SWODY1
SPC AC 121247
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0747 AM CDT MON OCT 12 2009
VALID 121300Z - 131200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
RECONFIGURATION OF THE LARGE SCALE FLOW PATTERN IS UNDERWAY IN
RESPONSE TO A STRONG MID-UPPER TROUGH THAT IS MOVING EWD AND WILL
REACH CENTRAL/NRN CA EARLY TUESDAY. A LEAD SHORTWAVE TROUGH W OF
THE SRN CA COAST THIS MORNING WILL EJECT NEWD OVER THE GREAT BASIN
BY TONIGHT AS THE STRONGER TROUGH APPROACHES FROM THE ERN PAC.
DOWNSTREAM...THE MID-UPPER JET STREAK NOW OVER THE NRN HIGH PLAINS
WILL TRANSLATE EWD TO THE GREAT LAKES...WITH REINFORCEMENT OF THE
BROAD/COLD SURFACE RIDGE EXPECTED IN ITS WAKE ACROSS THE NRN
PLAINS/UPPER MS VALLEY. ALONG THE SRN FRINGE OF THE STRONGER
MID-UPPER FLOW...A SLOW-MOVING BAROCLINIC ZONE WILL PERSIST ACROSS
THE GULF COAST/SE ATLANTIC STATES AND PROVIDE A GENERAL FOCUS FOR
THUNDERSTORM DEVELOPMENT.
...SRN PLAINS EWD TO THE SE ATLANTIC COAST THROUGH TONIGHT...
SOME LOOSE CLUSTERING OF ELEVATED THUNDERSTORMS HAS BEEN OBSERVED
OVERNIGHT FROM NRN LA EWD TO NRN AL/GA IN ASSOCIATION WITH AN
EMBEDDED SPEED MAX MOVING EWD OVER THE TN VALLEY. THIS LOW
AMPLITUDE SYSTEM WILL MOVE OFF THE SC/NC COASTS BY THIS
EVENING...THOUGH IN THE MEANTIME THERE WILL BE SOME INTERACTION WITH
THE SRN EDGE OF THE STRONGER MID-UPPER FLOW AND THE SLOW-MOVING
FRONT FROM E CENTRAL AL INTO CENTRAL GA. HERE...MLCAPE WILL REACH
1500-2500 J/KG IN RESPONSE TO BOUNDARY LAYER DEWPOINTS IN THE LOW
70S F AND SOME DAYTIME HEATING WITHIN CLOUD BREAKS...AND VERTICAL
SHEAR WILL BE MAXIMIZED ALONG THE FRONT/NRN EDGE OF THE WARM SECTOR.
STILL...POOR MID LEVEL LAPSE RATES/RELATIVELY WARM PROFILES
ALOFT...AND TALL/NARROW CAPE WILL LIMIT THE SEVERE STORM THREAT
PRIMARILY TO ISOLATED DOWNBURST WINDS WITH MULTICELL CLUSTERS AND/OR
SHORT-LIVED SUPERCELL STRUCTURES.
OTHERWISE...A FEW STORM CLUSTERS WILL CONTINUE TODAY FARTHER W IN
THE MOIST ENVIRONMENT ACROSS MS/LA/SE TX ALONG AND N OF THE
RETREATING FRONT. THERE WILL ALSO BE SOME THREAT FOR ISOLATED/
ELEVATED THUNDERSTORMS TONIGHT ACROSS W/NW TX AS A LOW-LEVEL WAA
REGIME DEVELOPS IN RESPONSE TO THE LEAD SHORTWAVE TROUGH EJECTING
NEWD OVER THE SRN/CENTRAL ROCKIES.
..THOMPSON/HURLBUT.. 10/12/2009
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