Convective Outlook Today Through Tonight: Thunderstorms 2% Chance of Tornadoes 5% Chance of Damaging Winds (SPC AC 232108 DAY 1 CONVECTIVE OUTLOOK RESENT 1 NWS STORM PREDICTION CENTER NORMAN OK 0408 PM CDT TUE JUL 23 2013 VALID 232000Z - 241200Z ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL PLAINS...OZARKS TO OH VALLEY...PORTIONS MID-SOUTH REGION TO CENTRAL GULF COAST... ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS NRN/CENTRAL HIGH PLAINS... --- UPDATES --- ...DIXIE... UPSCALE ORGANIZATION OF CONVECTION OVER NRN PORTIONS MS/AL HAS LED TO WELL-ORGANIZED QLCS MOVING SEWD INTO FAVORABLY MOIST/HEATED/UNSTABLE AIR MASS...WITH POTENTIAL FOR DAMAGING GUSTS AND SPORADIC SVR HAIL POTENTIALLY EXTENDING AS FAR S AS GULF COAST BY LATE AFTN OR EARLY EVENING. REF SPC WW 436 AND RELATED MESOSCALE DISCUSSIONS FOR LATEST NEAR-TERM GUIDANCE ON THIS SITUATION. ...OH VALLEY TO LOWER GREAT LAKES... BKN BAND OF STG-SVR TSTMS...WITH BOTH WIND AND HAIL RISK...HAS DEVELOPED ALONG PREFRONTAL CONFLUENCE/WIND-SHIFT LINE...FROM NERN OH SWWD ACROSS SRN INDIANA. THIS ACTIVITY WILL MOVE INTO SFC AIR MASS CHARACTERIZED BY DEW POINTS UPPER 60S TO LOW 70S F...SUPPORTING PRECONVECTIVE MLCAPE RANGING FROM AROUND 1000 J/KG OVER WRN PA TO 3000 J/KG IN SRN INDIANA WHERE DEEP-LAYER LAPSE RATES ARE HIGHER. REF WW 435 AND ACCOMPANYING MESOSCALE DISCUSSIONS FOR LATEST DEVELOPMENTS IN EVOLUTION OF THIS THREAT. ...SERN NY...NEW ENGLAND... WIDELY SCATTERED TSTMS WILL CONTINUE TO OFFER THREAT FOR SPORADIC ISOLATED SVR HAIL AND DAMAGING GUSTS FOR REMAINDER AFTN..ALONG AND AHEAD OF SFC TROUGH AND CONFLUENCE LINE THAT IS MOVING EWD ACROSS THIS REGION INTO AIR MASS CHARACTERIZED BY WEAK CINH AND 70S F SFC DEW POINTS. REF MESOSCALE DISCUSSION 1481 FOR MORE DETAILS. ...CENTRAL PLAINS TO OZARKS... SLGT SWD SHIFT HAS BEEN MADE TO OUTLOOK LINES IN DEFERENCE TO BOUNDARY/INSTABILITY TRENDS. REF SPC MESOSCALE DISCUSSION 1483...AS WELL AS WW 437 AND RELATED MESOSCALE DISCUSSIONS...FOR THIS CORRIDOR. ..EDWARDS.. 07/23/2013 .PREV DISCUSSION... /ISSUED 1125 AM CDT TUE JUL 23 2013/ ...SYNOPSIS... SOME AMPLIFICATION OF THE WESTERLIES IS ONGOING...CENTERED NEAR THE CANADIAN/U.S. BORDER AREA. WHILE UPPER RIDGING BECOMES MORE PROMINENT ACROSS THE PACIFIC NORTHWEST AND BRITISH COLUMBIA THROUGH ALBERTA AND THE NORTHERN U.S. ROCKIES...BROADLY CYCLONIC UPPER FLOW CONTINUES TO EVOLVE EAST OF THE PLAINS INTO THE ATLANTIC SEABOARD. A NUMBER OF SHORT WAVE IMPULSES ARE PROGRESSING THROUGH THIS LATTER REGIME...THE MOST SIGNIFICANT OF WHICH IS NOW DIGGING ACROSS EASTERN ONTARIO...BEFORE GRADUALLY TURNING EASTWARD INTO QUEBEC LATER TODAY AND TONIGHT. THIS FEATURE IS ACCOMPANIED BY A SIGNIFICANT COLD FRONT...WHICH IS EXPECTED TO ADVANCE SOUTH AND EAST OF THE GREAT LAKES REGION...INTO THE OHIO VALLEY/NORTHERN MID ATLANTIC COAST AND NEW ENGLAND BY 12Z WEDNESDAY. EAST OF THE ROCKIES...WHERE 70F SURFACE DEW POINTS REMAIN COMMON ACROSS THE CENTRAL/SOUTHERN PLAINS...INTO THE OHIO VALLEY AND GULF/SOUTH ATLANTIC COASTS...VERY WARM ELEVATED MIXED LAYER AIR CONTINUES TO ADVECT EAST SOUTHEASTWARD ACROSS THE CENTRAL PLAINS...TOWARD THE OHIO VALLEY. THIS WILL CONTRIBUTE TO LARGE CAPE...AND THERMODYNAMIC PROFILES POTENTIALLY SUPPORTIVE OF SEVERE STORM DEVELOPMENT OVER A SIZABLE AREA...IN THE PRESENCE OF WEAK TO MODERATE DEEP LAYER SHEAR BENEATH WEST NORTHWESTERLY MID/UPPER FLOW. ACROSS THE CENTRAL AND SOUTHERN INTERMOUNTAIN WEST AND ROCKIES ...AT LEAST A COUPLE OF IMPULSES EMBEDDED WITHIN