[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 211614
SWODY1
SPC AC 211613

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1113 AM CDT SUN MAY 21 2006

VALID 211630Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM SERN KS/NERN OK TO THE SC
COAST...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CENTRAL HIGH
PLAINS...

...TN VALLEY TO THE SOUTHEASTERN U.S. COAST...
SURFACE FRONT REMAINS IN PLACE FROM THE SERN NC COAST WNWWD INTO THE
MO BOOTHEEL REGION TODAY...WITH MODERATE TO STRONG WNWLY FLOW ALOFT
PERSISTING ALONG THIS BOUNDARY.  AIR MASS HAS BEEN OVERTURNED THE
PAST COUPLE DAYS AND INSTABILITY WILL NOT BE AS STRONG AS
YESTERDAY...THOUGH STRONG HEATING WILL AGAIN OCCUR WITHIN THE WARM
SECTOR.  AFTERNOON TEMPERATURES RISING THROUGH THE 80S AND SURFACE
DEW POINTS HOLDING IN THE LOWER 60S ARE EXPECTED TO SUPPORT MODEST
CAPE WITH MLCAPE FROM 1000-1500 J/KG.  IN ADDITION...WEAK IMPULSE
AIDING CONVECTIVE CLUSTER NOW MOVING INTO SERN TN WILL CONTINUE SEWD
INTO SC AGAIN TODAY.  GIVEN 40-50 KT EFFECTIVE SHEAR STILL IN
PLACE...ACTIVITY MAY INCREASE IN COVERAGE AND INTENSITY AS STORMS
SPREAD SEWD ACROSS THE SRN APPALACHIANS THIS AFTERNOON.  SEVERITY
WILL LIKELY NOT BE AS ROBUST AS YESTERDAY.  HOWEVER...ENVIRONMENT
STILL APPEARS SUPPORTIVE OF A FEW ORGANIZED CLUSTERS/SUPERCELLS
SHOULD STORMS ROOT INTO MODEST MIXED-LAYER CAPE DURING THIS
AFTERNOON.

...SERN KS ACROSS THE OZARK REGION INTO THE MID SOUTH...
MCV FROM SMALL MCS WHICH ERODED ACROSS SWRN KS OVERNIGHT WAS EVIDENT
ON SATELLITE IMAGERY OVER S-CENTRAL KS THIS MORNING.  SMALL SCALE
ENHANCEMENT OF LOW TO MID TROPOSPHERIC WINDS AND DEEP ASCENT SHOULD
SUPPORT INCREASED CLUSTER OF STRONG TO SEVERE THUNDERSTORMS INTO
SERN KS/FAR NERN OK AND SWRN MO AS CAP BREAKS THIS AFTERNOON.  AIR
MASS WILL LIKELY BECOME MODERATE TO STRONGLY UNSTABLE WITH STRONG
HEATING ALONG AND SOUTH OF EFFECTIVE SURFACE FRONT NOW EXTENDING
FROM SWRN MO WWD INTO FAR S-CENTRAL KS AND WSWWD ACROSS NWRN OK THIS
MORNING.  GIVEN LOCAL ENHANCEMENT OF DEEP LAYER SHEAR...STORMS MAY
DEVELOP INTO SUPERCELLS THOUGH ITS MORE LIKELY STORMS WILL INCREASE
INTO A CLUSTER/MCS WITH THREATS OF LARGE HAIL AND DAMAGING WINDS AS
ACTIVITY MOVES SLOWLY SEWD THROUGH THE EVENING.

...CENTRAL HIGH PLAINS...
RIDGING ALOFT WILL BUILD ACROSS THE CENTRAL ROCKIES TODAY. 
HOWEVER...SUFFICIENT WLY FLOW WILL PERSIST ACROSS NRN CO INTO ERN WY
FOR MODEST DEEP LAYER SHEAR...WHERE FORECAST SOUNDINGS MAINTAIN
35-40 KT EFFECTIVE SHEAR.  SURFACE WINDS ARE FORECAST BY ALL THE
SHORT-TERM MODELS TO BACK TO SELY ACROSS THE CENTRAL HIGH PLAINS
WITH WEAK LOW CENTER/TROUGH DEVELOPING INTO CENTRAL WY.  THIS SHOULD
SUSTAIN LOW 50F SURFACE DEW POINTS ALONG AND JUST EAST OF THE HIGHER
TERRAIN FROM NRN CO INTO MUCH OF ERN WY.  GIVEN STRONG HEATING...AIR
MASS SHOULD BECOME MODERATELY UNSTABLE BY MID TO LATE AFTERNOON WITH
INCREASING CONVECTION OVER HIGHER TERRAIN AND/OR INVOF LEE TROUGH. 
ACTIVITY WILL LIKELY PERSIST FOR SEVERAL HOURS WITH THREATS OF LARGE
HAIL AND DAMAGING WINDS AS IT SHIFTS EWD OVER THE HIGH PLAINS LATE
TODAY/THIS EVENING. CONSOLIDATION INTO A SMALL MCS IS POSSIBLE ALONG
NOSE OF MODEST SLY H85 WIND MAX ACROSS WRN NEB LATER THIS EVENING. 
THOUGH ISOLATED SEVERE MAY DEVELOP INTO THE NRN HIGH PLAINS AND SWD
INTO PORTIONS OF WEST TX ALONG LEE TROUGH TODAY...OVERALL SEVERE
THREAT WARRANTS ONLY LOW PROBABILITIES ACROSS THESE AREAS.

...NRN INTERMOUNTAIN REGION...
COMPLEX CONVECTIVE SCENARIO ACROSS THIS AREA TODAY AS RIDGE BUILDS
OVER THE ROCKIES AND A STRONG UPPER LOW STAYS OFF THE CA COAST. 
CONSIDERABLE CLOUDINESS HAS OVERSPREAD MUCH OF THE NWRN
INTERMOUNTAIN REGION THIS MORNING WHICH WILL LIMIT INSTABILITY AND
RESULTANT THUNDERSTORM POTENTIAL TODAY.  SHEAR WILL REMAIN MODEST
AND SUPPORT SOME ORGANIZATION WITH ANY STORM WHICH CAN BE SUSTAINED
OFF HIGHER TERRAIN...THOUGH OVERALL SEVERE THREAT APPEARS MARGINAL
ATTM.

...WRN MT INTO THE NRN HIGH PLAINS...
HEATING WILL BE ROBUST OVER THE NRN ROCKIES INTO CENTRAL MT AHEAD OF
A SHORTWAVE TROUGH NOW EJECTING NWD OUT OF NV TODAY.  THIS SYSTEM
WILL LIKELY MAINTAIN SUFFICIENT MID LEVEL MOISTURE/LIFT FOR
INCREASED THUNDERSTORMS OVER THE NRN ROCKIES THIS AFTERNOON WHICH
WILL SPREAD NEWD ACROSS CENTRAL MT LATER TODAY AND THIS EVENING. 
HOWEVER...AIR MASS IS DRIER TODAY OVER MT WITH PW/S AT TFX LESS THAN
.5 INCH AT 12Z.  THUS...INSTABILITY WILL LIKELY BE MARGINAL AND WILL
LIMIT SEVERITY WITH EXPECTED STORM CLUSTER/S TODAY.  ISOLATED
DAMAGING WINDS/LARGE HAIL MAY STILL ACCOMPANY STRONGER
STORMS...THOUGH APPEARS OVERALL THREAT WARRANTS LOWER PROBABILITIES
THAN EARLIER FORECAST.

..EVANS/GUYER.. 05/21/2006