Jump to content

Sign in to follow this  
susqushawn

5/1 Severe Thunderstorm Threat Discussion & OBS

Recommended Posts

...Eastern states...
   Models indicate strengthening of warm sector 850-500 mb wind fields
   to 40-70+ kt during the day today, particularly across the lower
   Great Lakes region, the upper Ohio Valley and the central
   Appalachians into the northern Mid Atlantic Coast region.  This
   should prove more than favorable for organized severe thunderstorm
   development, given at least weak boundary layer destabilization, and
   surface dew points in the 60s probably will contribute to this with
   daytime heating, despite relatively warm and initially capping
   mid-level layers.

   Beneath increasingly difluent flow aloft, frontal and orographic
   forcing for ascent are expected to aid initiation of thunderstorms
   near/east of Lake Erie, southward along the western slopes of
   central into southern Appalachians by 18-21Z.  This activity seems
   likely to eventually consolidate and grow upscale into an organizing
   squall line as it crosses the Allegheny mountains and plateau, and
   to the lee of the Blue Ridge, by early evening.  As it does, it
   probably will be accompanied by increasing potential for damaging
   surface gusts, given the strength of the ambient wind fields, with
   damaging straight line winds becoming the predominant severe threat.
   However, supercell structures, within and perhaps ahead of the line
   as it evolves, may be accompanied by a risk for tornadoes, one or
   two of which could be strong.

   Strong/severe storms may reach the Champlain/Hudson Valleys and Mid
   Atlantic coastal areas by this evening, before weakening within a
   more stable environment.

tenor.gif

day1otlk_1200.gif

  • Like 1

Share this post


Link to post
Share on other sites

That enhanced looks way to bullish to me. Granted we have a s/w moving on through, but the timing looks craptastic. The one they had last night makes more sense to me. I would of maybe went of enhanced to about lns/mdt area then maybe a slgt risk just west of phl then marginal everywhere else. We are lacking instability and are capped a decent amount during the day. There is some good shear and LLJ and a bit of an EML left over to help keep storms going. 

  • Like 1

Share this post


Link to post
Share on other sites

In terms of reflectivity, this looks like the peak from the NCAR mesoscale models.

cref_max_f026_MATL.thumb.png.32c737cc82c161d4dd14ceb615f38ace.png

Share this post


Link to post
Share on other sites
1 hour ago, tombo82685 said:

That enhanced looks way to bullish to me. Granted we have a s/w moving on through, but the timing looks craptastic. The one they had last night makes more sense to me. I would of maybe went of enhanced to about lns/mdt area then maybe a slgt risk just west of phl then marginal everywhere else. We are lacking instability and are capped a decent amount during the day. There is some good shear and LLJ and a bit of an EML left over to help keep storms going. 

Sometimes high dcape values are an indication that a squall line can just keep on trucking. I thought greater than 1K was ideal, and this one looks like its falling short at PHL (didnt look elsewhere).  Yes this looks about 3hrs too late for prime impact in our area. Much better set-up than Saturday regardless.

Capture.thumb.JPG.a18d3aa543e287e80959b75050866a72.JPG

Share this post


Link to post
Share on other sites
1 hour ago, Rainshadow said:

Sometimes high dcape values are an indication that a squall line can just keep on trucking. I thought greater than 1K was ideal, and this one looks like its falling short at PHL (didnt look elsewhere).  Yes this looks about 3hrs too late for prime impact in our area. Much better set-up than Saturday regardless.

Capture.thumb.JPG.a18d3aa543e287e80959b75050866a72.JPG

Pretty stout CAP in that sounding. 

Do think the spc enh area is too Far East. Hell, the slight risk is probably too Far East lol. We'll see I guess. We get the lift and good shear today. Just needed saturdays EML/Lapse rates and the cape! 

Share this post


Link to post
Share on other sites
25 minutes ago, irishbri74 said:

Pretty stout CAP in that sounding. 

