samedi 5 juillet 2014
mercredi 2 juillet 2014
Jul 2, 2014 0600 UTC Day 1 Convective Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1258 AM CDT WED JUL 02 2014 VALID 021200Z - 031200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE APPALACHIANS AND NORTHEAST/MID-ATLANTIC STATES... ...SUMMARY... WIDELY SCATTERED SEVERE STORMS WITH DAMAGING WIND GUSTS AND HAIL ARE LIKELY DURING THE DAY ACROSS THE NORTHEASTERN STATES AND APPALACHIANS VICINITY. A MORE ISOLATED AND MARGINAL SEVERE THREAT MAY ALSO EXIST ACROSS PARTS OF THE SOUTH-CENTRAL UNITED STATES. ...SYNOPSIS... A RELATIVELY AMPLIFIED LONGWAVE PATTERN WILL REMAIN OVER THE CONUS THROUGH TONIGHT. AN UPPER TROUGH OVER ONTARIO/QUEBEC AND THE GREAT LAKES REGION/MIDWEST WILL CONTINUE A SLOW EASTWARD PROGRESSION...WHILE A COLD FRONT ADVANCES EAST-SOUTHEASTWARD TOWARD THE APPALACHIANS/GULF COAST STATES. MEANWHILE...AN ADDITIONAL TROUGH WILL MOVE EASTWARD TOWARD BRITISH COLUMBIA...WITH ASSOCIATED HEIGHT FALLS ACROSS THE PACIFIC NORTHWEST/NORTHERN INTERMOUNTAIN REGION. OTHERWISE...TROPICAL STORM ARTHUR /REFERENCE NHC FOR THE LATEST DETAILS/ WILL REMAIN OFFSHORE WITH LITTLE THREAT IN TERMS OF SEVERE WIND/TORNADO RISK FOR THE MAINLAND. ...NORTHEAST/APPALACHIANS/MID-ATLANTIC STATES... WHILE CYCLONICALLY EMBEDDED IMPULSES MAY NOT BE OPTIMALLY TIMED AND HEIGHT FALLS WILL BE WEAK...INFLUENCES OF AN UPPER JET ENTRANCE REGION WITH AN INCREASINGLY MOIST/UNSTABLE AIR MASS WILL CONTRIBUTE TO AN INCREASE IN STRONG/POTENTIALLY SEVERE THUNDERSTORMS BY LATE MORNING AND AFTERNOON. THIS IS ANTICIPATED NEAR/AHEAD OF A COLD FRONT...AND RESIDUAL OUTFLOWS VIA OVERNIGHT CONVECTION MAY ALSO BE A FACTOR FOR FOCUSING RENEWED TSTM DEVELOPMENT. IN THE PRESENCE OF LOWER 70S F SURFACE DEWPOINTS...THE GREATEST DIURNAL DESTABILIZATION /2000-4000 J PER KG MLCAPE/ IS ANTICIPATED IN VICINITY OF A PRE-FRONTAL TROUGH ACROSS PARTS OF VA/MD/DE INTO PA/NJ. WHILE THE STRONGEST DEEP-LAYER WIND FIELD WILL LAG THE EFFECTIVE FRONT TO THE WEST...30-40 KT OF EFFECTIVE SHEAR IS EXPECTED COINCIDENT WITH MODERATE TO STRONG INSTABILITY. THIS WILL SUPPORT A FEW TRANSIENT SUPERCELLS AND A MORE PREVALENT MULTICELLULAR MODE WITH ASSOCIATED LINE SEGMENTS/SMALL BOWS. DAMAGING WINDS AND MARGINALLY SEVERE HAIL WILL ESPECIALLY BE POSSIBLE THIS AFTERNOON/EARLY EVENING. ...ARKLATEX/SOUTHERN PLAINS/SOUTHERN ROCKIES... UPPER-LEVEL INFLUENCES WILL REMAIN SUBTLE AT BEST...BUT RESIDUAL CONVECTIVELY-INDUCED VORTICITY MAXIMA AND/OR OUTFLOW MAY INFLUENCE A REDEVELOPMENT AND INTENSIFICATION OF TSTMS THIS AFTERNOON FROM THE SOUTHERN HIGH PLAINS TO THE ARKLATEX. VERTICAL SHEAR AND MID-LEVEL LAPSE RATES WILL BE WEAK...BUT SUFFICIENT MOISTURE/BUOYANCY MAY CONTRIBUTE TO A RISK FOR LOCALLY SEVERE WINDS AND/OR MARGINAL HAIL THIS AFTERNOON/EARLY EVENING. FARTHER WEST...OTHER WIDELY SCATTERED STRONG STORMS ARE EXPECTED TO DEVELOP ACROSS INTERIOR NM AND THE AZ MOUNTAINS...WITH A STORM OR TWO CAPABLE OF DOWNBURSTS AND POSSIBLY SOME HAIL.
