chase_stormz Posted February 20, 2014 Share Posted February 20, 2014 With the shear profiles (especially in the Tennessee Valley), I'd be concerned about embedded supercells even within a QLCS. I agree Tony. Different setup, same story. Those 0-1 srh values coming in on the RAP are alarming considering the NAM seemed to be underestimating that parameter by a long shot. The uptick in instability values on the 0z NAM and GFS runs also are nothing to laugh at. I'm really interested to see if we get any semi-discrete development tomorrow across TN and KY before the main squall line catches up because if we do I think there could be some big problems. As you were alluding to Tony, I'm also very concerned about a number of tornadoes occurring within the QLCS itself and strong tornadoes at that. It's going to be an interesting day. Link to comment Share on other sites More sharing options...
SirSonic Posted February 20, 2014 Share Posted February 20, 2014 The 03z RAP shows a pretty good idea where the warm sector and warm front could be tomorrow. S IL, S IN, OH, SW PA. This area looks like could be in play for some severe weather action Link to comment Share on other sites More sharing options...
andyhb Posted February 20, 2014 Share Posted February 20, 2014 The 03z RAP shows a pretty good idea where the warm sector and warm front could be tomorrow. S IL, S IN, OH, SW PA. This area looks like could be in play for some severe weather action You are much too far away from the main forcing for ascent to be in the main threat for severe wx tomorrow. Link to comment Share on other sites More sharing options...
SirSonic Posted February 20, 2014 Share Posted February 20, 2014 You are much too far away from the main forcing for ascent to be in the main threat for severe wx tomorrow. Just seeing tight gradient in temps along warm front, looks very impressive. This is one of the most challenging severe weather set ups to forecast Link to comment Share on other sites More sharing options...
Stebo Posted February 20, 2014 Share Posted February 20, 2014 Just seeing tight gradient in temps along warm front, looks very impressive. This is one of the most challenging severe weather set ups to forecast You need forcing to get stuff to go too though, and that far east along the warm front wont have much forcing on it. Link to comment Share on other sites More sharing options...
OHweather Posted February 20, 2014 Share Posted February 20, 2014 You are much too far away from the main forcing for ascent to be in the main threat for severe wx tomorrow. I could see some elevated convection with a marginal hail risk across northern IN/OH into even lower MI during the morning and into the afternoon on the nose of a strong LLJ with some elevated CAPE in place and good sheer, but I don't think that affects SW PA all that much. The northern extent of the damaging wind/tornado threat in the evening will be interesting. The ARW suggests temperatures approaching 60 north of I-70 in IN and OH tomorrow evening right ahead of the front (although not quite getting there). Even with the snow pack, I'd still be inclined to buy the warmer solutions here. It hit 47 in CLE last night with almost 10" of snow on the ground with much weaker WAA. I'm not an expert on the models but I think they initialize with snow cover areas, so they would already being accounting for snow cover. I'd usually expect mid 60's in Cleveland in this setup but with snow cover likely not completely disappearing it probably won't get quite that warm. It will be very interesting to see how warm it can get where snow remains on the ground tomorrow evening. It obviously won't take much to get the winds to near the ground with such high shear values, and there should be enough MUCAPE for convection, the question will be is there enough of a low level inversion to stop most of the wind from getting to the ground. Link to comment Share on other sites More sharing options...
BigBluesfan Posted February 20, 2014 Share Posted February 20, 2014 So guys what do you think about chances in St. Louis tomorrow? Over on Chris Higgins forum people are saying the models are more in our favor now. Any chance I might get nipped by some severe weather? I'm thinking it's like Nov of last year where the supercells formed right over us and then became tornadic when they got into IL. Hopefully they form sooner. I'd love to see some action. Also any chance someone gets put under a PDS tomorrow or a Mod or High risk? Link to comment Share on other sites More sharing options...
andyhb Posted February 20, 2014 Share Posted February 20, 2014 Also any chance someone gets put under a PDS tomorrow or a Mod or High risk? Moderate risk is pretty much a slam dunk at this point for at least damaging wind, the other two I'd doubt unless it is really expected to go off with a large amount of model consensus, especially the high res guidance. Link to comment Share on other sites More sharing options...
OHweather Posted February 20, 2014 Share Posted February 20, 2014 We'll find out soon but I'd expect a moderate risk for wind mainly south of the Ohio River. I could make an argument for a 15% tornado risk in parts of western/central KY and TN but I don't expect the SPC to go with those tornado probs right out of the shoot in a few minutes. Link to comment Share on other sites More sharing options...
BigBluesfan Posted February 20, 2014 Share Posted February 20, 2014 Moderate risk is pretty much a slam dunk at this point for at least damaging wind, the other two I'd doubt unless it is really expected to go off with a large amount of model consensus, especially the high res guidance. Do you have a link to the high res WRF radar simulation? Link to comment Share on other sites More sharing options...
andyhb Posted February 20, 2014 Share Posted February 20, 2014 Slight risk maintained, 5% tor and 30% hatched wind. Link to comment Share on other sites More sharing options...
chase_stormz Posted February 20, 2014 Share Posted February 20, 2014 Slight risk maintained, 5% tor and 30% hatched wind. No MOD for wind yet? What a joke SPC lol.. Link to comment Share on other sites More sharing options...
tornadotony Posted February 20, 2014 Share Posted February 20, 2014 It appears as though the NSSL-WRF likely picking up on the development of numerous mesovortices (or even perhaps embedded supercells) in the QLCS tomorrow night from KY down through wrn AL. Link to comment Share on other sites More sharing options...
andyhb Posted February 20, 2014 Share Posted February 20, 2014 What confused me was the mentioning of weak lapse rates limiting instability. That has always been (from day one) one of the stronger forecasted parameters with this event. Link to comment Share on other sites More sharing options...
chase_stormz Posted February 20, 2014 Share Posted February 20, 2014 What confused me was the mentioning of weak lapse rates limiting instability. That has always been (from day one) one of the stronger forecasted parameters with this event. Yea that confused me as well. Not sure how they missed that. Link to comment Share on other sites More sharing options...
Hoosier Posted February 20, 2014 Author Share Posted February 20, 2014 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1158 PM CST WED FEB 19 2014 VALID 201200Z - 211200Z ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OH AND TN VALLEY REGIONS TO CENTRAL GULF COAST... ..SYNOPSIS PROGRESSIVE UPPER-AIR PATTERN IS FCST ACROSS CONUS THIS PERIOD...FEATURING INITIALLY DISTINCT SHORTWAVE TROUGHS NOW ANALYZED OVER WRN DAKOTAS AND SRN CO/NRN NM REGION. SRN PORTION OF MID-UPPER-LEVEL VORTICITY FIELD ASSOCIATED WITH NRN-PLAINS PERTURBATION IS EXPECTED TO LINK WITH AMPLIFYING SRN-ROCKIES SYSTEM WHILE MOVING EWD ACROSS MAINLY CENTRAL/NRN PLAINS. COMBINED TROUGH SHOULD REACH FROM OZARKS TO UPPER MS VALLEY BY 21/06Z. BY THAT TIME...ACCOMPANYING/CLOSED 500-MB LOW SHOULD FORM OVER WI. BY END OF PERIOD...500-MB LOW SHOULD DEEPEN AND MOVE NEWD TO NNEWD ACROSS CENTRAL/WRN UPPER MI...WITH TROUGH ARCHING SEWD OVER WRN LOWER MI AND INDIANA THEN SSWWD ACROSS WRN TN. 250-MB JET OF 110-120 KT WAS ANALYZED AT 21/00Z OVER CO/NM...AND THIS SPEED MAX SHOULD EXPAND/ELONGATE AHEAD OF COMBINED PERTURBATION THROUGH PERIOD...WHILE GRADUALLY BECOMING MORE MERIDIONAL. AT SFC...CYCLONE NOW NEAR CO/KS BORDER SHOULD CONTINUE TO DEEPEN AS IT TRAVELS FROM ERN KS TO SWRN WI DURING 20/12-21/00Z TIME FRAME. AT THAT TIME...COLD FRONT SHOULD EXTEND IN ARC FROM LOW ACROSS CENTRAL-ERN IL...EXTREME WRN KY...SERN AR...AND MIDDLE-UPPER COASTAL PLAIN OF TX. ..OH AND TN VALLEY REGIONS TO CENTRAL GULF COAST SCATTERED-NUMEROUS TSTMS IN BANDS SHOULD POSE PRIMARY THREAT