SWODY2
SPC AC 190535
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1235 AM CDT TUE OCT 19 2010
VALID 201200Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
UPPER-AIR REX PATTERN...FCST TO DOMINATE WRN CONUS THROUGH FIRST
HALF OF PERIOD...WILL ERODE LATE DAY-2...DOWNSTREAM FROM STG
SHORTWAVE TROUGH AND RELATED HEIGHT FALLS DIGGING ESEWD OVER NERN
PAC. AS THIS OCCURS...PERSISTENT/CUT-OFF CYCLONE -- NOW MOVING
SLOWLY SEWD OFF CA COAST -- WILL EJECT SLOWLY NEWD FROM NRN BAJA
ACROSS SWRN AZ...BASED ON STG CONSENSUS OF SREF MEMBERS...19/00Z
OPERATIONAL WRF AND SPECTRAL...AND PRIOR ECMWF. MEANWHILE...DEEP
SYNOPTIC-SCALE TROUGHING IS FCST FROM HUDSON BAY SWD ACROSS LOWER
GREAT LAKES TO CENTRAL APPALACHIANS...WITH INTERVENING RIDGE FROM
DEEP S TX TO CENTRAL HIGH PLAINS AND NRN ROCKIES.
AT SFC...FRONTAL ZONE NOW MOVING SWD OVER KY...NRN AR...SWRN OK AND
W TX WILL SETTLE SWD ACROSS GULF COASTAL PLAIN FROM GA-TX BY
21/00Z...QUASISTATIONARY ACROSS S TX AND RETREATING NWD AS DIFFUSE
WARM FRONT OVER SRN HIGH PLAINS REGION. DESPITE WEAK LOW-LEVEL
WINDS AND LACK OF STG CONVERGENCE...FRONT SHOULD SUPPORT AT LEAST
ISOLATED TSTM POTENTIAL OVER PORTIONS GULF COAST STATES...WHILE COLD
AIR ALOFT AND STEEP LOW-LEVEL LAPSE RATES LEAD TO SHALLOW TSTMS OVER
AND VERY NEAR PORTIONS GREAT LAKES.
...SRN NV/LOWER CO VALLEY TO FAR W TX...
WIDELY SCATTERED TO SCATTERED TSTMS IN CLUSTERS SHOULD DEVELOP
DIURNALLY BENEATH BROAD REGION OF DIFLUENT FLOW ALOFT...ACROSS
SEVERAL FAVORABLE LOW-LEVEL REGIMES FOR AT LEAST STG TSTMS...
1. WRN LOBE OF FRONTAL ZONE FROM PECOS VALLEY REGION WNWWD OVER
SRN/CENTRAL NM...WHERE FRONTAL AND OROGRAPHIC ASCENT WILL AID
DEVELOPMENT IN TANDEM WITH SFC HEATING...DEW POINTS 50S F IN LOWER
ELEVATIONS...AND AREAS OF CAP-REMOVING SFC HEATING. DEEP-LAYER
SHEAR WILL BE AIDED BY PRESENCE OF THOSE BOUNDARY LAYER
SELYS...BENEATH MID-UPPER SWLYS OF 30-40 KT AT 500 MB AND NRN FRINGE
OF UPPER/SUBTROPICAL JET. ETA-KF FCST SOUNDINGS OVER PARTS OF SRN
NM AND FAR W TX INDICATE 40-50 KT EFFECTIVE SHEAR MAGNITUDE ALONG
WITH FAVORABLE LOW-LEVEL HODOGRAPHS FOR SUPERCELLS. MAIN CONCERN
PRECLUDING CATEGORICAL OUTLOOK ATTM IS COVERAGE OF RELATIVELY
DISCRETE/SUSTAINED CONVECTION DURING AFTERNOON. TSTM COVERAGE MAY
INCREASE AFTER DARK AND SPREAD EWD OVER ERN NM IN LOW-LEVEL
WAA/MOIST ADVECTION REGIME...ALONG WRN FRINGE OF 25-35 KT LLJ AND
ATOP DIABATICALLY COOLING NEAR-SFC LAYER.
2. CONVEYOR OF LOW-LEVEL MOIST ADVECTION...DIVERGENCE ALOFT...AND
SLY TO ELY MID-UPPER FLOW N THROUGH NE OF MID-UPPER CYCLONE...FROM
SRN NV TO WRN NM. STG SFC HEATING OF HIGHER TERRAIN AND WEAK
LARGE-SCALE ASCENT WILL CONTRIBUTE TO STEEP LOW-MIDDLE LEVEL LAPSE
RATES AND SUFFICIENTLY RICH LOW-LEVEL MOISTURE TO REMOVE CINH.
200-800 J/KG MLCAPE AND LOCALLY 30-40 KT EFFECTIVE SHEAR WILL
CONTRIBUTE TO STORM ORGANIZATION...WITH STG TO MRGL SVR HAIL/GUSTS
POSSIBLE.
3. PROXIMAL AREA TO COLD-CORE LOW...OVER LOWER CO RIVER VALLEY
REGION AND SWRN AZ...MAY YIELD HAIL FROM MOST INTENSE CELLS..ALONG
WITH STG GUSTS SUPPORTED BY WELL-MIXED THERMAL PROFILES IN DIURNAL
SUBCLOUD LAYER.
..EDWARDS.. 10/19/2010
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