SWODY1
SPC AC 051246
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0746 AM CDT WED MAY 05 2010
VALID 051300Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE UPR OH
VLY/LWR GRT LKS...
...SYNOPSIS...
A FAIRLY LOW AMPLITUDE PROGRESSIVE PATTERN WILL PREVAIL OVER THE LWR
48 THIS PERIOD...WITH MN UPR LOW CONTINUING ENE TO THE ONT/QUE
BORDER AS UPSTREAM SYSTEM MOVES FROM WA/ORE TO NW WY. A SHORTWAVE
IMPULSE ROTATING AROUND MN SYSTEM WILL REACH LK MI THIS EVE AND THE
LWR GRT LKS EARLY THU...ACCELERATING OH VLY COLD FRONT EWD ACROSS
NY/PA EARLY THU. IN THE WEST...STRONG COLD FRONT WITH WA/ORE SYSTEM
WILL MOVE ESE ACROSS THE NRN INTERMOUNTAIN REGION TODAY AND INTO THE
RCKYS TONIGHT.
...OH VLY/LWR GRT LKS...
A CURRENT OF WARM BUT COMPARATIVELY DRY PRE-FRONTAL AIR WILL SWEEP
NE ACROSS THE OH VLY AND LWR GRT LKS TODAY/TONIGHT BENEATH 50+ KT
WSWLY MID LVL FLOW ON SERN FRINGE OF STRONG...PROGRESSIVE UPR
TROUGH. THE COOLEST AIR ALOFT WILL REMAIN N OF ASSOCIATED COLD
FRONT IN NRN MI. BUT RELATIVELY COOL MID LVL TEMPERATURES /AROUND
MINUS 15C AT 500 MB/ WILL BE PRESENT AHEAD OF THE BOUNDARY...WHERE
STRONG SFC HEATING AND SFC DEWPOINTS IN THE 50S SHOULD BOOST SBCAPE
TO 500-1000 J/KG FROM ERN IL ENE INTO MUCH OF OH.
ALTHOUGH THE STRONGEST FORCING FOR ASCENT WILL REMAIN OVER THE UPR
GRT LKS THROUGH MOST OF THE PERIOD...COMBINATION OF SFC HEATING AND
FRONTAL UPLIFT WILL SUPPORT AFTN/EVE TSTMS ALONG THE COLD FRONT.
LONG...SLIGHTLY CURVED HODOGRAPHS /WITH 30 KT SWLY LOW LVL FLOW
VEERING TO 50+ KT WLY FLOW AT 500 MB/...COUPLED WITH EXPECTED
INSTABILITY AND LIKELIHOOD FOR SIZABLE TEMP-DEWPOINT SPREADS IN THE
PBL...SUGGESTS THE POTENTIAL FOR SCTD SUSTAINED STORMS WITH SVR
WIND/HAIL. THE STORMS COULD ORGANIZE INTO BKN LINE SEGMENTS WITH
SMALL BOWS THAT CONTINUE EWD INTO WRN NY/NW PA THROUGH THE EVE. BUT
THE SVR THREAT SHOULD DIMINISH AS THE RELATIVELY DRY PREFRONTAL AIR
QUICKLY COOLS.
...PAC NW INTO NRN GRT BASIN...
COLD MID LVL TEMPS /-30 TO -34 C AT 500 MB/ WILL ACCOMPANY UPR LOW
OVER THE NRN INTERMOUNTAIN REGION THIS AFTN/EVE. SFC
HEATING WITHIN THE POST-FRONTAL ENVIRONMENT WILL RESULT IN STEEP LOW
TO MID LVL LAPSE RATES...WITH SCTD SHOWERS AND TSTMS EXPECTED.
THESE COULD YIELD SMALL HAIL/GUSTY WINDS. FARTHER SE...WEAK
BUOYANCY ALSO WILL EXIST AHEAD OF FRONT OVER NRN UT/SW WY/NW
CO...WHERE ISOLD GUSTY EVE STORMS COULD OCCUR IN REGION FAST WSWLY
FLOW.
..CORFIDI/GARNER.. 05/05/2010
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