SWODY2
SPC AC 021729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CST THU FEB 02 2012
VALID 031200Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF CENTRAL/SRN OK
AND NRN TX INTO SOUTH CENTRAL AR/FAR NWRN LA...
...SYNOPSIS...
A LARGE CLOSED LOW FORMING DURING DAY 1 ACROSS MUCH OF THE U.S.
ROCKIES INTO THE WRN PART OF THE PLAINS STATES IS EXPECTED TO BECOME
CUTOFF FROM THE NRN STREAM BY THE START OF DAY 2. HEIGHT RISES
ACROSS WRN TO CENTRAL CANADA WILL SUPPORT THE EVOLUTION OF AN OMEGA
BLOCK WEST OF THE MS RIVER VALLEY ON FRIDAY. A SHORTWAVE TROUGH AND
STRONG SPEED MAX MOVING INTO THE BASE OF THE DEVELOPING CLOSED LOW
BY 12Z FRIDAY ARE FORECAST TO EMERGE ENEWD INTO THE CENTRAL PLAINS
AND OK/N TX THIS FORECAST PERIOD...RESULTING IN AN E-W ELONGATION OF
THE MID-UPPER LEVEL CLOSED LOW.
AT THE SURFACE...MODEL CONSENSUS SUGGESTS AN AREA OF LOW PRESSURE
/INITIALLY LOCATED OVER WRN TX 12Z FRIDAY BETWEEN LBB/MAF/ WILL
TRACK NEWD INTO NWRN TX/SWRN OK BY 04/00Z AND REACH SWRN MO/NWRN AR
BY 12Z SATURDAY. SLY LOW LEVEL FLOW WILL CONTINUE TO ADVECT
MOISTURE NWD FROM DAY 1 INTO DAY 2...WITH A WARM FRONT BECOMING
REPOSITIONED FROM NRN OK EWD ALONG THE AR/MO BORDER TO THE KY/TN
BORDER BY AFTERNOON/EARLY EVENING. MEANWHILE...A COLD FRONT
TRAILING SSWWD FROM THE LOW WILL PROGRESS E/SEWD FRIDAY NIGHT ACROSS
MUCH OF OK INTO CENTRAL TX.
...SRN PLAINS TO AR/NWRN LA...
GIVEN THE TRACK OF THE SURFACE LOW INTO NWRN TX/SWRN OK AREA BY LATE
FRIDAY AFTERNOON AND THE SUBSEQUENT POTENTIAL FOR SEVERE WEATHER
ACROSS THESE AREAS...THE DAY 2 SLIGHT RISK HAS BEEN EXPANDED A
LITTLE WWD. OTHERWISE...THE REST OF THE SLIGHT RISK HAS REMAINED
UNCHANGED WITH THIS OUTLOOK ISSUANCE.
PER THE DAY 1 DISCUSSION...TSTMS /SOME SEVERE/ SHOULD BE ONGOING
INTO MUCH OF CENTRAL OK AND PARTS OF SRN KS AT 12Z FRIDAY. THIS
ACTIVITY SHOULD ADVANCE EWD DURING THE FORECAST PERIOD...WITH
ADDITIONAL DETAILS IN THE FORECAST SUBSECTION BELOW FOR MO/NRN AR TO
THE LOWER OH VALLEY REGION. MEANWHILE...MODELS SUGGEST THE
STRONGEST DPVA AND SWLY MIDLEVEL WINDS WILL REMAIN N OF THE SURFACE
BOUNDARIES AND WARM SECTOR DURING DAY 2. HOWEVER...DIFFLUENT FLOW
ALOFT AND CONTINUED LOW LEVEL MOISTENING/WARM AIR ADVECTION WILL
SUPPORT SUFFICIENT DESTABILIZATION FOR SURFACE BASED STORMS.
CLOUDINESS ASSOCIATED WITH DAY 1 CONVECTION MAY TEND TO LIMIT
SURFACE HEATING AND THE DEVELOPMENT FOR STRONGER INSTABILITY.
HOWEVER...ASCENT ON THE SRN EXTENT OF THE APPROACHING UPSTREAM
TROUGH/SPEED MAX IS EXPECTED TO SUPPORT NEW TSTM DEVELOPMENT OVER
NRN/WRN OK INTO NWRN TX...WITH ACTIVITY ADVANCING EWD FRIDAY
EVENING/NIGHT ALONG THE COLD FRONT. INCREASING EFFECTIVE BULK SHEAR
WILL SUPPORT MIXED STORM MODES WITH ALL SEVERE WEATHER THREATS
POSSIBLE.
BY LATE IN THE FORECAST PERIOD /04/06-12Z/...PERSISTENT BOUNDARY
LAYER DESTABILIZATION INTO SRN/CENTRAL AR SUGGESTS PARCELS WILL BE
NEAR SURFACE BASED...AND THUS COULD POSE A SEVERE WEATHER THREAT AS
THE COLD FRONT APPROACHES FROM THE WEST.
...MO/NRN AR/LOWER OH VALLEY REGION...
12Z NAM/GFS AND 00Z ECMWF INDICATED A LEAD WEAK IMPULSE SHOULD MOVE
NEWD INTO SHORTWAVE RIDGING FROM ERN KS/MO/OZARKS TO LOWER OH VALLEY
FRIDAY AFTERNOON/NIGHT. SOME FORCING FOR ASCENT ALOFT COMBINED WITH
STRONG LOW LEVEL WAA FROM KS/MO INTO THE LOWER OH VALLEY WILL
SUPPORT DESTABILIZATION EWD WITH TIME ATOP A STABLE BOUNDARY LAYER.
MUCAPE GENERALLY LESS THAN 500 J/KG ROOTED AROUND 850 MB AND WEAK
EFFECTIVE BULK SHEAR SUGGEST A FEW STORMS MAY PRODUCE HAIL
APPROACHING 1 INCH DIAMETER AS FAR N AS SRN MO/NERN AR. THUS...LOW
SEVERE WEATHER PROBABILITY /MAINLY FOR A HAIL THREAT/ HAS BEEN
EXTENDED INTO NERN AR/SRN MO.
..PETERS.. 02/02/2012
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