DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 160549
SWODY1
SPC AC 160547

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1247 AM CDT TUE OCT 16 2012

VALID 161200Z - 171200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A PROGRESSIVE LARGE SCALE UPPER FLOW PATTERN WILL STEADILY AMPLIFY
ESPECIALLY DURING THE LAST HALF OF THE PERIOD AS A LONGWAVE TROUGH
BEGINS TO EVOLVE EAST OF THE ROCKIES. WITHIN THIS REGIME...SEVERAL
SHORTWAVE TROUGHS WILL STEADILY MOVE THROUGH RELATIVELY FAST
MID/HIGH LEVEL WESTERLIES ACROSS THE NORTHERN HALF OF THE
CONUS...WITH THE MOST SUBSTANTIAL WAVE EXPECTED TO AMPLIFY OVER THE
CANADIAN/NORTHERN ROCKIES TO NORTHERN PLAINS TONIGHT INTO WEDNESDAY.

...NORTHERN ROCKIES TO NORTHERN PLAINS...
TIED TO SHORTWAVE TROUGH AMPLIFICATION AS PREVIOUSLY
DESCRIBED...CONSIDERABLE FORCING FOR ASCENT WILL GRADUALLY SPREAD
EAST-SOUTHEASTWARD FROM THE NORTHERN ROCKIES TO THE NORTHERN PLAINS
LATER TONIGHT. WHILE RELATIVELY COOL/DRY THERMODYNAMIC PROFILES WILL
TEMPER UPDRAFT STRENGTH...LOW-TOPPED CONVECTION WILL BE CAPABLE OF
ISOLATED/PERIODIC LIGHTNING...ESPECIALLY THIS AFTERNOON/EARLY
EVENING NEAR THE EAST-SOUTHEASTWARD MOVING COLD FRONT. THIS INCLUDES
PARTS OF MT/ID/WY...AND PERHAPS EVENTUALLY PORTIONS OF THE
DAKOTAS/WESTERN NEB. WHILE SOME CONVECTIVELY ENHANCED WIND GUSTS
WILL BE POSSIBLE AMID 50-75 KT 3-6 KM WESTERLIES...THE OVERALL
SEVERE WIND POTENTIAL APPEARS LOW GIVEN THE EXPECTED THERMODYNAMIC
ENVIRONMENT.

...MIDDLE/UPPER MS VALLEY TO GREAT LAKES...
WHILE A DRY CONTINENTAL AIRMASS INITIALLY EXISTS OVER THE REGION...A
LOW AMPLITUDE SHORTWAVE TROUGH AND GRADUALLY STRENGTHENING
SOUTHWESTERLY LOW LEVEL JET WILL ACCOUNT FOR GRADUAL MOISTENING
DURING THE PERIOD NEAR/ABOVE THE SURFACE. A FEW LIGHTNING STRIKES
COULD OCCUR TODAY ACROSS AREAS SUCH AS THE UPPER MS RIVER VALLEY.
HOWEVER...MORE PROBABLE WILL BE FOR AN INCREASE IN ELEVATED
CONVECTION INCLUDING ISOLATED TSTMS TONIGHT ACROSS THE SOUTHERN LAKE
MI AND LOWER MI VICINITY...AS POSSIBLY ADJACENT PARTS OF NORTHERN
IL/INDIANA/PERHAPS NORTHWEST OH. SEVERE TSTMS ARE NOT EXPECTED GIVEN
THE LIMITED MOISTURE/BUOYANCY.

...SOUTH TX...
A RELATIVELY MOIST AIRMASS ACROSS DEEP SOUTH TX/ADJACENT GULF OF
MEXICO WILL SLOWLY RETURN NORTHWARD THROUGH TONIGHT...WITH A WARM
ADVECTION REGIME AIDED BY GRADUAL SOUTHERN HIGH PLAINS SURFACE
CYCLOGENESIS. AS THIS OCCURS...SUFFICIENT LIFT/MODEST INSTABILITY
MAY ACCOUNT FOR ISOLATED/WIDELY SCATTERED TSTMS DURING THE DAY. WEAK
LAPSE RATES ALOFT AND LIMITED OVERALL BUOYANCY IS EXPECTED TO
PRECLUDE SEVERE TSTM POTENTIAL.

...FAR SOUTH FL...
A COUPLE OF TSTMS MAY BE POSSIBLE TODAY NEAR/SOUTH OF SOUTHEASTWARD
PROGRESSING COLD FRONT AS TEMPERATURES WARM THROUGH THE 80S F DURING
THE AFTERNOON. WEAKENING CONVERGENCE ASIDE...POOR LAPSE RATES ALOFT
WILL TEMPER UPDRAFT INTENSITY...WITH A LIMITED TSTM
COVERAGE/LIKELIHOOD AND SEVERE TSTMS NOT EXPECTED.

..GUYER/ROGERS.. 10/16/2012

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