mardi 1 juillet 2014
Jul 1, 2014 0600 UTC Day 1 Convective Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1255 AM CDT TUE JUL 01 2014 VALID 011200Z - 021200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE OZARKS/OH VALLEY AND NORTHEAST STATES... ...SUMMARY... SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED ESPECIALLY THIS AFTERNOON AND EVENING ACROSS THE LOWER GREAT LAKES...OHIO VALLEY...AND THE OZARKS. OTHER ISOLATED SEVERE THUNDERSTORMS WILL BE POSSIBLE ACROSS PORTIONS OF THE SOUTHERN PLAINS. ...SYNOPSIS... THE LONGWAVE PATTERN WILL UNDERGO ADDITIONAL AMPLIFICATION DURING THE PERIOD. AN UPPER LOW WILL PROGRESS EASTWARD OVER NORTHERN PORTIONS OF ONTARIO/QUEBEC...WITH HEIGHT FALLS CONTINUING TO OVERSPREAD THE MIDWEST/OH VALLEY IN ASSOCIATION WITH THE BASE OF THE UPPER TROUGH. SHOWERS/TSTMS WILL BE SEMI-FOCUSED ALONG/AHEAD OF A SOUTHEASTWARD-MOVING COLD FRONT ACROSS THE NORTHEAST STATES/OH VALLEY/OZARKS...TO THE SOUTHERN HIGH PLAINS/NM. SHOWERS/TSTMS WILL ALSO OCCUR ACROSS THE SOUTHEAST STATES/FL ON THE PERIPHERY OF TROPICAL DEPRESSION ONE /REFERENCE NHC FOR DETAILS/. ...OZARKS/OH VALLEY TO NORTHEAST STATES... CONSIDERABLE OUTFLOW/CLOUD DEBRIS VIA AN OVERNIGHT SQUALL LINE IS EXPECTED TO BE LOCATED ACROSS PARTS OF THE LOWER GREAT LAKES AND MIDDLE/UPPER OH RIVER VALLEY THIS MORNING. THIS HAS UNCERTAIN RAMIFICATIONS ON THE DOWNSTREAM SEVERE POTENTIAL LATER TODAY. HOWEVER...CONVECTION SHOULD REDEVELOP/REINVIGORATE ALONG RESIDUAL OUTFLOW/CORRIDORS OF DIFFERENTIAL HEATING INTO THE AFTERNOON...AND/OR NEAR THE SLOW SOUTHEASTWARD-MOVING SYNOPTIC COLD FRONT. STRONGER CYCLONIC MID/HIGH-LEVEL WESTERLIES WILL TEND TO THE LAG THE COLD FRONT /TO THE WEST/...BUT AROUND 25-30 KT OF EFFECTIVE SHEAR COMBINED WITH A MOISTURE-RICH BOUNDARY LAYER AND MODERATE TO STRONG INSTABILITY WILL ALLOW FOR SUSTAINED MULTICELLS FROM THE OZARKS TO THE UPPER OH VALLEY AND PARTS OF PA/NY. DAMAGING WINDS AND ISOLATED SEVERE HAIL WILL BE THE PRIMARY HAZARDS INTO THIS EVENING. ...OK/NM/SOUTHERN CO AND WEST/NORTH TX... A COLD FRONT...EFFECTIVELY MODIFIED BY CONVECTIVE OUTFLOW IN SOME AREAS...WILL CONTINUE TO SAG GENERALLY SOUTHWARD ACROSS THE REGION TODAY. UPPER FORCING WILL BE RELATIVELY WEAK/NEBULOUS...BUT ISOLATED/WIDELY SCATTERED THUNDERSTORMS SHOULD DEVELOP BY MID/LATE AFTERNOON ALONG/JUST BEHIND THE SURFACE FRONT...AND IN ASSOCIATION WITH A WESTWARD-MOISTURE SURGE/LOW-LEVEL UPSLOPE REGIME ACROSS INTERIOR NM/SOUTHERN CO. EFFECTIVE SHEAR IN MOST AREAS NEAR THE FRONT WILL BE 30 KT OR LESS...WHICH WILL TEND TO LIMIT OVERALL STORM INTENSITY/LONGEVITY. EVEN SO...MODERATE DESTABILIZATION WILL ALLOW FOR SOME SUSTAINED MULTICELLS AND POSSIBLY A TRANSIENT SUPERCELL OR TWO WITH ISOLATED BOUTS OF SEVERE HAIL/WIND THIS AFTERNOON/EARLY EVENING.
Inscription à :
Articles (Atom)