Friday, April 8, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 080529
SWODY1
SPC AC 080527

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1227 AM CDT FRI APR 08 2011

VALID 081200Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE OH/TN
VALLEY INTO SRN MO...

...MID MS/OH/TN VALLEY REGION...

ASIDE FROM A PSEUDO-STATIONARY FRONTAL ZONE DRAPED ACROSS THE OH
VALLEY INTO MO...A RATHER NONDESCRIPT LARGE SCALE PATTERN WILL BE
SITUATED ACROSS THE REGION FRIDAY WITH WEAK HEIGHT RISES EXPECTED
THROUGH THE PERIOD. WEAK LARGE SCALE FORCING THROUGH THE AFTERNOON
HOURS WILL ENSURE THE SIGNIFICANCE OF THE AFOREMENTIONED SFC
BOUNDARY IN REGARDS TO ORGANIZED THUNDERSTORM DEVELOPMENT. LATEST
MODEL GUIDANCE SUGGEST STRONG BOUNDARY LAYER HEATING WILL BE NOTED
ACROSS SRN IL INTO NRN KY/SRN OH. THIS SHOULD ENHANCE THE PROSPECT
FOR CONVECTIVE DEVELOPMENT WITHIN STRONGLY SHEARED ENVIRONMENT
FAVORABLE FOR SUSTAINED ROTATING UPDRAFTS. FORECAST SOUNDINGS FAVOR
SUPERCELL DEVELOPMENT EARLY IN THE CONVECTIVE CYCLE AND THIS SEEMS
REASONABLE GIVEN THE WEAK FORCING. WITH TIME STORM MERGERS AND
CONVECTIVE INTERFERENCE COULD LEAD TO STORM CLUSTERS AS MEAN WIND
VECTOR DRIVES TSTMS SEWD AT ROUGHLY 30KT. FOR THIS REASON IT
APPEARS THERE WILL BE A THREAT FOR LARGE HAIL...DAMAGING WINDS AND
PERHAPS EVEN A FEW TORNADOES AS BOUNDARY LAYER MOISTURE AND RH
VALUES WILL HAVE RISEN SIGNIFICANTLY BY THIS TIME.

FARTHER WEST ACROSS MO...IT/S NOT ENTIRELY CLEAR HOW MUCH DIURNAL
ACTIVITY WILL DEVELOP ALONG THE FRONT AS LOW LEVEL CONVERGENCE WILL
BE ESPECIALLY WEAK ACROSS THIS REGION. HOWEVER...LLJ SHOULD
INCREASE MARKEDLY NEAR SUNSET INTO THE EVENING HOURS. STRONG WARM
ADVECTION ACROSS THIS REGION WILL LIKELY FORCE A BOUT OF SEVERE
THUNDERSTORMS AFTER DARK THAT WILL EVOLVE WITHIN A VERY UNSTABLE
ENVIRONMENT CHARACTERIZED BY STEEP LAPSE RATES AND MUCAPE
APPROACHING 2000-3000 J/KG. LARGE HAIL IS CERTAINLY POSSIBLE IF
ACTIVITY CAN BECOME SUSTAINED BENEATH THE LLJ ACROSS THIS REGION.

...TX/OK...

STRONG DIURNAL HEATING WILL ONCE AGAIN BE NOTED ACROSS THE SRN
PLAINS...ESPECIALLY ALONG/WEST OF THE DRYLINE. UNCAPPED THERMALS
NEAR THE DRYLINE WILL LIKELY STRUGGLE TO SUSTAIN THEMSELVES WITHIN A
RIDGY MID LEVEL ENVIRONMENT. HOWEVER...SIGNIFICANT MOISTENING
WITHIN THE BOUNDARY LAYER AND WEAK LOW LEVEL CONVERGENCE MAY RESULT
IN ONE OR TWO SEVERE THUNDERSTORMS NEAR 09/00Z. IF STORMS MANAGE TO
INITIATE LARGE HAIL AND DAMAGING WINDS COULD OCCUR. THIS ACTIVITY
SHOULD DISSIPATE WITHIN A FEW HOURS AS BOUNDARY LAYER COOLS.

...GULF STATES...

EARLY EVENING WV IMAGERY SUGGESTS A WEAK UPPER VORT/SHORTWAVE TROUGH
IS EJECTING NEWD ACROSS MEXICO INTO DEEP SOUTH TX. THIS FEATURE MAY
NOT BE HANDLED WELL WITHIN BROADER HEIGHT RISES THAT SHOULD
OVERSPREAD THE SRN STATES LATER TODAY. AS A RESULT...WEAK ASCENT
MAY ENHANCE THE PROSPECT FOR ISOLATED THUNDERSTORMS ALONG THE ERN
PLUME OF STEEPER LAPSE RATES...ESPECIALLY ACROSS AL INTO GA. IF
SO...STRONG SHEAR AND SUBSTANTIALLY MORE MOIST/UNSTABLE AIRMASS WILL
BE IN PLACE FOR POSSIBLE SEVERE. WILL MAINTAIN LOW PROBS FOR
WIND/HAIL PRIMARILY DUE TO THE SUBTLE SHORTWAVE AND WEAK FORCING.
HOWEVER IF IT APPEARS A MORE ORGANIZED CONVECTIVE SCENARIO WILL
UNFOLD THEN A SLIGHT RISK MAY BE REQUIRED.

..DARROW/HURLBUT.. 04/08/2011

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