SPC AC 091259
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 AM CDT WED JUN 09 2010
VALID 091300Z - 101200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LWR OH/TN VLYS INTO
THE CNTRL/SRN APPALACHIANS...
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE CNTRL HI PLNS...
...THERE IS A SLGT RISK OF SVR TSTMS OVER SE TX...
...SYNOPSIS...
PATTERN WILL AMPLIFY ACROSS THE LWR 48 THIS PERIOD AS E PACIFIC
TROUGH CONTINUES SE INTO THE PACIFIC NW...AND DOWNSTREAM RIDGE
BUILDS ACROSS THE PLNS IN WAKE OF PROGRESSIVE SYSTEM NOW OVER THE
UPR GRT LKS. ELSEWHERE...UPR LOW/TROUGH EXPECTED TO REMAIN QSTNRY
OVER CNTRL/NE TX AS SEVERAL DISTURBANCES SHEAR ENE ACROSS THE LWR MS
VLY AND MID SOUTH.
MAIN SFC LOW ASSOCIATED WITH UPR GRT LKS TROUGH WILL TRACK ESE
ACROSS SRN ONT...WHILE TRIPLE POINT WAVE REDEVELOPS SE FROM LWR MI
INTO MD. THE LATTER LOW SHOULD DEEPEN OFF THE MID ATLANTIC CST
TONIGHT/EARLY THU. COLD FRONT TRAILING SW FROM THIS LOW WILL MOVE
ESE ACROSS THE OH VLY/CNTRL APPALACHIANS TODAY. THE WRN PART OF THE
SAME BOUNDARY WILL REDEVELOP N ACROSS THE CNTRL PLNS LATER
TODAY/TONIGHT...IN CONJUNCTION WITH STRENGTHENING LEE TROUGH.
...LWR TN/OH VLYS TO CNTRL/SRN APPALACHIANS THROUGH EARLY EVE...
CORRIDORS OF MODERATE INSTABILITY /SBCAPE OF 1500-2500 J PER KG/
WILL DEVELOP WITH SFC HEATING ALONG AND S OF AFOREMENTIONED COLD
FRONT AND ASSOCIATED OUTFLOW BOUNDARIES OVER KY/TN AND THE SRN HALF
OF THE APPALACHIANS TODAY. MOIST...CONFLUENT LOW LVL FLOW SHOULD
SUPPORT SOME STRENGTHENING OF EXISTING TSTMS OVER THE REGION THROUGH
MIDDAY...WITH ADDITIONAL DEVELOPMENT LIKELY FARTHER W AND S BY
EARLY/MID AFTN.
DEEP SHEAR WILL REMAIN COMPARATIVELY MODEST...RANGING FROM 25-30 KTS
IN THE TN VLY TO AROUND 40 KTS IN ERN KY/WV...BUT SUFFICIENT FOR
STORM ORGANIZATION/SUSTENANCE. BANDS OF MULTICELLS AND PERHAPS A
FEW MARGINAL SUPERCELLS COULD YIELD HAIL AND DMGG WIND THROUGH EARLY
EVE. DESTABILIZATION MAY BE SUFFICIENT TO ALLOW THIS THREAT TO
SPREAD E OF THE SRN APPALACHIANS INTO THE SC/NC PIEDMONT. FARTHER
N...LOW LVL AIR MASS RECOVERY LIKELY WILL REMAIN MORE LIMITED.
THUS...ONLY LOW CONDITIONAL SVR PROBABILITIES ARE DEPICTED IN THE
MORE STRONGLY SHEARED ENVIRONMENT E OF THE MOUNTAINS OVER VA/MD.
...CNTRL HI PLNS LATE THIS AFTN THROUGH TONIGHT...
SSELY LOW LVL FLOW AND MOISTURE RETURN STRENGTHEN OVER ERN CO AND WY
LATER TODAY/TONIGHT ALONG AND E OF LEE TROUGH...WITH SFC
DEWPOINTS IN THE UPR 50S/LWR 60S EXPECTED EWD INTO THE NEB
PANHANDLE. GIVEN CONTINUING PRESENCE OF EML...EXPECT SBCAPE OF
1500-2500 J/KG BY AFTN.
WHILE LARGE SCALE FORCING FOR ASCENT FOR THE MOST PART WILL REMAIN
WEAK...COMBINATION OF STRONG INSTABILITY/MOISTURE INFLUX WITH
UPSLOPE FLOW SHOULD SUPPORT STRONG STORM DEVELOPMENT BY MID/LATE
AFTN. 40-50 KT DEEP W TO WNWLY SHEAR WITH A SIZABLE LOW LVL
DIRECTIONAL COMPONENT WILL SUPPORT A THREAT FOR TORNADOES IN
ADDITION TO LARGE HAIL/LOCALLY DMGG WIND.
SLIGHTLY STRONGER FORCING FOR ASCENT WILL OVERSPREAD WY AND WRN NEB
THIS EVE AHEAD OF A WEAK SHORTWAVE DISTURBANCE ON THE SRN EDGE OF
THE WLYS. THIS MAY ENCOURAGE UPSCALE DEVELOPMENT OF THE STORMS INTO
AN MCS THAT SHOULD MOVE MAINLY E OR ESE INTO NEB/SRN SD EARLY THU.
THIS ASCENT ALSO MAY SUPPORT ISOLD STG TO BRIEFLY SVR STORMS IN ERN
MT.
...SE TX INTO TONIGHT...
HIGH PW /2+ INCHES/ WILL PERSIST IN ERN QUADRANT OF NEARLY STNRY
CNTRL TX UPR LOW. AREA VWP DATA SHOW ENHANCED SLY LOW TO MID LVL
FLOW OVER REGION...WITH SOME BACKING AT LOW LVLS. SFC HEATING
SHOULD SUPPORT STRONGER UPDRAFT DEVELOPMENT OVER SE TX BY
MIDDAY...WITH ACTIVITY TENDING TO MOVE/PROPAGATE MAINLY NE THROUGH
EARLY EVE. SETUP COULD SUPPORT LOCALLY DMGG WIND GUSTS AND PERHAPS
TORNADOES INTO AT LEAST EARLY TONIGHT.
...NRN MI THIS AFTN...
SFC HEATING...COLD MID LVL TEMPERATURES...AND ASCENT ASSOCIATED WITH
AN IMPULSE ROUNDING BASE OF ONT UPR TROUGH WILL SUPPORT AFTN TSTMS
OVER NRN MI. COUPLED WITH 35-40 KT DEEP WNWLY SHEAR... SETUP COULD
YIELD A BAND OR TWO OF LOW-TOPPED STORMS WITH MARGINALLY SVR HAIL
AND ISOLD STRONG WIND GUSTS.
..CORFIDI/STOPPKOTTE.. 06/09/2010
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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