Thursday, March 4, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 040519
SWODY1
SPC AC 040517

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1117 PM CST WED MAR 03 2010

VALID 041200Z - 051200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
AS THE UPSTREAM PATTERN BEGINS TO AMPLIFY...MODELS SUGGEST THAT THE
SOUTHERN PORTION OF A SPLITTING SHORT WAVE TROUGH OVER THE NORTHEAST
PACIFIC WILL BEGIN TO DIG AND GRADUALLY EVOLVE INTO ANOTHER
SIGNIFICANT CLOSED LOW DURING THIS PERIOD. WHILE THIS FEATURE IS
EXPECTED TO REMAIN GENERALLY WEST OF THE PACIFIC COAST
...IT IS ALREADY CLOSE ENOUGH TO CONTRIBUTE TO THE EASTWARD
PROGRESSION OF A DOWNSTREAM CLOSED LOW...INLAND AND ACROSS THE
SIERRA NEVADA. GUIDANCE INDICATES THAT THIS LEAD IMPULSE WILL
ADVANCE ACROSS THE GREAT BASIN AND CENTRAL ROCKIES BY 12Z FRIDAY
...SLOWLY WEAKENING WITHIN BROADER SCALE RIDGING.

OTHERWISE...LITTLE CHANGE TO THE LARGE-SCALE BLOCKING PATTERN
ENCOMPASSING MUCH OF NORTH AMERICA IS FORECAST. SURFACE RIDGING
APPEARS LIKELY TO REMAIN PROMINENT ACROSS MUCH OF THE EASTERN U.S.
AND THE GULF OF MEXICO...BENEATH A LINGERING CONFLUENT MID-LEVEL
FLOW REGIME. THIS WILL CONTINUE TO CONTRIBUTE TO GENERALLY STABLE
CONDITIONS WITH LOW TO NEGLIGIBLE CONVECTIVE POTENTIAL ACROSS MOST
AREAS.

...GREAT BASIN...
A MODEST INFLUX OF PACIFIC MOISTURE AHEAD OF THE INLAND PROGRESSING
CLOSED LOW/SHORT WAVE TROUGH IS ALREADY BECOMING CUT- OFF. AND
MOISTURE ACROSS MUCH OF THE INTERMOUNTAIN WEST IS LIMITED.
HOWEVER...LARGE-SCALE ASCENT AND COOLING ALOFT ASSOCIATED WITH THE
IMPULSE APPEAR LIKELY TO REMAIN SUFFICIENT TO SUPPORT AT LEAST LOW
PROBABILITIES FOR THUNDERSTORMS TODAY. THE BEST CHANCE FOR THIS
POTENTIAL BECOMING REALIZED APPEARS TO BE ACROSS UTAH...WHERE
STRONGEST DIFFERENTIAL THERMAL ADVECTION ON THE LEADING EDGE OF THE
MID-LEVEL COLD CORE IS EXPECTED TO BECOME FOCUSED DURING THE PEAK
AFTERNOON HEATING HOURS.

..KERR/STOPPKOTTE/GARNER.. 03/04/2010

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