SPC AC 152002
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0302 PM CDT FRI SEP 15 2006
VALID 152000Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE GRT
BASIN AND THE CNTRL ROCKIES...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE PLAINS...
...CNTRL/SRN PLAINS...
MODEST BOUNDARY LAYER MOISTURE CONTINUES TO SURGE NWD THROUGH THE
PLAINS THIS AFTN BENEATH STEEP LAPSE RATES ALOFT. THIS WAS
CONTRIBUTING TO A NARROW AXIS OF INSTABILITY ALONG/E OF A
DRYLINE/LEE-TROUGH SITUATED FROM THE NWRN TX PNHDL NWD TO A SFC LOW
OVER SWRN ND.
PRIMARY SEVERE THREAT SHOULD DEVELOP LATE THIS AFTN/EVE FROM SRN SD
SWD. VSBL SATL SHOWS AGITATED BOUNDARY LAYER CUMULUS BEGINNING TO
SPROUT INTO CB/S JUST E OF THE DRYLINE/LEE-TROUGH ACROSS NCNTRL NEB.
THIS REGION WILL BE GRAZED BY A MID-LEVEL SHORTWAVE TROUGH
MIGRATING NEWD THROUGH THE HIGH PLAINS. AS THE FEATURE TRANSLATES
NEWD...IT WILL LIKELY AUGMENT ASCENT AND SUPPORT INCREASING TSTM
PROBABILITIES AS CINH IS ERODED VIA LIFT/MOISTENING. TSTMS WILL
TEND TO DEVELOP SWWD ALONG THE DRYLINE/LEE-TROUGH INTO NCNTRL/WCNTRL
KS LATER THIS AFTN. VERTICAL SHEAR OF AROUND 40 KTS OBSERVED ON
AREA PROFILERS WILL BE FAVORABLE FOR SUPERCELLS WITH LARGE HAIL AND
DAMAGING WINDS. AN ISOLD TORNADO OR TWO WILL ALSO BE
POSSIBLE...THOUGH LCL/S WILL TEND TO BE SOMEWHAT HIGH. ACTIVITY
SHOULD MOVE ENEWD INTO PARTS OF THE MO VLY...NRN PLAINS AND CORN
BELT OVERNIGHT...BUT THE SEVERE THREAT SHOULD DIMINISH.
FARTHER S...CONVECTIVE INITIATION IS MORE UNCERTAIN OWING TO
STRONGER CAP AND WEAKER FORCING FOR ASCENT. SHORT-TERM MESOSCALE
MODELS SUGGEST AT LEAST ISOLD TSTMS WILL FORM ACROSS THE TX
PNHDL...PROBABLY ALONG THE CAPROCK/LEE-TROUGH. CUMULUS SEEMS TO BE
INCREASING ACROSS THIS REGION AT MID-AFTN AND CONTINUED HEATING AND
MOISTENING OF THE BOUNDARY LAYER MAY SUPPORT STORM INITIATION AFTER
22Z. GIVEN A STORM...THE ROUGHLY 35-40 KTS OF VERTICAL SHEAR WILL
BE ENOUGH FOR SUPERCELLS WITH LARGE HAIL AND DAMAGING WINDS.
COVERAGE IS EXPECTED TO BE COMPARATIVELY LESS THAN FARTHER N IN
NEB/NRN KS. STORMS THAT CAN BECOME ESTABLISHED WILL MOVE NEWD INTO
PARTS OF NWRN/WCNTRL OK THIS EVE/OVERNIGHT.
...GRT BASIN/CNTRL ROCKIES...
A VERY STRONG UPPER LEVEL JET AXIS WAS BEGINNING TO SHIFT EWD FROM
SRN NV INTO PARTS OF THE SRN GRT BASIN THIS AFTN...PLACING MUCH OF
CNTRL/NRN UT...NWRN CO AND SWRN WY BENEATH STRONG ASCENT IN THE EXIT
REGION. TSTMS HAVE FORMED ALONG THE SW-NE ORIENTED BAROCLINIC ZONE
ACROSS NWRN UT AND WITHIN THE WARM SECTOR IN ERN UT/WRN CO. THE
STRONG UPPER LEVEL Q-VECTOR CONVERGENCE WILL SHIFT NEWD INTO THE
CNTRL ROCKIES THIS EVENING.
COOLING ALOFT ASSOCD WITH THE UPPER LEVEL SYSTEM AND STEEP LOW-LEVEL
LAPSE RATES WILL BE FAVORABLE FOR STRONG UPDRAFTS. VERTICAL SHEAR
AOA 40 KTS WILL ENCOURAGE ORGANIZED STORMS/POSSIBLE BRIEF SUPERCELLS
WITH LARGE HAIL AND DAMAGING WIND GUSTS. ACTIVITY WILL LIKELY
DEVELOP INTO LINE SEGMENTS CLOSER TO THE FRONT WITH DAMAGING WINDS
THE MAIN THREAT ACROSS NRN UT AND WRN WY THROUGH THE EVE.
..RACY.. 09/15/2006
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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