SWODY2
SPC AC 031709
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1209 PM CDT MON SEP 03 2007
VALID 041200Z - 051200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
PROGRESSIVE FLOW PATTERN IS FORECAST WITHIN THE STRONGER WESTERLIES
ACROSS THE NRN STATES TOMORROW. A WELL-DEFINED UPPER LOW OFF THE
PACIFIC NW COAST IS EXPECTED TO MOVE INLAND EARLY IN THE PERIOD AND
REACH THE GREAT BASIN BY THE END OF THE PERIOD...WHILE UPPER LOW
CURRENTLY OVER NRN QUEBEC MOVES INTO THE CANADIAN MARITIMES. LOWER
LATITUDE UPPER TROUGH AXIS FROM NRN MEXICO/SWRN TX INTO THE TX
PANHANDLE IS FORECAST TO DRIFT NEWD WITH A WEAK LOW DEVELOPING OVER
OK TOMORROW NIGHT.
AT THE SURFACE...A COLD FRONT ASSOCIATED WITH THE NWRN UPPER LOW
WILL MOVE ACROSS THE NRN ROCKIES AND GREAT BASIN...WHILE A WARM
FRONT EXTENDING ACROSS THE UPPER MS VALLEY INTO LOWER MI MOVES
SLOWLY NWD.
..GREAT BASIN/NRN INTERMOUNTAIN REGION...
PLUME OF RESIDUAL DEEP LAYER MOISTURE WITH PRECIPITABLE WATER VALUES
OF 0.75-1.0 INCH FROM SRN CA/LOWER CO RIVER VALLEY INTO THE SRN
GREAT BASIN IS EXPECTED TO SPREAD NNEWD TOMORROW AS SSWLY LOW/MID
LEVEL FLOW INCREASES IN ADVANCE OF APPROACHING UPPER LOW. COLUMN
MOISTURE WILL ALSO BE ENHANCED BY PERSISTENT SYNOPTIC SCALE ASCENT
AHEAD OF THE LOW. GRADUAL COOLING ALOFT COUPLED WITH DIABATIC
HEATING ALONG/AHEAD OF THE COLD FRONT WILL CONTRIBUTE TO
DESTABILIZATION DURING THE AFTERNOON...WITH AIR MASS BECOMING
MARGINALLY UNSTABLE WITH MUCAPE OF 500-800 J/KG. THUNDERSTORMS ARE
EXPECTED TO INCREASE DURING THE AFTERNOON AND EVENING FROM SRN ID
INTO CENTRAL/ERN NV AND NWRN UT IN RESPONSE TO INCREASING DYNAMIC
AND OROGRAPHIC FORCING. MODERATELY STRONG SWLY MID LEVEL FLOW OF
35-45 KT WILL RESULT IN SUFFICIENT DEEP LAYER SHEAR TO ENHANCE STORM
ORGANIZATION WITH POTENTIAL FOR SHORT LINE SEGMENTS TO DEVELOP.
MORE INTENSE CELLS WILL BE CAPABLE OF STRONG WIND GUSTS AND POSSIBLE
HAIL. OVERALL SEVERE THREAT APPEARS TO BE LIMITED BY WEAK
INSTABILITY SO WILL MAINTAIN LOW SEVERE PROBABILITY ATTM...BUT
POSSIBILITY OF GREATER INSTABILITY DEVELOPING WILL NEED TO BE
MONITORED.
..SRN/ERN TX...
VERY MOIST ENVIRONMENT IS EXPECTED TO CONTINUE OVER PARTS OF SRN/ERN
TX AS DEEP LAYER SSWLY FLOW ALOFT WILL PERSIST TOMORROW EAST OF THE
UPPER LOW/TROUGH AXIS. ALTHOUGH WIDESPREAD CLOUDS AND SCATTERED
PRECIPITATION ARE EXPECTED TO INHIBIT DIABATIC HEATING...HIGH
THETA-E VALUES IN THE BOUNDARY LAYER WILL CONTRIBUTE TO MLCAPE OF
1500-2000 J/KG. GFS AND SREF GUIDANCE INDICATE STRONGER SWLY MID
LEVEL FLOW THAN THE NAM...RESULTING IN SUFFICIENT DEEP LAYER SHEAR
/35-45 KT IN THE LOWEST 6-8 KM/ TO ENHANCE THUNDERSTORM ORGANIZATION
AND INTENSITY. ISOLATED STRONG/SEVERE STORMS CAPABLE OF WET
DOWNBURSTS MAY BE POSSIBLE BUT WEAK LAPSE RATES AND MINIMAL DYNAMIC
FORCING SUGGEST SEVERE THREAT WILL BE LIMITED.
.WEISS.. 09/03/2007
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