SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0742 AM CDT SAT AUG 17 2013 VALID 171300Z - 181200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LITTLE CHANGE TO THE UPPER PATTERN IS FORECAST THROUGH THE PERIOD...AS A RIDGE PERSISTS OVER THE ROCKIES AND A TROUGH REMAINS ALIGNED ROUGHLY ALONG THE MS VALLEY. MEANWHILE...A RELATIVELY WEAK UPPER LOW OFF THE CA COAST IS FORECAST TO MAKE SLOW EWD PROGRESS THROUGH THE PERIOD. AT THE SURFACE...HIGH PRESSURE WILL PREVAIL OVER MUCH OF THE EASTERN CONUS...THOUGH TROUGHING WILL EXTEND NWD/NEWD FROM A WEAK LOW OVER THE CENTRAL/WRN GULF. MEANWHILE...LEE TROUGHING WILL PERSIST OVER THE HIGH PLAINS...WHILE A WEAK COLD FRONT TRAILING SWD OUT OF THE CANADIAN PRAIRIE SAGS INTO THE NRN INTERMOUNTAIN REGION. ...SRN HIGH PLAINS... ELEVATED THUNDERSTORMS ARE ONGOING THIS MORNING FROM PARTS OF SWRN KS INTO THE NERN TX PANHANDLE...AIDED BY WARM ADVECTION ASSOCIATED WITH THE REMNANT NOCTURNAL LOW-LEVEL JET. THOUGH CONVECTION SHOULD DIURNALLY DIMINISH OVER THE NEXT FEW HOURS...ISOLATED THREAT FOR MARGINAL HAIL MAY PERSIST FOR ANOTHER HOUR OR TWO. LATER...DIURNAL HEATING OF A MODESTLY MOIST BOUNDARY LAYER OVER ERN NM AND ADJACENT W TX WILL YIELD SOME INCREASE IN BUOYANCY. WITH PRESENCE OF A LEE TROUGH AND WEAK SELY UPSLOPE FLOW E OF THIS BOUNDARY...ISOLATED STORM DEVELOPMENT SHOULD OCCUR -- WITH SOME ASSOCIATED THREAT FOR AN ISOLATED HAIL/WIND EVENT NEAR SEVERE LEVELS. ...WRN AND CENTRAL MT... WEAK DISTURBANCES ALOFT MOVING ENEWD ACROSS MT AND VICINITY MAY SUPPORT ISOLATED CONVECTIVE DEVELOPMENT THIS AFTERNOON...AS DIURNAL HEATING SUPPORTS A MODEST INCREASE IN CAPE. WITH DEEP-LAYER SHEAR IN THE 30 TO 50 KT RANGE ACROSS THIS AREA SUPPORTIVE OF SUSTAINED UPDRAFTS...THREAT FOR MARGINALLY SEVERE HAIL AND/OR A LOCALLY DAMAGING GUST CANNOT BE RULED OUT. ...CENTRAL GULF COAST... AS THE SOMEWHAT ILL-DEFINED SYSTEM OVER THE CENTRAL GULF DRIFTS NWD WITH TIME...MODEST INCREASE IN LOW-LEVEL SHEAR IS FORECAST ACROSS THE CENTRAL GULF COAST REGION. WHILE BANDS OF PERIODIC CONVECTION WILL PERSIST ACROSS THE GULF COAST REGION/SOUTHEAST U.S. THROUGH THE PERIOD...MODEL FORECAST HINTS OF AN INCREASE IN CONVECTION LATE IN THE PERIOD INVOF THE MOUTH OF THE MS RIVER ARE EVIDENT. WITH THIS POSSIBLE CONVECTIVE INCREASE COINCIDING WITH AN UPTICK IN LOW-LEVEL SHEAR...POTENTIAL FOR SOME UPDRAFT ROTATION WARRANTS MAINTENANCE OF 2% TORNADO PROBABILITY ACROSS THIS AREA. ..GOSS/MOSIER.. 08/17/2013
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1300.html
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