Wednesday, March 14, 2012

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 141632
SWODY1
SPC AC 141630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT WED MAR 14 2012

VALID 141630Z - 151200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON FOR SE MO...SRN
IL...WRY KY...AND SW INDIANA...

...MS/LOWER OH VALLEY REGION THIS AFTERNOON/EVENING...
THE PRIMARY BELT OF WLYS IS CONFINED TO A CORRIDOR FROM THE PAC NW
TO HUDSON BAY...WITH A DOWNSTREAM CLOSED LOW MOVING ESEWD OVER NEW
ENGLAND. THIS LEAVES A RATHER NEBULOUS WLY/SWLY FLOW REGIME ALOFT
OVER THE MS VALLEY AND PLAINS...ABOVE AN EXPANDING WARM SECTOR FROM
THE SRN PLAINS/GULF COAST STATES NWD TO WI/MI. REGIONAL 12Z
SOUNDINGS FROM THE PLAINS AND MS VALLEY REVEALED SUBSTANTIAL
LOW-LEVEL MOISTURE BENEATH THE ERN EXTENT OF AN EML...WITH MORNING
MUCAPE VALUES OF 2000-3000 J/KG IN THE AREA ROUGHLY BOUNDED BY AN
OUN-ILX-JAN TRIANGLE. ONCE SURFACE TEMPERATURES WARM INTO THE
LOW-MID 70S WITH DAYTIME HEATING...MLCAPE WILL INCREASE TO 2500-3000
J/KG IN THIS SAME AREA.

THE FAVORABLE THERMODYNAMIC PROFILES WILL BE OFFSET SOMEWHAT BY A
LACK OF FOCUS FOR STORM DEVELOPMENT...INCLUDING NO CLEARLY
IDENTIFIABLE SURFACE BOUNDARIES OR WAVES ALOFT APPROACHING THE
UNSTABLE WARM SECTOR. THUS...THE BEST GUESS FOR STORM DEVELOPMENT
WILL BE IN AREAS IMMEDIATELY E/NE OF THE WARMEST EML AND ALONG THE
AXIS OF THE LOW-MID 60S DEWPOINTS AND PW VALUES AOA 1 INCH THIS
AFTERNOON/EVENING...OR ROUGHLY FROM SE MO INTO SRN IL/WRN KY/SW
INDIANA. THE STEEP MIDLEVEL LAPSE RATES AND LARGE BUOYANCY WILL
CONTRIBUTE TO A RISK FOR ISOLATED LARGE HAIL/DAMAGING GUSTS IN A
DEEP-LAYER VERTICAL SHEAR ENVIRONMENT ON THE LOWER MARGINS FOR
PERSISTENT STORMS /EFFECTIVE BULK SHEAR OF 25-30 KT/.

...TX PANHANDLE LATE THIS AFTERNOON/EVENING...
MID MORNING SATELLITE IMAGERY SHOWS WIDESPREAD CLOUDS FROM LBB-SPS
SWD IN TX...WHERE LOW-LEVEL MOISTURE IS RETURNING NWD BENEATH A
PRONOUNCED CAP. THE STRONGER DAYTIME HEATING IS EXPECTED ALONG THE
WRN/NRN FRINGES OF THE MOIST BOUNDARY LAYER FROM THE SE NM/W TX
BORDER INTO THE TX PANHANDLE...WHERE A WEAK NE-SW ORIENTED DRYLINE
WILL DEVELOP THIS AFTERNOON. THE ODDS OF CONVECTIVE INITIATION
ALONG THE DRYLINE APPEAR LOW...BUT WILL MAINTAIN A TSTM AREA IN
RESPONSE TO THE ARRIVAL OF A SUBTLE SPEED MAX /NOW LOCATED JUST SW
OF ELP/. IF ISOLATED STORMS DO FORM...THERE WILL BE SOME RISK FOR
LARGE HAIL AND/OR DAMAGING OUTFLOW GUSTS FOR A COUPLE OF HOURS
BEFORE CONVECTIVE INHIBITION STRENGTHENS AGAIN BY LATE EVENING.

...ELSEWHERE...
A BROAD AREA OF POTENTIALLY MODERATE INSTABILITY WILL COINCIDE WITH
SOME RISK FOR AT LEAST ISOLATED THUNDERSTORM DEVELOPMENT ACROSS THE
SE STATES...BUT WEAK VERTICAL SHEAR AND WEAKER INSTABILITY COMPARED
TO AREAS FARTHER W/NW SUGGEST THAT THE SEVERE STORM RISK WILL BE
NEGLIGIBLE. AREAS OF CENTRAL/N/E TX INTO SE OK OVERNIGHT WILL
BECOME MODERATELY UNSTABLE...AND DEEP-LAYER VERTICAL SHEAR WILL BE
MARGINAL FOR ORGANIZED SEVERE STORMS/SUPERCELLS. HOWEVER...THERE IS
NO CLEAR FOCUS FOR STORM DEVELOPMENT IN MUCH OF THIS AREA...SO WILL
OPT NOT TO ADD LOW SEVERE PROBABILITIES IN THIS UPDATE.

..THOMPSON.. 03/14/2012

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