July 23th-25th Mid-Atl/NE Severe Weather, SPC Risk Level: slight Options

[justintime2989]

first time making a board so try to take it easy on me if its bad. but spc has updated day one so most of pa,southern ny and alot of jersey are under a slight risk of storms. http://www.spc.noaa.gov/products/outlook/day1otlk.html

now lets take a look at cape: http://www.twisterdata.com/index.php?prog=...p;archive=false average seems to be around 1750-2000 while pa is 2000+

LIFT:-4 to -5 average. http://www.twisterdata.com/index.php?prog=...p;archive=false


bulk shear: appears be not even there unless go to ny where even still just 30-35 http://www.twisterdata.com/index.php?prog=...p;archive=false

This post has been edited by justintime2989: Jul 23 2011, 02:57 PM

[Niyologist]

first time making a board so try to take it easy on me if its bad. but spc has updated day one so most of pa,southern ny and alot of jersey are under a slight risk of storms. http://www.spc.noaa.gov/products/outlook/day1otlk.html

now lets take a look at cape: http://www.twisterdata.com/index.php?prog=...p;archive=false average seems to be around 1750-2000 while pa is 2000+

LIFT:-4 to -5 average. http://www.twisterdata.com/index.php?prog=...p;archive=false


bulk shear: appears be not even there unless go to ny where even still just 30-35 http://www.twisterdata.com/index.php?prog=...p;archive=false

The GFS is the most aggressive. I really hope the GFS is correct about this.

[justintime2989]

yea bring cape in jersey area to 2000+ but used nam since isnt it higher res and used more for severe weather.

[Undertakerson]

Posted this in the heat thread before I noticed " justin" opened this up:

SPC Cape shows some pretty large values in the airmass that should pass over PA this afternoon (2K+), PWAT values in the airmass are also pretty decent though not off the charts. Stream suggests that those values can slide over most of PA. Therefore,I truly expect some heavy showers/storms later today.

[STEVE392]

i hope this all verifies for some severe weather for nothern nj.

[Undertakerson]

SPC discussion (in pertinent part)


...SRN GREAT LAKES INTO NORTHERN MID ATLANTIC STATES...
DETAILS CONCERNING POTENTIAL CONVECTIVE EVOLUTION REMAIN FAR FROM
CERTAIN...BUT INSTABILITY AND VERTICAL SHEAR ON THE SOUTHERN FRINGE
OF WESTERLY TO NORTHWESTERLY MID-LEVEL FLOW ARE EXPECTED TO BECOME
AT LEAST MARGINALLY FAVORABLE FOR ORGANIZED CONVECTIVE DEVELOPMENT.
AND SOME OF THIS ACTIVITY MAY BECOME CAPABLE OF PRODUCING
POTENTIALLY DAMAGING WIND GUSTS. IT COULD BE THAT THE REMNANTS OF A
CONVECTIVE CLUSTER...NOW SPREADING TOWARD/THROUGH SOUTHERN LAKE
MICHIGAN...CONTRIBUTE TO ANOTHER EVOLVING STORM CLUSTER ACROSS THE
UPPER OHIO VALLEY INTO THE NORTHERN MID ATLANTIC COAST STATES LATE
THIS AFTERNOON AND EVENING.

[NYCSuburbs]

Today looks more like an isolated storm day to me. There are high parameters in the region, but yesterday also had high parameters and all we had was isolated convection. I think that today should bring slightly more widespread convection than yesterday as the cold front approaches, but I'm not sold on any widespread activity today that would meet slight risk criteria across a widespread area. None of the main models show any precipitation through this evening, with the GFS only showing some weak activity around 06z tonight. Even the HRRR/RR, which can be bullish with storm activity, show only isolated activity today. In addition, if the cold front was moving through today, there'd be a better risk of storms, but it's still well to our west, and will only move through tomorrow, when it should dry out.

The parameters definitely suggest that a severe weather risk is there, and any storms that do develop have the potential to become severe especially around PA/NJ/NY, but IMO, activity should stay mostly isolated today, and I'm not counting on today to break the storm bubble (though it is getting a little exhausted from the heat as my new avatar shows).

This post has been edited by NYCSuburbs: Jul 23 2011, 08:34 AM

[Astella2]

sadly I think your right NYCsub. The cap over the area is very big and although its early like you said,the cold front isn't even a cold front more of a cooler front that is losing its power as it approaches. Mid level lapse rates are marginal at best and we have virtually no sheer. This doesnt mean that a sea breeze can work to our advantage like it did for us at the jersey shore yestarday afternoon,just not a very widespread event like most of us are hoping for to take this heat away

[Niyologist]

sadly I think your right NYCsub. The cap over the area is very big and although its early like you said,the cold front isn't even a cold front more of a cooler front that is losing its power as it approaches. Mid level lapse rates are marginal at best and we have virtually no sheer. This doesnt mean that a sea breeze can work to our advantage like it did for us at the jersey shore yestarday afternoon,just not a very widespread event like most of us are hoping for to take this heat away

All of this instability is going to waste and when was the last time we had a lackluster severe thunderstorm season in a La Nina Season? None.

[Fire/Rescue]

Had a quick shower with a bit of thunder move thru my region around 8am, however now it's nothing but brilliant sunshine and the temperatures are quickly rising.

