Aug 17, 2005 1730 UTC Day 2 Convective Outlook Updated: Wed Aug 17 17:45:36 UTC 2005
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SPC AC 171743 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1243 PM CDT WED AUG 17 2005 VALID 181200Z - 191200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM MKG GRR 35 WNW FDY DAY LUK 40 SSE SDF BWG PAH CGI VIH 50 N SZL 55 ENE OMA FRM MKT MSP EAU CWA MTW MKG. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 SE IPL EDW FAT TVL RNO WMC OWY SUN BTM HLN LWT MLS DIK 70 NE MOT ...CONT... 40 NNW BUF PSB MRB CHO LYH DAN RDU GSB HSE ...CONT... LRD COT SAT AUS SHV 35 ENE TXK FSM EMP BIE LNK OLU BUB BBW MCK EHA MAF 40 S P07. ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SERN MN/IA TO WRN OH/NRN KY... ...SYNOPSIS... PROGRESSIVE NRN STREAM FLOW PATTERN WILL BE DOMINATED BY MID/UPPER LEVEL LOW NOW TAKING SHAPE OVER SRN BC AND PACIFIC NW. THIS FEATURE IS PROGGED TO TURN EWD ACROSS SRN ALTA AND SRN SASK THROUGH PERIOD...WITH ASSOCIATED TROUGH SWD INTO N-CENTRAL ROCKIES. AS THIS GRADUALLY OCCURS...LEADING SHORTWAVE TROUGH -- NOW EVIDENT IN VWP/PROFILER DATA AND MOISTURE CHANNEL IMAGERY OVER ERN WY -- IS EXPECTED TO EJECT EWD OVER UPPER MS VALLEY AND LM REGION. QUASISTATIONARY SFC FRONTAL ZONE -- NOW ANALYZED ACROSS NRN/ERN MT...SRN ND AND NRN MN -- IS EXPECTED TO BECOME COLD FRONT AS NWRN TROUGH/LOW APCH AREA...MOVING SEWD ACROSS NRN/CENTRAL PLAINS AND NRN MN. ATTACHED SFC LOW SHOULD MOVE EWD ACROSS NRN MN...WHILE MIDLEVEL TROUGH MOVES OVHD. WARM FRONT SHOULD LIFT NWD OVER PORTIONS IA/WI/IL/LM AND LOWER MI THROUGH PERIOD. ...MID MS VALLEY...SRN GREAT LAKES...LOWER OH VALLEY... STRONGEST DEEP-LAYER ASCENT IS EXPECTED TO OCCUR INVOF SFC LOW...AND ALONG AND N OF WARM FRONT OVER UPPER MIDWEST. HOWEVER...TIGHTEST FLOW GRADIENTS ALOFT AND STRONGEST DEEP-LAYER SHEAR IS EXPECTED TO BE GENERALLY S OF SFC WARM FRONT ACROSS WARM SECTOR...FROM ERN IA ACROSS WRN IL BY AFTERNOON. HORIZONTAL DISPLACEMENT BETWEEN STRONGEST PROGGED LIFT AND STRONGEST BUOYANCY/SHEAR LENDS SOME UNCERTAINTY ABOUT LOCATION/COVERAGE OF CONVECTION..AND WHERE TO ASSIGN HIGHER PROBABILITIES WITHIN BROAD 15% ENVELOPE. HOWEVER...WEAK CAP IS EVIDENT IN MODIFIED ETA FCST SOUNDINGS...SUGGESTING ANY CONVECTION THAT DOES DEVELOP WILL BECOME SEVERE WITH DAMAGING GUSTS, HAIL AND A FEW TORNADOES POSSIBLE. ALSO...OUTFLOW BOUNDARY FROM POSSIBLE MCS OVERNIGHT DAY-1 MAY MAKE PROFILES MORE FAVORABLE ON MESOSCALE AND OPTIMAL SEVERE THREAT AREA MORE PRECISELY DEFINED. GREATEST SUPERCELL POTENTIAL SHOULD BE INVOF WARM FRONT OR OUTFLOW BOUNDARY WHERE SFC FLOW IS MOST STRONGLY BACKED...OPTIMALLY ENLARGING LOW LEVEL HODOGRAPHS WHERE THERE STILL IS SUBSTANTIAL SFC-BASED INSTABILITY. MODIFIED MODEL SOUNDINGS SHOW 0-1 KM SRH 200-300 J/KG NEAR WARM FRONT...AND A STILL-FAVORABLE 100-200 J/KG SWD TOWARD NERN MO/WRN IL DESPITE NEARLY UNIDIRECTIONAL DEEP-LAYER FLOW S OF WARM FRONT. WARM SECTOR EFFECTIVE SHEARS MAY REACH 45-50 KT. BUOYANCY WILL BE MAXIMIZED S OF WARM FRONT...AS VERY RICH BOUNDARY LAYER MOISTURE AND SFC DIABATIC HEATING CONTRIBUTE TO MLCAPES 2000-3000 J/KG. STRONGEST DEEP-LAYER SHEAR WILL SHIFT EWD ACROSS IL/INDIANA DURING EVENING AND OVERNIGHT. AFTERNOON ACTIVITY MAY EVOLVE INTO EVENING/OVERNIGHT COMPLEX THAT WOULD MOVE ACROSS PORTIONS IL/WI/LM AND POSSIBLY LOWER MI BEFORE WEAKENING. DAMAGING GUSTS AND OCCASIONAL HAIL ARE POSSIBLE. ...UPPER MIDWEST TO WY... SCATTERED TO WIDELY SCATTERED TSTMS ALSO ARE POSSIBLE ALONG AND BEHIND FCST SFC COLD FRONT...WITH ACTIVITY OVER ERN WY/SERN MT AIDED BY POSTFRONTAL UPSLOPE COMPONENT TO BOUNDARY LAYER WINDS. DEEP-LAYER SHEAR WILL BE FAVORABLE AND INCREASING THROUGHOUT DAY WITH APCH OF STRONG NWRN TROUGH...I.E. 50-60 KT OF 0-6 KM AND EFFECTIVE SHEARS PROGGED IN NERN WY. ALTHOUGH LOW LEVEL MOISTURE AND INSTABILITY WILL BE MORE LIMITED IN THIS AREA...STEEPENING MIDLEVEL LAPSE RATES MAY YIELD ENOUGH BUOYANCY TO SUPPORT HAIL/WIND THREAT WITH STRONGER CELLS. ..EDWARDS.. 08/17/2005 ...NOTICE... THE STATION RELATIVE POINTS IN THIS PRODUCT ARE NOW AVAILABLE SEPARATELY UNDER THE WMO HEADINGS WUUS01 PTSDY1... WUUS02 PTSDY2...WUUS03 PTSDY3. THE INCLUSION OF POINTS IN THIS DISCUSSION WILL BE DISCONTINUED AFTER THE 2005 CONVECTIVE SEASON. A PUBLIC NOTIFICATION STATEMENT (PNS) WILL PROVIDE DETAILS ON THE TRANSITION. CLICK TO GET WUUS02 PTSDY2 PRODUCT NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0800Z |