SWODY2
SPC AC 191730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CST MON NOV 19 2007
VALID 201200Z - 211200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
IN MID/UPPER LEVELS...PROGRESSIVE NRN STREAM PATTERN WILL RESULT IN
POSITIVELY TILTED TROUGHING FROM HUDSON BAY TO GREAT BASIN BY MIDDLE
OF PERIOD. SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL
IMAGERY INVOF COASTAL PACIFIC NW -- IS FCST TO MOVE ACROSS NRN
ROCKIES AROUND 20/12Z. THIS FEATURE THEN SHOULD DEAMPLIFY AND EJECT
NEWD FROM MEAN TROUGH POSITION...CROSSING UPPER MS VALLEY AND LS
DURING 21/00Z-21/06Z TIME FRAME. MEANWHILE...UPSTREAM SPEED MAX IS
FCST TO RESULT IN INTENSIFYING SHORTWAVE TROUGH MOVING FROM NRN
GREAT BASIN ESEWD TO CENTRAL ROCKIES BY END OF PERIOD. WEAK LOW NOW
OVER NRN MEX SHOULD DEVOLVE INTO OPEN-WAVE TROUGH AND EJECT NEWD
ACROSS S TX. MODELS APPEAR TO RESOLVE THIS FEATURE POORLY
INITIALLY...OVER PORTION OF MEX WITH SPARSE UPPER AIR DATA...AND
AMBIENT SRN STREAM PATTERN IS DIFFUSE. THEREFORE...FCSTS OF ITS
STRENGTH/TIMING ARE HIGHLY UNCERTAIN ATTM.
AT SFC...FRONTAL LOW IS EXPECTED OVER WRN/NRN KS BY
20/12Z...PROPAGATING NEWD ALONG FRONTAL ZONE TO LOWER GREAT LAKES
THROUGH 21/12Z. TRAILING COLD FRONT WILL MOVE SEWD ACROSS UPPER-MID
MS VALLEY...CENTRAL PLAINS AND SRN HIGH PLAINS...REACHING CLOSE TO
LINE FROM TOL-TBN-MWL-SJT BY END OF PERIOD.
..LOWER MI TO S TX...
MODIFIED NAM-KF AND NAM SOUNDINGS SUGGEST MRGL MIDLEVEL LAPSE RATES
JUST SLIGHTLY GREATER THAN MOIST ADIABATIC ALONG/AHEAD OF FRONT.
PLUME OF LOW LEVEL MOISTURE IS EXPECTED TO SPREAD NEWD AHEAD OF COLD
FRONT...BECOMING CHARACTERIZED GENERALLY BY SFC DEW POINTS TRENDING
FROM LOW-MID 50S OVER OH TO MID-UPPER 60S OVER TX COASTAL PLAIN.
THIS PROCESS GRADUALLY SHOULD RESULT IN ENOUGH BUOYANCY TO SUPPORT
POTENTIAL FOR ISOLATED TO WIDELY SCATTERED TSTMS ALONG/AHEAD OF
FRONT...MAINLY DURING LATTER HALF OF PERIOD. SEVERAL EPISODES OF
MRGL THUNDER POTENTIAL MAY DEVELOP IN ASSOCIATION WITH...
1. BAND OF LOW LEVEL WAA AND WEAK DPVA NEAR SFC FRONT...FROM LOWER
MI SWWD TO OZARKS AND PERHAPS NERN OK
2. WITHIN BROAD SWATH FROM S TX ACROSS LOWER MS VALLEY -- WEAK LOW
LEVEL WAA...FAVORABLE MOISTURE AND DESTABILIZATION ALOFT
ACCOMPANYING WEAK MIDLEVEL FORCING AHEAD OF EJECTING MEX TROUGH.
.EDWARDS.. 11/19/2007
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