SWODY2
SPC AC 070552
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1252 AM CDT THU APR 07 2011
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MIDDLE/LOWER OH VALLEY
INTO SERN MO...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF CENTRAL/ERN OK
TO NORTH CENTRAL TX...
...SYNOPSIS...
LATEST DETERMINISTIC MODELS ARE A LITTLE SLOWER THAN YESTERDAY WITH
THE SEWD PROGRESSION OF THE WRN TROUGH. HOWEVER...THEY DO AGREE
THAT THE CLOSED LOW LOCATED WITHIN THE SRN EXTENT OF THIS SYSTEM
WILL SHIFT SSEWD FROM CENTRAL CA TO SRN CA AND OFF THE NRN BAJA
COAST BY 12Z SATURDAY. DOWNSTREAM...A RIDGE WILL BUILD NWD ACROSS
THE MS VALLEY IN THE WAKE OF A MIDLEVEL SHORTWAVE TROUGH TRACKING
THROUGH THE OH VALLEY TO THE MID ATLANTIC STATES.
...OH VALLEY...
A SURFACE LOW ATTENDANT TO THE MIDWEST/OH VALLEY SHORTWAVE TROUGH
INITIALLY LOCATED OVER IL...AND AN ESEWD EXTENDING WARM FRONT...
WILL SHIFT EWD ON FRIDAY. THE SURFACE LOW SHOULD REACH SRN/ERN OH
BY 09/00Z. ELEVATED TSTMS SHOULD BE ONGOING ALONG AND EAST OF THE
NW-SE ORIENTED WARM FRONT IN THE LOWER OH VALLEY. THIS ACTIVITY
WILL PROGRESS EWD ACROSS OH AND INTO WV BY EARLY FRIDAY AFTERNOON.
LOW LEVEL SWLY FLOW WILL ADVECT MOISTURE EWD THROUGH THE OH VALLEY
WITH LOWER 60S SURFACE DEWPOINTS REACHING SRN OH/ERN KY IN THE
AFTERNOON...WITH MID 60S INTO SERN MO. SURFACE HEATING WITHIN THE
WARM SECTOR COMBINED WITH THE AVAILABLE MOISTURE SHOULD RESULT IN
MODERATE INSTABILITY /MLCAPE 1000-2000 J PER KG/. FORCING FOR
ASCENT WITH THE TRANSIENT SHORTWAVE TROUGH AND LOW LEVEL CONVERGENCE
INVOF THE SURFACE LOW AND TRAILING WIND SHIFT THROUGH THE LOWER OH
VALLEY TO SRN MO IS EXPECTED TO SUPPORT TSTM DEVELOPMENT.
UNIDIRECTIONAL DEEP LAYER WLY WINDS AND EFFECTIVE BULK SHEAR UP TO
50 KT SHOULD SUPPORT ORGANIZED STRONG TO SEVERE STORMS...WITH
DAMAGING WINDS AND HAIL THE PRIMARY THREATS.
...SRN PLAINS...
HEIGHT RISES ARE EXPECTED ACROSS THE SRN PLAINS DURING DAY 2. WHILE
THIS WOULD NORMALLY BE A LIMITING FACTOR FOR CONVECTIVE
DEVELOPMENT...MODELS HAVE REMAINED CONSISTENT SHOWING A WEAK IMPULSE
TRACKING NEWD ACROSS NRN TX AND OK FRIDAY AFTERNOON. FORCING FOR
ASCENT WITH THIS FEATURE ALOFT MAY PROVE SUFFICIENT IN PRODUCING AT
LEAST ISOLATED TSTMS ALONG THE DRY LINE FROM NRN TX INTO CENTRAL OK.
THE DRY LINE SHOULD RESIDE FROM CENTRAL KS SWD THROUGH CENTRAL OK
/TO THE WEST OF I-35/ INTO CENTRAL AND SRN TX. INCREASING SLY LOW
LEVEL WINDS WILL ALLOW BETTER MOISTURE RETURN ALONG AND E OF THE DRY
LINE...WITH SURFACE DEWPOINTS IN THE LOWER-MID 60S REACHING CENTRAL
OK BY PEAK HEATING. STEEP MIDLEVEL LAPSE RATES AND ERN EXTENT OF
STRONG DIABATIC HEATING JUXTAPOSED WITH WRN EXTENT OF GREATER
MOISTURE WILL RESULT IN MODERATE INSTABILITY /MLCAPE 1500-2500 J PER
KG/. GUIDANCE CONTINUES TO SHOW EFFECTIVE BULK SHEAR UP TO 50 KT
AND CROSSING PERPENDICULAR TO THE DRY LINE SUPPORTIVE OF
SUPERCELLS. GIVEN THE WEAK FORCING FOR ASCENT...THIS ACTIVITY IS
EXPECTED TO BE DIURNAL AND MAY BE LIMITED IN OVERALL COVERAGE.
HOWEVER...THE DEGREE OF INSTABILITY AND DEEP LAYER SHEAR SUGGESTS A
CONDITIONAL SLIGHT RISK REMAINS WARRANTED IF TSTMS CAN FORM FRIDAY
AFTERNOON.
..PETERS.. 04/07/2011
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