SWODY1
SPC AC 051946
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0246 PM CDT SUN APR 05 2009
VALID 052000Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE MID MS/TN/OH VALLEY
REGION...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
SOUTHEAST...
...MID MS/OH/TN VALLEYS...
WHILE SOME BOUNDARY-LAYER MOISTENING CONTINUES TO SHIFT NEWD AHEAD
OF THE ADVANCING FRONT...INSTABILITY REMAINS LIMITED THIS
AFTERNOON...WITH LATEST OBJECTIVE ANALYSES INDICATING MIXED-LAYER
CAPE AOB 500 J/KG. NONETHELESS...THE LACK OF GREATER
DESTABILIZATION SHOULD CONTINUE TO BE OFFSET BY INCREASING
DEEP-LAYER WIND FIELD...WITH 100 KT SWLY H5 FLOW AND H7 SWLYS IN
EXCESS OF 50 KT NOW INTO THE MID MS VALLEY.
THOUGH SLOW TO EVOLVE GIVEN LIMITED THERMODYNAMICS...IT STILL
APPEARS THAT AN ORGANIZED/PERSISTENT CLUSTER OF THUNDERSTORMS WILL
SHIFT ACROSS THE OH VALLEY THROUGH THIS EVENING...WITH A CONTINUED
THREAT FOR DAMAGING WINDS...HAIL...AND AN ISOLATED TORNADO OR TWO.
...SERN AL/SRN GA/NRN FL...
STRONG/BOWING STORM CLUSTER CONTINUES MOVING ESEWD ACROSS SERN GA
ATTM...AND WILL INTERSECT AN INLAND-MOVING SEA BREEZE BOUNDARY IN
THE NEXT HOUR BEFORE MOVING OFFSHORE. EXPECT THE THREAT FOR
DAMAGING WINDS AND HAIL ALONG WITH ISOLATED TORNADO POTENTIAL TO
CONTINUE OVER SERN GA.
SOME CONVECTIVE REDEVELOPMENT IS INDICATED ATTM ACROSS SWRN GA AND
THE FL PANHANDLE...INVOF THE MARINE BOUNDARY AT THE LEADING EDGE OF
THE MORE TROPICAL /UPPER 60S TO LOW 70S DEWPOINTS/ BOUNDARY LAYER.
STORMS DEVELOPING HERE COULD INTENSIFY AND POSE SOME SEVERE
THREAT...THOUGH WEAK SHORT-WAVE RIDGING EVIDENT ON WV IMAGERY MAY
LIMIT THIS POTENTIAL IN THE SHORT TERM.
LATER...SEVERE THREAT MAY INCREASE INVOF THE COLD FRONT AS IT
CROSSES MS THIS AFTERNOON...AND MOVES ACROSS AL TOWARD WRN GA THIS
EVENING. WHILE THE STRONGER UPPER FORCING WILL REMAIN TO THE N AND
W OF THE SURFACE FRONT AS IT CROSSES THIS REGION...ISOLATED STORM
DEVELOPMENT WILL BE POSSIBLE -- WITH AN ACCOMPANYING/CONDITIONAL
THREAT FOR DAMAGING WINDS AND HAIL...AND A TORNADO OR TWO INVOF THE
AFOREMENTIONED MARINE FRONT.
..GOSS.. 04/05/2009
.PREV DISCUSSION... /ISSUED 1108 AM CDT SUN APR 05 2009/
...SYNOPSIS...
NEXT IN SERIES OF STRONG VORT MAXES ROTATING THRU LARGE CENTRAL U.S.
TROUGH MOVING RAPIDLY EWD ACROSS LOWER MO AND THEN ACROSS OH VALLEY
TONIGHT. 100KT MID LEVEL JET MAX ASSOCIATED WITH THIS FEATURE
DRIVES EWD ACROSS NRN AR/MO BOOTHEEL BY MID-AFTERNOON TO CENTRAL
APPALACHIANS BY LATER TONIGHT. IN RESPONSE TO THIS POTENT LARGE
SCALE FORCING...SURFACE LOW NOW MOVING EWD INTO CENTRAL IL WILL
DEEPEN AS IT TRACKS ACROSS CENTRAL IND INTO OH BY THIS EVENING.