THE BROADER SCALE RIDGING WILL CONTRIBUTE TO AREAS OF THUNDERSTORM ACTIVITY...IN THE PRESENCE OF A FAIRLY MOIST ENVIRONMENT AND STRONG DAYTIME HEATING. ...CNTRL PLAINS INTO THE VICINITY OF THE APPALACHIANS... THE COLD FRONT ACROSS THE GREAT LAKES APPEARS PRECEDED BY DRYING IN THE WAKE OF A LEADING WIND SHIFT/CONVECTIVELY GENERATED BOUNDARY NOW CURVING ACROSS NORTH CENTRAL INDIANA AND CENTRAL ILLINOIS THROUGH THE INTERSTATE 70 CORRIDOR OF MISSOURI. ANOTHER CONVECTIVELY GENERATED BOUNDARY APPEARS TO HAVE ADVANCED SOUTHWARD ACROSS MUCH OF NORTHERN AND CENTRAL KANSAS. ADDITIONALLY...OVERNIGHT CONVECTION HAS LEFT A SIZABLE COLD/STABLE SURFACE BUBBLE ACROSS MUCH OF SOUTHEAST MISSOURI/NORTHWESTERN ARKANSAS AND ADJACENT WESTERN KENTUCKY/TENNESSEE AND NORTHERN MISSISSIPPI. OUTSIDE OF THIS LATTER FEATURE...AND SOUTH OF THE PRE-FRONTAL BOUNDARIES...DAYTIME HEATING IS EXPECTED TO CONTRIBUTE TO CAPE OF 2000-3000+ J/KG. MODELS CONTINUE TO SUGGEST THE SOUTHEASTWARD DEVELOPMENT OF AN AREA OF LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION...NOW ASSOCIATED WITH WEAK CONVECTION OVER THE MID MISSOURI VALLEY... THROUGH THE REMAINDER OF THE PERIOD. SPECIFICS REMAIN UNCLEAR... BUT THE ENVIRONMENT STILL APPEARS CONDUCIVE TO THE DEVELOPMENT OF ADDITIONAL CONVECTION...AND UPSCALE GROWTH INTO ONE OR MORE ORGANIZED CONVECTIVE CLUSTERS...ACROSS PARTS OF KANSAS/OKLAHOMA AND MISSOURI THROUGH THE OZARK PLATEAU AND ADJACENT LOWER MISSISSIPPI VALLEY LATER TODAY AND TONIGHT. FARTHER TO THE EAST...POTENTIAL FORCING IS A BIT MORE UNCLEAR...TO THE SOUTH OF A WEAK IMPULSE NOW SHIFTING INTO THE LOWER GREAT LAKES AND UPPER OHIO VALLEY REGION. BUT...AN ASSOCIATED BELT OF MODEST LOWER/MID TROPOSPHERIC FLOW NOSING THROUGH THE OHIO VALLEY COULD STILL ENHANCE ANY CONVECTIVE DEVELOPMENT THAT MAY OCCUR IN THE PEAK AFTERNOON HEATING...AS MID-LEVEL INHIBITION REMAINS RELATIVELY WEAK. ...NORTHERN HIGH PLAINS... RESIDUAL LOW-LEVEL MOISTURE IN A SOUTHEASTERLY UPSLOPE REGIME...BENEATH NORTHWESTERLY MID-LEVEL FLOW...COUPLED WITH STEEPENING LAPSE RATES ARE STILL EXPECTED TO CONTRIBUTE TO A FAVORABLE ENVIRONMENT FOR AT LEAST SCATTERED STRONG/SEVERE STORMS LATE THIS AFTERNOON AND EVENING. THIS PROBABLY WILL INCLUDE A COUPLE OF SUPERCELLS AND ONE OR TWO SMALL ORGANIZED STORM CLUSTERS. ...GREAT BASIN... CONVECTION EXPECTED TO DEVELOP ALONG A SLOWLY NORTHWARD ADVANCING SHEAR AXIS LIKELY WILL BE PRECEDED BY THE DEVELOPMENT OF A VERY WARM/HOT...DEEPLY MIXED BOUNDARY LAYER ACROSS MUCH OF CENTRAL/ SOUTHERN UTAH INTO PARTS OF EASTERN NEVADA. THIS ENVIRONMENT PROBABLY WILL BE CONDUCIVE TO THE RISK FOR AT LEAST LOCALIZED STRONG CONVECTIVE SURFACE GUSTS LATE THIS AFTERNOON AND EVENING. ...LONG ISLAND AREA INTO SOUTHERN NEW ENGLAND... VIGOROUS CONVECTIVE DEVELOPMENT STILL APPEARS POSSIBLE NEAR A WEAK SURFACE LOW...WITHIN THE LEE SURFACE TROUGH...MIGRATING NORTHEASTWARD ACROSS THE REGION THIS AFTERNOON. DEEP LAYER LAPSE RATES ARE RATHER WEAK...AND FLOW FIELDS...PARTICULARLY AT LOWER/MID-LEVELS...SEEM MARGINAL AT BEST. HOWEVER...PRECIPITABLE WATER IS HIGH...AND IT MAY NOT BE OUT OF THE QUESTION THAT HEAVY PRECIPITATION LOADING COULD CONTRIBUTE TO STRONG WIND GUSTS NEAR STRONGER CONVECTION. CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z CURRENT UTC TIME: 2122Z (5:22PM), RELOAD THIS PAGE TO UPDATE THE TIME) Convective Outlook Tomorrow Through Tomorrow Night: Thunderstorms
Posted on: Tue, 23 Jul 2013 21:23:43 +0000
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