SWODY2
SPC AC 261716
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1216 PM CDT TUE MAY 26 2009
VALID 271200Z - 281200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
STRONGER WESTERLIES WILL REMAIN NEAR OR JUST NORTH OF THE
CANADIAN/U.S. BORDER THROUGH THIS FORECAST PERIOD. IN A WEAKER
STREAM TO THE SOUTH...UPPER RIDGING APPEARS LIKELY TO BROADEN ACROSS
PARTS OF THE PACIFIC NORTHWEST/INTERMOUNTAIN REGION AND
NORTHERN/CENTRAL ROCKIES WEDNESDAY...DOWNSTREAM OF AN AMPLIFYING
UPPER TROUGH OVER THE EASTERN PACIFIC. AS THIS OCCURS...A
DOWNSTREAM TROUGH IS PROGGED TO FINALLY SHIFT EAST OF THE PLAINS. A
CONSOLIDATING LOWER/MID TROPOSPHERIC CYCLONE ACCOMPANYING THIS
LATTER FEATURE IS PROGGED TO MIGRATE FROM UPPER PORTIONS OF THE
MIDDLE MISSISSIPPI VALLEY THROUGH THE GREAT LAKES REGION. WHILE A
TRAILING COLD FRONT MAY SLOWLY ADVANCE SOUTHEASTWARD THROUGH PARTS
OF THE MIDDLE MISSISSIPPI VALLEY...THE BOUNDARY IS EXPECTED TO
WEAKEN/BECOME MORE DIFFUSE ACROSS THE OZARK PLATEAU INTO THE
SOUTHERN PLAINS.
...SRN/ERN TEXAS THROUGH THE LOWER GREAT LAKES REGION...
INTERACTING IMPULSES WITHIN WEAK POLAR AND SUBTROPICAL STREAMS MAY
CONTRIBUTE AN EVOLVING PRE-FRONTAL CLUSTER OR CLUSTERS OF STORMS
LATER TODAY/TONIGHT...WHICH COULD LINGER INTO EARLY WEDNESDAY BEFORE
DIMINISHING ACROSS PARTS OF SOUTHERN/EASTERN TEXAS.
HOWEVER...CONSIDERABLE SPREAD EXISTS AMONG MODEL DATA CONCERNING
THIS POSSIBLE DEVELOPMENT...WHICH IN TURN WILL PROBABLY HAVE A
SUBSTANTIAL IMPACT ON POTENTIAL DESTABILIZATION FROM PARTS OF THE
RIO GRANDE VALLEY INTO THE LOWER MISSISSIPPI VALLEY LATER
WEDNESDAY/WEDNESDAY NIGHT. WHERE BOUNDARY LAYER HEATING
OCCURS...LOW-LEVEL MOISTURE CHARACTERIZED BY DEW POINTS NEAR 70F
APPEARS LIKELY TO BE SUPPORTIVE OF MIXED LAYER CAPE OF 2000-3000
J/KG. AND...THIS WILL PROVIDE POTENTIAL FOR THE DEVELOPMENT OF A
FEW STRONG/GENERALLY HIGHLY LOCALIZED SEVERE STORMS CAPABLE OF
PRODUCING GUSTY WINDS AND SOME HAIL.
DESTABILIZATION MAY NOT BE QUITE AS STRONG FARTHER TO THE
NORTH...ACROSS THE MIDDLE MISSISSIPPI/LOWER OHIO VALLEYS INTO THE
GREAT LAKES...BUT STRONGER FORCING IN CLOSER PROXIMITY TO THE
SURFACE LOW IS EXPECTED TO COMPENSATE...CONTRIBUTING TO A FAIRLY
HIGH LIKELIHOOD OF CONVECTIVE DEVELOPMENT. DEEP LAYER SHEAR IS
EXPECTED TO BE GENERALLY WEAK...BUT SOUTHWESTERLY MEAN FLOW ON THE
ORDER OF 20 KTS...COUPLED WITH THE CONSOLIDATION OF CONVECTIVELY
GENERATED COLD POOLS...MAY BE ENOUGH TO CONTRIBUTE TO THE POTENTIAL
FOR GUSTY WINDS AT LEAST APPROACHING SEVERE LIMITS... MAINLY DURING
THE LATE AFTERNOON AND EARLY EVENING HOURS.
...FLORIDA...
MID-LEVEL CAPPING IS EXPECTED TO REMAIN WEAK WEDNESDAY...AND NCEP
SREF GUIDANCE SUGGESTS MODERATE DESTABILIZATION IS PROBABLE WITH
DAYTIME HEATING. THIS IS ONCE AGAIN EXPECTED TO FAVOR WIDESPREAD
THUNDERSTORM ACTIVITY ALONG THE SEA BREEZES...PARTICULARLY ACROSS
INTERIOR AND EASTERN PORTIONS OF THE PENINSULA...SOME OF WHICH MAY
BE ACCOMPANIED BY LOCALIZED DOWNBURSTS...PERHAPS SOME HAIL.
..KERR.. 05/26/2009
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