OF DAMAGING GUSTS...A FEW OF WHICH MAY REACH 65-KT/SIGNIFICANT-SVR CRITERIA. TORNADO RISK EXISTS BUT IS SECONDARY TO DAMAGING TSTM WIND IN TERMS OF COVERAGE...DURATION AND NUMBER OF EVENTS PROBABLE. ALTHOUGH LOW-LEVEL AND DEEP SHEAR EACH WILL BE FAVORABLE FOR SUPERCELLS...LIKELY DOMINANCE OF LINEAR STORM MODE INDICATES PREDOMINANT SOURCE OF TORNADO RISK WILL BE QLCS-TYPE SPINUPS AND EMBEDDED MESOCIRCULATIONS ASSOCIATED WITH LEWPS AND SMALL BOWS. TORNADOES WITH SUCH REGIMES TEND BE RELATIVELY SHORT-LIVED AND SMALL...BUT ALSO...FAST-MOVING AND RAIN-WRAPPED. THIN BAND OF CONVECTION MAY DEVELOP DURING AFTN IN ZONE OF STRONG FORCING ALONG SFC COLD FRONT...HOWEVER PRIMARY SVR-PRODUCING SWATH IS LIKELY TO ARISE IN SW-NE ORIENTED/PREFRONTAL CONVERGENCE ZONE FROM LATE AFTN INTO EARLY OVERNIGHT HOURS. 50-60 KT EFFECTIVE SHEAR MAGNITUDES WILL BE COMMON WHEREVER SFC-BASED INFLOW EXISTS WITH MAIN SQUALL LINE. 60S SFC DEW POINTS MAY REACH TO NEAR OH RIVER IN NARROW CORRIDOR PRIOR TO TSTMS...BUT RICHEST MOISTURE SHOULD RESIDE FROM TN SWD. MLCAPE SHOULD REMAIN BELOW 1000 J/KG OVER MOST OF OUTLOOK AREA BECAUSE OF WEAK LAPSE RATES ALOFT...THOUGH POCKETS OF PRECONVECTIVE DIABATIC HEATING OVER GULF COAST STATES CAN BOOST VALUES HIGHER ON MESOBETA SCALE. AS TSTM REGIME MOVES EWD ACROSS KY/TN/AL OVERNIGHT...IT WILL OUTPACE FAVORABLE DESTABILIZATION/WAA FROM N-S...AND MOVE INTO PROGRESSIVELY LOWER-CAPE AIR WITH EWD EXTENT. NET RESULT SHOULD BE DECREASE IN OVERALL SVR POTENTIAL FROM NW-SE AND WITH TIME. HOWEVER...BECAUSE OF GREATER MOISTURE PREVALENT CLOSER TO GULF COAST...SVR RISK MAY LAST FOR MUCH OF OVERNIGHT HOURS AS CONVECTION CROSSES TN VALLEY AND GULF-COAST STATES. FARTHER N OVER NRN PORTIONS INDIANA/OH AND LOWER MI...SVR WIND POTENTIAL DIMINISHES DUE TO PROGRESSIVELY WEAKER BUOYANCY. ALSO...LOSS OF SFC-BASED PARCELS IS EXPECTED IN RELATION TO PROGRESSIVELY DEEPER STABLE LAYER WITH NWD EXTENT...ATOP SNOW PACK. MEANWHILE...EVEN FOR THOSE STG/NEAR-SVR GUSTS THAT CAN PENETRATE TO SFC...SUBSTANTIAL TREE DAMAGE/TOPPLING ALSO BECOMES LESS PROBABLE WITH NWD EXTENT DUE TO FROZEN GROUND AND LACK OF LEAVES. ..MO-IA-IL REGION...MORNING EXTENSION OF STG LOW-LEVEL WAA REGIME FROM PRIOR PERIOD WILL SUPPORT CARRY-OVER POTENTIAL FOR SCATTERED TSTMS IN CLUSTERS ACROSS THIS REGION. ACTIVITY WILL BE SUPPORTED BY ISENTROPIC LIFT TO LFC...AMIDST ELEVATED MUCAPE 500-800 J/KG AND 35-45 KT EFFECTIVE SHEAR MAGNITUDES FROM ASSORTED FCST SOUNDINGS. ISOLATED SVR HAIL MAY OCCUR WITH THIS ACTIVITY DURING FIRST FEW HOURS OF PERIOD BEFORE IT MOVES NNEWD AWAY FROM MOST FAVORABLE ELEVATED INSTABILITY. ..EDWARDS/GUYER.. 02/20/2014 Link to comment Share on other sites More sharing options...
Stebo Posted February 20, 2014 Share Posted February 20, 2014 I am more confused by the lack of a north and west shift on the risk, if anything it looks a bit further east. I honestly am a bit surprised by this outlook. Link to comment Share on other sites More sharing options...
nwburbschaser Posted February 20, 2014 Share Posted February 20, 2014 No MOD for wind yet? What a joke SPC lol.. A little surprising, but I'm never really a fan of questioning the SPC in the sense of calling something a joke. Still have some morning outlooks for them to adjust if they feel it is warranted. Link to comment Share on other sites More sharing options...
