Friday, May 28, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 281615
SWODY1
SPC AC 281614

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1114 AM CDT FRI MAY 28 2010

VALID 281630Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER ERN MT AND WRN ND...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE TN VALLEY EWD INTO VA
AND THE CAROLINAS...

...ERN MT AND WRN ND...
COLD FRONT STRETCHED FROM NORTH CENTRAL ND SWWD INTO CENTRAL WY WITH
AREAS OF WEAK LOW PRESSURE LOCATED ALONG THE FRONT IN FAR SWRN ND
AND SWRN WY. WATER VAPOR LOOPS SHOW A STRONG SHORTWAVE
TROUGH...MOVING NEWD ACROSS NV THIS MORNING...WILL MOVE INTO THE
GREAT BASIN/NRN ROCKIES TONIGHT. WHILE ENVIRONMENTAL CONDITIONS
NORTH OF THE FRONT ARE COOL AND STABLE...APPROACHING SHORTWAVE
TROUGH SHOULD DRIVE WY LOW NEWD INTO SERN MT OVERNIGHT AND RETURN
UNSTABLE AIR MASS BACK INTO PORTIONS OF ERN MT/WRN ND OVERNIGHT. THE
COMBINATION OF INCREASING FORCING AND RETURNING INSTABILITY SHOULD
AID IN THUNDERSTORMS FORMING AFTER DARK NEAR OR NORTH OF THE SURFACE
BOUNDARY ACROSS ERN MT...AND PERHAPS FAR NERN WY. AS THESE STORMS
SPREAD/DEVELOP NEWD ACROSS ERN MT AND WRN ND...MOSTLY ELEVATED
SUPERCELLS CAPABLE OF VERY LARGE HAIL APPEARS TO BE THE PRIMARY
THREAT. HOWEVER...GIVEN THE STRONG LOW/DEEP LAYER SHEAR...DAMAGING
WINDS OR AN ISOLATED TORNADO WOULD BE POSSIBLE WITH ANY STORMS THAT
ARE ABLE TO INGEST THE STRONGER BOUNDARY LAYER INSTABILITY NEAR THE
LOW PRESSURE/FRONT.

...TN VALLEY EWD INTO THE VA AND THE CAROLINAS...
SHEAR IS FAIRLY WEAK ACROSS THE REGION...WHICH SHOULD RESULT IN
MOSTLY PULSE TYPE STORMS ACROSS THE REGION. HOWEVER...A WEAK UPPER
LEVEL LOW...EVIDENT IN WATER VAPOR IMAGERY OVER FAR SRN IL...IS
FORECAST TO MOVE SWD INTO SWRN TN BY 00Z...RESULTING IN WEAK FORCING
ACROSS THE REGION. THIS UPPER FEATURE WAS ALREADY RESULTING IN A FEW
THUNDERSTORMS FROM CENTRAL KY INTO TN AND SHOULD AID IN NUMEROUS
THUNDERSTORMS DEVELOPING ACROSS THE SLIGHT RISK AREA...ESPECIALLY
FROM 18Z-01Z. WHILE VERY WEAK DEEP LAYER SHEAR VALUES WILL LIMIT
CONVECTIVE ORGANIZATION..RESULTING IN CHAOTIC STORM MOTIONS AND
INTERACTIONS...500 MB TEMPERATURES FROM -10C TO -12C...MLCAPES NEAR
3000 J/KG AND A VERY MOIST BOUNDARY LAYER WILL FAVOR STORMS WITH
LOCALIZED DOWNBURSTS AND ISOLATED SEVERE HAIL AROUND 1 INCH.

..IMY/BOTHWELL.. 05/28/2010

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