SPC AC 290657
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1257 AM CST WED NOV 29 2006
VALID 291200Z - 301200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS TO THE MID
MS VALLEY...
RESENT PER REQUEST
...SYNOPSIS...
BROAD WRN U.S UPPER TROUGH IS EXPECTED TO TRACK EWD AND UNDERGO
AMPLIFICATION TODAY AS A STRONG SHORT WAVE TROUGH DIGS SEWD FROM THE
GREAT BASIN...REACHING THE SRN HIGH PLAINS BY 12Z THURSDAY. THE
UPPER TROUGH AXIS SHOULD EXTEND FROM CENTRAL CANADA SWWD TO THE SRN
HIGH PLAINS/FAR NRN MEXICO BY THE END OF THE FORECAST PERIOD. A
WEAKER MID LEVEL IMPULSE EMANATING FROM THE NRN BAJA REGION...AT
THIS TIME...SHOULD TRANSLATE NEWD WITHIN STRENGTHENING MID/UPPER
LEVEL SWLY FLOW BETWEEN UPPER TROUGH AND BUILDING RIDGE ALONG/OFF
THE EAST COAST. THIS IMPULSE SHOULD MOVE ACROSS THE SRN PLAINS
TODAY AND INTO THE MID MS/LOWER OH VALLEYS TONIGHT.
IN THE LOW LEVELS...STRONG COLD FRONT ALONG LEADING EDGE OF UPPER
TROUGH WILL CONTINUE TO MOVE E AND S INTO THE GREAT LAKES...MIDWEST
AND SRN PLAINS.
...CENTRAL/NRN TX TO ERN OK/OZARKS AND NEWD TO IL...
CONTINUED MOISTURE TRANSPORT AHEAD OF THE COLD FRONT IS EXPECTED TO
MAINTAIN LOWER TO MID 60S SURFACE DEWPOINTS ACROSS THE SRN PLAINS...
WHILE MID TO UPPER 50S DEWPOINTS SPREAD NEWD INTO IL AND SRN GREAT
LAKES REGION. WEAK MID LEVEL LAPSE RATES WILL TEND TO PRECLUDE
DEVELOPMENT OF STRONGER INSTABILITY ALONG NRN EXTENT OF COLD FRONT
WITH MUCAPE VALUES GENERALLY AOB 500 J/KG. GREATER BOUNDARY LAYER
MOISTURE AND THE POTENTIAL FOR SURFACE HEATING FROM TX TO SERN OK
SHOULD COMPENSATE FOR WEAK MID LEVEL LAPSE RATES AND RESULT IN
MODERATE INSTABILITY FROM PARTS OF SRN OK SWD INTO CENTRAL TX.
DEEP LAYER SHEAR WILL BE INCREASING THROUGH THE DAY ALONG THE
FRONTAL ZONE...AS DEEP SWLY WIND FIELDS STRENGTHEN WITH THE APPROACH
OF THE AMPLIFYING UPPER TROUGH.
AT 12Z TODAY...TSTMS MAY BE ONGOING ACROSS PARTS OF NERN OK/NWRN AR
INTO MO. THIS ACTIVITY SHOULD DEVELOP/SPREAD NEWD ALONG THE
ADVANCING COLD FRONT...WITH INCREASINGLY STRONG UNIDIRECTIONAL SHEAR
PROFILES SUGGESTING SOME POTENTIAL FOR NEAR SURFACE-BASED CONVECTION
TO POSE A THREAT FOR SEVERE HAIL AND/OR HIGH WINDS.
GIVEN FAVORABLE LARGE SCALE SUPPORT AS DEEP LAYER ASCENT INCREASES
WITHIN THE ENTRANCE REGION OF THE INTENSIFYING UPPER JET...TSTMS
SHOULD NOT ONLY DEVELOP NEWD FROM THE ONGOING ACTIVITY...BUT ALSO
SWWD ALONG THE FRONT THIS AFTERNOON AS THE AIR MASS DESTABILIZES.
HAIL AND STRONG WINDS WILL BE A THREAT GIVEN SHEAR PROFILES BECOMING
SUPPORTIVE OF SUSTAINED UPDRAFTS. A SUPERCELL TORNADO AND/OR LARGE
HAIL THREAT APPEAR POSSIBLE ACROSS THE RED RIVER VALLEY REGION AND
SWD INTO CENTRAL TX THIS AFTERNOON AND EVENING. LOW LEVEL SHEAR
VALUES SHOULD BE ENHANCED ACROSS THESE AREAS WHERE THE PROGRESSIVE
COLD FRONT INTERSECTS A SWD EXTENDING DRY LINE.
BULK OF CONVECTION IS LIKELY TO LINE UP ALONG OR IMMEDIATELY BEHIND
THE DEEPER FRONTAL CIRCULATION DEVELOPING ESEWD THROUGH THE EVENING.
IT IS POSSIBLE A LINEAR MCS WITH A CONTINUING SEVERE THREAT COULD
EVOLVE FROM CENTRAL/NERN TX INTO THE OZARKS TONIGHT.
..PETERS/GRAMS.. 11/29/2006
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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