SWODY2
SPC AC 131722
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1222 PM CDT TUE MAR 13 2012
VALID 141200Z - 151200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
PRIMARY BELT OF STRONGER WLYS WILL BECOME CONFINED TO THE PACIFIC NW
TO THE NRN PLAINS AS A SHORT WAVE TROUGH MOVES E/NEWD ACROSS THE
CANADIAN PRAIRIES. ATTENDANT TO THIS IMPULSE...TRAILING PORTION OF A
WEAKENING COLD FRONT SHOULD PUSH ACROSS THE UPPER MS VALLEY TO THE
UPPER GREAT LAKES. SW OF THIS BOUNDARY...A DRYLINE WILL SHARPEN
ACROSS THE CNTRL TO THE SRN HIGH PLAINS.
...SRN HIGH PLAINS TO THE GREAT LAKES...
PERSISTENT S/SWLY LOW-LEVEL FLOW REGIME WILL RESULT IN A BROAD SWATH
OF MIDDLE 50S TO LOWER 60S SURFACE DEW POINTS ENCOMPASSING A LARGE
PART OF THE CNTRL CONUS. BY WED AFTERNOON...THIS MOISTURE RETURN
COMBINED WITH DAYTIME HEATING AND VERY STEEP LAPSE RATES WILL YIELD
MODERATE TO STRONG INSTABILITY WITH MLCAPE OF 1500-3500 J/KG FROM WI
TO WRN TX. HOWEVER...LARGE-SCALE FORCING FOR ASCENT APPEARS NEBULOUS
WITH JUST A MODEST W/SWLY MID-LEVEL FLOW REGIME AND LACK OF
SUBSTANTIAL UPSTREAM IMPULSES. AS SUCH...CONVECTIVE DEVELOPMENT
APPEARS LIKELY TO REMAIN SPARSE THROUGH THE PERIOD DESPITE THE
PRESENCE OF A DRYLINE AND WEAK COLD FRONT. THE RELATIVELY BETTER
POTENTIAL AREAS FOR CONVECTIVE DEVELOPMENT APPEAR TO BE OVER PARTS
OF THE SRN HIGH PLAINS AND IN THE GREAT LAKES.
IN THE SRN HIGH PLAINS...THE 12Z GFS IS THE MOST AGGRESSIVE WITH
DRYLINE DEVELOPMENT TIED TO THIS MODEL STRENGTHENING A WEAK
MID-LEVEL IMPULSE AND ATTENDANT SPEED MAX CURRENTLY OFF THE NRN BAJA
COAST. OTHER GUIDANCE SUGGESTS CONVECTION WOULD REMAIN QUITE
ISOLATED. SHOULD TSTMS FORM HERE...DEEPLY VEERED WIND PROFILES WOULD
BE SUFFICIENT FOR SUPERCELLS PRIMARILY CAPABLE OF LARGE HAIL.
ACROSS THE GREAT LAKES...WEAK MID-LEVEL RIDGING SHOULD EVENTUALLY
SHIFT E LATE IN THE PERIOD AS THE REGION IS GLANCED BY THE INFLUENCE
OF THE CANADIAN PRAIRIE SHORT WAVE IMPULSE AND A WEAKENING COLD
FRONT INTERCEPTS THE WARM/MOIST SECTOR. A FEW NOCTURNAL /PRIMARILY
ELEVATED/ TSTMS MAY FORM AIDED BY THE ABOVE FEATURES ALONG WITH A
30-40 KT SWLY LLJ. EFFECTIVE SHEAR AROUND 30-35 KT WOULD YIELD A
RISK FOR SUPERCELLS CAPABLE OF LARGE HAIL.
GIVEN THE LOW CONFIDENCE IN SUFFICIENT TSTM COVERAGE AND
SPATIOTEMPORAL UNCERTAINTY OF WHERE ISOLATED TSTMS WOULD FORM...WILL
DEFER TO LATER OUTLOOKS FOR POSSIBLE CATEGORICAL SLIGHT RISK.
..GRAMS.. 03/13/2012
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