SWODY2
SPC AC 130547
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1147 PM CST MON DEC 12 2011
VALID 141200Z - 151200Z
...THERE IS A SLGT RISK OF SVR TSTMS WED AFTN AND EVE ACROSS PARTS
OF CNTRL AND NE TEXAS INTO THE ARKLATEX REGION...
...SYNOPSIS...
MODELS CONTINUE TO INDICATE THAT A 90-100+ KT SOUTHWESTERLY 500 MB
JET STREAK WILL NOSE ACROSS THE CENTRAL PLAINS TOWARD THE GREAT
LAKES REGION DURING THIS FORECAST PERIOD...ASSOCIATED WITH AN
INCREASINGLY SHEARED UPPER IMPULSE EMERGING FROM THE SOUTHERN
PLATEAU AND ROCKIES REGION. CONSIDERABLE VARIABILITY PERSISTS AMONG
THE MODELS CONCERNING THE INTERACTION OF THIS FEATURE WITH ANOTHER
IMPULSE DIGGING WITHIN A MORE NORTHERN STREAM ACROSS THE CENTRAL
CANADIAN/U.S. BORDER INTO THE UPPER MISSISSIPPI VALLEY. AND THIS
RESULTS IN UNCERTAINTY CONCERNING HOW SURFACE CYCLOGENESIS PROCEEDS
ACROSS THE CENTRAL PLAINS INTO THE GREAT LAKES REGION WEDNESDAY AND
WEDNESDAY NIGHT. IT CURRENTLY APPEARS THAT MORE RAPID DEEPENING OF
THE SURFACE LOW CENTER MAY NOT COMMENCE UNTIL LATE IN THE PERIOD
NEAR THE GREAT LAKES REGION. NEVERTHELESS...WIND FIELDS ARE STILL
PROGGED TO BE STRONG THROUGH MUCH OF THE WARM SECTOR OF THE
DEVELOPING LOW BY WEDNESDAY MORNING ...INCLUDING A 50+ KT SOUTH TO
SOUTHWESTERLY 850 MB JET...WHICH APPEARS LIKELY TO SHIFT FROM THE
CENTRAL AND SOUTHERN PLAINS THROUGH THE OHIO VALLEY AND GREAT LAKES
REGION BY 12Z THURSDAY.
...SOUTHERN PLAINS INTO MIDDLE MS AND LOWER OH VALLEYS...
GIVEN THE STRENGTH OF THE DEEP LAYER MEAN AMBIENT FLOW /50+ KT THRU
MUCH OF THE WARM SECTOR/ AND VERTICAL SHEAR...BOUNDARY LAYER
DESTABILIZATION REMAINS THE PRIMARY UNCERTAINTY IMPACTING THE SEVERE
WEATHER POTENTIAL FOR THIS PERIOD. A PLUME OF SEASONABLY HIGH
PRECIPITABLE WATER IS EXPECTED IN ASSOCIATION WITH AN INFLUX OF
MOISTURE OFF THE MODIFYING WESTERN GULF OF MEXICO BOUNDARY
LAYER...AHEAD OF A DEVELOPING COLD FRONT TRAILING FROM THE SURFACE
LOW. HOWEVER...IT APPEARS THAT MOISTENING WILL OCCUR ABOVE A
RESIDUAL COOL/STABLE NEAR SURFACE LAYER...WHICH GUIDANCE SUGGESTS
MAY NOT MODIFY MUCH PRIOR TO THE FRONTAL PASSAGE...PARTICULARLY
NORTH OF THE RED RIVER AND ARKLATEX REGION.
ACROSS CENTRAL INTO NORTHEAST TEXAS...IT DOES APPEAR THAT BOUNDARY
LAYER WARMING AND MOISTENING /SURFACE DEW POINTS INCREASING INTO THE
LOWER TO MID 60S/ WILL RESULT IN A LEAST A CORRIDOR OF WEAK TO
MODERATE BOUNDARY LAYER DESTABILIZATION BY LATE WEDNESDAY AFTERNOON.
ALTHOUGH STRONGER FLOW FIELDS MAY BE IN THE PROCESS OF LIFTING TO
THE NORTH OF THE REGION...VERTICAL SHEAR STILL SHOULD BE MORE THAN
FAVORABLE FOR ORGANIZED CONVECTIVE DEVELOPMENT...INCLUDING
SUPERCELLS...IN THE PRESENCE OF MIXED LAYER CAPE OF 500 TO 1000
J/KG. WITH STRONGEST MID-LEVEL FORCING FOR UPWARD VERTICAL MOTION
ALSO PASSING WELL TO THE NORTH...THE WINDOW OF OPPORTUNITY FOR
STRONG/SEVERE STORMS MAY BE SOMEWHAT LIMITED. HOWEVER...THE RISK
FOR LARGE HAIL... LOCALLY DAMAGING WIND GUSTS AND PERHAPS AN
ISOLATED TORNADO MAY PERSIST INTO THE EVENING HOURS BEFORE
DIMINISHING.
..KERR.. 12/13/2011
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