Kmlwx Posted August 20, 2011 Share Posted August 20, 2011 We are near the edge of the slight risk for tomorrow but the SPC discussion is quite robust. I've included both parts of the discussion below. ...ERN NY/PA...MD/DE/NJ INTO SRN ME... SHOWERS AND STORMS WILL BE ONGOING ALONG THE COLD FRONT EARLY IN THE DAY ACROSS WRN NY/PA. AS THE ATMOSPHERE DESTABILIZES ACROSS THE WARM SECTOR...ACTIVITY ALONG THE FRONT SHOULD REJUVENATE AND BECOME SEVERE BY AFTERNOON. FORECAST SOUNDINGS SHOW VERY FAVORABLE DEEP LAYER SHEAR PROFILES FOR SEVERE...INCLUDING DAMAGING WINDS AND LARGE HAIL. WHILE FORCING WILL BE LINEAR ALONG THE FRONT...SHEAR PROFILE ORIENTATION SUGGESTS THAT SUPERCELLS WILL BE LIKELY...PERHAPS SOME SPLITTING GIVEN ONLY MODEST LOW LEVEL HODOGRAPH CURVATURE. MESOSCALE DETAILS WILL DETERMINE TORNADO THREAT...WHICH MAY BE LOCALLY ENHANCED ALONG THE RESIDUAL WARM FRONT WITH LOCALLY BACKED SURFACE WINDS. HOWEVER...THE PRIMARY THREAT WILL BE HAIL AND WIND. ...MID ATLANTIC REGION WWD INTO THE TN VALLEY... WIND FIELDS WILL NOT BE AS STRONG AS POINTS N...BUT NWLY DEEP LAYER FLOW ON THE ORDER OF 20-30 KT WILL STRETCH WWD INTO THE OH VALLEY ALONG THE BASE OF THE UPPER TROUGH. HERE..STRONG DAYTIME HEATING WILL LEAD TO STEEP LOW LEVEL LAPSE RATES. MARGINALLY SEVERE HAIL AND WIND GUSTS WILL BE POSSIBLE ACROSS A LARGE AREA MAINLY DURING THE AFTERNOON. Link to comment Share on other sites More sharing options...
Ellinwood Posted August 20, 2011 Share Posted August 20, 2011 Good lapse rates up to about 650mb on both models... good ML/UL winds (though LL winds suffer a bit). Models having some problems with the details of the jet streak(s) in the area. I think Sunday warrants a full write-up... will get that done later today. Link to comment Share on other sites More sharing options...
Kmlwx Posted August 20, 2011 Author Share Posted August 20, 2011 Good lapse rates up to about 650mb on both models... good ML/UL winds (though LL winds suffer a bit). Models having some problems with the details of the jet streak(s) in the area. I think Sunday warrants a full write-up... will get that done later today. Don't put a curse on us! - Just predict nothing so we get something. It seems like the best threat might be up north right? Link to comment Share on other sites More sharing options...
Ellinwood Posted August 20, 2011 Share Posted August 20, 2011 Don't put a curse on us! - Just predict nothing so we get something. It seems like the best threat might be up north right? Right now it looks like the best potential is in the NE PA / N NJ / SE NY (yet again), but there's a lot of mesoscale messiness with this system, so it's a bit difficult to say anything with confidence. It's kinda sad that we have been doing so much better with pulsers vs. organized storms this year... it's nearly impossible to chase pulsers. Link to comment Share on other sites More sharing options...
TalcottWx Posted August 20, 2011 Share Posted August 20, 2011 Plenty of shear for severe down here too Link to comment Share on other sites More sharing options...
Ellinwood Posted August 20, 2011 Share Posted August 20, 2011 Discussion: I'm not particularly thrilled with the setup locally, though it does raise an eyebrow. Most of the concern comes with how the mesoscale features pan out, which the models have had a hard time dealing with since the upper-level energy isn't that organized. The complicated and convoluted upper-levels, along with weak low-level winds, has been our biggest downfall this summer. Stronger, more highly concentrated features would help improve not only lift but the mid-level lapse rates as well, which is another key to getting well-organized and sustained storms (at least in our region). Tomorrow looks a bit better than previous setups this summer (mostly due to the better looking lapse rates and possibility of a low-level "jet") as a cold front and upper-level jet streak move into the region. Lapse rates are good up to 650mb, but the 650mb-300mb lapse rates are fairly poor. A low-level jet could develop tomorrow across the eastern parts of the region, which would help boost storm formation and organization. Another issue is timing, with the storms expected to form before peak heating in most of the region. Pre-frontal rain/clouds are also a concern, thought not so much as they have been in previous setups. Chase-wise, I would pick eastern PA/NJ or even the Delmarva Peninsula as possible targets unless good storms can get going early in MD/NoVA/central PA. I may have to sit this one out as I am working the overnight tonight, and sleep will weigh into the decision. Link to comment Share on other sites More sharing options...
Ellinwood Posted August 20, 2011 Share Posted August 20, 2011 12z WRF keeps the storms out until peak for the I-95 corridor, with no pre-frontal worries... Link to comment Share on other sites More sharing options...
yoda Posted August 20, 2011 Share Posted August 20, 2011 SPC did mention a conditional threat for isolated tornadoes in the Mid-Atlantic tomorrow in their 1730 OTLK Link to comment Share on other sites More sharing options...
Ian Posted August 20, 2011 Share Posted August 20, 2011 tomorrow's the type of day that should produce a few supercells if we maximize potential Link to comment Share on other sites More sharing options...
Kmlwx Posted August 20, 2011 Author Share Posted August 20, 2011 tomorrow's the type of day that should produce a few supercells if we maximize potential Glad to have you on board (somewhat) Captain Party Pooper. Link to comment Share on other sites More sharing options...
wxmeddler Posted August 20, 2011 Share Posted August 20, 2011 This was the top 15 analogs and their combined storm reports from last nights 0z NAM 48 hr. forecast. Take it for what it's worth. Link to comment Share on other sites More sharing options...
Ellinwood Posted August 20, 2011 Share Posted August 20, 2011 This was the top 15 analogs and their combined storm reports from last nights 0z NAM 48 hr. forecast. Take it for what it's worth. Where the hell did you get that? Link to comment Share on other sites More sharing options...
wxmeddler Posted August 20, 2011 Share Posted August 20, 2011 Where the hell did you get that? Ahhh.. you like? CIPS Warm-Season Analog guidance.. picked up on it while at NE Storms Conf. in Taunton,MA in March. Nice site, worth bookmarking. Link to comment Share on other sites More sharing options...
Kmlwx Posted August 21, 2011 Author Share Posted August 21, 2011 18z WRF-ARW from LWX Hour 24 - Link to comment Share on other sites More sharing options...
Kmlwx Posted August 21, 2011 Author Share Posted August 21, 2011 18z WRF-NMM from LWX Hour 24 - Link to comment Share on other sites More sharing options...
Ian Posted August 21, 2011 Share Posted August 21, 2011 We're all gonna die!¡ Link to comment Share on other sites More sharing options...
Ellinwood Posted August 21, 2011 Share Posted August 21, 2011 Ahhh.. you like? CIPS Warm-Season Analog guidance.. picked up on it while at NE Storms Conf. in Taunton,MA in March. Nice site, worth bookmarking. Awesome... gonna have to play with it a bit when I've got time. Link to comment Share on other sites More sharing options...
mappy Posted August 21, 2011 Share Posted August 21, 2011 The wrf-arw looks sweet Link to comment Share on other sites More sharing options...
Kmlwx Posted August 21, 2011 Author Share Posted August 21, 2011 The wrf-arw looks sweet I'm going to use my weenie post of the day and say that those look like individual supercells merging into a line. I'm going to have to agree with Ian here and say that we are all going to die. Those of us that aren't done in by the storms tomorrow will be done in by the Irene mega outbreak we will endure. Link to comment Share on other sites More sharing options...
Kmlwx Posted August 21, 2011 Author Share Posted August 21, 2011 21z ARW run for 17z tomorrow afternoon... Goes on to weaken a bit for the 95 corridor in parts. Link to comment Share on other sites More sharing options...
Kmlwx Posted August 21, 2011 Author Share Posted August 21, 2011 12pm-6pm time to watch? Link to comment Share on other sites More sharing options...
H2O Posted August 21, 2011 Share Posted August 21, 2011 12pm-6pm time to watch? 3-6 DC proper IMO Link to comment Share on other sites More sharing options...
Kmlwx Posted August 21, 2011 Author Share Posted August 21, 2011 3-6 DC proper IMO Agree - just speaking to include our far west folks as well you IMBY poster Also - updated mid evening discussion from LWX OTW...BUMPED UP POPS A BIT /PARTICULARLY ACROSS NRN SECTIONS OF THECWA FOR SUNDAY LATE MORNING THROUGH THE AFTERNOON/ GIVEN 18Z GUIDANCE MAINTAINING THE POTENTIAL FOR A GOOD WIDESPREAD THUNDERSTORM EVENT. MAX POPS KEPT IN THE LIKELY RANGE GIVEN DISCRETE CONVECTIVE MODE GIVEN STRAIGHT LINE HODOGRAPH ABOVE 1KM. 70 POPS WERE GIVEN FOR BALT-WASH METRO CONSIDERING LATE AFTERNOON TIMING AND EXPECTED PRESENCE OF MESOSCALE BOUNDARIES THAT WOULD INCREASE COVERAGE OF THUNDERSTORMS. My copy paste skills are filling in for Yoda since he is active over in the tropical threads. Link to comment Share on other sites More sharing options...
mappy Posted August 21, 2011 Share Posted August 21, 2011 I'm going to use my weenie post of the day and say that those look like individual supercells merging into a line. I'm going to have to agree with Ian here and say that we are all going to die. Those of us that aren't done in by the storms tomorrow will be done in by the Irene mega outbreak we will endure. Death is good when it's from killer storms Link to comment Share on other sites More sharing options...
Kmlwx Posted August 21, 2011 Author Share Posted August 21, 2011 Death is good when it's from killer storms That sounds poetic Link to comment Share on other sites More sharing options...
mappy Posted August 21, 2011 Share Posted August 21, 2011 That sounds poetic <img src='http://208.71.34.143/public/style_emoticons/default/laugh.gif' class='bbc_emoticon' alt='' /> Or redundant Link to comment Share on other sites More sharing options...
BethesdaWX Posted August 21, 2011 Share Posted August 21, 2011 21z ARW run for 17z tomorrow afternoon... Goes on to weaken a bit for the 95 corridor in parts. Looks like more outflow-type look there though, kind of like the hard-hiting outflow on 7/25, well before the actual Mircoburst within the rain-shaft/cell. Link to comment Share on other sites More sharing options...
Ian Posted August 21, 2011 Share Posted August 21, 2011 Death is good when it's from killer storms Maybe no better way to go Link to comment Share on other sites More sharing options...
Ian Posted August 21, 2011 Share Posted August 21, 2011 I want a supercell IMBY Link to comment Share on other sites More sharing options...
yoda Posted August 21, 2011 Share Posted August 21, 2011 I want a supercell IMBY Make it so #1 Link to comment Share on other sites More sharing options...
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