SWODY1
SPC AC 100520
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1220 AM CDT THU MAY 10 2007
VALID 101200Z - 111200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS SRN TX...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NWRN
STATES...
..THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE
NORTHEAST...
..SYNOPSIS...
STRONGEST MID-LEVEL FLOW IS FORECAST TO EXTEND FROM THE PAC NW ALONG
THE U.S./CANADIAN BORDER THIS PERIOD...WITH WEAK/EMBEDDED FEATURES
FORECAST TO AFFECT BOTH THE NORTHWEST AND NORTHEAST PORTIONS OF THE
CONUS THIS PERIOD. MEANWHILE...A CUTOFF LOW IS FORECAST TO DRIFT
EWD ACROSS THE SRN PLAINS THROUGH THE DAY.
AT THE SURFACE...COLD FRONT IS FORECAST TO MOVE SLOWLY SWD ACROSS
THE NRN PLAINS/UPPER GREAT LAKES...AND THEN WWD ACROSS THE NRN
ROCKIES. MEANWHILE...SUBTROPICAL STORM ANDREA SHOULD LINGER/SLOWLY
WEAKEN OFF THE SERN U.S. COAST. PLEASE SEE THE LATEST STATEMENTS
FROM THE NATIONAL HURRICANE CENTER FOR UPDATES ON THIS STORM.
..SRN PORTIONS OF TX...
DAYTIME HEATING OF VERY MOIST BOUNDARY LAYER ACROSS S TX WILL ALLOW
AIRMASS DESTABILIZATION...WITH 1000 TO 1500 J/KG MEAN-LAYER CAPE
FORECAST DURING THE AFTERNOON. AS UPPER LOW MOVES EWD ACROSS TX
THROUGH THE DAY...EXPECT BANDS/CLUSTERS OF THUNDERSTORMS TO DEVELOP
ACROSS MUCH OF CENTRAL AND ERN TX.
THOUGH GENERALLY PULSE-TYPE STORMS ARE FORECAST FROM CENTRAL AND
INTO NERN TX...BELT OF STRONGER WLY/NWLY MID-LEVEL FLOW /AROUND 40
KT/ S OF UPPER LOW IS FORECAST TO SHIFT ACROSS S TX -- RESULTING IN
DEEP-LAYER WIND FIELD SUFFICIENT FOR SUPERCELLS. THEREFORE...EXPECT
POTENTIAL FOR HAIL AND LOCALLY-DAMAGING WIND GUSTS WITH A FEW OF THE
STRONGER STORMS. THOUGH SEVERE THREAT SHOULD DECREASE SLOWLY AFTER
SUNSET WITH THE LOSS OF DAYTIME HEATING...STORMS MAY LINGER THROUGH
THE OVERNIGHT HOURS ACROSS THIS REGION.
..NERN OREGON/SERN WA EWD ACROSS MT...
SHORT-WAVE TROUGH EMBEDDED IN ENHANCED BELT OF MID-LEVEL FLOW -- NOW
APPROACHING THE NRN CA/SWRN OREGON COAST -- SHOULD MOVE NEWD ACROSS
OREGON AND INTO ID/MT THROUGH THE DAY...ABOVE LOW-LEVEL BAROCLINIC
ZONE. THOUGH LIMITED LOW-LEVEL MOISTURE WILL LIMIT POTENTIAL FOR
DESTABILIZATION...500 TO 750 J/KG MEAN-LAYER CAPE SHOULD DEVELOP AS
DAYTIME HEATING MAXIMIZES DURING THE LATE AFTERNOON. THIS WILL
SUPPORT THE DEVELOPMENT OF THUNDERSTORMS INVOF AFOREMENTIONED
SURFACE BOUNDARY...LIKELY FROM CENTRAL/ERN OREGON EWD INTO MT.
DESPITE LIMITED INSTABILITY...DEEP-LAYER WIND FIELD WILL BE
SUPPORTIVE OF ORGANIZED/SUPERCELL STORMS. THOUGH DEGREE OF
INSTABILITY SHOULD LIMIT THE OVERALL COVERAGE OF THE SEVERE
THREAT...LOCALLY-DAMAGING WINDS AND HAIL WILL BE POSSIBLE WITH THE
STRONGEST STORMS. THREAT SHOULD LINGER/SHIFT EWD ACROSS MT THROUGH
THE EVENING...BEFORE TAPERING OFF OVERNIGHT.
..PARTS OF THE NORTHEAST...
WEAK SURFACE LOW/TROUGH IS FORECAST TO MOVE ACROSS NY/PA DURING THE
DAY...AS COMPACT UPPER LOW MOVES ACROSS THE LOWER LAKES.
BOUNDARY-LAYER MOISTENING ON SLY FLOW AHEAD OF THIS FEATURE COMBINED
WITH DAYTIME HEATING SHOULD YIELD 500 TO 1000 J/KG MEAN-LAYER
CAPE...SUFFICIENT TO SUPPORT THE DEVELOPMENT OF AFTERNOON
THUNDERSTORMS.
THOUGH DEEP-LAYER WIND FIELD SHOULD REMAIN RELATIVELY WEAK WITH
MID-LEVEL FLOW AOB 30 KT...EXPECT PRIMARY STORM MODE TO BE
MULTICELLULAR AND/OR SMALL-SCALE LINES. STRONGER STORM CLUSTERS
WILL BE CAPABLE OF PRODUCING HAIL...ALONG WITH LOCALLY STRONG/GUSTY
WINDS. THREAT SHOULD DECREASE THROUGH THE EVENING WITH THE LOSS OF
HEATING...AS STORMS SPREAD INTO PARTS OF NEW ENGLAND.
.GOSS/JEWELL.. 05/10/2007
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