SPC Day 1 Thunderstorm Outlook Issued 12Z 20030512


ZCZC SPCSWODY1 ALL
ACUS01 KWNS 120524
SPC AC 120522

STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK 
DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS.

VALID 121200Z - 131200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM
50 SSW P07 50 WSW INK 10 NE CNM 45 WNW HOB 40 N HOB 50 NE HOB
45 NNW BGS 15 SSE BGS 50 NW DRT.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 60 WNW MRF
40 WNW ROW 20 N LVS 30 SSW LHX 30 NW LAA 35 SSE AKO 25 N AKO
40 WNW BFF 25 SE CPR 25 SSE BAM 10 SW TVL 15 SSW MHS 35 E EUG
35 NNE DLS 15 NW EPH 40 NNE 4OM ...CONT... 75 NW ISN 25 NNE MBG
25 W FSD 35 E OMA 15 NE MKC 20 WSW JLN 40 S PGO 40 WNW POE
25 SSW LCH.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 50 NNE BML 20 NW PSM
30 S CON 15 NW BAF 15 NE ITH 10 NE ROC.

...SWRN TX...
A DEEP OCCLUDED LOW WILL TRACK FROM SRN ONTARIO INTO NEW ENGLAND
TODAY AS AN UPPER RIDGE BUILDS NWD OVER THE CENTRAL STATES.  A
RELATIVELY COOL/DRY AIR MASS IS EXPECTED OVER MUCH OF THE ERN U.S.
IN THE WAKE OF THE LOW.  DESPITE A RIDGE BUILDING OVER THIS
REGION...WSWLY MID/UPPER LEVEL FLOW FROM THE SWRN STATES INTO THE
SRN PLAINS WILL INDUCE A TROUGH IN LEE OF THE ROCKIES WITH SSELY
LOW-LEVEL FLOW RETURNING MOISTURE FROM THE LOWER RIO GRANDE VALLEY
WNWWD INTO THE SRN HIGH PLAINS.  SURFACE DEWPOINTS IN THE UPPER 50S
TO AROUND 60 ARE EXPECTED AS FAR NORTH AS MAF TO SERN NM BY LATE
AFTERNOON.  

STEEP LAPSE RATES WITHIN AN ELEVATED MIXED LAYER MOVING EWD OVER
THIS REGION COMBINED WITH RETURNING LOW-LEVEL MOISTURE AND
AFTERNOON HEATING WILL SUPPORT MODERATE INSTABILITY BY MID-LATE
AFTERNOON FROM SWRN TX INTO SERN NM.  THE COMBINATION OF SURFACE
HEATING AND UPSLOPE FLOW INTO THE MOUNTAINS OF SWRN TX TO SERN-ERN
NM IS EXPECTED TO RESULT IN CONVECTIVE DEVELOPMENT THIS AFTERNOON
OVER THE HIGHER TERRAIN.  AS STORMS MOVE EWD OFF THE MOUNTAINS...
MODERATE INSTABILITY AND STRONG DEEP LAYER SHEAR WILL SUPPORT
SUPERCELLS PRODUCING LARGE HAIL AND DAMAGING WIND GUSTS.  

THUNDERSTORMS SHOULD WEAKEN OVER SWRN TX THIS EVENING AS
INSTABILITY WEAKENS WITH THE LOSS OF DAY TIME HEATING.

...TX PANHANDLE SEWD TO SWRN OK/NWRN TX...
A SLY LLJ IS EXPECTED TO STRENGTHEN THIS EVENING AND OVERNIGHT FROM
SWRN TX TO SWRN KS WITH SPEEDS UP TO 40-45 KT BY LATE TONIGHT.  A
SURFACE BOUNDARY WILL BE RETURNING NWD THROUGH THE DAY AND REACH
EAST CENTRAL NM TO NRN TX OVERNIGHT.  ELEVATED CONVECTION IS
EXPECTED THIS EVENING OVER THE TX PANHANDLE WITHIN A LOW-LEVEL WAA
REGIME...WITH STORMS MOVING/DEVELOPING SEWD INTO SWRN OK/NWRN TX
OVERNIGHT.  HAIL WILL BE THE PRIMARY THREAT WITH THIS ACTIVITY...
THOUGH COVERAGE IS EXPECTED TO BE ISOLATED...RESULTING IN A LOW
HAIL PROBABILITY OVERNIGHT.
 
..PETERS/BANACOS.. 05/12/03

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