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

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