Hoosier Posted February 20, 2014 Author Share Posted February 20, 2014 Well, I think it would be fair to characterize that outlook as leaning on the conservative side. With the strong shear and forcing, rapidly deepening surface low and good enough instability, it seems like a pretty textbook setup for a moderate risk type wind event imo. Maybe there'll be an upgrade on one of the future outlooks. Link to comment Share on other sites More sharing options...
Stebo Posted February 20, 2014 Share Posted February 20, 2014 Well, I think it would be fair to characterize that outlook as leaning on the conservative side. With the strong shear and forcing, rapidly deepening surface low and good enough instability, it seems like a pretty textbook setup for a moderate risk type wind event imo. Maybe there'll be an upgrade on one of the future outlooks. The question I have is what model did they look at with low lapse rates and have the risk that far east, all the mesoscale models have trended north and west all day. The Euro has been further west for a while as well. Only the GFS is that far east and honestly going with the GFS over everything else is a bad idea for many reasons. Link to comment Share on other sites More sharing options...
Hoosier Posted February 20, 2014 Author Share Posted February 20, 2014 The question I have is what model did they look at with low lapse rates and have the risk that far east, all the mesoscale models have trended north and west all day. The Euro has been further west for a while as well. Only the GFS is that far east and honestly going with the GFS over everything else is a bad idea for many reasons. I'm not sure what the lapse rate comment is based on either. Granted I've only checked GFS/NAM forecast soundings but almost everywhere I've checked has 700-500 mb lapse rates ranging anywhere from a bit under 7 to near 8 C/km Link to comment Share on other sites More sharing options...
Stebo Posted February 20, 2014 Share Posted February 20, 2014 I'm not sure what the lapse rate comment is based on either. Granted I've only checked GFS/NAM forecast soundings but almost everywhere I've checked has 700-500 mb lapse rates ranging anywhere from a bit under 7 to near 8 C/km To me that isn't weak lapse rates, anything under 6.5 and realistically 6.0 C/km is weak lapse rates. Link to comment Share on other sites More sharing options...
chase_stormz Posted February 20, 2014 Share Posted February 20, 2014 Just South of Bowling Green, KY at 23z Link to comment Share on other sites More sharing options...
SirSonic Posted February 20, 2014 Share Posted February 20, 2014 The new day 1 outlook, looks very conservative, due to uncertainties across the risk area. I think later outlooks will expand of the Slight Risk into North into areas of N IL, N IL, OH, W PA. I think there will likely be a Moderate Risk from Western/Central OH, S IN down to KY/TN for damaging winds. I wouldn't be surprised if we a 15% tornado risk area too in that area. I think the tornado risk area will expand and cover a large area from the south to the ohio valley/southern great lakes Link to comment Share on other sites More sharing options...
andyhb Posted February 20, 2014 Share Posted February 20, 2014 Just South of Bowling Green, KY at 23z You'll notice there is a bit of a BVB profile there with the winds also weakening a bit just above the 700 mb level, although with the strong speed shear throughout the column I'm not sure how much effect that will otherwise have. Link to comment Share on other sites More sharing options...
huronicane Posted February 20, 2014 Share Posted February 20, 2014 I'm a bit confused by this "cell" in Stephenson County. It pulsed down and then pulsed way back up over the past 6 scans while remaining stationary...a fire perhaps? And as of the most recent scan, completely gone. Link to comment Share on other sites More sharing options...
SirSonic Posted February 20, 2014 Share Posted February 20, 2014 I'm a bit confused by this "cell" in Stephenson County. It pulsed down and then pulsed way back up over the past 6 scans while remaining stationary...a fire perhaps? And as of the most recent scan, completely gone. I was looking at the past radar frames. this cell pulsed up and down before you took the screencap. Large fire or strange anomaly Link to comment Share on other sites More sharing options...
Chicago Storm Posted February 20, 2014 Share Posted February 20, 2014 I'm a bit confused by this "cell" in Stephenson County. It pulsed down and then pulsed way back up over the past 6 scans while remaining stationary...a fire perhaps? And as of the most recent scan, completely gone. Wind farm. Link to comment Share on other sites More sharing options...
RCNYILWX Posted February 20, 2014 Share Posted February 20, 2014 Moderate Risk out with this outlook, 45% hatched wind in MDT area but kept 5% tor. Sent from my SCH-I535 using Tapatalk Link to comment Share on other sites More sharing options...
wxmeddler Posted February 20, 2014 Share Posted February 20, 2014 Check out the EML from SGF this morning, this should advect into Central IL by 18-21z Link to comment Share on other sites More sharing options...
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