SPC 2000Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0240 PM CDT SUN MAY 19 2013 VALID 192000Z - 201200Z ...THERE IS A MDT RISK OF SVR TSTMS FROM CNTRL OK TO WRN MO... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM NCNTRL TX TO CNTRL MN... ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF MIDDLE TN INTO SRN GA... ...FEW STRONG TORNADOES POSSIBLE ACROSS MDT RISK AREA... STRONG HEATING ACROSS WRN OK HAS REMOVED THE CAP ALONG THE DRYLINE...PER DEEPENING CU FROM THE RED RIVER NEAR SPS...NWD ACROSS CADDO COUNTY INTO SCNTRL KS OVER HARPER COUNTY WHERE LIGHTNING IS NOW OBSERVED WITH DEEPEST CONVECTION. WITH TEMPERATURES CONTINUING TO RISE THERE IS REASON TO BELIEVE SCATTERED SUPERCELLS WILL EMERGE ALONG THE DRYLINE...ESPECIALLY NORTH OF I-40 INTO ERN KS WHERE VERY MOIST/BUOYANT AIRMASS CURRENTLY RESIDES. VERTICAL SHEAR PROFILES ARE SUCH THAT LONG-LIVED SUPERCELLS ARE EXPECTED...AND IF SUFFICIENT COUPLING WITH MOIST BOUNDARY LAYER OCCURS A FEW STRONG TORNADOES MAY BE NOTED ACROSS THE MDT RISK INTO THE EVENING HOURS...ESPECIALLY INVOF OLD OUTFLOW BOUNDARY THAT WAS DRAPED ACROSS NERN OK/SERN KS. ALTHOUGH IT HAS LOST ITS IDENTITY...BOUNDARY LAYER WINDS ARE BACKED A BIT ACROSS THIS REGION AND THIS MAY SERVE TO ENHANCE LOW LEVEL SHEAR. ...ERN TN...NERN AL/NWRN GA... HAVE OPTED TO INCREASE SEVERE PROBS ACROSS PARTS OF ERN TN INTO NERN AL/NWRN GA TO ACCOUNT FOR NW-SE ORIENTED CONVECTIVE CLUSTER THAT SHOULD PROPAGATE SWD ACROSS THIS REGION. LOCALLY DAMAGING WINDS MAY ACCOMPANY THIS UPWARD EVOLVING COMPLEX OF STORMS BEFORE DIURNAL COOLING RESULTS IN WEAKENING. ...ELSEWHERE... EARLIER THOUGHTS REGARDING DEEP CONVECTION REMAIN AND ONLY MINOR CHANGES HAVE BEEN MADE TO 1630Z FORECAST. ..DARROW.. 05/19/2013 .PREV DISCUSSION... /ISSUED 1115 AM CDT SUN MAY 19 2013/ ...SYNOPSIS... A DEEP LAYER CYCLONE APPEARS LIKELY TO CONTINUE TO EVOLVE THROUGH THIS FORECAST PERIOD OVER THE MID MISSOURI VALLEY REGION. IN ASSOCIATION WITH THIS FEATURE...MID/UPPER FLOW HAS ALREADY STRENGTHENED ACROSS THE TEXAS/OKLAHOMA PANHANDLE REGION THROUGH THE CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY...IN A BELT CURVING CYCLONICALLY OUT OF THE INTERMOUNTAIN REGION. WITHIN THIS REGIME...A SERIES OF SHORT WAVE IMPULSES/SPEED MAXIMA HAVE AND WILL CONTINUE TO EMERGE FROM THE INTERMOUNTAIN WEST...WHILE ADDITIONAL PERTURBATIONS CONTINUE TO DIG INTO THE GREAT BASIN. EAST OF THE ROCKIES...MID-LEVEL LAPSE RATES REMAIN VERY STEEP OVER A BROAD AREA...FROM THE CENTRAL PLAINS AND MIDDLE MISSISSIPPI VALLEY SOUTHWARD TO GULF COASTAL AREAS. ATOP A RELATIVELY MOIST BOUNDARY LAYER...THIS WILL CONTRIBUTE TO SUBSTANTIAL CONVECTIVE INSTABILITY AND SIZABLE CAPE ACROSS A BROAD AREA OF THE PLAINS AND MISSISSIPPI VALLEY REGION. THIS IS EXPECTED TO BE ACCOMPANIED BY CONSIDERABLE THUNDERSTORM ACTIVITY...INCLUDING ANOTHER OUTBREAK OF SEVERE WEATHER...PARTICULARLY ACROSS PARTS OF