SWODY1
SPC AC 050545
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1145 PM CST WED MAR 04 2009
VALID 051200Z - 061200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS INDICATE THAT SHARP UPPER RIDGING OVER THE NORTHEAST PACIFIC
WILL BE FLATTENED DURING THIS FORECAST PERIOD...AS A VIGOROUS SHORT
WAVE TROUGH PROGRESSES ACROSS AND EAST OF THE ALEUTIANS. THE
LINGERING RIDGE AXIS IS PROGGED TO SHIFT INTO BRITISH COLUMBIA AND
PACIFIC NORTHWEST COASTAL AREAS...BUT FLOW WILL REMAIN SPLIT
DOWNSTREAM...INTO LARGER-SCALE TROUGHING ACROSS MUCH OF THE INTERIOR
WEST AND CENTRAL CANADA. AS ONE SIGNIFICANT EMBEDDED SHORT WAVE
IMPULSE DIGS INTO SOUTHERN STREAM TROUGHING OVER THE WESTERN
U.S....ANOTHER IMPULSE IS PROGGED TO ACCELERATE INLAND ACROSS THE
CENTRAL CALIFORNIA COAST...BECOMING INCREASINGLY SHEARED IN A
CONFLUENT REGIME EXTENDING INTO THE GREAT BASIN. AT THE SAME
TIME...A LOW AMPLITUDE DOWNSTREAM SHORT WAVE TROUGH...COMPRISED OF A
COUPLE OF SMALLER SCALE PERTURBATIONS...IS FORECAST TO LIFT OUT OF
THE GREAT BASIN THROUGH THE UPPER MISSISSIPPI VALLEY...WITHIN FAST
SOUTHWESTERLY UPPER FLOW TOPPING STRONG SUBTROPICAL RIDGING ACROSS
THE CENTRAL/SOUTHERN TIER STATES EAST OF THE ROCKIES. THIS LATTER
SYSTEM IS EXPECTED TO BE ACCOMPANIED BY A FAIRLY DEEP AND
CONSOLIDATING SURFACE LOW ACROSS THE UPPER MISSISSIPPI VALLEY/UPPER
GREAT LAKES REGION BY 12Z FRIDAY.
...NORTHERN HIGH PLAINS...
A MID-LEVEL COLD CORE...WITH 500 MB TEMPERATURES OF -30 TO -32C...
IS PROGGED TO MIGRATE ACROSS THE BIG HORNS INTO THE ADJACENT
NORTHERN PLAINS DURING THE PEAK AFTERNOON HEATING HOURS TODAY.
DESPITE FAIRLY COOL/DRY LOW-LEVELS...FORECAST SOUNDINGS INDICATE
THAT THIS WILL CONTRIBUTE TO A STEEP LAPSE RATE ENVIRONMENT
SUPPORTIVE OF DEEP CONVECTIVE DEVELOPMENT...MOSTLY ALONG/NORTH OF A
QUASI-STATIONARY FRONT EXTENDING EAST OF THE MOUNTAINS INTO SOUTHERN
SOUTH DAKOTA. AIDED BY OROGRAPHIC FORCING...A FEW STORMS ARE
EXPECTED TO INITIATE ACROSS THE HIGHER TERRAIN BY 18-20Z.
AND...ONCE FORMED...LARGE-SCALE FORCING...COUPLED WITH A MODEST
WESTERLY MEAN CLOUD BEARING LAYER FLOW FIELD...APPEAR SUFFICIENT TO
MAINTAIN ACTIVITY EASTWARD ACROSS PARTS OF SOUTHEAST MONTANA AND
NORTHEAST WYOMING INTO WESTERN SOUTH DAKOTA PRIOR TO NIGHTFALL.
...REMAINDER OF THE NATION EAST OF THE ROCKIES...
GIVEN THE NORTHERN LATITUDE OF THE SURFACE CYCLONE...THE SLOW
BOUNDARY LAYER MODIFICATION OVER THE WESTERN GULF OF MEXICO...AND
WEAK INLAND RETURN FLOW...CONVECTIVE POTENTIAL IS EXPECTED TO REMAIN
NEGLIGIBLE THROUGH THIS PERIOD.
...CALIFORNIA COAST...
WITH THE PRIMARY MID-LEVEL CYCLONIC VORTICITY CENTER FORECAST TO
WEAKEN AS IT MIGRATES INLAND NEAR/SOUTH OF MONTEREY THIS AFTERNOON
...WEAK TO NEGLIGIBLE DESTABILIZATION APPEARS UNSUPPORTIVE OF AN
APPRECIABLE RISK FOR THUNDERSTORMS AT THE PRESENT TIME.
..KERR/JEWELL.. 03/05/2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment