is, the ultimate track of the 700mb warmth and general pattern supported a suppressed solution. This doesn't mean severe weather can't happen this weekend up our way, but we will not see a classic EML - sig severe event. Oh and LOL at the morning thunder tomorrow waking us up. At least on Monday I was up well before it hit.

July is a funny month. You have two things always pulling at you and it makes for a tricky long range forecast. Despite the general signals in retrogression you're seeing, the month also sees a significant wave shortening as the barotropic atmosphere becomes firmly entrenched. The widespread drought will have a significant feedback on the warm anomaly for sure, as you have alluded too. I see a period of progression after the holiday as the Aleutian High advances eastward BEFORE waves begin to shorten to a point where that doesn't matter. I think the ridge will try to make a run eastward before retracting West. Having a trough dive Southeast after that only increases my confidence for a good severe weather episode. Take my word with a grain; I don't have access to data anymore and I don't look everyday now. :)

Yeah Monday i was safely into the office by then, and had a great view of the pitch blackness ensuing.

Despite not having access to the best data, you still appear to have a great handle on where the pattern may be going. Excellent general climo knowledge as always too!

Well to stay on topic of the thread, I think July 8-10 has a higher than normal risk for an EML induced severe weather outbreak. I would also urge caution about any lengthy cool period afterwards despite the shifting warm anomaly west. As the waves shorten, that could actually mean a western Atlantic ridge could pop too. What a ridiculous time of year in pinpointing anomalies.

:axe:

..And apologies for diverging a bit off the core topic here

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They'll be cells moving in during the morning and some of those could be strong, but I don't think the afternoon is SNE's turn.

I completely agree with this statement. Just looked at the latest guidance from the NAM, GFS, and Euro. They all have the vort max centered around the midway(somewhere between Worcester and Springfield) point of SNE by 18Z tomorrow. So I would expect most of us to be able to see something tomorrow morning. And then for the afternoon, extreme Eastern areas of SNE could possibly see some action. All three pieces of guidance do develop a region of QPF centered along the south coast. Basically SE Mass, RI and the Cape.

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