DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 091259
SWODY1
SPC AC 091257

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0757 AM CDT SAT JUN 09 2012

VALID 091300Z - 101200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN PLNS/UPR
MS VLY...

...SYNOPSIS...
NRN RCKYS/NRN GRT BASIN UPR LOW/TROUGH WILL CONTINUE E TO THE NRN HI
PLNS/CNTRL RCKYS THIS PERIOD AS DOWNSTREAM RIDGE AMPLIFIES OVER THE
UPR GRT LKS/OH VLY. ELSEWHERE...WEAK UPR LOW NOW CENTERED ALONG THE
WRN LA CST EXPECTED TO EDGE NWD INTO THE LWR MS VLY AND FURTHER
ELONGATE N-S.

AT LWR LVLS...SFC LOW NOW IN WRN ND SHOULD MOVE NNE TO NEAR WINNIPEG
BY LATE TNGT...WHILE A NEW LOW FORMS OVER SE WY/NE CO IN RESPONSE TO
UPR IMPULSE ROUNDING BASE OF RCKYS/GRT BASIN UPR LOW.
COLD FRONT EXTENDING SSW FROM THE ND LOW SHOULD ADVANCE ONLY SLOWLY
EWD TODAY...BEFORE ACCELERATING ESEWD TNGT/EARLY SUN AS THE UPR
IMPULSE REACHES WY/CO.

TSTMS...SOME POSSIBLY SVR...MAY ACCOMPANY THE WAA ZONES ASSOCIATED
WITH BOTH SFC LOWS TODAY THROUGH TNGT. THE RISK FOR A FEW STRONG TO
POSSIBLY SVR STORMS ALSO WILL EXIST WITH AREAS OF WEAKER WAA ALONG
THE CNTRL GULF CST AND OVER THE NORTHEAST.

...DAKOTAS/NW MN TODAY THROUGH EARLY SUN...
ON-GOING SLIGHTLY ELEVATED SQLN IN N CNTRL ND MAY PERSIST THROUGH
LATER THIS MORNING AS IT CONTINUES GENERALLY EWD. NEW DEVELOPMENT
PREFERENTIALLY MAY OCCUR ON SRN END OF SYSTEM...BUT THE SQLN SHOULD
AT LEAST TEMPORARILY WEAKEN TOWARD MIDDAY AS STOUT EML BUILDS NNE
ACROSS REGION.

RENEWED STORM DEVELOPMENT SHOULD OCCUR ALONG THE COLD FRONT AS SFC
HEATING/CONVERGENCE OVERCOME EML LATER THIS AFTN INTO TNGT FROM SRN
MB SWD INTO ND. EML CAP MAY KEEP ACTIVITY FAIRLY ISOLD S OF NERN
ND. THIS NOTION IS SUPPORTED BY THE FACT THAT THE LATEST
SHORT-RANGE MODELS REMAIN TOO MOIST IN THE LWR LVLS...WITH SFC
DEWPOINTS EXPECTED TO REMAIN IN THE UPR 50S TO LOW 60S F... RATHER
THAN IN THE UPR 60S. NEVERTHELESS...STEEP LOW TO MID LVL LAPSE
RATES WILL FAVOR STRONG UPDRAFTS/LARGE HAIL WITH ANY SUSTAINED
UPDRAFTS THAT DO BREACH CAP GIVEN THE STRONGLY SHEARED ENVIRONMENT.

FARTHER SSW...SFC HEATING MAY SUPPORT ISOLD HIGH-BASED STORMS IN
DEEPLY-MIXED ENVIRONMENT ALONG LEE TROUGH/DRY LINE IN WRN SD/WRN
NEB/FAR ERN WY. THESE MAY YIELD A LOCALLY DMGG WIND GUST OR TWO. A
MORE SUBSTANTIAL SVR THREAT MAY DEVELOP THIS EVE THROUGH TNGT ALONG
THE LEE TROUGH/COLD FRONT OVER WRN AND CNTRL SD AS NEW STORMS FORM
IN RESPONSE TO INCREASING ASCENT AHEAD OF APPROACHING UPR IMPULSE.
COUPLED WITH INCREASING DEEP SHEAR AND STRENGTHENING LLJ/MOISTURE
INFLOW...A CLUSTER OR TWO OF ELEVATED STORMS WITH HAIL AND POSSIBLY
DMGG WIND MAY PERSIST INTO EARLY SUN.

...PA/NY/NJ THIS AFTN...
WEAK WAA ON ERN EDGE OF AMPLIFYING RIDGE WILL FOCUS OVER PARTS OF
NY...PA...AND NJ THIS AFTN/EVE. ALTHOUGH WEAK HEIGHT RISES WILL TO
SOME EXTENT OFFSET ASSOCIATED DESTABILIZATION...SFC HEATING ON SRN
FRINGE OF WAA STRATIFORM CLOUD FIELD SHOULD SUPPORT ISOLD TO
POSSIBLY SCTD TSTM DEVELOPMENT BENEATH MODERATE /30-40 KT/ NWLY MID
LVL FLOW. AS IN THE NRN PLNS...GUIDANCE APPEARS TO BE
OVERESTIMATING LOW LVL MOISTURE PER CURRENT SFC OBS. BUT SETUP MAY
NEVERTHELESS YIELD A FEW STORMS WITH MARGINALLY SVR HAIL/WIND GIVEN
RELATIVELY STEEP MID LVL LAPSE RATES. THE CONVECTION SHOULD BE
MAINLY DIURNAL AND WEAKEN WITH SUNSET.

...CNTRL/ERN GULF CST LATER TODAY THROUGH EARLY SUN...
WAA/MOISTURE TRANSPORT WILL INCREASE THROUGH THE PERIOD ALONG
THE CNTRL GULF CST AS LOW LVL FLOW STRENGTHENS IN ASSOCIATION WITH
ELONGATING UPR LOW/TROUGH. THIS WILL LEAD TO CONSIDERABLE COVERAGE
OF SHOWERS/STORMS...ESPECIALLY INVOF DIFFUSE WARM FRONT ATTM
EXTENDING FROM EXTREME SRN LA ESE INTO THE NERN GULF. WHILE THIS
WILL HINDER INLAND PENETRATION OF LOW LVL
DESTABILIZATION...ASSOCIATED INCREASE IN LOW LVL SHEAR AND MOISTURE
/PW AROUND 2 INCHES/ MAY PROVE SUFFICIENT TO SUPPORT A LOW
CONDITIONAL RISK FOR A TORNADO OR TWO...AND/OR FOR LOCALLY DMGG
WIND.

..CORFIDI/LEITMAN.. 06/09/2012

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