DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1255 AM CST FRI DEC 25 2015 VALID 261200Z - 271200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CENTRAL AND NRN TX/SERN OK VICINITY... ...THERE IS A MRGL RISK OF SVR TSTMS FROM THE MIDDLE RIO GRANDE VALLEY NEWD ACROSS MUCH OF THE OH VALLEY AREA... ...SUMMARY... SEVERE THUNDERSTORMS WILL BE POSSIBLE FOR SATURDAY AND SATURDAY NIGHT FROM PORTIONS OF THE LOWER OHIO VALLEY TO THE SOUTHERN GREAT PLAINS...WITH THE GREATEST POTENTIAL FOR THIS ACTIVITY ACROSS PARTS OF SOUTHEASTERN OKLAHOMA TO CENTRAL AND SOUTH TEXAS AND VICINITY. ...SYNOPSIS... THE UPPER PATTERN AT THE START OF THE PERIOD IS PROGGED TO FEATURE A LARGE...POSITIVELY TILTED SRN STREAM TROUGH EXTENDING FROM THE NRN PLAINS SWWD TO THE DESERT SW...AND RIDGES FLANKING THE TROUGH IN BOTH THE ERN AND WRN STATES. WITH TIME HOWEVER...THE ENERGETIC SRN PORTION OF THIS TROUGH WILL EVOLVE INTO A DEEPENING CLOSED LOW...WITH THIS LOW TO SHIFT EWD ROUGHLY ALONG THE U.S./MEXICO BORDER REACHING FAR W TX LATE. AS THE UPPER LOW ADVANCES EWD...SURFACE CYCLOGENESIS IS PROGGED OVER INVOF THE RIO GRANDE. GRADUAL EWD ADVANCE OF THIS DEEPENING CYCLONE -- REACHING S TX BY THE END OF THE PERIOD -- IS EXPECTED. AHEAD OF THE LOW...A LARGE/MOIST WARM SECTOR WILL REMAIN IN PLACE FROM ERN PORTIONS OF THE SRN PLAINS EWD ACROSS THE SOUTHEAST AND TN VALLEY REGION. WHILE LOW-LEVEL WARM/MOIST ADVECTION EARLY IN THE PERIOD OVER THE OH VALLEY IS EXPECTED...AN EVENTUAL ADVANCE OF COLD AIR SEWD ACROSS THE PLAINS/MIDWEST WILL BEGIN SUPPRESSING THE BAROCLINIC ZONE SEWD THROUGH THE END OF THE PERIOD. ...CENTRAL AND NERN TX/SERN OK... STRONG WARM ADVECTION AT LOW-LEVELS WILL PERSIST OVER THE SRN PLAINS REGION THIS PERIOD...AS THE DEEPENING UPPER LOW ADVANCES AND A SURFACE CYCLONE STRENGTHENS/PROGRESSES EWD ACROSS NRN MEXICO/S TX. WHILE CAPPING OVER THE WARM SECTOR SHOULD LARGELY HINDER CONVECTIVE DEVELOPMENT ACROSS ERN AND DEEP S TX...ELEVATED CONVECTION WILL BECOME WIDESPREAD IN THE WARM ADVECTION REGIME NEAR AND N OF THE BAROCLINIC ZONE -- I.E. ACROSS WRN AND NRN TX AND INTO OK. AS LAPSE RATES ALOFT STEEPEN INTO TX CONJUNCTION WITH THE ADVANCING MID-LEVEL COLD POOL...A FEW STRONGER ELEVATED STORMS MAY POSE MARGINAL HAIL RISK. MEANWHILE...BETWEEN THE CAPPED AIRMASS TO THE S AND THE ELEVATED CONVECTION PROGGED TO THE N...INCREASING ASCENT OVER CENTRAL AND NRN TX AS MID LEVEL HEIGHTS FALL WITH THE APPROACH OF THE UPPER LOW MAY PERMIT STORM DEVELOPMENT NEAR THE SURFACE BAROCLINIC ZONE. THE AFOREMENTIONED STEEPENING LAPSE RATES ATOP A MOIST -- AND AT LEAST PARTIALLY HEATED -- AFTERNOON BOUNDARY LAYER SHOULD RESULT IN A ZONE A FAVORABLE CAPE...POSSIBLY FUELING A FEW STRONGER CELLS. WITH STRONG/VEERING FLOW WITH HEIGHT CONSISTENT WITH A WARM ADVECTION REGIME AHEAD OF A CYCLOGENETIC SYSTEM...UPDRAFT ROTATION WITHIN ANY SURFACE-BASED STORM WILL SUPPORT THREATS FOR LARGE HAIL AND PERHAPS A FEW LOCALLY DAMAGING GUSTS. IN ADDITION...A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE -- PARTICULARLY GIVEN POTENTIAL FOR A STORM OR TWO TO MOVE ROUGHLY ALONG THE VORTICITY-RICH FRONTAL ZONE FOR A SUSTAINED PERIOD OF TIME. OVERNIGHT...CONVECTION MAY BECOME MORE WIDESPREAD ACROSS CENTRAL AND NRN TX...SPREADING EWD WITH TIME AS THE PARENT SYSTEM STRENGTHENS/ADVANCES. AT LEAST SOME SEVERE RISK WILL LIKEWISE PERSIST INTO THE OVERNIGHT HOURS ACROSS PARTS OF CENTRAL AND ERN TX AND INTO ADJACENT SERN OK. ...THE OZARKS AREA NEWD ACROSS THE OH VALLEY... FARTHER TO THE NORTHEAST...A LOW-LEVEL WARM-ADVECTION REGIME WILL REMAIN IN PLACE...SUPPORTING BANDS OF SHOWERS AND THUNDERSTORMS NEAR AND N OF THE SURFACE BAROCLINIC ZONE PROGGED TO LIE IN THE GENERAL VICINITY OF THE MID MS/OH VALLEY THROUGH THE PERIOD. WHILE SUFFICIENT INSTABILITY NEAR THE FRONT AND AMPLY STRONG/FAVORABLY VEERING WINDS WITH HEIGHT SUGGEST SOME RISK FOR ROTATING STORMS -- AND ASSOCIATED SEVERE RISK...COVERAGE OF STRONGER STORMS MAY BE LIMITED DUE TO A LARGER-SCALE/BACKGROUND PATTERN ALOFT FEATURING SHORT-WAVE RIDGING ACROSS THE AREA UPSTREAM OF THE DEEPENING UPPER LOW. THUS...WILL MAINTAIN ONLY 5%/MRGL RISK ACROSS THIS AREA ATTM TO COVER POTENTIAL FOR LOCALLY DAMAGING WINDS AND POSSIBLY A TORNADO OR TWO DURING THE PERIOD. ..GOSS.. 12/25/2015Read more
from SPC Forecast Products http://ift.tt/sd6f6z
No comments:
Post a Comment