DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 251250
SWODY1
SPC AC 251247

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0747 AM CDT TUE SEP 25 2012

VALID 251300Z - 261200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE MID-MS/LOWER
OH VALLEYS THIS AFTERNOON AND EVENING...

...THERE IS A SLGT RISK OF SVR TSTMS FOR WRN OK INTO FAR S-CNTRL KS
DURING THE LATE AFTERNOON AND EVENING...

...SYNOPSIS...
A SHORT WAVE TROUGH CENTERED OVER UT WILL SLOWLY SHIFT EWD INTO WRN
CO BY EARLY WED. A SERIES OF WEAK DISTURBANCES DOWNSTREAM OF THIS
TROUGH WILL INTERACT WITH A QUASI-STATIONARY FRONT FROM THE SRN
PLAINS TO THE OH VALLEY...AND SERVE AS THE FOCUS FOR AREAS OF TSTM
DEVELOPMENT THROUGH THE PERIOD.

...MID-MS/LOWER OH VALLEYS...
AN EXPANSIVE CLUSTER OF ELEVATED TSTMS DRIVEN BY ROBUST LOWER-LEVEL
WARM THETA-E ADVECTION MAY POSE A RISK FOR MARGINALLY SEVERE HAIL
THIS MORNING. THIS ACTIVITY WILL LARGELY RETARD THE NEWD ADVANCEMENT
OF THE SURFACE WARM FRONT ANALYZED FROM CNTRL MO INTO WRN TN. THIS
SHOULD AID IN FAIRLY PRONOUNCED DIFFERENTIAL SURFACE HEATING AS THE
WARM SECTOR DESTABILIZES WITH MLCAPE POTENTIALLY REACHING 1500-3000
J/KG...WITH 700-500 MB LAPSE RATES AROUND 8.5 DEG C/KM IN THE 12Z
LZK RAOB. CONVERGENCE ALONG THE FRONT SHOULD BE SUFFICIENT TO YIELD
ONE OR MORE TSTM CLUSTERS BY LATE AFTERNOON. 35-45 KT W/SWLYS AT 700
MB COULD FOSTER UPSCALE GROWTH INTO AN ORGANIZED LINE SEGMENT
CAPABLE OF DAMAGING WIND AND SEVERE HAIL. UNCERTAINTY OVER WHERE
THIS MAY OCCUR PRECLUDES MORE THAN LOW-END SLIGHT RISK PROBABILITIES
ATTM.

...WRN OK TO SERN KS...
AN UPPER-LEVEL IMPULSE/SPEED MAX INFERRED FROM WATER VAPOR IMAGERY
ACROSS THE SRN ROCKIES AND SAMPLED BY THE 12Z ABQ RAOB WILL BE
FAVORABLY TIMED WITH PEAK HEATING ALONG THE DRYLINE EXPECTED TO
SETUP FROM NWRN OK INTO THE SERN TX PANHANDLE...INTERSECTING A
QUASI-STATIONARY FRONT DRAPED ACROSS SERN KS. CONVERGENCE ALONG
THESE BOUNDARIES AND WEAK LARGE-SCALE ASCENT SHOULD PROMOTE TSTM
DEVELOPMENT BY LATE AFTERNOON AS 50S SURFACE DEW POINTS CONTRIBUTE
TO MODERATE BUOYANCY. VEERING OF THE WIND PROFILE WITH HEIGHT ALONG
WITH AN INCREASE IN HIGH-LEVEL FLOW SHOULD BE SUFFICIENT FOR
MULTICELLS AND A FEW SUPERCELL STRUCTURES. VERY STEEP LOW/MID-LEVEL
LAPSE RATES...AROUND 9 DEG C/KM FROM 700-500 MB IN THE 12Z AMA
RAOB...WILL PROMOTE ISOLATED LARGE HAIL AND SEVERE WIND...WITH
ACTIVITY WEAKENING TOWARDS MIDNIGHT.

..GRAMS/SMITH.. 09/25/2012

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