Wednesday, August 15, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 160100
SWODY1
SPC AC 160057

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0757 PM CDT WED AUG 15 2007

VALID 160100Z - 161200Z

..THERE IS A SLGT RISK OF SVR TSTMS THIS EVE ACROSS PARTS OF THE
MIDDLE MISSISSIPPI VALLEY INTO PARTS OF THE GREAT LAKES REGION....

..THERE IS A SLGT RISK OF SVR TSTMS TONIGHT ACROSS PARTS OF LWR/MID
TX COASTAL AREAS....

..SYNOPSIS...
THE BULK OF THE CONVECTIVE DEVELOPMENT TODAY HAS BEEN MOSTLY
CONFINED TO PORTIONS OF THE INTERMOUNTAIN WEST/ROCKIES...IN
ASSOCIATION WITH MONSOONAL MOISTURE PLUME AND STRONG HEATING ACROSS
THE HIGHER TERRAIN. MUCH OF THIS ACTIVITY IS EXPECTED TO BEGIN TO
DIMINISH MORE RAPIDLY BY THE 02-04Z TIME FRAME...AS THE BOUNDARY
LAYER BEGINS TO COOL WITH THE LOSS OF DAYTIME HEATING. THIS
INCLUDES THE CLUSTER OF STRONG/ISOLATED SEVERE STORMS WHICH HAS
DEVELOPED EAST OF THE COLORADO FRONT RANGE INTO THE CENTRAL HIGH
PLAINS...PERHAPS SUPPORTED BY FORCING ACCOMPANYING A WEAK
CONVECTIVELY GENERATED OR ENHANCED MID-LEVEL IMPULSE WITHIN THE
MOISTURE PLUME.

EAST OF THE ROCKIES...WITH A COUPLE OF EXCEPTIONS...WEAKENING/
DIMINISHING TRENDS ARE ALREADY WELL UNDERWAY WITH RATHER SPARSE
ONGOING THUNDERSTORM ACTIVITY.

..UPR MIDDLE MISSISSIPPI VALLEY INTO THE SRN GREAT LAKES...
AS A VIGOROUS SHORT WAVE TROUGH WITHIN THE MAIN BELT OF POLAR
WESTERLIES DIGS FROM MANITOBA INTO ONTARIO TONIGHT...A BROAD LOWER
AMPLITUDE IMPULSE WITHIN THE WEAK SUBTROPICAL WESTERLIES IS PROGGED
TO SHIFT EASTWARD THROUGH THE SOUTHERN/LOWER GREAT LAKES REGION.
STRONGER LOW/MID-LEVEL WARM ADVECTION ASSOCIATED WITH THIS FEATURE
IS NOW SPREADING ACROSS PARTS OF NORTHERN ILLINOIS/INDIANA...TO THE
NORTH OF A SIGNIFICANT FRONTAL ZONE. THIS APPEARS TO BE
CONTRIBUTING TO RECENT INTENSIFICATION OF STORMS ACROSS THE CHICAGO
AREA. AND...FURTHER DEVELOPMENT INTO GROWING CONVECTIVE CLUSTER
STILL APPEARS POSSIBLE THIS EVENING...WITHIN A MODERATE TO STRONGLY
UNSTABLE ENVIRONMENT CHARACTERIZED BY MOST UNSTABLE CAPE OF
2000-3000 J/KG. IF THIS OCCURS...A 30-40 KT MEAN WESTERLY FLOW
REGIME WITH MODERATE TO STRONG DEEP LAYER SHEAR WILL CONTRIBUTE TO
ORGANIZATION AND POTENTIAL FOR HAIL AND STRONG GUSTY WINDS. THIS
THREAT SHOULD DIMINISH OVERNIGHT AS STRONGER FORCING BEGINS TO
DEVELOP INTO LESS MOIST/POTENTIALLY LESS UNSTABLE ENVIRONMENT ACROSS
THE LOWER GREAT LAKES REGION.

..LOWER/MID TEXAS COASTAL AREAS...
STRENGTHENING WIND FIELDS/LOW-LEVEL SHEAR ASSOCIATED WITH THE
APPROACH OF ERIN WILL SUPPORT INCREASING POTENTIAL FOR ISOLATED
TORNADOES LATE TONIGHT. THE BOUNDARY LAYER ACROSS THIS REGION IS
ALREADY FAVORABLY WARM...VERY MOIST WITH SURFACE DEW POINTS IN THE
MID/UPPER 70S...AND POTENTIALLY UNSTABLE.

.KERR.. 08/16/2007

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