Kmlwx Posted September 7, 2012 Share Posted September 7, 2012 So where did this come from? 30% HATCHED risk from SPC for Day 2 (Saturday) Discuss here - I'll leave this for Yoda and Ian and Ellinwood in the AM. Link to comment Share on other sites More sharing options...
Ellinwood Posted September 7, 2012 Share Posted September 7, 2012 Just saw it... will take a detailed look in a bit. A bit of a surprise fo sho. Link to comment Share on other sites More sharing options...
Kmlwx Posted September 7, 2012 Author Share Posted September 7, 2012 I know that the 00z run of the NAM last night was printing out 10/18/1990 as a top analog in CIPS. Link to comment Share on other sites More sharing options...
Ellinwood Posted September 7, 2012 Share Posted September 7, 2012 Pros: Good wind shear, potent vort max, right-entrance region of a jet streak, good surface wind convergence along the cold front. Cons: Best shear and dynamics are further north up into PA, instability will be a concern (750-1500 J/kg), mid-level lapse rates are poor everywhere, and pre-frontal clouds and rain could muck stuff up a bit. Also, GFS low-level winds aren't as backed as the NAM, which raises concerns as the GFS tends to be more correct in that regard in our region. Conclusion: A strong to severe line of storms along the cold front with damaging winds is the biggest concern. Hail is a low risk, and a couple of tornadoes are possible, but that risk is more to our north. I would be more excited about this setup if I were up in PA and/or if the instability improves. Chase potential is questionable... might be best just to chill at home and find a good view. Link to comment Share on other sites More sharing options...
mappy Posted September 7, 2012 Share Posted September 7, 2012 I want the temperatures behind the front Link to comment Share on other sites More sharing options...
The Dude Posted September 7, 2012 Share Posted September 7, 2012 I want the temperatures behind the front +100 (to the post, not the temps) Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 Just saw it... will take a detailed look in a bit. A bit of a surprise fo sho. I'm not the trough is wicked Link to comment Share on other sites More sharing options...
Ellinwood Posted September 7, 2012 Share Posted September 7, 2012 I'm not the trough is wicked It's a good trough, but what surprised me was the vort max being as far south and as strong as it is. I never really took a good look at it recently but I recall thinking the energy was going to be too far north to do us much good aside from "just a line of regular storms" along the cold front. One of the few times we've gotten a nice vort max to dig down in just the right spot for us this year, though it is just a little bit north of ideal placement. Link to comment Share on other sites More sharing options...
yoda Posted September 7, 2012 Share Posted September 7, 2012 Just for posterity ...ERN PORTIONS OF OH VALLEY...MID ATLANTIC THROUGH NERN STATES... A PRE-FRONTAL SQUALL LINE WILL LIKELY BE IN PROGRESS SATURDAY MORNING FROM THE OH VALLEY SWWD INTO THE TN VALLEY. RICH GULF MOISTURE /UPPER 60S TO 70F DEWPOINTS/ NOW RESIDING OVER THE MID ATLANTIC AND SRN PORTIONS OF NERN STATES WILL ADVECT THROUGH REMAINDER OF THE WARM SECTOR SATURDAY AS SLY LLJ STRENGTHENS IN ASSOCIATION WITH EJECTING SHORTWAVE TROUGH AND DEEPENING SFC LOW. WEAK MID LEVEL LAPSE RATES AND AREAS OF CLOUDS WILL MITIGATE INSTABILITY SOMEWHAT. HOWEVER...BREAKS IN CLOUDS SHOULD ALLOW FOR SOME DIABATIC WARMING OF THE MOIST BOUNDARY LAYER...CONTRIBUTING TO MLCAPE FROM 500-1000 J/KG. STORMS ARE EXPECTED TO INTENSIFY ALONG AND AHEAD OF PRE-EXISTING PROGRESSIVE OUTFLOW BOUNDARY AS WARM SECTOR DESTABILIZES. DEEP LAYER WINDS WILL INCREASE IN ASSOCIATION WITH THE SHORTWAVE TROUGH AND ITS ATTENDANT SFC LOW WITH LARGE HODOGRAPHS AND 40+ KT 0-6 KM SHEAR. ORGANIZED STORMS INCLUDING LEWP/BOWING STRUCTURES AND EMBEDDED SUPERCELLS WILL BE POSSIBLE AS ACTIVITY DEVELOPS EWD. DAMAGING WIND AND MAYBE A FEW TORNADOES WILL BE THE PRIMARY THREATS. Link to comment Share on other sites More sharing options...
