Wednesday, March 21, 2012

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 211625
SWODY1
SPC AC 211623

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1123 AM CDT WED MAR 21 2012

VALID 211630Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE LOWER MS VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS FROM CENTRAL OK INTO N CENTRAL
TX...

...LOWER MS VALLEY...
BAND OF STRONG/SEVERE STORMS FROM EXTREME NERN LA ACROSS SWRN MS AND
SERN LA IS EXPECTED TO TRANSLATE SLOWLY EWD THIS AFTERNOON ON THE
ERN PERIPHERY OF THE UPPER LOW OVER NWRN TX. STORMS WILL REMAIN
WITHIN A WELL-DEFINED NARROW MOISTURE AXIS WITHIN A LOW LEVEL
CONFLUENT ZONE. STRONGEST DIURNAL HEATING WILL LIKELY OCCUR FROM
EXTREME SERN LA INTO SERN/EAST CENTRAL MS WHERE VISIBLE IMAGERY
EXHIBITS THINNING CLOUD COVER. VAD WIND PROFILES FROM KLIX AND
SHORT-TERM MODEL GUIDANCE INDICATE 40-50 KT WINDS THAT VEER WITH
HEIGHT IN THE LOWEST 2 KM OVER THE REGION. WHEN COUPLED WITH 40-50
KT DEEP LAYER SHEAR...THERE WILL CONTINUE TO BE A FAVORABLE
KINEMATIC ENVIRONMENT FOR SEVERE STORMS INCLUDING EMBEDDED
SUPERCELLS AND OCCASIONAL SHORT BOWING LINE SEGMENTS. A THREAT FOR
DAMAGING WINDS AND A FEW TORNADOES WILL PERSIST THROUGH THE
AFTERNOON HOURS AS THE CONVECTIVE BAND PROGRESSES FROM LA INTO MS.

...CENTRAL OK INTO N CENTRAL TX...
COMPACT UPPER LOW CIRCULATION OVER NWRN TX IS ASSOCIATED WITH VERY
COLD MID LEVEL TEMPERATURES /MINUS 25-27C AT 500 MB/. SATELLITE
IMAGERY SHOWS THIS SYSTEM MOVING VERY SLOWLY EWD...WITH WELL-DEFINED
VORTICITY MAX NEAR BWD CURRENTLY MOVING EWD. GENERALLY CLEAR SKIES
WILL ALLOW STRONG HEATING TO OCCUR THIS AFTERNOON AND WHEN COMBINED
WITH COOLING ALOFT...RESULT IN STEEPENING LOW-MID LEVEL LAPSE RATES
AND DESTABILIZATION WITH CAPE OF 500-1000 J/KG DEVELOPING.

CONVECTION IS EXPECTED TO DEVELOP THIS AFTERNOON AS THE CAP
WEAKENS...WITH LOW-TOPPED THUNDERSTORMS FORMING NEAR/AHEAD OF THE
UPPER LOW WITHIN A WEAKLY CONVERGENT REGION ASSOCIATED WITH A BROAD
SURFACE LOW. THE STEEP LAPSE RATES WILL PROMOTE STRONG UPDRAFT
DEVELOPMENT WITH POTENTIAL FOR MORE INTENSE CELLS TO PRODUCE SEVERE
HAIL. IN ADDITION...FUNNEL CLOUDS AND A BRIEF TORNADO WILL ALSO BE
POSSIBLE.

...VA INTO NC REGION...
SATELLITE IMAGERY SHOWS THE UPPER LOW/VORTICITY MAX OVER NRN VA
MOVING SWD. COLDER MID LEVEL TEMPERATURES /-16C AT 500 MB/ ARE
ASSOCIATED WITH THIS FEATURE AND WILL CONTRIBUTE TO STEEPENING MID
LEVEL LAPSE RATES ACROSS PARTS OF ERN VA INTO NERN NC THIS
AFTERNOON. VISIBLE IMAGERY SHOWS CLOUDS THINNING FROM SRN VA INTO
PARTS OF NRN NC WHERE STRONGER DIURNAL HEATING WILL OCCUR...AND THIS
WILL ENHANCE LOW LEVEL LAPSE RATES AS WELL. AS THE CAP WEAKENS THIS
AFTERNOON CONVECTION WILL DEVELOP ACROSS THE AREA...ALTHOUGH WEAK
WINDS ALOFT AND MINIMAL VERTICAL SHEAR WILL NOT BE CONDUCIVE FOR
PERSISTENT ORGANIZED STORM STRUCTURES. NEVERTHELESS...FAVORABLE
LAPSE RATES SUGGEST POTENTIAL FOR STRONGER STORMS TO PRODUCE
MARGINALLY SEVERE HAIL INTO THE EARLY EVENING.

..WEISS/LEITMAN.. 03/21/2012

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