SPC DAY-1 CONVECTIVE OUTLOOK
05 Jun 1999 - 20:01:24 UTC
ZCZC MKCSWODY1 000 ACUS1 KMKC 052001 MKC AC 052001 CONVECTIVE OUTLOOK...REF AFOS NMCGPH94O. VALID 052000Z - 061200Z REF WW NUMBER 390...VALID TIL 0100Z THERE IS A HIGH RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER SOUTHWESTERN MINNESOTA...THE SOUTHEASTERN THIRD OF SOUTH DAKOTA... MUCH OF NEBRASKA...AND NORTHWESTERN IOWA. THE HIGH RISK AREA IS TO THE RIGHT OF A LINE FROM 20 NNE MCK 30 SW MHN 60 E CDR 35 SSE PHP 45 WNW HON 35 S AXN 20 NW MKT 30 W MCW 35 SSE OMA 30 SE HSI 20 NNE MCK. SURROUNDING THE HIGH RISK AREA...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER PARTS OF KANSAS...CENTRAL IOWA... WESTERN WISCONSIN...SOUTHERN MINNESOTA...THE SOUTHEASTERN HALF OF SOUTH DAKOTA...AND WESTERN NEBRASKA. THE MDT RISK AREA IS TO THE RIGHT OF A LINE FROM 10 ENE LBL 40 SSW ICT 20 NW STJ 35 W DBQ 40 WNW OSH 50 WNW IWD 20 NNW AXN 15 NNE PHP 30 ENE CDR 50 WSW MHN 15 WNW MCK 10 ENE LBL. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 E DTW 25 NE MLI 30 NNW IRK 10 NNE OJC 25 NW MWL 30 WSW JCT 75 NNW DRT 65 SSE MAF 50 NNE AMA 55 NNW GCK 15 SE IML 30 N BFF 35 E 81V 40 SW BIS 45 ENE INL. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 SE PFN 15 WSW ABY 35 ESE VLD 35 WNW ORL 50 WNW PBI 70 ENE EYW. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 NW PBG 40 WSW SLK 15 E SYR 50 SE BUF ERI ...CONT... 40 SE DTW 20 NNE BMI 10 S UIN 30 WSW JLN 20 SSW FTW 65 WSW COT ...CONT... 25 S P07 45 E 4LJ 40 NW GLD 40 ENE DEN 40 W PUB 30 NNW SAF 30 E GCN 35 S TPH 20 NW NFL 45 WSW BKE 60 N FCA. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 SE BVE CBM 20 SSW BWG 10 SE LEX 40 W TRI 35 NNW AGS 35 ESE SAV. STRONG UPPER LEVEL LOW OVER THE CENTRAL ROCKIES IS EXPECTED TO CONTINUE NORTHEASTWARD ACROSS THE CENTRAL AND NORTHERN PLAINS THROUGH THE REMAINDER OF THE PERIOD. LATEST SURFACE ANALYSIS SHOWS AN AREA OF LOW PRESSURE OVER WESTERN NEBRASKA...AND ANOTHER ONE OVER NORTHEASTERN COLORADO. A COLD FRONT EXTENDED FROM NORTHWESTERN MINNESOTA...SOUTHWESTWARD THROUGH THE NEBRASKA LOW INTO CENTRAL COLORADO. ...UPPER MISSISSIPPI VALLEY/NORTHERN AND CENTRAL PLAINS... LATEST VISIBLE IMAGERY SHOWS LOW TO MID LEVEL BASED CONVECTION WERE CONTINUING THIS AFTERNOON OVER PARTS OF NEBRASKA AND IOWA INTO MINNESOTA. VERY STRONG HEATING HAS OCCURRED TODAY...ALLOWING TEMPERATURES TO CLIMB INTO THE 80S AND 90S...PARTICULARLY ACROSS THE HIGH RISK AREA. PLENTIFUL LOW LEVEL MOISTURE REMAINS IN PLACE OVER THE ENTIRE CENTER OF THE NATION...AND AS A RESULT...SURFACE BASED CAPE VALUES ARE WELL IN EXCESS OF 3000 J/KG IN NEBRASKA... IOWA...AND SOUTHERN MINNESOTA. THE 18Z MINNEAPOLIS SOUNDING EXHIBITED A MOST UNSTABLE CAPE VALUES OF AROUND 5000 J/KG. A STRONG MID LEVEL JET MAX IS FORECAST TO MOVE OUT ACROSS THE PLAINS AND INTO THE UPPER MISSISSIPPI VALLEY THROUGH THE AFTERNOON AND EVENING. THE AFTERNOON SOUNDING AT MINNEAPOLIS SHOWS STRONG