Tuesday, September 14, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 141239
SWODY1
SPC AC 141238

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0738 AM CDT TUE SEP 14 2010

VALID 141300Z - 151200Z

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

...CENTRAL/NORTHERN PLAINS...
A FLAT UPPER RIDGE WILL REMAIN OVER THE SOUTHERN UNITED STATES
TODAY...WHILE RELATIVELY FAST WESTERLY FLOW PERSISTS OVER THE
CENTRAL/NORTHERN STATES. MORNING WATER VAPOR IMAGERY AND MODEL
GUIDANCE AGREE THAT FORCING MECHANISMS OVER THE ROCKIES ARE WEAK AND
HARD TO IDENTIFY /SIMILAR TO YESTERDAY/. NEVERTHELESS...THE
ENVIRONMENT OVER THE CENTRAL/NORTHERN HIGH PLAINS WILL BECOME
INCREASINGLY FAVORABLE FOR ISOLATED INTENSE THUNDERSTORMS BY LATE
AFTERNOON. STEEP LOW/MID LEVEL LAPSE RATES WILL COMBINE WITH FULL
SUNSHINE AND 30-40 KNOTS OF EFFECTIVE SHEAR TO PROMOTE SUPERCELL
STORM STRUCTURES WHEN/WHERE DEEP CONVECTION CAN DEVELOP. THIS WILL
LIKELY BE NEAR THE SURFACE LEE TROUGH AS LOW LEVEL CYCLOGENESIS
OCCURS BY LATE AFTERNOON/EVENING. ISOLATED SEVERE STORMS CAPABLE OF
DAMAGING WINDS AND HAIL ARE POSSIBLE IN AN AXIS FROM WESTERN SD INTO
WESTERN KS. STORMS MAY PERSIST WELL INTO THE NIGHT WITH RISK OF
STRONG/SEVERE STORMS SHIFTING EASTWARD ACROSS PARTS OF SD/NEB/KS
OVERNIGHT.

ELSEWHERE ACROSS THE NATION...A FEW THUNDERSTORMS CAPABLE OF
DAMAGING WINDS AND SOME HAIL WILL OCCUR OVER PARTS OF MT/ID AS
HEATING OVER THE MOUNTAINS AIDS CONVECTIVE DEVELOPMENT IN
ENVIRONMENT OF STEEP LAPSE RATES AND STRONG FLOW ALOFT. LIMITED
MOISTURE WILL PRECLUDE A MORE ROBUST SEVERE EVENT.

OTHER STRONG STORMS WILL BE POSSIBLE SOUTHWARD ALONG THE LEE TROUGH
FROM WESTERN KS INTO WESTERN OK. STRONG HEATING AND WEAK BUT
SUFFICIENT VERTICAL SHEAR MAY LEAD TO ANOTHER BOUT OF LOCALLY
INTENSE STORMS TODAY.

..HART/STOPPKOTTE.. 09/14/2010

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