SPC AC 012018
DAY 1 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0318 PM CDT MON JUN 01 2009
VALID 012000Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL PLAINS EWD
THROUGH THE OH VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE SRN HIGH
PLAINS...
CORRECTED FOR HAIL AND WIND GRAPHIC AND TEXT IN FIRST AND SECOND
PARAGRAPH
...CNTRL PLAINS THROUGH MID AND UPPER MS VALLEY...
ONLY MINOR ADJUSTMENTS TO PREVIOUS FORECAST. STORMS ARE ON TRACK TO
INCREASE IN COVERAGE AND INTENSITY ALONG AND SOUTH OF E-W ORIENTED
FRONT THAT CURRENTLY EXTENDS FROM SRN NEB EWD THROUGH SRN WI. WARM
SECTOR HAS BECOME MODERATELY UNSTABLE AS TEMPERATURES CLIMB THROUGH
THE 80S WITH MLCAPE GENERALLY FROM 1500 TO 2000 J/KG. MUCH OF THE
STRONGER FLOW REMAINS POST FRONTAL WITH ONLY MODEST BULK SHEAR IN
WARM SECTOR. STORMS DEVELOPING FROM THE CNTRL PLAINS EWD THROUGH THE
MID MS VALLEY WILL PROBABLY REMAIN MULTICELLULAR IN CHARACTER WITH A
THREAT OF ISOLATED LARGE HAIL AND DAMAGING WIND GUSTS. BELT OF
STRONGER 35-45 KT MID-UPPER FLOW OVER THE OH VALLEY WILL RESULT IN
THE POTENTIAL FOR STORMS TO BECOME MORE ORGANIZED WITH ISOLATED
DAMAGING WIND AND HAIL POSSIBLE THROUGH EARLY-MID EVENING.
...SRN HIGH PLAINS ...
SEVERE THREAT IN THIS REGION IS MORE MARGINAL. STORMS ARE DEVELOPING
OVER THE HIGHER TERRAIN OF ERN NM ALONG ERN FRINGE OF LARGE SCALE
ASCENT ASSOCIATED WITH UPPER LOW CIRCULATION. OTHER STORMS ARE
DEVELOPING FARTHER EAST OVER WRN TX WITHIN LOW LEVEL CONFLUENT FLOW
REGIME. THE BOUNDARY LAYER HAS MIXED OUT WITH STEEP LAPSE RATES AND
40S TO LOW 50S DEWPOINTS SUPPORTING MLCAPE AOB 1000 J/KG. HIGH BASED
MULTICELL STORMS CAPABLE OF PRODUCING ISOLATED HAIL AND STRONG WIND
GUSTS WILL REMAIN POSSIBLE THROUGH EARLY EVENING.
..DIAL.. 06/01/2009
.PREV DISCUSSION... /ISSUED 1126 AM CDT MON JUN 01 2009/
...CENTRAL PLAINS TO OH VALLEY...
GULF MOISTURE HAS CONTINUED TO INCREASE THRU THE SOUTHERN AND
CENTRAL PLAINS AHEAD OF A SLOW MOVING FRONTAL BAND EXTENDING
CURRENTLY FROM LM SWWD THRU SRN IA TO NWRN KS. WHILE THE FRONT WILL
BE FOCUS FOR PRIMARILY A DIURNAL THREAT OF SEVERE THUNDERSTORMS THE
FAVORED AREA OF DEVELOPMENT IS DISPLACED IN THE SRN FRINGE OF THE
PRIMARY WESTERLIES WHICH ARE ACROSS NRN PLAINS/UPR MS VALLEY. THE
MARGINAL SHEAR PROFILES...PARTICULARLY THAT PORTION OF THE FRONT
ACROSS THE PLAINS WILL LIMIT SOMEWHAT THE SEVERE POTENTIAL WITH
PRIMARILY A MULTICELLULAR MODE EXPECTED. WITH LAPSE RATES OF 7C/KM
AND POTENTIALLY MLCAPES TO 2000 J/KG...LARGE HAIL AND DOWNBURST
WINDS EXPECTED TO BE PRIMARY THREAT. BY EVENING AS LOW LEVEL JET
RAMPS UP TO 30KT INCREASING THE LARGE SCALE ASCENT THRU WARM
ADVECTION...ONE OR MORE MCS/S COULD DEVELOP LEADING TO A LITTLE
GREATER RISK OF AN ORGANIZED WIND THREAT AS THEY TRACK EWD ALONG/N
OF FRONTAL ZONE INTO OH VALLEY.
...SRN HI PLNS...
SCTD AFTN/EVE STORMS ARE EXPECTED ALONG LEE TROUGH/DRYLINE OVER WRN
PORTIONS OF THE CNTRL/SRN PLNS...AHEAD OF APPROACHING SRN STREAM
VORT. ALTHOUGH BOUNDARY LAYER WILL NOT BE ESPECIALLY MOIST /SFC
DEWPOINTS MOSTLY IN THE 50S/...PW WILL BE ON THE INCREASE. IN
ADDITION...WITH EML ALOFT...SFC HEATING WILL BOOST SBCAPE TO
AOA 1500 J/KG. THIS WOULD SUPPORT A CONDITIONAL RISK FOR MULTICELLS
OR WEAK SUPERCELLS WITH SVR HAIL/WIND FROM WRN/CNTRL KS SW INTO WRN
OK/NW TX.
HAVE SHIFTED THE LITTLE HIGHER SVR PROBS/SLIGHT RISK NWD INTO THE TX
PANHANDLE. IN THIS AREA THE COMBINATION OF STRONG HEATING...25-30KT
OF DEEP LAYER SHEAR AND MLCAPES TO 1500 J/KG..SUPPORT A FEW SEVERE
THUNDERSTORMS LATER THIS AFTN/EVENING...WITH LARGE HAIL AND A
DOWNBURST WIND THREAT.
..NRN GRT BASIN TO NRN RCKYS...
PW VALUES UP TO 1.0 INCH AND STEEP MID LVL LAPSE RATES WILL
YIELD MODERATE INSTABILITY BY AFTN OVER ORE AND S/W OF FRONT NOSING
S INTO THE NRN RCKYS/HI PLNS. HEATING AND TERRAIN CIRCULATIONS
SHOULD INITIATE SCTD AFTN/EVE STORMS WITH A THREAT FOR MARGINALLY
SVR WIND/HAIL. THE GREATEST CONCENTRATION OF STORMS MAY OCCUR OVER
THE ORE CASCADES AND THE NRN CA SIERRA/ SISKYOUS...WHERE ASCENT MAY
MAXIMIZE BENEATH BAND OF ENHANCED SLY FLOW E OF OFFSHORE UPR LOW.
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