[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 170545
SWODY1
SPC AC 170544

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1244 AM CDT MON APR 17 2006

VALID 171200Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS MAINLY THIS AFTERNOON ACROSS
NC/SC...

...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON THROUGH
TONIGHT ACROSS PARTS OF NEB/SD/ND...

...NC/SC...
OH VALLEY MID-LEVEL TROUGH WILL UNDERGO FURTHER DE-AMPLIFICATION
TODAY AS IT TRACKS ESEWD TOWARD VA/NC/SC...EVENTUALLY BECOMING
ABSORBED BY NERN STATES UPPER TROUGH...AND EJECTING EWD OVER THE WRN
ATLANTIC.  ACCOMPANYING BAND OF STRONG WLY MID-LEVEL WINDS AT 60-65
KT WILL TRANSLATE EWD ACROSS NC/SC THIS MORNING/AFTERNOON.  

IN THE LOW-LEVELS...SURFACE BOUNDARY INITIALLY EXTENDING W-E OVER
NRN NC IS EXPECTED TO MOVE SSE ACROSS THE CAROLINAS AND SHOULD BE
THE PRIMARY FOCUS FOR THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING
AS IT MOVES SWD ACROSS NC/SC.  SURFACE LOW EXPECTED TO BE LOCATED
OVER ERN KY AT 12Z TODAY WILL WEAKEN AS IT MOVES INTO WV. 
DOWNSTREAM HEIGHT FALLS SHOULD AID SECONDARY SURFACE WAVE
DEVELOPMENT ALONG SURFACE FRONT IN WRN/CENTRAL NC THIS MORNING
BEFORE THIS LOW TRACKS OFFSHORE BY 00Z WITH THE FRONT. DESPITE
MODEST MID-LEVEL LAPSE RATES ACROSS THE CAROLINAS...STRONG SURFACE
HEATING EXPECTED S OF COLD FRONT AND SURFACE DEWPOINTS POTENTIALLY
NEAR 60 F SHOULD SUPPORT MODERATE INSTABILITY BY AFTERNOON.  

THUNDERSTORMS MAY BE ONGOING OVER WV/NERN TN AT START OF DAY 1
PERIOD...WITH THIS ACTIVITY TRACKING ESEWD ACROSS THE HIGHER TERRAIN
AND THEN INTO SRN VA/NRN NC THIS MORNING WITHIN WEAK WAA REGIME. 
ADDITIONAL STORMS EXPECTED TO DEVELOP AS COLD FRONT MOVES SWD INTO
MODERATELY UNSTABLE AIR MASS.  STRONG DEEP LAYER SHEAR VECTORS
ORIENTED PARALLEL TO THE FRONT SUGGEST STORM MODE SHOULD BE
LINEAR...BUT HIGH SHEAR VALUES MAY SUPPORT A FEW EMBEDDED
SUPERCELLS.  HAIL WILL BE POSSIBLE WITH THE STRONGEST ACTIVITY...
WHILE STEEP LOW-LEVEL LAPSE RATES SHOULD ENHANCE STRONG WIND GUST
POTENTIAL.  SEVERE THREAT SHOULD DIMINISH BY 00Z AS FRONT MOVES
OFFSHORE. 

...ND/SD/NEB...
SHORT WAVE TROUGH...CURRENTLY MOVING INLAND OVER NRN CA PER WATER
VAPOR IMAGERY...WITHIN BASE OF WRN STATES LONG WAVE TROUGH...IS
EXPECTED TO MOVE EWD WITH MAIN TROUGH APPROACHING THE CENTRAL/NRN
HIGH PLAINS BY 12Z TUESDAY.  SURFACE CYCLOGENESIS IS EXPECTED OVER
ERN WY IN RESPONSE TO HEIGHT FALLS IN ADVANCE OF THE APPROACHING
UPPER TROUGH.  THIS LOW SHOULD BE LOCATED ALONG THE INTERSECTION OF
A LEE-SIDE TROUGH AND A PACIFIC COLD FRONT WHICH SHOULD EXTEND FROM
WRN ND INTO NRN WY BY LATE THIS AFTERNOON.  THIS LOW WILL THEN
DEVELOP/TRACK SEWD INTO THE CENTRAL PLAINS ALONG A NWD RETREATING
WARM FRONT.  STRENGTHENING SELY LOW-LEVEL WINDS ACROSS THE
CENTRAL/NRN PLAINS WILL LIKELY ADVECT RESIDUAL MOISTURE /SURFACE
DEWPOINTS IN THE LOWER 50S CURRENTLY LOCATED OVER EAST CENTRAL
PLAINS/ NWWD INTO WRN PORTIONS OF SD/NEB BY LATE AFTERNOON.  STEEP
MID-LEVEL LAPSE RATES OVER WRN PORTIONS OF THE NRN/CENTRAL PLAINS
ATOP THE MOISTURE RETURN WILL SUPPORT A NARROW AXIS OF MUCAPES
AROUND 1000 J/KG EXTENDING NNWWD ACROSS THE SLIGHT RISK AREA BY LATE
AFTERNOON/EARLY EVENING.

THUNDERSTORMS SHOULD DEVELOP IN THE VICINITY OF THE SURFACE LOW OVER
NERN WY TO SWRN ND BY LATE AFTERNOON AS LARGE SCALE ASCENT SPREADS
ACROSS REGION AHEAD OF UPPER TROUGH.  SEVERE THREAT WILL LIKELY BE
ISOLATED WITH INITIAL ACTIVITY...SINCE INSTABILITY SHOULD BE WEAKER
DUE TO LESS BOUNDARY LAYER MOISTURE WITHIN A DEEPLY MIXED
ENVIRONMENT.  A GREATER SEVERE THREAT IS EXPECTED AS THE COLD FRONT
MOVES EWD INTO THE INSTABILITY AXIS ACROSS WRN PORTIONS OF SD/NEB
THIS EVENING/OVERNIGHT.  STRONG DEEP LAYER SHEAR WILL SUPPORT STORM
ORGANIZATION WITH HAIL AND STRONG WIND GUSTS THE PRIMARY
THREATS...WITH ACTIVITY POTENTIALLY BECOMING MORE ELEVATED WITH EWD
EXTENT.

..PETERS/GRAMS.. 04/17/2006