Nov 12, 2005 2000 UTC Day 1 Convective Outlook Updated: Sat Nov 12 20:18:13 UTC 2005 Probabilistic to Categorical Outlook Conversion Table in HTML, or PDF formats.
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SPC AC 122016 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0216 PM CST SAT NOV 12 2005 VALID 122000Z - 131200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 W FLV 20 ESE YKN 20 NNW BKX 20 NNE RWF 35 SE MSP 30 WNW LSE 45 NNW DBQ 25 NW MLI 25 SSE BRL 45 WSW FAM 30 SSE BVX 25 ENE ELD 50 WNW POE UTS 20 SSE ACT 10 W DAL 35 NE TUL 25 ENE CNU 20 W FLV. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 50 E CRP 25 NE COT 25 NNW HDO 15 WSW FTW 20 E OKC 30 ENE CNK 10 WSW OLU 35 E ONL 20 ENE VTN 35 NNW VTN 25 NNE PIR 15 N INL ...CONT... 35 NW CLE 45 ESE BWG 40 E TUP 30 N HEZ 45 NW LFT 55 SW 7R4. ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE FAR SERN SD/SRN MN SWD TO NERN TX... ...MIDDLE/LOWER MO VALLEY... EARLY AFTERNOON SURFACE ANALYSES INDICATED A DEEP SURFACE LOW OVER FAR NERN NEB WITH THE TRAILING DRY LINE AND COLD FRONT MOVING QUICKLY EWD ACROSS ERN NEB...CENTRAL/ERN KS AND OK. SURFACE LOW IS PROGGED TO DEEPEN FURTHER AS STRONG HEIGHT FALLS /180-200 METERS/ SPREAD ACROSS THE UPPER MS VALLEY...WITH THE LOW REACHING CENTRAL MN THIS EVENING AND WRN LAKE SUPERIOR BY 12Z SUNDAY. STRONG SLY LOW LEVEL FLOW AHEAD OF THESE BOUNDARIES HAD CONTINUED TO ADVECT A NARROW PLUME OF MOISTURE NWD WITH SURFACE DEWPOINTS INTO THE MID 50S FROM SERN SD TO CENTRAL IA...AND LOWER 60S ALONG THE KS/MO BORDER REGION. GIVEN TRACK OF SURFACE LOW...WARM SECTOR IS EXPECTED TO DEVELOP NWD INTO SRN MN AIDING IN THE THREAT FOR SURFACE BASED STORMS. STRONG SURFACE HEATING WITHIN THE MID LEVEL DRY SLOT AND ALONG WRN EDGE OF LOW LEVEL MOISTURE PLUME ACROSS ERN NEB/KS WILL CONTINUE TO RESULT IN MLCAPE VALUES AROUND 1000 J/KG... AND UP TO 1500 J/KG OVER NRN TX. 18Z SOUNDINGS AT TOP/OMA BOTH INDICATED A LOW LEVEL CAP. 19Z OBJECTIVE ANALYSIS SHOWED THE CAP IS CONTINUING TO WEAKEN AS STRONG LARGE SCALE FORCING/PV ADVECTION SPREADS RAPIDLY ENEWD AHEAD OF THE CENTRAL PLAINS TROUGH AND WITHIN THE EXIT REGION OF A 70-90 KT WNWLY MID LEVEL JET NOSING INTO THE CENTRAL PLAINS. FURTHER WEAKENING OF THIS CAP COMBINED WITH THE NARROW AXIS OF MODERATE INSTABILITY AND STRONG DEEP LAYER SHEAR SUGGEST THUNDERSTORM INITIATION WILL BE ALONG THE DRY LINE IN FAR ERN NEB/WRN IA/SERN SD AND THEN SWD INTO ERN KS BY 20-21Z. STORM MODE IS EXPECTED TO BE LINEAR GIVEN DEEP UNI-DIRECTIONAL WIND PROFILES AND SHEAR VECTORS ORIENTED NEARLY PARALLEL TO THE DRY LINE/COLD FRONT. HOWEVER...EMBEDDED SUPERCELLS WITH AN ATTENDANT TORNADO THREAT WILL ALSO BE LIKELY GIVEN LOW LEVEL HODOGRAPH CURVATURE AS INDICATED ON THE 18Z TOP/OMA SOUNDINGS. ONCE STORMS INITIATE...THE ACTIVITY IS EXPECTED TO SPREAD FAIRLY QUICKLY ENEWD ACROSS SRN MN/IA AND INTO MO. THE LOSS OF INSTABILITY THIS EVENING SUGGESTS OVERALL SEVERE THREAT WILL GRADUALLY DECREASE WITH EWD EXTENT AS COLD FRONT/FORCING WITH UPPER TROUGH MOVE AWAY FROM STRONGER LOW LEVEL MOISTURE. THE DAMAGING WIND THREAT IS EXPECTED TO BE THE GREATER THREAT THIS EVENING GIVEN SPEED OF SYSTEM AND CONTINUATION OF STRONG WIND FIELDS/DEEP LAYER SHEAR FOR LOW TOPPED STORMS. THIS THREAT MAY REACH INTO PARTS OF WI/IL. ...ERN OK/WRN AR/NORTH CENTRAL AND NERN TX/NWRN LA... VIS IMAGERY SHOWED CU FIELD DEVELOPING SWD ALONG THE DRY LINE INTO NORTH CENTRAL-NERN OK EARLY THIS AFTERNOON. AIR MASS ALONG/E OF THIS BOUNDARY HAS BECOME MODERATELY UNSTABLE WITH INCREASING DEEP LAYER SHEAR TO SUPPORT ORGANIZED STORMS. FOR ADDITIONAL INFORMATION ABOUT THE NEAR TERM SEVERE THREAT...PLEASE REFER TO SPC MESOSCALE DISCUSSION /SPCSWOMCD/ 2404. LATER THIS EVENING...INSTABILITY IS EXPECTED TO DIMINISH SOMEWHAT WITH OVERALL SEVERE THREAT TENDING TO DECREASE. HOWEVER... SUFFICIENT INSTABILITY/SHEAR VALUES SHOULD REMAIN ACROSS PARTS OF NERN TX TO THE ARKLATEX REGION FOR A FEW SEVERE STORMS INTO THE OVERNIGHT PERIOD AS THE COLD FRONT/DRY LINE MOVE SEWD. ..PETERS.. 11/12/2005 ...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 WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z |