[Undertakerson]

NWS State College (update) speaks of many of the same points I came away with after viewing the SPC Meso Scale Analysis of this morning: (which means that it must be pretty evident - if I was able to pick up on it)

MADE SOME UPWARD ADJUSTMENTS TO AFTERNOON POPS /FOR SCATTERED
SHRA...AND A CHC FOR A GUSTY MID TO LATE AFTERNOON/EVENING TSRA/...
ACROSS THE NCENT MTNS AND MIDDLE SUSQ VALLEY WHERE THE LATEST
NAM...RUC...AND 13Z HRRR APPEAR TARGET THE BEST CHC FOR A STRONG
TO LOCALLY SVR TSRA /WITHIN THE BROADEST AREA OF LLVL THETA-E
CONVERGENCE...COMBINED WITH SLIGHTLY STRONGER NWRLY 700 MB WINDS
OF AROUND 30 KTS...AND 0-3KM EHIS OF 1.5-2 M2/S2.

THE WEAKENED...BUT STILL EVIDENT MCV /NOW JUST SE OF KCLE/ WILL
CONTINUE TO TRACK ESE AT NEARLY 25 KT AND COULD SPARK A SECOND
AREA OF STRONG TO LOCALLY SVR CONVECTION /IN THE FORM OF A BKN
LINE OF TSRA/ OVER THE LAURELS AND SCENT PENN DURING THE MID TO
LATE AFTERNOON...REACHING THE LOWER SUSQ VALLEY AFTER 21Z.

SPC`S SLIGHT RISK COVERS THE AREA...MOST LIKELY DUE THE CRAZY HIGH
CAPE VALUES POSSIBLE IN THIS NEAR-RECORD HEAT. MEAN CAPES FROM
SREF MEMBERS ARE RUNNING AROUND 2000 IN THE AFTN.

LASTLY...PWATS AROUND 2 INCHES AND SHORT MBE VECTORS SCREAM HEAVY
RAINFALL. ON THE OTHER HAND - THE GROUND IS SO DRY OVER MOST OF
THE AREA AND FFG VALUES ARE NEAR 4 INCHES IN 3 HRS...THAT THERE IS
NOT A HIGH ENOUGH CONFIDENCE IN A FF THREAT TO POST A WATCH. WILL
MENTION HEAVY RAIN POSS AS WELL AS THE GUSTY WINDS.-- End Changed Discussion --
Currently, the Altocum of this morning is waning and may allow for the conditions to combine as outlined in my earlier post and the NWS confirmation update.

I believe NYCS is correct in that the "no storm" zone may remain intact - the action should be confined to areas south of I-80 (how far into MD that extends is confounding me at the moment - Cape is ~4K or better down near NVA and DC.
http://www.spc.noaa.gov/exper/mesoanalysis...9&parm=pmsl#

[phillyfan]

Not seeing anything develop so far today.

[justintime2989]

yea i know all i see its out in ohio thats about it.

[NYCSuburbs]

Not seeing anything develop so far today.

Other than some isolated activity in Virginia, there's nothing interesting going on across the region right now. The better time frame for storms is usually towards the late afternoon/evening, and I think that we should probably see some more activity develop later this afternoon especially towards southern PA/MD, with some of these storms becoming strong/severe, but activity should stay more isolated than widespread today, and I'm still not so sure that we reach slight risk criteria in a widespread part of SPC's slight risk area.

Looking at the parameters, they aren't too supportive as well, as other than moderately high CAPE/LI values, there's basically no bulk shear, mid level lapse rates are near 6 which is still OK but not very high, and the models still show almost no precipitation today. Some isolated activity should continue to take place today, and tomorrow as well, but Monday will bring a much better risk of widespread precipitation (this thread should be extended through the 25th).



This post has been edited by NYCSuburbs: Jul 23 2011, 02:35 PM

[NYCSuburbs]

I believe NYCS is correct in that the "no storm" zone may remain intact - the action should be confined to areas south of I-80 (how far into MD that extends is confounding me at the moment - Cape is ~4K or better down near NVA and DC.
http://www.spc.noaa.gov/exper/mesoanalysis...9&parm=pmsl#

The Anti-Storm Bubble is still holding strong today, tomorrow the models are showing some isolated activity here as well but I'm not too sure about that yet. The activity today should mostly stay from southern PA and further south, along with locally severe storms, but severe activity should stay isolated today. Monday will bring a better risk of widespread precipitation, but the severe weather risk doesn't look too impressive at this time.

[justintime2989]

umm ill have figure how to end the title to the 25th

[Undertakerson]

and I think that we should probably see some more activity develop later this
afternoon especially towards southern PA/MD, with some of these storms becoming
strong/severe

RUC shows a small bout with quick hitters aound 7 p.m. as they put down <0.5" in my region and increasingly more to the south.[attachment=137256:ruc_slp_006s.gif]

[attachment=137257:hiresw_p12_012m.gif]

As we've discussed, you can see the bulk of the precip (as per HIRES ARW) is generally south of I-80 in PA and "no storm for you" to the east.

[phillyfan]

According to Steve D:

The threat for severe thunderstorm or even rain is over as the mid levels were far too warm to support thunderstorms.

[NYCSuburbs]

According to Steve D:

The currently isolated activity is already starting to dissipate with no signs of new development. Of course, I'm not ruling out any isolated activity, but we're not going to end up with widespread storm development today. Southern PA/MD should might still have a low chance of seeing something isolated, but the risk of anything more than isolated precipitation across the region was never solid anyways.

[phillyfan]

The currently isolated activity is already starting to dissipate with no signs of new development. Of course, I'm not ruling out any isolated activity, but we're not going to end up with widespread storm development today. Southern PA/MD should might still have a low chance of seeing something isolated, but the risk of anything more than isolated precipitation across the region was never solid anyways.

I just want some rain here haven't had any accumulating rain since the 8th. 2 small showers that didn't add up to anything since then.