SWODY1
SPC AC 241240
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0740 AM CDT MON OCT 24 2011
VALID 241300Z - 251200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
UPPER-LEVEL SHORTWAVE TROUGH LOCATED OVER THE GREAT LAKES REGION
THIS MORNING...AS WELL AS ASSOCIATED SURFACE COLD FRONT...WILL SHIFT
EWD INTO NEW ENGLAND BY THE END OF THE PERIOD. MEANWHILE...UPSTREAM
DISTURBANCE OVER THE PAC NW WILL AMPLIFY SLIGHTLY OVERNIGHT. SURFACE
CYCLONE AHEAD OF THE WRN TROUGH WILL EMERGE OUT OF THE HIGH PLAINS
AND MOVE EWD TOWARD THE MID MO VALLEY BY 25/12Z...WITH A COLD FRONT
DROPPING SWD INTO KS AND WARM FRONT LIFTING NWD INTO IA.
...OH VALLEY EWD INTO NEW ENGLAND...
NARROW LINE OF SHOWERS WITH EMBEDDED ISOLATED/SCATTERED
THUNDERSTORMS WILL BE FOCUSED ALONG AN EWD PROGRESSING COLD FRONT
TODAY. THESE STORMS ARE FORECAST TO MOVE ACROSS THE OH VALLEY DURING
THE MID/LATE MORNING INTO EARLY AFTERNOON...AND THEN ENTER NEW
ENGLAND BY MID AFTERNOON. NARROW CORRIDOR OF SURFACE HEATING MAY
DEVELOP AHEAD OF THE FRONT OVER WV/NRN VA INTO CNTRL PA DURING THE
LATE MORNING INTO MID-AFTERNOON...AIDING IN BOOSTING MUCAPE VALUES
TO AROUND 500 J/KG. THIS INSTABILITY COMBINED WITH COLD MIDLEVEL
TEMPERATURES /NEAR -20C AT 500 MB/ AND MEAN DEEP LAYER WLY FLOW FROM
30-40 KT COULD FAVOR A FEW STORMS BRIEFLY PRODUCING GUSTY WINDS OR
SMALL HAIL. HOWEVER...SVR STORMS ARE NOT EXPECTED GIVEN NARROW ZONE
OF SURFACE BASED DESTABILIZATION AND LIMITED LOW-LEVEL MOISTURE.
...SERN MN...NERN IA...FAR NRN IL...SRN/CNTRL WI...
AS A LOW-LEVEL CYCLONE APPROACHES THE MID/UPR MS VALLEY LATER
TONIGHT...EXIT REGION OF 50+ KT LLJ WILL BECOME FOCUSED OVER NERN IA
INTO SRN WI/NRN IL...AIDING IN STRENGTHENING WAA AND ASCENT OVER THE
REGION. AS THIS TAKES PLACE...PLUME OF STEEP MIDLEVEL LAPSE RATES
WILL ADVECT EWD INTO THE REGION ABOVE MODEST LOW-LEVEL MOISTURE
RETURN. AIRMASS DESTABILIZATION SHOULD OCCUR AS A RESULT...WITH
MUCAPE VALUES ROOTED IN THE 700-850 MB LAYER INCREASING TO AROUND
100-500 J/KG. THIS ENVIRONMENT MAY SUPPORT ISOLATED ELEVATED
THUNDERSTORM DEVELOPMENT DURING THE OVERNIGHT HOURS...THOUGH MEAGER
INSTABILITY SHOULD PRECLUDE A SVR WEATHER THREAT.
..GARNER/CORFIDI.. 10/24/2011
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