DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 191614
SWODY1
SPC AC 191611

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1111 AM CDT SAT MAY 19 2007

VALID 191630Z - 201200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF CENTRAL/EASTERN
MT AND NORTHEAST WY...

BROAD UPPER RIDGE PERSISTS OVER THE CENTRAL PLAINS TODAY. WATER
VAPOR LOOPS SHOW ONE STRONG SHORTWAVE MOVING INLAND ACROSS WA/ORE
INTO ID...WHILE ANOTHER OVER ND/MN IS TURNING SOUTHEASTWARD AROUND
UPPER RIDGE INTO THE GREAT LAKES. STRONGER WESTERLIES ARE CONFINED
TO THE NORTHERN PLAINS...WHERE GREATER THREAT OF ORGANIZED
THUNDERSTORMS WILL BE PRESENT TODAY.

..MT...
UPPER TROUGH NOW APPROACHING BOI WILL TRACK EASTWARD AND INTO
WESTERN MT BY THIS AFTERNOON. RELATIVELY STRONG LARGE SCALE FORCING
FOR ASCENT WILL OVERSPREAD THE MOUNTAINS OF WESTERN/CENTRAL MT WHERE
SUNNY SKIES AND STEEPENING LAPSE RATES ARE HELPING TO DESTABILIZE
AIR MASS. SCATTERED THUNDERSTORMS WILL DEVELOP OVER THE HIGHER
TERRAIN SOUTH OF GTF AND WEST OF BIL...SPREADING EASTWARD INTO THE
ADJACENT PLAINS DURING THE LATE AFTERNOON AND EVENING. LOW LEVEL
TRAJECTORIES OVER NORTHEAST MT WILL LIKELY LIMIT RETURN OF GREATER
MOISTURE AND UNSTABLE AIR. THIS MAY CONFINE GREATER RISK OF SEVERE
STORMS TO HLN/LWT SOUTHWARD. FORECAST SOUNDINGS IN THIS REGION
APPEAR FAVORABLE FOR HIGH BASED SUPERCELLS CAPABLE OF LARGE HAIL AND
DAMAGING WINDS. EVOLUTION INTO SQUALL LINE IS POSSIBLE THIS EVENING
AS STORMS MOVE EASTWARD INTO SOUTHEAST MT AND PERHAPS NORTHEAST WY.

..WI/MN/SD/NEB...
WEAK COLD FRONT EXTENDS FROM NEAR DLH - HON - RAP. THIS BOUNDARY IS
LIKELY TO CONTINUE MOVING SLOWLY SOUTHEASTWARD THROUGH THE DAY AS
SHORTWAVE TROUGH OVER MN SHIFTS EASTWARD. CONVERGENCE ALONG
FRONT...COUPLED WITH STEEP LOW LEVEL LAPSE RATES AND DAYTIME HEATING
MAY RESULT IN ISOLATED THUNDERSTORMS ANYWHERE FROM CENTRAL WI INTO
WESTERN NEB. VERTICAL SHEAR PROFILES ARE RELATIVELY WEAK THROUGHOUT
THE REGION...BUT STRONGEST OVER MN/WI /25-30 KNOTS OF EFFECTIVE
SHEAR/. ISOLATED...SLOW MOVING THUNDERSTORMS ALONG THIS BOUNDARY
WILL POSE A RISK OF LOCALLY GUSTY WINDS AND HAIL THIS AFTERNOON AND
EVENING. AREAL COVERAGE AND ORGANIZATION OF STORMS IS FORECAST TO
BE TOO LOW TO WARRANT A SLIGHT RISK.

..FL...
MOIST AND MODERATELY UNSTABLE AIR MASS REMAINS OVER THE SOUTHERN FL
PENINSULA TODAY WITH DEWPOINTS IN THE MID/UPPER 60S AND STRONG
HEATING. SIMILAR TO YESTERDAY...COMBINATION OF SEA BREEZE
INTERACTIONS AND SLOW MOVING COLD FRONT MAY RESULT IN SCATTERED
AFTERNOON THUNDERSTORMS. GUSTY WINDS AND HAIL ARE POSSIBLE IN
STRONGEST CELLS.

.HART/JEWELL.. 05/19/2007

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