EASTERN KANSAS AND OKLAHOMA INTO PARTS OF MISSOURI. ADDITIONALLY...ON THE WESTERN PERIPHERY OF A WEAK CYCLONIC BELT OF FLOW DEVELOPING EASTWARD ACROSS THE SOUTH ATLANTIC COAST REGION...LIFT AND STEEPENING MID-LEVEL LAPSE RATES ASSOCIATED WITH LOWER/MID TROPOSPHERIC WARM ADVECTION WILL MAINTAIN A RISK FOR THUNDERSTORM ACTIVITY FROM PARTS OF THE TENNESSEE VALLEY INTO GEORGIA AND NORTHERN FLORIDA. MARGINALLY SEVERE WIND AND HAIL DO NOT APPEAR OUT OF THE QUESTION IN STRONGER STORMS...PARTICULARLY WITH ADDITIONAL HEATING AHEAD OF AN ORGANIZING STORM CLUSTER NOW ADVANCING WEST THROUGH SOUTH OF ATLANTA GA. ...PLAINS/MISSISSIPPI VALLEY... ONE SHORT WAVE IMPULSE IS CURRENTLY IN THE PROCESS OF TURNING NORTHEAST OF THE CENTRAL PLAINS INTO THE UPPER MISSISSIPPI VALLEY. THIS FEATURE IS AIDING INCREASING STORM DEVELOPMENT ACROSS PARTS OF NORTHEAST MISSOURI INTO WEST CENTRAL ILLINOIS. SOME SEVERE HAIL/WIND POTENTIAL MAY EXIST WITH THIS ACTIVITY... BUT A MORE SUBSTANTIVE SEVERE WEATHER RISK MAY AWAIT FURTHER BOUNDARY LAYER DESTABILIZATION AND WEAKENING INHIBITION ACROSS IOWA NORTHWARD INTO PARTS OF MINNESOTA AND WISCONSIN LATER TODAY. THE PRIMARY SEVERE WEATHER POTENTIAL IS EXPECTED TO DEVELOP IN THE WAKE OF THIS INITIAL IMPULSE...AS ANOTHER CONTINUES TO PIVOT EAST OF THE CENTRAL HIGH PLAINS THIS AFTERNOON. THIS SEEMS MOST LIKELY TO BECOME FOCUSED ALONG/SOUTH AND EAST OF A REMNANT CONVECTIVELY GENERATED BOUNDARY THAT CURRENTLY CURVES FROM THE MISSOURI OZARKS INTO NORTHERN OKLAHOMA. A NORTHWARD RETREAT OF THIS BOUNDARY INTO SOUTHERN KANSAS IS STILL EXPECTED...AND LATEST HIGH RESOLUTION RAPID REFRESH APPEARS REASONABLE SUGGESTING INITIATION OF STORMS ALONG THE INTERSECTION OF THIS BOUNDARY AND AN EASTWARD ADVANCING DRYLINE...ACROSS NORTH CENTRAL OKLAHOMA OR SOUTH CENTRAL KANSAS...BY 19-20Z. AIDED BY FORCING IN THE EXIT REGION OF A MID-LEVEL SPEED MAXIMUM NOSING NORTHEASTWARD ACROSS THE SOUTH CENTRAL PLAINS...UPSCALE CONVECTIVE GROWTH INTO A SUBSTANTIAL MESOSCALE CONVECTIVE SYSTEM IS EXPECTED LATE THIS AFTERNOON AND EVENING. IN THE PRESENCE OF STRONG DEEP LAYER SHEAR...40-50 KT SOUTHERLY 850 MB FLOW NEAR AND SOUTH OF THE CONVECTIVE BOUNDARY WILL CONTRIBUTE TO SIZABLE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS SUPPORTIVE OF THE RISK FOR TORNADOES. HIGHEST PROBABILITIES FOR TORNADOES...SOME POSSIBLY STRONG...MAY BE SUPERCELLS ON THE SOUTHERN FLANK OF THE EVOLVING CONVECTIVE SYSTEM...ACROSS SOUTHEAST KANSAS INTO PARTS OF WEST CENTRAL/SOUTHEAST MISSOURI...AS WELL AS WITH STORMS INITIATING AND ADVANCING NORTHEASTWARD OFF THE DRYLINE...ACROSS NORTHEASTERN OKLAHOMA. FURTHER STRENGTHENING OF THE 850 MB JET ACROSS EASTERN OKLAHOMA INTO SOUTHWEST MISSOURI WILL MAINTAIN TORNADIC POTENTIAL WELL INTO THE EVENING HOURS...WITH ONE OR TWO LONG-LIVED TORNADIC SUPERCELLS POSSIBLE.
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_2000.html
Be First to Comment