Saturday, November 14, 2009

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 141845
SWODY2
SPC AC 141844

DAY 2 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
1244 PM CST SAT NOV 14 2009

VALID 151200Z - 161200Z

...NO SVR TSTM AREAS FORECAST...

CORRECTED FOR GEOGRAPHICAL DESCRIPTOR

...SYNOPSIS...

LARGE-SCALE PATTERN WILL REMAIN AMPLIFIED YET PROGRESSIVE THROUGH
THE DAY TWO PERIOD WITH THE PRIMARY FEATURE OF INTEREST BEING
MID/UPPER-LEVEL LOW WHICH WILL TRANSLATE GENERALLY EWD FROM THE
CNTRL/SRN ROCKIES INTO CNTRL/SRN PLAINS. MODEL DIFFERENCES IN THE
EVOLUTION OF THIS UPPER SYSTEM BECOME MORE APPARENT WITH TIME AS THE
GFS SUGGESTS CLOSED MID-LEVEL CIRCULATION OVER KS/OK BY 16/12Z. IN
CONTRAST...THE NAM MAINTAINS A MORE POSITIVELY-TILTED TROUGH
CONFIGURATION WITH THE CLOSED CIRCULATION SITUATED OVER THE SRN HIGH
PLAINS BY MONDAY MORNING. THE GFS SOLUTION IS QUITE SIMILAR TO THAT
OF THE 14/00Z ECMWF AND GENERALLY FOLLOWED FOR THIS FORECAST.

AT THE SURFACE...WRN EXTENSION OF SYNOPTIC COLD FRONT INITIALLY
ORIENTED IN E-W FASHION FROM THE MID MS VALLEY INTO SRN HIGH PLAINS
WILL PIVOT CYCLONICALLY THROUGH THE PERIOD AS BROAD SURFACE LOW
DEVELOPS FROM THE SRN PLAINS INTO MID MS VALLEY. ANY THREAT FOR
STRONG TO SEVERE TSTMS IS EXPECTED TO BECOME FOCUSED ALONG COLD
FRONT FROM SERN OK/WRN AR INTO CNTRL TX SUNDAY AFTERNOON INTO
NIGHT.

...SERN OK/WRN AR INTO CNTRL TX...

THE RETURN OF A MODIFIED CP AIR MASS WILL CONTINUE ACROSS THE SRN
PLAINS THROUGH THE DAY ONE AND TWO PERIODS IN ADVANCE OF SYNOPTIC
COLD FRONT WITH DEWPOINTS EVENTUALLY INCREASING THROUGH THE 60S
WITHIN SYSTEM WARM SECTOR. HOWEVER...THE PRESENCE OF WIDESPREAD
CLOUDS AND WEAK LAPSE RATES WILL EFFECTIVELY LIMIT MLCAPE TO
GENERALLY LESS THAN 1000 J/KG.

SHORT WAVE TROUGH CURRENTLY PROGRESSING EWD THROUGH THE LOWER CO
VALLEY AND NRN BAJA/GULF OF CA IS EXPECTED TO PRECEDE PRIMARY UPPER
SYSTEM EWD ACROSS THE SRN PLAINS SUNDAY. FORCING FOR ASCENT
ASSOCIATED WITH THIS FEATURE COUPLED WITH FRONTAL CONVERGENCE ARE
EXPECTED TO SUPPORT AN INCREASE IN STORM COVERAGE AND INTENSITY
ALONG THE FRONT BY AFTERNOON FROM SERN OK INTO N-CNTRL TX. STORMS
SHOULD CONTINUE TO DEVELOP BOTH N AND S ALONG EWD-MOVING FRONTAL
ZONE SUNDAY NIGHT WITHIN WEAKLY UNSTABLE ENVIRONMENT.

WHILE DEEP-LAYER SHEAR WILL BE MORE THAN SUFFICIENT /I.E. 45-60 KT
THROUGH THE LOWEST 6 KM AGL/...THE ABSENCE OF A MORE ROBUST LLJ /AND
RESULTANT LOW-LEVEL SHEAR/ IN CONJUNCTION WITH THE WEAK LAPSE RATES
ARE EXPECTED TO LIMIT THE POTENTIAL FOR A MORE SUBSTANTIAL SEVERE
WEATHER THREAT. NONETHELESS...SETUP WILL BE SUPPORTIVE OF
EPISODIC...EMBEDDED SUPERCELL AND/OR BOWING STRUCTURES CAPABLE OF
MAINLY STRONG WIND GUSTS AND PERHAPS A BRIEF TORNADO DURING THE
AFTERNOON AND NIGHTTIME HOURS.

..MEAD.. 11/14/2009

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