SWODY1
SPC AC 081251
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0651 AM CST SAT DEC 08 2007
VALID 081300Z - 091200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
INCREASINGLY AMPLIFIED SPLIT FLOW PATTERN WILL PREVAIL THROUGH THE
WEEKEND AS HEIGHTS RISE ACROSS THE SOUTHEAST AND VORT MAX NOW NEAR
PDX DROPS S ALONG THE CA CST TO REPLACE IMPULSE EJECTING NE FROM SRN
CA. PDX SYSTEM LIKELY WILL EVOLVE INTO A FAIRLY TIGHT CLOSED LOW
THAT SHOULD REACH THE SBA AREA BY 12Z SUNDAY. DOWNSTREAM FROM THE
LOW...EXISTING SRN CA SYSTEM EXPECTED TO REACH THE CNTRL HI PLNS
EARLY SUNDAY...WITH DISTURBANCE NOW OVER NW MEXICO BECOMING ABSORBED
INTO STRENGTHENING SW FLOW OVER THE SRN PLNS.
AT LWR LVLS...CURRENT SFC AND VWP DATA SHOWING PERSISTENT ENE FLOW
AIMED AT THE CNTRL RCKYS SUGGESTS THAT SHALLOW COLD AIR MASS LIKELY
WILL CONTINUE TO SETTLE SLOWLY S ACROSS WRN PARTS OF THE SRN PLNS
THROUGH E PERIOD...WITH SOMEWHAT SLOWER SWD ADVANCE FARTHER E. WEAK
WAVE DEVELOPMENT EXPECTED LATER TODAY IN SE OK MAY ALLOW FOR A
SLIGHT NWD DRIFT OF BOUNDARY IN AR. FRONT SHOULD EXTEND FROM NRN KY
WSW INTO NRN AR...AND THEN SW INTO SE OK...CNTRL TX AND ERN NM BY
12Z SUNDAY.
..SRN PLNS TO LWR OH VLY...
SFC DATA AND BLENDED PW DATA FROM SATELLITE SHOW SUBSTANTIAL
MOISTURE RETURN /PW AOA 1 INCH/ UNDERWAY ATTM FROM THE ERN HALF OF
TX AND LA NNE INTO THE LWR MS VLY. SHORT WAVE RIDGING ON FRINGE EOF
BUILDING SERN U.S. RIDGE WILL KEEP MID LVL LAPSE RATES WEAK. BUT
COMBINATION OF INCREASING MOISTURE...ALONG WITH GRAZING INFLUENCE OF
AFOREMENTIONED SHORTWAVE IMPULSES EJECTING NE FROM MEXICO AND THE SW
U.S...WILL SUPPORT AN INCREASING CHANCE FOR TSTMS WITH TIME FROM N
CNTRL/NE TX NEW INTO THE NRN AR AND MO OZARKS.
TSTM PROBABILITIES LIKELY WILL BE GREATEST TONIGHT THROUGH EARLY
SUNDAY. THIS ACTIVITY SHOULD BE MAINLY ELEVATED AND WILL BE
SUPPORTED BY 40-50 KT SWLY LLJ ASSOCIATED WITH EJECTING UPR
DISTURBANCES. SUFFICIENT ELEVATED INSTABILITY /MUCAPE OF 500 TO
PERHAPS 750 J PER KG/ MAY DEVELOP TO POSE A RISK FOR MARGINALLY SVR
HAIL GIVEN QUALITY OF ELEVATED MOISTURE INFLOW AND MODERATE TO
STRONG DEEPLY UNIDIRECTIONAL UPR FLOW. THIS SETUP MAY ALSO FOSTER A
FEW BANDS OF REGENERATIVE STORMS WITH HEAVY RAIN.
..CNTRL AND SRN CA...
VERY COLD AIR ALOFT /MINUS 28 TO MINUS 30 C AT 500 MB/ WILL
ACCOMPANY UPR VORT MOVING S ALONG THE CA CST TODAY/TONIGHT. THE LWR
LVLS ACROSS CNTRL PORTIONS OF THE STATE HAVE DRIED/COOLED SOMEWHAT
IN WAKE OF SYSTEM NOW EXITING SRN CA. NEVERTHELESS...SUFFICIENT
RESIDUAL MOISTURE REMAINS OVER THE CNTRL VLY AND S OF SFO TO SUPPORT
DIURNALLY-ENHANCED CONVECTION/POSSIBLE THUNDER LATER TODAY...GIVEN
EXPECTED COMBINATION OF MODERATE SFC HEATING AND COOLING ALOFT.
WHILE WIND SHEAR WILL BE WEAK...COLD THERMODYNAMIC PROFILES COULD
YIELD SMALL HAIL IN STRONGER UPDRAFTS DURING THE MID TO LATE AFTN.
FARTHER S...A SEPARATE AREA OF CONVECTION/POSSIBLE STORMS MAY FORM A
BIT LATER IN THE DAY THROUGH TONIGHT ALONG THE SRN CA CST AND OVER
THE SRN CA CSTL MOUNTAINS. IN THIS REGION...TERRAIN WILL ENHANCE
UPLIFT IN WLY FLOW ON S SIDE OF APPROACHING UPR VORT. THIS ACTIVITY
MAY ALSO YIELD SOME HAIL AND PERHAPS A WATERSPOUT OR TWO THROUGH
EARLY SUNDAY.
.CORFIDI.. 12/08/2007
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