AGAIN TODAY THE ONLY LACKING PARAMETER FOR WIDESPREAD SEVERE
THUNDERSTORMS IS THE LIMITED LOW LEVEL MOISTURE. DEWPOINTS HOWEVER
ARE RISING RAPIDLY INTO LOWER OH/WRN TN VALLEY ATTM AND MODELS
SUPPORT MID 50 DEWPOINTS SPREADING EWD ACROSS OH VALLEY TO S OF
SURFACE LOW TRACK LATER THIS AFTERNOON/EVENING AS LOW LEVEL JET IN
WARM SECTOR INCREASES TO AOA 50KT.
...MID MS AND OH VALLEY...
THE STRONG HEATING NOW OCCURRING MUCH OF OH VALLEY WILL STEEPEN LOW
LEVEL LAPSE RATES AND WITH MOISTURE INCREASING FROM THE SW THRU THE
AFTERNOON RESULT IN SBCAPES RISING TO 500-1000 J/KG. STRONG SHEAR
PROFILES IN PLACE WILL BECOME EVEN MORE FAVORABLE FOR ORGANIZED
THUNDERSTORMS INCLUDING SUPERCELLS WITH THE APPROACH OF THE 100KT
MID LEVEL JET MAX AND RAMPING UP OF BOUNDARY LAYER FLOW IN RESPONSE
TO SURFACE LOW DEEPENING.
CURRENT ELEVATED THUNDERSTORMS WRN OH VALLEY WILL QUICKLY TRANSITION
TO SURFACE BASED STORMS EARLY THIS AFTERNOON ALONG AND AHEAD OF COLD
FRONT NOW MOVING EWD ACROSS SERN MO INTO CENTRAL AR. SUPERCELLS WILL
LIKELY DEVELOP WHICH WILL BOTH ENHANCE LARGE HAIL/DAMAGING WIND
POTENTIAL AND INCLUDE RISK OF A FEW TORNADOES.
REF MCD 398
BY MID/LATE AFTERNOON SEVERE THUNDERSTORMS EXPECTED TO BECOME MORE
NUMEROUS AND LIKELY DEVELOP INTO ONE OR MORE SQUALL LINES GIVEN THE
STRONG SHEAR. THIS WILL RESULT IN AN INCREASING THREAT FOR WIND
DAMAGE AS THE ACTIVITY MOVES RAPIDLY EWD ACROSS OH AND NRN TN
VALLEYS. HAVE EXTENDED THE SLIGHT RISK EWD TONIGHT TO THE
APPALACHIANS GIVEN THE INTENSITY OF THE SYSTEM AND CONTINUED INFLUX
OF GULF MOISTURE OCCURRING IN ADVANCE OF THE COLD FRONT. PRIMARY
THREAT WILL CONTINUE TO BE WIND DAMAGE ASSOCIATED WITH THE SQUALL
LINE/S BUT TORNADOS CAN NOT BE RULED OUT THRU THE EVENING ACROSS
MUCH OF KY INTO SRN OH.
...SRN AL/GA/NRN FL...
CLUSTER OF THUNDERSTORMS CONTINUING THIS MORNING IN LOW LEVEL
WARM ADVECTION REGIME OVER CENTRAL AL/GA. THESE STORMS APPEAR TO BE
CONSISTENTLY HANDLED BY THE VARIOUS MODELS...SHOWING INCREASING
COVERAGE AND INTENSITY AS THE CLUSTER MOVES ACROSS CENTRAL GA TODAY.
THE STORMS WILL LIKELY REINFORCE AN OUTFLOW BOUNDARY THROUGH
AFTERNOON...WHICH MAY BE A FOCUS FOR CONTINUED DEVELOPMENT. THIS
REGION WILL SEE GREATER MOISTURE VALUES THAN FARTHER NORTH...AND
SHOULD SEE POCKETS OF MODERATE CAPE /1500-2000 J/KG/. TORNADOES WILL
BE POSSIBLE IN THIS REGION AS WELL...BUT LARGE HAIL AND DAMAGING
WINDS SHOULD BE THE MAIN THREAT. AFTER DARK...LOW LEVEL WINDS ARE
FORECAST TO STRENGTHEN. THIS MAY RE-INVIGORATE THE TORNADO RISK
OVER PARTS OF GA/FL...MAINLY ALONG AND SOUTH OF THE REMNANT OUTFLOW
BOUNDARY.
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