Thursday, February 26, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 260606
SWODY1
SPC AC 260605

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1205 AM CST THU FEB 26 2009

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE
MIDWEST/OZARKS/MID-SOUTH...

...MIDWEST/OZARKS/MID-SOUTH...
AMIDST A LOW AMPLITUDE UPPER FLOW REGIME...THE EASTWARD ADVANCEMENT
OF A MID LEVEL SHORTWAVE TROUGH OVER THE UPPER MIDWEST AND
STRENGTHENING FLOW ALOFT WILL CONTRIBUTE TO INCREASING TSTM
POTENTIAL AND A SEVERE RISK ACROSS THE REGION TODAY.
INITIALLY...ALONG/NORTH OF A RETREATING WARM FRONT...CLUSTERS OF
ELEVATED TSTMS WILL LIKELY BE ONGOING AND EXPAND NORTHWARD THROUGH
EARLY/MID MORNING ACROSS PORTIONS OF MO/IL/IA. AIDED BY A
STRENGTHENING LOW LEVEL JET...STEEP LAPSE RATES AND ELEVATED MUCAPE
TO 500-1000 J/KG MAY BE SUFFICIENT FOR AN ISOLATED SEVERE HAIL RISK
EARLY IN THE DAY.

OTHERWISE...AHEAD OF A DEEPENING SURFACE LOW AND EAST-SOUTHEAST
DEVELOPING COLD FRONT ACROSS THE MISSOURI VALLEY...AN INCREASINGLY
MOIST BOUNDARY LAYER WILL EXIST WITH SURFACE DEWPOINTS RISING INTO
THE 50S F ACROSS MUCH OF THE LOWER MISSOURI VALLEY/OZARKS...WITH
LOWER 60S F DEWPOINTS OVER THE ARKLATEX. BENEATH A STRONG/EASTWARD
ADVANCING ELEVATED MIXED LAYER...SURFACE-BASED STORM DEVELOPMENT IS
NOT ANTICIPATED UNTIL MID/LATE AFTERNOON...WITH INITIAL DEVELOPMENT
LIKELY ACROSS MO IN CONCERT WITH THE DEEPENING SURFACE LOW/ADVANCING
COLD FRONT. STRONG DEEP LAYER WIND FIELDS/45-55 KT
WEST-SOUTHWESTERLY MID LEVEL FLOW AND CONSIDERABLE TURNING WITH
HEIGHT WILL SUPPORT WELL ORGANIZED STORMS INCLUDING SUPERCELLS AND
BOWS EVEN WITH RELATIVELY MODEST INSTABILITY. SEVERE HAIL/DAMAGING
WINDS SHOULD BE THE PRIMARY RISK...ALTHOUGH A TORNADO MAY BE
POSSIBLE AS WELL. AT LEAST AN ISOLATED SEVERE THREAT MAY PERSIST
ACROSS THE MID-SOUTH REGION OVERNIGHT...WITH A CONTINUED RISK FOR
DAMAGING WIND/PERHAPS A TORNADO.

..GUYER.. 02/26/2009

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