[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 271626
SWODY1
SPC AC 271624

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1124 AM CDT SAT MAY 27 2006

VALID 271630Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NORTHERN
PLAINS AND UPPER MIDWEST...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF WEST TX AND
SOUTHWEST OK...

...DAKOTAS AND NWRN MN...
UPPER TROUGH OVER THE WESTERN STATES CONTINUES TO AMPLIFY
TODAY...WHILE UPPER RIDGE BUILDS OVER THE CENTRAL AND EASTERN U.S. 
MAIN SURFACE LOW WILL DEVELOP FROM NORTHEAST WY ACROSS SD INTO ND
TONIGHT...ALONG SURFACE WARM FRONT.  MODEL SOUNDINGS IN THIS AREA
SHOW STEEP LOW AND MID LEVEL LAPSE RATES AND MLCAPE VALUES OVER 3500
J/KG.  SCATTERED THUNDERSTORMS WILL LIKELY DEVELOP AHEAD OF LOW FROM
BLACK HILLS REGION INTO CENTRAL/WESTERN ND...MAINLY AFTER 00Z. 
SUPERCELLS CAPABLE OF LARGE HAIL/DAMAGING WINDS AND PERHAPS ISOLATED
TORNADOES ARE EXPECTED.  STORMS MAY SPREAD EASTWARD DURING THE LATE
EVENING INTO NORTHWEST MN.  DEVELOPMENT FARTHER SOUTH IS EXPECTED TO
BE PRECLUDED BY CAPPING INVERSION AND WARM TEMPERATURES ALOFT.

...MN/WI/IA/IL...
CLUSTER OF THUNDERSTORMS IS ONGOING THIS MORNING OVER SOUTHWEST IA. 
THIS ACTIVITY IS JUST NORTH OF REMNANT OUTFLOW BOUNDARY...AND ON
NOSE OF STRONGER SOUTHERLY LOW LEVEL JET.  WARMING TEMPERATURES
ALOFT SHOULD TEND TO WEAKEN STORMS IN THIS REGION BY EARLY
AFTERNOON.  HOWEVER...NEW STORMS MAY DEVELOP FARTHER NORTHEASTWARD
INTO PARTS OF MN/WI/IA AND NORTHERN IL AS MCV DRIFTS INTO AREA. 
MODELS AGREE ON DEVELOPING MODERATE-STRONG INSTABILITY IN THIS
REGION...FAVORABLE FOR HAIL AND GUSTY WINDS.  MODELS ALSO SUGGEST
THAT ACTIVITY MAY PERSIST MUCH OF THE NIGHT DUE TO STRENGTHENING
NOCTURNAL LOW LEVEL JET AND ENHANCED LOW LEVEL WARM ADVECTION.

...WEST TX INTO SOUTHWEST OK...
DIFFUSE DRYLINE IS EXPECTED TO BECOME ESTABLISHED THIS AFTERNOON
FROM SOUTHWEST OK INTO THE BIG BEND REGION OF TX.  HOT SURFACE
TEMPERATURES APPROACHING 100F...COUPLED WITH DEWPOINTS NEAR 60F EAST
OF DRYLINE...WILL RESULT IN A ZONE OF HIGH INSTABILITY /MLCAPE
VALUES OF 2000-3000 J/KG/.  FORECAST SOUNDINGS SHOW A DEEP MIXED
BOUNDARY LAYER AND NO CAP...LIKELY RESULTING IN SCATTERED
THUNDERSTORM DEVELOPMENT NEAR/JUST AFTER PEAK HEATING. WATER VAPOR
IMAGERY HINTS AT A WEAK UPPER FEATURE MOVING INTO WEST TX.  THIS MAY
HELP TO ORGANIZE CONVECTION AND ENHANCE THREAT OF LOCALLY DAMAGING
WINDS AND HAIL IN STRONGER CELLS.  THUS...HAVE INTRODUCED A SLIGHT
RISK FOR THIS AREA.

...TN VALLEY INTO THE SOUTHEAST...
WEAK SURFACE BOUNDARY CURRENTLY EXTENDS FROM SC/GA INTO IL.  AIR
MASS ALONG AND SOUTH OF BOUNDARY REMAINS VERY MOIST/UNSTABLE WITH
AFTERNOON MUCAPE VALUES EXPECTED TO RANGE FROM 3000-4000 J/KG. 
VERTICAL SHEAR PROFILES ARE WEAK IN THIS AREA. HOWEVER...ISOLATED
PULSE OR MULTICELL SEVERE STORMS ARE POSSIBLE ALONG THIS AXIS. 
THREAT SHOULD SUBSIDE BY EARLY EVENING.

...SOUTH FL...
SUBTROPICAL JET REMAINS ACROSS SOUTH FL TODAY...WITH WATER VAPOR
IMAGERY SHOWING WELL-DEFINED SHORTWAVE TROUGH OVER THE CENTRAL GULF
OF MEXICO.  AMPLE MOISTURE/INSTABILITY ARE PRESENT OVER THIS
REGION...LIKELY LEADING TO SCATTERED AFTERNOON THUNDERSTORMS. 
SUFFICIENT UPPER LEVEL WIND FIELDS AND FAVORABLE THERMODYNAMIC
PARAMETERS SUGGEST A THREAT OF GUSTY WINDS AND HAIL IN STRONGER
CELLS.

..HART/TAYLOR.. 05/27/2006