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Apr 29, 2014 0600 UTC Day 1 Convective Outlook

April 29, 2014

Apr 29, 2014 0600 UTC Day 1 Convective Outlook

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DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0107 AM CDT TUE APR 29 2014

VALID 291200Z – 301200Z

…THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF AL AND ERN MS…

…THERE IS A SLGT RISK OF SVR TSTMS ACROSS A LARGE PORTION OF THE ERN U.S. E OF THE MS VALLEY…

…SUMMARY…
WIDESPREAD THUNDERSTORMS ARE FORECAST ACROSS THE CENTRAL GULF COAST REGION…WITH SEVERAL SEVERE/SUPERCELL STORMS POSSIBLE — ALONG WITH ATTENDANT RISK FOR HAIL…DAMAGING WINDS…AND TORNADOES. STRONG/SEVERE STORMS ARE ALSO EXPECTED ACROSS SOUTHERN VIRGINIA AND THE CAROLINAS…WHERE HAIL AND DAMAGING WINDS ARE EXPECTED ALONG WITH THE POTENTIAL FOR A TORNADO OR TWO. SHOWERS AND ISOLATED THUNDERSTORMS — ALONG WITH RISK FOR HAIL AND LOCALLY DAMAGING WINDS — WILL ALSO DEVELOP ACROSS PARTS OF THE MID OHIO VALLEY AND NORTH INTO SOUTHERN LOWER MICHIGAN DURING THE AFTERNOON.

…SYNOPSIS…
A LARGE MID- AND UPPER-LEVEL LOW OVER THE LOWER MO VALLEY VICINITY WILL DRIFT SLOWLY NWD WITH TIME…WITH A BROAD ZONE OF STRONG CYCLONIC FLOW SURROUNDING THIS SYSTEM. AT THE SURFACE…AN OCCLUDED LOW IS PROGGED TO LINGER INVOF THE ERN IA/NRN IL VICINITY MUCH OF THE PERIOD…WITH A TRAILING COLD FRONT TO MAKE SLOW EWD PROGRESS ACROSS THE MID OH AND TN VALLEYS/CENTRAL GULF COAST REGION. AREAS AHEAD OF THIS BOUNDARY WILL AGAIN FALL UNDER A RISK FOR FAIRLY WIDESPREAD SEVERE STORMS.

…ERN TN VICINITY SWD ACROSS THE CENTRAL GULF COAST REGION…
A COMPLEX/UNCERTAIN SCENARIO IS EXPECTED TO EVOLVE DURING THE DAY TUE…AS AN EXTENSIVE BAND OF CONVECTION ONGOING AT THE START OF THE PERIOD CONTINUES TO SHIFT SEWD ACROSS GA/FAR SERN AL AND THE FL PANHANDLE THROUGH THE MORNING. SOME SEVERE RISK IS EXPECTED WITH THESE STORMS — PARTICULARLY WITH SWD EXTENT INTO SWRN GA/FAR SERN AL AND THE FL PANHANDLE…WHERE HAIL AND DAMAGING WINDS WILL BE POSSIBLE. PRESUMING SOME ROTATION WITH STRONGER STORMS WITHIN THE CONVECTIVE BAND…ISOLATED TORNADO RISK WOULD ALSO BE POSSIBLE.

AFTER PASSAGE OF THE CONVECTION…A CONTAMINATED BOUNDARY LAYER ACROSS MS/AL AND VICINITY WILL REQUIRE FAIRLY SUBSTANTIAL RECOVERY. PRESUMING AMPLE HEATING OF THE VERY MOIST BOUNDARY LAYER CAN OCCUR…POTENTIAL FOR REDEVELOPMENT OF CONVECTION NEAR/AHEAD OF THE SURFACE FRONT PUSHING SLOWLY EWD ACROSS THE MS/NWRN AL VICINITY WILL EXIST. HIGH-RES MODEL RUNS — WHILE VARYING WITH RESPECT TO STORM LOCATION AND MODE — GENERALLY AGREE THAT REDEVELOPMENT WILL OCCUR INVOF THE MS/AL BORDER AFTER 20 TO 21Z. GIVEN BACKGROUND SHEAR QUITE FAVORABLE FOR ROTATING STORMS…EXPECT SOME STORMS TO BECOME SUPERCELLULAR — WITH ATTENDANT RISK FOR HAIL/DAMAGING WINDS ALONG WITH A FEW TORNADOES — WITH THE RISK PEAKING FROM LATE AFTERNOON THROUGH MID EVENING.

GIVEN UNCERTAINTY WHICH PERSISTS ATTM…DEGREE OF RISK REMAINS UNCLEAR…AND THUS HAVE OPTED NOT TO INCLUDE SIGNIFICANT SEVERE/TORNADO AREAS ATTM. ONCE THE SCENARIO BECOMES MORE CLEAR…FURTHER REFINEMENTS OF THE FORECAST WILL BE MADE TO BETTER HIGHLIGHT MORE SPECIFIC AREAS/RISK LEVELS.

…THE CAROLINAS AND SRN VA…
MODERATE DESTABILIZATION IS FORECAST TO OCCUR ACROSS PARTS OF SRN VA AND THE CAROLINAS…NEAR AND S OF A PERSISTENT WEDGE FRONT PROGGED TO LIE ROUGHLY FROM WSW-ENE ACROSS THE REGION. THOUGH NOT AS STRONG AS AREAS FARTHER W…DEEP-LAYER SHEAR IS FORECAST TO BE SUFFICIENT FOR ORGANIZED/ROTATING STORMS. AS A RESULT…RISK FOR DAMAGING WINDS AND HAIL — AND POSSIBLY A TORNADO OR TWO — IS EXPECTED WITH STRONGER CELLS AS THEY SPREAD NEWD ACROSS THE AREA THROUGH THE AFTERNOON AND EARLY EVENING HOURS.

…LOWER MI SWD ACROSS THE MID OH VALLEY AREA…
AFTERNOON SHOWERS AND THUNDERSTORMS ARE FORECAST TO DEVELOP ACROSS THE MID OH VALLEY AND NWD INTO LOWER MI…AS THE LEFT EXIT REGION OF A 120-PLUS KT JET ROUNDS THE SOUTHEAST SIDE OF THE UPPER LOW AND SPREADS ACROSS THIS REGION. WITH 500 TO 1000 J/KG OF RELATIVELY LOW-TOPPED MIXED-LAYER CAPE PROGGED TO DEVELOP…A ISOLATED SEVERE STORMS ARE EXPECTED — WITH ORGANIZATION POTENTIAL TO BE ENHANCED BY STRONG FLOW THROUGH THE MID AND UPPER TROPOSPHERE. ALONG WITH A RISK FOR HAIL…LOCALLY DAMAGING WINDS CAN BE EXPECTED THROUGH EARLY EVENING — AFTER WHICH A DIMINISHING TREND IS EXPECTED IN CONJUNCTION WITH DIURNAL BOUNDARY-LAYER STABILIZATION.

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