SWODY1
SPC AC 281248
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0748 AM CDT WED OCT 28 2009
VALID 281300Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SRN PLNS...
...SYNOPSIS...
POWERFUL NLY JET STREAK /WITH 250 MB WIND AROUND 200 KTS/ NOW OVER
THE WRN GRT BASIN WILL CONTINUE SWD TODAY TO FURTHER DEEPEN INTENSE
UPR LOW CENTERED ALONG THE AZ/UT BORDER. THE LOW SHOULD TURN E INTO
SRN CO/NRN NM EARLY THU AS SSW TO SWLY FLOW BACKS AND STRENGTHENS
OVER THE PLAINS.
AT THE SFC...LEE CYCLONE WILL REDEVELOP SLOWLY E ACROSS ERN NM/W TX
TODAY/EARLY TONIGHT...BEFORE ELONGATING NNE ACROSS WRN OK AND
WRN/CNTRL KS LATER TONIGHT/EARLY THU. IN SO DOING...ASSOCIATED COLD
FRONT WILL SWEEP E ACROSS THE SRN HI PLNS AND OVERTAKE EXISTING LEE
TROUGH BY MID EVE. FARTHER SE...WRN END OF FRONT ASSOCIATED WITH
IMPULSE NOW IN PA WILL REFORM NWD ACROSS SE TX/SRN LA.
...SRN PLNS...
SATELLITE PW DATA SHOW MOISTURE ALREADY BEGINNING TO SPREAD N ACROSS
THE NWRN GULF OF MEXICO ATTM AS LOW LVL SLY FLOW STRENGTHENS
DOWNSTREAM FROM WRN TROUGH. MOISTURE WILL CONTINUE TO SPREAD N IN A
FAIRLY BROAD SWATH ACROSS THE SRN AND CNTRL PLNS THROUGH THE PERIOD.
PW AOA 1.25 INCHES SHOULD REACH THE RED RVR BY 00Z THU...WITH
VALUES AROUND 1.50 INCHES LIKELY INTO SRN KS BY 12Z. SFC DEWPOINTS
SHOULD MARKEDLY INCREASE AS WELL...WITH THE 60 F ISODROSOTHERM TO
THE RED RVR BY EVE...AND INTO SRN KS EARLY THU.
DESPITE THE INCREASING MOISTURE...SUBSTANTIAL CIN SHOULD PROHIBIT
DAYTIME STORM DEVELOPMENT ALONG LEE TROUGH IN W TX...ALTHOUGH SCTD
SHOWERS COULD ACCOMPANY COLD FRONT IN NM.
COMBINATION OF INCREASING MOISTURE...LARGE SCALE FORCING FOR
ASCENT...AND STRENGTHENING LOW LVL CONVERGENCE WILL...HOWEVER...
LIKELY LEAD TO RAPID DEVELOPMENT OF A BAND OF STORMS AS COLD FRONT
OVERTAKES LEE TROUGH FROM THE CNTRL/ERN TX PANHANDLE NWD INTO SW KS
THIS EVE. THE BAND OF STORMS SHOULD DEVELOP BOTH NWD AND SWD WITH
TIME...AND LIKELY WILL EXTEND FROM NEAR JCT NNE INTO CNTRL KS BY 12Z
THU.
THE TIME OF DAY WILL LIMIT LOW LVL LAPSE RATES/CAPE. IN ADDITION
...THE STORMS LIKELY WILL REMAIN SLIGHTLY ELEVATED ATOP THE FRONT
WITH NWD EXTENT ACROSS OK/KS. BUT WITH EVEN MODEST INSTABILITY
...STRENGTHENING DEEP SSWLY WIND FIELD /700 MB SPEEDS AOA 50 KTS/
NEARLY PARALLEL TO FRONT WILL YIELD AN ENVIRONMENT FAVORABLE FOR
BROKEN LINE SEGMENTS WITH EMBEDDED SUPERCELLS/SMALL BOWS. THESE
WILL HAVE THE POTENTIAL FOR DMGG SFC WINDS AND...ESPECIALLY FROM W
CNTRL TX INTO SW OK...TORNADOES.
...SE TX INTO SRN LA...
A SEPARATE AREA OF LOW PROBABILISTIC SVR THREAT MAY DEVELOP LATE IN
THE PERIOD /AFTER 06Z/ WITH SHOWERS AND POSSIBLE STORMS INVOF
AFOREMENTIONED WARM FRONT OVER SE TX AND SRN LA. THIS THREAT WOULD
EVOLVE FROM DEEPENING AND STRENGTHENING OF EXISTING LOW-TOPPED
CONVECTION OCCURRING IN RESPONSE TO PERSISTENT MOISTENING/UPLIFT
AHEAD OF WRN TROUGH. COMBINATION OF HI PW /AROUND 2 INCHES/ AND
MODERATELY SHEARED LOW LVL WIND FIELD COULD POSE A THREAT FOR ISOLD
TORNADOES...IF SUSTAINED DISCRETE STORMS DO INDEED DEVELOP.
..CORFIDI/GRAMS.. 10/28/2009
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