SWODY2
SPC AC 051730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT FRI JUN 05 2009
VALID 061200Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL
PLAINS/MIDDLE MO VALLEY...
...MIDDLE MO VALLEY/CENTRAL PLAINS TO UPPER MS VALLEY...
EARLY DAY HEIGHT FALLS ARE ANTICIPATED ACROSS THE CENTRAL PLAINS ON
SATURDAY...WITH PERTURBED WEST-SOUTHWESTERLY FLOW ALOFT IN
ASSOCIATION WITH A SHORTWAVE TROUGH EXPECTED TO CROSS THE NORTH
CENTRAL HIGH PLAINS. AS THIS OCCURS...SURFACE COLD FRONT IS EXPECTED
TO MOVE SOUTHWARD ACROSS NEB/IA DURING THE DAY...WITH A SURFACE LOW
ACROSS WESTERN KS AND A ROUGHLY NORTH-SOUTH ORIENTED DRYLINE ACROSS
WEST CENTRAL KS INTO SOUTHERN NEB.
A STRENGTHENING ELEVATED MIXED LAYER/STRONG CAP PUTS THE COVERAGE OF
PRE-DARK SURFACE BASED TSTMS A BIT IN QUESTION ACROSS THE WARM
SECTOR. HOWEVER...AT LEAST ISOLATED TSTM DEVELOPMENT SEEMS PROBABLE
BY MID/LATE AFTERNOON ALONG THE EASTERN NEB/WESTERN IA WSW-ENE
ORIENTED FRONTAL ZONE...WITH ADDITIONAL DEVELOPMENT POSSIBLE AMIDST
A STRONGLY HEATED/MIXED BOUNDARY LAYER IN VICINITY OF SURFACE
LOW/DRYLINE ACROSS WEST CENTRAL KS/SOUTHERN NEB. AMPLE WARM SECTOR
HEATING AND AROUND 60F SURFACE DEWPOINTS WILL LIKELY SUPPORT MLCAPE
TO AROUND 2000-2500 J/KG. VERTICAL SHEAR /45-55 KT/ WILL BE MORE
THAN ADEQUATE FOR SUPERCELLS/WELL-ORGANIZED MULTICELLS CAPABLE OF
LARGE HAIL AND DAMAGING WINDS. A FEW TORNADOES WILL BE POSSIBLE AS
WELL...BUT MODEST LOW LEVEL SHEAR AND/OR DEEPER MIXING ACROSS KS MAY
TEND TO LIMIT THE OVERALL TORNADO POTENTIAL. AIDED BY A NOCTURNALLY
INTENSIFYING LOW LEVEL JET ACROSS KS INTO THE MIDDLE MO RIVER
VALLEY...AT LEAST AN ISOLATED HAIL/PERHAPS STRONG WIND GUST THREAT
MAY CONTINUE WELL THROUGH THE NIGHT ACROSS THE CORN BELT.
...WESTERN OK AND WEST/SOUTHWEST TX...
A MORE ISOLATED/CONDITIONAL SEVERE POTENTIAL WILL EXTEND SOUTHWARD
ALONG THE DRYLINE FROM WESTERN OK TO SOUTHWEST TX...WITH STRONG
HEATING AND DEEP MIXING LIKELY TO LOCALLY ERODE THE CAP AND RESULT
IN ISOLATED TSTM DEVELOPMENT BY LATE AFTERNOON. IN ADDITION TO THE
12Z WRF-NMM...THIS IDEA IS SUPPORTED BY 00Z ECMWF GUIDANCE AND
ASSORTMENT OF NAM/ETA-BMJ AND NAMKF MEMBERS FROM THE 09Z SREF.
MODERATE POTENTIAL INSTABILITY AND ADEQUATE WIND PROFILES WOULD
CONDITIONALLY SUPPORT A FEW HIGH-BASED SUPERCELLS/ORGANIZED
MULTICELLS WITH LARGE HAIL/DAMAGING WINDS AS THE PRIMARY RISK.
...MAINE...
SCATTERED TSTMS ARE LIKELY TO DEVELOP MAINLY ACROSS NORTHERN MAINE
ON SATURDAY AHEAD OF WESTERN QUEBEC UPPER TROUGH AND
APPROACHING/PRONOUNCED MID LEVEL JET STREAK AND ASSOCIATED SURFACE
COLD FRONT. WHILE THE BOUNDARY LAYER WILL NOT BE PARTICULARLY MOIST
OR UNSTABLE...PLUME OF STEEP MID LEVEL LAPSE RATES/MODEST BUOYANCY
AND STRENGTHENING/BUT LARGELY UNIDIRECTIONAL LOW TO MID TROPOSPHERIC
WIND FIELDS WOULD SUPPORT FAST MOVING/LOW-TOPPED CLUSTERS OF TSTMS
WITH A DAMAGING WIND AND HAIL RISK...MAINLY ACROSS NORTHERN MAINE
SATURDAY AFTERNOON.
...NORTHERN INTERMOUNTAIN WEST...
LARGE SCALE HEIGHT FALLS AND A SOUTHWARD SAGGING COLD FRONT ARE
EXPECTED ACROSS THE REGION AHEAD/SOUTH OF SHORTWAVE TROUGH ADVANCING
FROM BRITISH COLUMBIA/ALBERTA INTO MT/NORTHERN ID. RESIDUALLY
MOIST/WEAKLY UNSTABLE AIRMASS WITH PRECIPITABLE WATER VALUES IN
EXCESS OF 0.75 INCHES WILL SUPPORT SOME STRONGER TSTMS CAPABLE OF
HAIL/PERHAPS SOME STRONG WIND GUSTS.
..GUYER.. 06/05/2009
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