ZCZC SPCSWODY1 ALL ACUS01 KWNS 301233 SPC AC 301233 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0633 AM CST THU OCT 30 2003 VALID 301300Z - 311200Z GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM OTH EUG RDM 85 E 4LW SVE RBL 60 S EKA. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM MLD 50 W BPI RWL CAG PUC DPG MLD. ...NO SVR TSTM AREAS FORECAST... LATEST WATER VAPOR LOOPS INDICATE BROAD ANTICYCLONIC UPPER CIRCULATION HAS BECOME ESTABLISHED OVER THE GULF AND SOUTH ATLANTIC COAST STATES AND GULF OF MEXICO. AMPLIFYING UPPER RIDGE EXTENDS NORTHWARD ALONG AN AXIS FROM THE CENTRAL GULF COAST INTO THE UPPER GREAT LAKES...WHILE UPSTREAM TROUGH CONTINUES TO DIG SOUTHWARD ACROSS THE NORTHERN PACIFIC STATES. MODELS SUGGEST STRONGER HEIGHT RISES WILL SHIFT FROM THE LOWER GREAT LAKES/UPPER OHIO VALLEY INTO THE CANADIAN MARITIMES DURING THIS FORECAST PERIOD...WHILE STRONGEST HEIGHT FALLS DEVELOP FROM NORTHERN CALIFORNIA INTO AREAS OF THE PACIFIC OFF THE CENTRAL/SOUTHERN CALIFORNIA COAST. BY LATE TONIGHT...STRONGER WESTERLIES ARE PROGGED TO EXTEND IN A BROAD...GENERALLY STRAIGHT SOUTHWESTERLY BAND FROM SOUTHERN CALIFORNIA INTO QUEBEC...WITH ANY EMBEDDED PERTURBATIONS LOW IN AMPLITUDE. ...NORTH CENTRAL PACIFIC COASTAL AREAS... VERY COLD MID-LEVEL AIR MASS ACCOMPANIES UPPER TROUGH ACROSS THE PACIFIC NORTHWEST COAST STATES AND NORTHERN INTERMOUNTAIN REGION ...WITH 500 MB TEMPERATURES AS LOW AS -30C. LEADING EDGE OF THIS COLD POOL HAS SPREAD FROM SOUTHERN OREGON INTO NORTHERN CALIFORNIA OVERNIGHT...AND WILL CONTINUE TO SLOWLY ADVANCE SOUTH/SOUTHWESTWARD THROUGH THE DAY. LOW-LEVEL LAPSE RATES WILL SLOWLY STEEPEN ACROSS THE SOUTHERN CASCADES AND SHASTA/SISKIYOU REGION...AS WELL AS ALONG NEARBY COASTAL AREAS...WITH DAYTIME HEATING...AND POINT FORECAST SOUNDINGS SUGGEST THERMODYNAMIC ENVIRONMENT WILL BECOME SUFFICIENT FOR WIDELY SCATTERED LOW-TOPPED THUNDERSTORMS. ACTIVITY MAY BE ENHANCED BY MID-LEVEL FORCING FOR UPWARD VERTICAL MOTION ASSOCIATED WITH WEAK CYCLONIC VORTICITY CENTER/LOBE DURING PEAK HEATING...BUT ANY CONVECTION WILL DIMINISH RAPIDLY WITH LOSS OF DAYTIME HEATING. ...GREAT BASIN... LOW-LEVEL BAROCLINIC ZONE NOW EXTENDING ALONG THE WYOMING/COLORADO AND UTAH BORDER INTO THE SALT LAKE AREA WILL REMAIN NEARLY STATIONARY OR PROGRESS ONLY SLOWLY SOUTHWARD LATE IN THE PERIOD. THIS FEATURE IS EXPECTED TO PROVIDE FOCUS FOR DESTABILIZATION AND CONVECTIVE DEVELOPMENT BY MIDDAY...AS MID-LEVEL COOLING/FORCING FOR UPWARD MOTION INCREASE IN LEFT EXIT REGION OF JET STREAK GRADUALLY PROPAGATING ACROSS CENTRAL/SOUTHERN NEVADA. POINT FORECAST SOUNDINGS INDICATE CONVECTION WILL BE LOW TOPPED WITH CAPE ONLY ON THE ORDER OF A FEW HUNDRED J/KG...BUT THERMODYNAMIC ENVIRONMENT APPEARS FAVORABLE FOR SCATTERED WEAK THUNDERSTORMS THROUGH THE LATE AFTERNOON HOURS. ...EAST OF THE ROCKIES... RETURN FLOW OF GULF MOISTURE IS UNDERWAY ON SOUTHWESTERN/WESTERN PERIPHERY OF ATLANTIC COAST SURFACE RIDGE. DEW POINTS NEAR 60F HAVE ALREADY ADVECTED AS FAR NORTH AS THE ARKLATEX. NORTHWARD TRANSPORT/ISENTROPIC ASCENT OF THE MOIST AIR MASS WILL CONTINUE THROUGH THE REMAINDER OF THE FORECAST PERIOD ALONG BROAD SOUTHWESTERLY LOW-LEVEL JET FROM THE SOUTHERN PLAINS INTO THE GREAT LAKES REGION. MODELS DO SUGGEST SATURATION OCCURS TONIGHT IN THE 850-700 MB LAYER... ALONG AND JUST SOUTH OF BAROCLINIC ZONE FROM NORTHEAST MISSOURI INTO PARTS OF SOUTHERN MICHIGAN/NORTHERN INDIANA AND OHIO. HOWEVER...WITH MINIMAL MID-LEVEL FORCING FOR UPWARD VERTICAL MOTION...WARM LAYER ALOFT APPEARS MORE THAN LIKELY TO MINIMIZE POTENTIAL FOR DEEP CONVECTION AND RISK OF THUNDERSTORMS. ..KERR.. 10/30/2003 ...NOTICE... FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3. THE INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED. $$ |