SPC AC 261246
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0746 AM CDT MON MAR 26 2007
VALID 261300Z - 271200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SOUTH TX...
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN SACRAMENTO
VALLEY...
...SRN TX...
STRONG UPPER LOW CONTINUES TO MOVE EWD ACROSS NRN CHIHUAHUA MEXICO
EARLY THIS MORNING...SUPPORTING AN EXTENSIVE AREA OF CONVECTION
ACROSS WRN AND CENTRAL TX. THIS ACTIVITY WILL LIKELY PERSIST THIS
MORNING ACROSS CENTRAL/NRN TX BUILDING NNEWD OVER A LARGE PART OF
THE SRN PLAINS THROUGH THE PERIOD. MODEST HEATING AND STRONGER LIFT
MAY SUPPORT AN ISOLATED LARGE HAIL/DAMAGING WINDS ALONG SRN
PERIPHERY OF THIS ACTIVITY. WELL DEFINED DRY SLOT ON WV IMAGERY NOW
OVERSPREADING THE BIG BEND REGION AND EXTENDING INTO THE HILL
COUNTRY WILL LIKEWISE SHIFT EWD OVER MUCH OF THE LOWER RIO GRANDE
VALLEY/SRN TX BY THE AFTERNOON. THIS WILL ALLOW SUFFICIENT
HEATING/CLEARING TO OCCUR NEAR THE RIO GRANDE FOR AN AXIS OF
MODERATE TO LOCALLY STRONG INSTABILITY...AS COLD MID LEVEL
TEMPERATURES /H5 TEMPS AROUND -14C/ SUPPORT VERY STEEP LAPSE RATES.
IN ADDITION...WEAK SURFACE LOW LIFTING NWD INTO CENTRAL TX WILL
MAINTAIN INFLUX OF SSELY SURFACE WINDS ACROSS SRN TX AND KEEP
MID/UPPER 60F DEW POINTS IN PLACE OVER DEEP SOUTH TX.
APPEARS INTENSE THUNDERSTORM DEVELOPMENT WILL OCCUR NEAR THE NRN
SIERRA MADRE ORIENTAL RANGE OF NERN MEXICO BY THE EARLY AFTERNOON
IMMEDIATELY AHEAD OF APPROACHING UPPER LOW. THIS ACTIVITY WILL
LIKELY TRACK ENEWD AND SHOULD PERSIST WITHIN AXIS OF 1000-1500 J/KG
MLCAPES SOUTH OF MORNING CONVECTION NOW MOVING ACROSS THE HILL
COUNTRY AND WEST OF MID LEVEL MOISTURE PLUME EXTENDING ACROSS DEEP
SOUTH TX TO THE ARKLATEX ATTM. REGION WILL REMAIN UNDER INFLUENCE
OF 50+ KT SSWLY MID LEVEL JET ASSOCIATED WITH EJECTING UPPER LOW AND
FORECAST SOUNDINGS SUGGEST EFFECTIVE BULK SHEAR IN EXCESS OF 45 KT
WILL BE MORE THAN ADEQUATE FOR SUPERCELLS ALONG WITH ORGANIZED
LINES. LARGE HAIL MAY BE PRIMARY SEVERE THREAT...THOUGH A FEW
TORNADOES ALONG WITH ISOLATED WIND DAMAGE ARE ALSO EXPECTED WITH THE
MORE ORGANIZED STORMS. ACTIVITY WILL SPREAD EWD AND MAY SUSTAIN AN
ISOLATED SEVERE THREAT TOWARDS THE TX COASTAL BEND REGION THIS
EVENING.
...NRN SACRAMENTO VALLEY...
VERY STRONG KINEMATIC FIELDS WILL OVERSPREAD NRN/CENTRAL CA TODAY
AND TONIGHT AS 100 KT MID LEVEL /125 KT AT H25/ JET APPROACHES THE
CENTRAL CA COAST. THESE WILL ACCOMPANY A POTENT MID/UPPER LEVEL
TROUGH EXPECTED TO OVERSPREAD THE PAC NW/NRN CA COAST BY THIS
EVENING. FAST MOVING PAC COLD FRONT IS EXPECTED TO SPREAD INTO THE
NRN INTERMOUNTAIN REGION BY LATER TODAY...WITH STRONG ONSHORE FLOW
IN ITS WAKE DEVELOPING ACROSS NRN CA. VERY COLD MID LEVEL
TEMPERATURES WILL AUGMENT MODEST SURFACE HEATING AND MAY SUPPORT
SHALLOW INSTABILITY WITH SBCAPE POSSIBLY APPROACHING 500 J/KG OVER
THE NRN SAC VALLEY. IN ADDITION...OROGRAPHIC INFLUENCES WILL LIKELY
FORCE SURFACE WINDS ACROSS THE NRN SAC VALLEY TO A MORE SLY
DIRECTION AND ENHANCE LOW LEVEL SHEAR THIS AFTERNOON AND EVENING.
THEREFORE...SETUP MAY SUPPORT A FEW LOW-TOPPED/MINI SUPERCELLS
DURING THE MID TO LATE AFTERNOON. NAM-KF FORECAST SOUNDINGS
INDICATE SFC-3 KM SBCAPE IN EXCESS OF 100 J/KG WITH SFC-1 KM SRH
AROUND 200 M2/S2...BOTH OF WHICH SHOULD BE FAVORABLE FOR A TORNADO
OR TWO SHOULD WINDS REMAIN SSELY AT THE SURFACE ALONG WITH
NEAR-SEVERE HAIL.
...MIDWEST INTO THE SRN GREAT LAKES AND CENTRAL APPALACHIANS...
UNSEASONABLY WARM TEMPERATURES ARE EXPECTED TO DEVELOP ACROSS THIS
REGION TODAY AS WEAKENING...FAST MOVING SHORTWAVE TROUGH SHIFTS
ACROSS SRN ONTARIO. GIVEN INFLUX OF MODIFIED GULF MOISTURE ACROSS
MUCH OF THE CENTRAL U.S...APPEARS AREAS OF MARGINAL TO MODERATE
INSTABILITY WILL DEVELOP DURING THE AFTERNOON. GLANCING INFLUENCE
OF NRN STREAM IMPULSE SHOULD THEREFORE SUPPORT SCATTERED
THUNDERSTORMS INTO THE SRN/ERN GREAT LAKES INTO THE CENTRAL
APPALACHIANS THIS AFTERNOON. OPERATIONAL MODELS SUGGEST A SUBTLE
SRN STREAM IMPULSE WILL SHIFT NEWD AND THEN EWD ACROSS THE MID MS
RIVER VALLEY LATER TODAY. THIS MAY SUPPORT A FEW THUNDERSTORMS
WITHIN AREA OF MODERATE INSTABILITY WITH ATTENDANT MARGINAL SEVERE
THREAT LATER TODAY AND THIS EVENING.
..EVANS/CROSBIE.. 03/26/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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