Kmlwx Posted September 7, 2012 Author Share Posted September 7, 2012 Just for posterity Copy and paste master is hard at work! Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 It's a good trough, but what surprised me was the vort max being as far south and as strong as it is. I never really took a good look at it recently but I recall thinking the energy was going to be too far north to do us much good aside from "just a line of regular storms" along the cold front. One of the few times we've gotten a nice vort max to dig down in just the right spot for us this year, though it is just a little bit north of ideal placement. I'm not sure there'll be a big tornado threat -- or at least not one worth trying for. A nice line seems more likely. But around here usually good dynamics is more important than anything. Link to comment Share on other sites More sharing options...
Ellinwood Posted September 7, 2012 Share Posted September 7, 2012 I'm not sure there'll be a big tornado threat -- or at least not one worth trying for. A nice line seems more likely. But around here usually good dynamics is more important than anything. Agreed on all points. The mid-level lapse rates are sketching me out big time, but I imagine the dynamics are strong enough to create a good line of storms regardless. Link to comment Share on other sites More sharing options...
yoda Posted September 7, 2012 Share Posted September 7, 2012 Agreed on all point. The mid-level lapse rates are sketching me out big time, but I imagine the dynamics are strong enough to create a good line of storms regardless. LWX in their morning disco did state that they expect them to steepen some more in later model runs Link to comment Share on other sites More sharing options...
Ellinwood Posted September 7, 2012 Share Posted September 7, 2012 LWX in their morning disco did state that they expect them to steepen some more in later model runs I would agree to a point... should see that better further north than in DC/MD specifically (just from looking at the gradient in the height falls). Even then, you're taking the mid-level lapse rates from "bad" to "not as bad but still not good," so while it's notable it's not necessarily going to lead to a significant change (though given the delicate balance of features it could). Link to comment Share on other sites More sharing options...
Ellinwood Posted September 7, 2012 Share Posted September 7, 2012 Just a FYI: I'm not trying to dial back the SPC forecast... just indicating that the risk would be more towards underperforming rather than overperforming. Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 The weird thing is the SREF has continually kept the best parameters out ahead of the line in areas where it's unlikely there will be much activity. Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 I'm mostly hoping for a nice shelf cloud. That was my goal for the yr locally and still haven't had it. Running out of time climo wise tho I guess this fall might be somewhat active. Link to comment Share on other sites More sharing options...
Ellinwood Posted September 7, 2012 Share Posted September 7, 2012 The weird thing is the SREF has continually kept the best parameters out ahead of the line in areas where it's unlikely there will be much activity. Perhaps mostly the result of better daytime heating but no trigger? Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted September 7, 2012 Share Posted September 7, 2012 FWIW the new NAM Hi-Res sim rad is pretty nice for our area... Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 Perhaps mostly the result of better daytime heating but no trigger? yeah could be tho i guess it's close enough not to necessarily overanalyze it. im mainly basing timing off sref/nam. Link to comment Share on other sites More sharing options...
wxmeddler Posted September 7, 2012 Share Posted September 7, 2012 OMG DERECHO!!! \ Link to comment Share on other sites More sharing options...
Kmlwx Posted September 7, 2012 Author Share Posted September 7, 2012 OMG DERECHO!!! \ You're wrong - only a "hint" of a derecho Link to comment Share on other sites More sharing options...
H2O Posted September 7, 2012 Share Posted September 7, 2012 FWIW the new NAM Hi-Res sim rad is pretty nice for our area... That looks fun Link to comment Share on other sites More sharing options...
mattie g Posted September 7, 2012 Share Posted September 7, 2012 You're wrong - only a "hint" of a derecho How long until JB2 starts talking about a posible derecho? Link to comment Share on other sites More sharing options...
snowfan Posted September 7, 2012 Share Posted September 7, 2012 Are we thinking late afternoon (5-6) or possibly earlier? Link to comment Share on other sites More sharing options...
Ellinwood Posted September 7, 2012 Share Posted September 7, 2012 Are we thinking late afternoon (5-6) or possibly earlier? I'd give it a little wider range and say 4-7, but yeah around that general time. Link to comment Share on other sites More sharing options...
usedtobe Posted September 7, 2012 Share Posted September 7, 2012 I'd give it a little wider range and say 4-7, but yeah around that general time. The dynamics certainly suggest a pretty good line will come through the area so there should be some severe embedded within the line. Link to comment Share on other sites More sharing options...
MN Transplant Posted September 7, 2012 Share Posted September 7, 2012 NCEP's WRFs are in. Much less messy out in front of the line than the NAM is. Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 Mod risk north of us now! Link to comment Share on other sites More sharing options...
mappy Posted September 7, 2012 Share Posted September 7, 2012 Mod risk north of us now! I'm just outside it Link to comment Share on other sites More sharing options...
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