SPC AC 061959
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT TUE MAY 06 2008
VALID 062000Z - 071200Z
...THERE IS A MDT RISK OF SVR TSTMS PORTIONS NEB AND WRN/NRN KS...
...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM PORTIONS UPPER
MIDWEST SWWD ACROSS W TX...
...SYNOPSIS...
MID-UPPER LEVEL LOW -- INITIALLY LOCATED OVER EXTREME NRN GULF OF CA
AND NWRN SONORA -- IS FCST TO EJECT ENEWD ACROSS BORDERLANDS OF SRN
AZ/NM AND FAR W TX THROUGH REMAINDER PERIOD...REACHING SERN NM BY
7/12Z. AS THIS FEATURE APCHS SRN PLAINS...SFC PRESSURE FALLS ARE
EXPECTED TO INCREASE...YIELDING BETTER DEFINED LOW INVOF CDS BY END
OF PERIOD. POSITION OF THIS CYCLONE BY THEN WILL BE INFLUENCED
STRONGLY BY NEARBY CONVECTIVE PROCESSES...AND MAY BE
DISPLACED/DIFFUSED BY OUTFLOW FROM ANY NEARBY MCS ACTIVITY.
SFC ANALYSIS INDICATES WARM FRONTAL ZONE FROM SE TX WNWWD ACROSS AUS
AREA AND CENTRAL PORTIONS OF TX HILL COUNTRY...BECOMING DIFFUSE
WNWWD ACROSS SOUTH PLAINS REGION OF W TX AND INTO ADJOINING ERN NM.
THIS BOUNDARY DENOTED NRN PORTION OF RICHEST LOW LEVEL
MOISTURE...AND SHOULD CONTINUE TO LOSE IDENTITY ACROSS W TX AMIDST
CONTINUED SLY-SELY BOUNDARY LAYER FLOW AND BROAD SWATH OF THETAE
ADVECTION. DRYLINE AT 19Z IS ANALYZED FROM SWRN SD SWD ACROSS WRN
NEB AND KS/CO BORDER AREA...THEN SSWWD ACROSS NWRN PORTIONS TX
PANHANDLE...BETWEEN TCC-CVS...NEAR ROW...SSEWD INTO BIG BEND REGION.
AS MID/UPPER LOW APCHS...ASSOCIATED LOW LEVEL FRONTAL ZONE SHOULD
MERGE WITH DRYLINE...THEN COMBINED BOUNDARY WILL MOVE EWD TO ROUGHLY
100W ACROSS TX BY END OF PERIOD. MEANWHILE...WEAK SFC LOWS
INITIALLY OVER SWRN SD AND N-CENTRAL SD SHOULD CONSOLIDATE AND MOVE
ENEWD ACROSS SRN MN AND WI OVERNIGHT. TRAILING COLD FRONT WILL MOVE
SEWD ACROSS MUCH OF MN...NEB...SD...NERN CO AND PERHAPS NWRN KS
BEFORE 7/12Z.
...CENTRAL-NRN PLAINS...
BOW ECHO OVER ERN PORTIONS SD/NEB BORDER SHOULD CONTINUE TO POSE
THREAT FOR HAIL...WITH INCREASING WIND DAMAGE POTENTIAL AS IT MOVED
INTO PROGRESSIVELY MORE MOIST/UNSTABLE AIR MASS. REF WW 265 AND
ACCOMPANYING MESOSCALE DISCUSSIONS FOR LATEST SHORT-TERM PROGNOSIS.
ACTIVITY MAY EVOLVE UPSCALE INTO BROADER MCS AS IT MOVES THROUGH
PORTIONS NERN NEB/IA LATE THIS AFTERNOON AND THIS EVENING...WITH
RELATIVELY DRY SFC AIR MASS AUGMENTING WIND POTENTIAL.
ADDITIONAL/RAPID DEVELOPMENT IS LIKELY FARTHER S ACROSS WRN/CENTRAL
NEB AND KS THIS AFTERNOON AND EVENING...ALONG/AHEAD OF DRYLINE.
FCST DEEP-LAYER VERTICAL SHEAR PROFILES WILL FAVOR
SUPERCELLS...PARTICULARLY INVOF OUTFLOW BOUNDARY FROM NERN NEB/SERN
SD CONVECTION. THIS BOUNDARY AT 19Z WAS QUASISTATIONARY FROM ONL
AREA WNWWD ACROSS SANDHILLS...AND MAY FOCUS LOCALIZED TORNADO
POTENTIAL WITH ANY SUPERCELL THAT MAY INTERACT WITH AND MOVE ALONG
BOUNDARY. OTHERWISE...DAMAGING HAIL AND OCCASIONAL SVR GUSTS WILL
BE PRIMARY CONCERNS. REF MESOSCALE DISCUSSION 796...WW 266 AND
SUBSEQUENT MESOSCALE DISCUSSIONS FOR NEAR-TERM DETAILS ON POTENTIAL
IN THIS AREA. ADDITIONAL TSTMS -- DEVELOPING BEHIND DRYLINE ACROSS
PORTIONS ERN CO -- MAY BECOME SVR AS THEY MOVE TOWARD MOIST SECTOR.
ANOTHER MCS MAY EVOLVE FROM AFTERNOON ACTIVITY BETWEEN NRN NEB AND
CENTRAL KS...WHICH WOULD POSE THREAT FOR SVR WIND/HAIL AS IT MOVES
ACROSS NRN KS OR NEB OVERNIGHT.
...SRN PLAINS...
SCATTERED TO WIDELY SCATTERED TSTMS...EVOLVING INTO SUPERCELLS WITH
TORNADO/DAMAGING HAIL POSSIBLE...ARE EXPECTED IN CORRIDOR FROM BIG
BEND/DAVIS MOUNTAIN AREA OF W TX..NWD ACROSS SOUTH PLAINS AND
PANHANDLES. REF SPC MESOSCALE DISCUSSION 795 FOR MORE DETAILED
COVERAGE OF THIS POTENTIAL.
AFTER DARK...SWATH OF STRONGEST DPVA ALOFT -- AHEAD OF EJECTING
MID-UPPER LEVEL CYCLONE -- IS FCST TO IMPINGE UPON PROGRESSIVELY
MORE MOIST AND BUOYANT AIR MASS WITH EWD EXTENT...SUPPORTED BY STG
LLJ UP TO NEAR 50 KT. SCATTERED-NUMEROUS TSTMS ARE EXPECTED TO
FORM...EITHER ANEW OR LINKED WITH UPSCALE GROWTH OF
AFTERNOON/EVENING ACTIVITY. RATHER EXPANSIVE AND PROBABLY LINEAR
MCS SHOULD DEVELOP LATE TONIGHT AND MOVE EWD TO ENEWD ACROSS LARGE
PART OF NW TX AND WRN OK...PERHAPS BACKBUILDING SWD INTO W-CENTRAL
TX. FCST SOUNDINGS SUGGEST EFFECTIVE LIFTED PARCELS IN PERSPECTIVE
INFLOW LAYER WILL REMAIN SFC-BASED...OR VERY NEARLY SO...MAINTAINING
HAIL/WIND/TORNADO THREATS CONDITIONAL TO LOCALIZED STORM
MODE...I.E.. BOWS/LEWPS WITHIN LINE OR SUPERCELLS AWAY FROM PRIMARY
LINE.
..EDWARDS.. 05/06/2008
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