VEERING IN THE LOW LEVELS...WITH SPEEDS INCREASING TO 60 KNOTS AT 500 MB. THIS TYPE OF WIND FIELD IS VERY FAVORABLE FOR SUPERCELLS AND SCATTERED TORNADOES. WET BULB ZERO HEIGHTS ARE BELOW 10 KFT... INDICATING VERY LARGE HAIL IS POSSIBLE WITH SOME OF THE STRONGER STORMS. SOME DRY AIR ALOFT AS NOTED ON THE MINNEAPOLIS SOUNDING ALSO INDICATES A POTENTIAL FOR DAMAGING WINDS. WIDELY SCATTERED SEVERE THUNDERSTORMS SHOULD DEVELOP THROUGH THE AFTERNOON. THESE STORMS WILL RAPIDLY BECOME SEVERE ACROSS PORTIONS OF NEBRASKA AND SOUTH DAKOTA. WITH THE STRONG AND INCREASING WINDS ...THESE STORMS WILL BECOME TORNADO PRODUCING SUPERCELLS AS THEY MOVE THROUGH THE NORTHERN PLAINS INTO SOUTHERN MINNESOTA AND NORTHERN IOWA. AS THE UPPER TROUGH CONTINUES TO APPROACH THE AREA LATER THIS EVENING...THE ACTIVITY SHOULD BECOME MORE WIDESPREAD. THE SCATTERED SEVERE STORMS SHOULD EVOLVE INTO AN MCS LATER TONIGHT AS IT MOVES ACROSS WISCONSIN INTO LOWER MICHIGAN. AT THAT TIME... LARGE HAIL AND DAMAGING WINDS ARE LIKELY. ...SOUTHERN PLAINS... A CAPPING INVERSION REMAINS IN PLACE ACROSS A LARGE PART OF THE AREA AS NOTED ON THE 18Z NORMAN AND DODGE CITY SOUNDINGS. THIS CAP APPEARS TO BE SOMEWHAT WEAKER THAN IN THE PAST COUPLE OF DAYS. THE AMARILLO SOUNDING SHOWS THE CAP HAS WEAKENED SIGNIFICANTLY SINCE 12Z THIS MORNING. THIS WEAKENING OF THE CAP COMBINED WITH CONVERGENCE ALONG THE DRYLINE MAY ALLOW THUNDERSTORMS TO DEVELOP THROUGH THE AFTERNOON HOURS ACROSS PARTS OF WEST TEXAS AND WESTERN KANSAS. LOW TO MID LEVEL FLOW IS SOMEWHAT WEAK ACROSS PARTS OF OKLAHOMA AND WEST TEXAS...BUT INCREASES QUICKLY OVER THE NORTHERN PART OF THE REGION. LOW LEVEL FLOW CONTINUES TO BACK...AND THIS IS CREATING A FAVORABLE SHEAR ENVIRONMENT FOR SEVERE THUNDERSTORMS... INCLUDING SUPERCELLS. EXTENSIVE CLOUD COVER HAS LIMITED SURFACE HEATING THIS AFTERNOON... BUT TEMPERATURES ARE STILL IN THE 80S...AND DEWPOINTS ARE IN THE 60S AND 70S. THIS IS RESULTING IN SURFACE BASED CAPE VALUES OF 1500 TO 3000 J/KG. ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP THROUGH THE AFTERNOON. GIVEN THE MODERATE TO STRONG INSTABILITY AND INCREASED VEERING PROFILES...LARGE HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES ARE POSSIBLE. ...SOUTHEAST U.S... SCATTERED THUNDERSTORMS WERE CONTINUING TO DEVELOP THIS AFTERNOON ACROSS EXTREME SOUTHERN GEORGIA SOUTHWARD INTO THE FLORIDA PENINSULA. THE AIR MASS REMAINS VERY UNSTABLE ACROSS THIS REGION WITH SURFACE BASED CAPE VALUES OF 2000 TO 4000 J/KG. THE STRONGEST ACTIVITY WAS LOCATED OVER WESTERN PARTS OF THE PENINSULA ALONG THE WEST COAST SEA BREEZE. OTHER STORMS WERE MOVING WESTWARD OVER THE CENTRAL PARTS OF THE PENINSULA WITH THE EAST COAST SEA BREEZE. WITH THE STRONG INSTABILITY...ISOLATED PULSE SEVERE STORMS ARE LIKELY THROUGH THE AFTERNOON. LARGE HAIL AND DAMAGING DOWNBURST WINDS ARE LIKELY. ..REHBEIN.. 06/05/99 NNNN
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