Do think the spc enh area is too Far East. Hell, the slight risk is probably too Far East lol. We'll see I guess. We get the lift and good shear today. Just needed saturdays EML/Lapse rates and the cape! 

We have pretty solid EML during the day, but we are capped 7-7.5 LR is pretty solid around here

nam_2017050106_018_39.93--75.32.png

Share this post


Link to post
Share on other sites
2 hours ago, Rainshadow said:

Sometimes high dcape values are an indication that a squall line can just keep on trucking. I thought greater than 1K was ideal, and this one looks like its falling short at PHL (didnt look elsewhere).  Yes this looks about 3hrs too late for prime impact in our area. Much better set-up than Saturday regardless.

 

Yea I'm not arguing for no storms, I just don't see a big severe risk worthy of enhanced or even slgt risk really. This just looks like a general thunder/lighting with a couple stronger storms thrown in. We will see what they do at noon time but I would move everything west

Share this post


Link to post
Share on other sites

The high wind threat being the main issue makes sense with a solid LLJ just above our heads. 

Share this post


Link to post
Share on other sites

New issue and they already shifted enhance further west to where I was thinking lns on west

day1otlk_1300.gif?1493647164027

Share this post


Link to post
Share on other sites
1 hour ago, irishbri74 said:

Hmmm.. where's the warm front?!

IMG_3472.PNG

Hard to tell ;)

 

image.png

image.png

  • Like 1

Share this post


Link to post
Share on other sites
2 hours ago, irishbri74 said:

Pretty stout CAP in that sounding. 

Do think the spc enh area is too Far East. Hell, the slight risk is probably too Far East lol. We'll see I guess. We get the lift and good shear today. Just needed saturdays EML/Lapse rates and the cape! 

I agree with the westward shift that SPC made with the latest outlook. This may be a switch of what occurred Saturday (with dew points being fcst too high), doubt we are that cool (sfc) by 8 pm on that sounding. Regardless this looks late to the party for us.  Ok enough short wave to think that this will have more eastward sustainability than average.  April/May convection is like December snow, its nice if it happens, but its not the meat of our season.  Come Memorial Day....

 

Share this post


Link to post
Share on other sites

Party sunny - 78F. Have golf league tonight increasing the storm odds.

Share this post


Link to post
Share on other sites

This makes more sense and what I outlined should of happened this morning 

IMG_0220.PNG

Share this post


Link to post
Share on other sites

Finally cleared out here. Winds are crankin'

Share this post


Link to post
Share on other sites

Still fairly cloudy here, made it to 76F. Probably not enough to provide any major destabilizing of the atmosphere around the general area.

Share this post


Link to post
Share on other sites

82F in West Chester with a delicious 68F dewpoint.

I'm entertaining myself by watching the PA Turnpike cameras as the front rolls through and the images turn from sunny dry concrete to ominous dark clouds to 0.1 mile visibility in rain.  Don't judge me! B)

  • Like 1

Share this post


Link to post
Share on other sites

Kudos to Tom for the solid analysis on trimming the eastern extent.  Put down the weedwhacker and apply at NWS.  Mitch could use some company.  Hopefully we get a line later tonight.

  • Like 2

Share this post


Link to post
Share on other sites
1 hour ago, cbelke said:

Still fairly cloudy here, made it to 76F. Probably not enough to provide any major destabilizing of the atmosphere around the general area.

Destabilizing was always an issue, CAPE was virtually nothing. For us it's all being driven by the s/w moving in with strong LLJ, shear, and somewhat of an EML left. 

  • Like 2

Share this post


Link to post
Share on other sites

Looking at the radar, hard to foresee a concrete line even making it to LNS.  Just talked to my mom in Altoona, she said that was the heaviest rain she's seen in some time.

Share this post


Link to post
Share on other sites
8 minutes ago, mshaffer526 said:

Looking at the radar, hard to foresee a concrete line even making it to LNS.  Just talked to my mom in Altoona, she said that was the heaviest rain she's seen in some time.

PWATS are pretty high for this time of the year, so that makes sense

hrrr_pwat_pennsylvania_1.png

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×