DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 070608
SWODY2
SPC AC 070607

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1207 AM CST FRI DEC 07 2012

VALID 081200Z - 091200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
VARIABILITY AMONG THE MODELS AND SPREAD AMONG THE MODEL ENSEMBLES
BEGINS TO INCREASE DURING THIS FORECAST PERIOD...CONCERNING SHORT
WAVE DEVELOPMENTS WITHIN THE EVOLVING UPPER FLOW REGIME. BUT...
GUIDANCE CONTINUES TO INDICATE SIGNIFICANT AMPLIFICATION WITHIN THE
LARGE-SCALE PATTERN ACROSS THE EASTERN PACIFIC...WHERE A LARGE UPPER
RIDGE AND EMBEDDED HIGH CENTER ARE FORECAST TO BUILD. AS THIS
OCCURS...AND COINCIDING WITH A SIGNIFICANT LOW-LEVEL COLD INTRUSION
TO THE LEE OF THE NORTHERN AND CENTRAL ROCKIES...A VIGOROUS
DOWNSTREAM SHORT WAVE IMPULSE APPEARS LIKELY TO DIG ACROSS PARTS OF
THE EASTERN GREAT BASIN. THIS IS EXPECTED TO OCCUR IN THE WAKE OF
ANOTHER SHORT WAVE IMPULSE...THE TRACK OF WHICH REMAINS MORE UNCLEAR
EAST OF THE ROCKIES...ACROSS PARTS OF THE NORTHERN AND CENTRAL
PLAINS. FARTHER SOUTH AND EAST...WEAK MID-LEVEL HEIGHT RISES APPEAR
POSSIBLE ACROSS PARTS OF THE GULF AND SOUTH ATLANTIC COAST REGION.
HOWEVER...MID/UPPER FLOW IS EXPECTED TO REMAIN BROADLY CYCLONIC
ACROSS MUCH OF THE REMAINDER OF THE CENTRAL AND EASTERN
STATES...WITH MORE SUBTLE EMBEDDED SHORT WAVE IMPULSES.

THESE SMALLER SCALE FEATURES MAY CONTRIBUTE TO SCATTERED
THUNDERSTORM ACTIVITY SATURDAY/SATURDAY NIGHT...FROM PARTS OF THE
SOUTHERN PLAINS EAST NORTHEASTWARD INTO PARTS OF THE LOWER OHIO AND
TENNESSEE VALLEYS. THIS IS WHERE A MOISTENING CONFLUENT
SOUTHWESTERLY LOW-LEVEL FLOW REGIME MAY CONTRIBUTE TO WEAK TO MODEST
DESTABILIZATION.

...ARKLATEX THROUGH SRN AR/NW LA/NW MS AND WRN TN...
GUIDANCE...INCLUDING NAM FORECAST SOUNDINGS...INDICATES THE
DEVELOPMENT OF MIXED LAYER CAPE AT LEAST ON THE ORDER OF 500 J/KG OR
SO ACROSS THE REGION BY SATURDAY AFTERNOON. UNCERTAINTY EXISTS
CONCERNING FORCING FOR UPWARD VERTICAL MOTION...BUT LOWER/MID
TROPOSPHERIC CAPPING IS NOT EXPECTED TO BE SUBSTANTIALLY INHIBITIVE
TO STORM DEVELOPMENT DURING THE LATE AFTERNOON AND EVENING HOURS.
AND...VERTICAL SHEAR BENEATH 40-50 KT WESTERLY 500 MB FLOW MAY
CONTRIBUTE TO AN ENVIRONMENT MARGINALLY CONDUCIVE TO SEVERE
STORMS...INCLUDING AN ISOLATED SUPERCELL OR TWO...GIVEN STORM
INITIATION.

..KERR.. 12/07/2012

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