SPC AC 251958
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT MON JUN 25 2007
VALID 252000Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN PLNS...
...NRN PLNS...
AS OF MID AFTERNOON...A STATIONARY FRONT EXTENDED FROM NRN MN WSW
ACROSS CNTRL ND INTO N CNTRL WY. FARTHER N...THE LEADING EDGE OF A
NEW SURGE OF COLD AIR ASSOCIATED WITH POTENT MB UPR TROUGH WAS
ENTERING ERN MT. THE BOUNDARY WILL REINFORCE EXISTING FRONT OVER WY
AND THE WRN DAKOTAS TONIGHT...AND WILL HELP ACCELERATE THE LEAD
BOUNDARY SE INTO THE CNTRL PLNS EARLY TUESDAY.
ALOFT...SATELLITE AND VWP DATA SUGGEST THAT PRONOUNCED EML WARM NOSE
REMAINS IN PLACE FROM WY/CO NE INTO THE DAKOTAS AND CNTRL/SRN MN.
ASSOCIATED CAP LIKELY WILL CONTINUE TO PROHIBIT DEEP CONVECTIVE
DEVELOPMENT OVER MUCH OF THE REGION UNTIL LATE IN THE DAY. ON THE
NERN FRINGE OF THE EML...ELEVATED TSTMS HAVE PERSISTED OVER EXTREME
NRN MN.
LARGE SCALE FORCING FOR ASCENT WILL REMAIN WEAK AS MB IMPULSE TRACKS
MAINLY N OF THE CANADIAN BORDER. HEATING AND WEAK UPSLOPE FLOW IN
WAKE OF STALLED FRONT SHOULD...HOWEVER...SUPPORT TSTM DEVELOPMENT
OVER THE HIGHER TERRAIN OF NRN WY/WRN SD LATER THIS AFTERNOON.
ISOLATED STORMS MAY ALSO FORM INVOF LEE TROUGH EXTENDING S FROM SD
SFC LOW INTO WRN NEB/NE CO. THIS ACTIVITY WILL BE VERY HIGH
BASED...POSING A THREAT FOR DAMAGING WIND AND ISOLATED LARGE HAIL.
OUTFLOW FROM THESE STORMS MAY MERGE...RESULTING IN ONE OR TWO
ENE-MOVING CLUSTERS THROUGH MID EVENING. THE STORMS MOVING OFF
HIGHER TERRAIN...MEANWHILE...WILL ENCOUNTER GREATER BOUNDARY LAYER
MOISTURE AND ARE MORE LIKELY TO BECOME SUPERCELLULAR. THESE MAY
PERSIST INTO EARLY TUESDAY AS THEY MOVE/DEVELOP E INTO STRENGTHENING
LLJ OVER SD/SRN ND.
FARTHER NE...OTHER STORMS MAY PERSIST OR DEVELOP IN ZONE OF
SUSTAINED WAA INVOF SFC FRONT/STORM OUTFLOW IN NE ND/NW MN. VERY
MOIST WARM SECTOR IN THIS AREA...COUPLED WITH BACKED LOW LEVEL FLOW
E OF SD SFC LOW...WILL SUPPORT A CONDITIONAL THREAT FOR SUPERCELLS
WITH VERY LARGE HAIL AND ISOLATED TORNADOES. THIS ACTIVITY MAY
EXPAND SW ALONG FRONT THROUGH EARLY TUESDAY AND EVENTUALLY MERGE
WITH STORMS SPREADING ENE FROM SD. ANY THREAT SHOULD DIMINISH AS
THE STORMS BECOME UNDERCUT/ELEVATED BY ACCELERATING COLD FRONT EARLY
TUESDAY.
IN MT...WINDS ARE VEERING IN SE MT AHEAD OF AFOREMENTIONED COLD
SURGE NOW NEAR GGW. BUT WEAK SE FLOW CONTINUES ATTM IN AREA OF LOW
LEVEL CLOUDS IN NW ND. POTENTIAL WILL EXIST FOR ISOLATED STORM
DEVELOPMENT ALONG THE COLD FRONTAL SURGE AS IT REACHES THIS AREA
LATER TODAY. GIVEN STRENGTH OF SHEAR/INSTABILITY...ANY SUCH
ACTIVITY COULD YIELD SVR WIND/HAIL THROUGH EARLY EVENING.
...NRN NEW ENGLAND...
FAST-MOVING IMPULSE IS ENTERING THE ADIRONDACKS ATTM AND WILL
CONTINUE ESE INTO NRN NEW ENGLAND BY EVENING. MODERATE TO STRONG
DEEP NWLY SHEAR WILL BE OFFSET BY WEAK INSTABILITY DUE TO LIMITED
MOISTURE AVAILABILITY. WHILE A RISK WILL EXIST FOR ISOLATED
STRONG/MARGINALLY SVR WIND GUSTS WITH ANY STORMS THAT DO FORM
THROUGH EARLY EVENING...WEAK INSTABILITY SHOULD LIMIT
INTENSITY/COVERAGE OF ANY SUCH THREAT.
...SRN HI PLNS...
MODERATE NLY FLOW ATOP SSELY SURFACE WINDS WILL MAINTAIN 20-25 KT
DEEP NLY SHEAR ACROSS ERN NM AND THE ERN PANHANDLES REGION. MOIST
UPSLOPE REGIME...ESPECIALLY INVOF THE ROTAN DIVIDE...MAY SUPPORT
STORM DEVELOPMENT A BIT LATER TODAY. DRY AIR ALOFT AND LARGE T-TD
SPREADS MAY ENHANCE ORGANIZATION INTO CLUSTERS/LINES...WITH AN
ATTENDANT RISK FOR MARGINALLY SEVERE WIND/HAIL.
...TN VLY INTO CNTRL/SRN APLCNS...
ANOTHER ROUND OF SCTD PULSE STORMS WITH SVR HAIL/WIND WILL CONTINUE
THROUGH EARLY EVENING IN MOIST...WEAKLY CAPPED ENVIRONMENT OVER
PARTS OF THE EAST AND SOUTHEAST. THIS INSTABILITY DRIVEN ACTIVITY
SHOULD BE MOST CONCENTRATED OVER THE TN VLY AND SRN APPALACHIANS.
..CORFIDI.. 06/25/2007
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