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

VALID 121300Z - 131200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM
30 SE JAX 30 W CTY ...CONT... GLS 40 NNE HOU 30 NNW POE 50 WSW MLU
ELD 35 NNE TXK PGO FYV TBN BLV SLO 35 SE BMG SDF 30 E BWG
30 NW CHA RMG ATL 35 SE AHN SOP 35 N RWI 40 WNW ECG 25 ENE ECG.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 ESE PSX 50 W HOU
45 E CLL 45 NW LFK TYR PRX MLC TUL CNU OJC IRK BRL CGX BEH AZO JXN
DTW ...CONT... 45 SSE JAX 20 SSW CTY.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM ERI HLG 50 ENE CRW
SSU 30 N LYH CHO DCA ACY.

--- SYNOPSIS ---
PATTERN TRANSITION CONTINUES ACROSS CONUS AS MIDWESTERN LONGWAVE
TROUGH AND W COAST RIDGE EACH BUILD.  MIDDLE-UPPER LEVEL CYCLONE
NOW EVIDENT IN FSD/SUX AREA IS FORECAST TO CONTINUE EJECTING NEWD
ACROSS MN...BECOMING AN OPEN WAVE.  MEANWHILE...UPSTREAM SHORTWAVE
TROUGH OVER SASK SHOULD DIG SEWD AND TAKE ITS PLACE -- MAINTAINING
GREAT LAKES/UPPER MS VALLEY TROUGH.  SEPARATE SHORTWAVE TROUGH NOW
FROM ND TO SERN WY SHOULD MOVE SEWD ACROSS MO/IL/AR TONIGHT.  THIS
WILL HELP TO TIGHTEN HEIGHT GRADIENT OVER SERN STATES AND MAINTAIN
FAVORABLE DEEP-LAYER SHEAR OVER A BROAD SECTION OF MS VALLEY AND
SERN CONUS.

SURFACE COLD FRONT -- NOW ANALYZED FROM IA CYCLONE SWWD ACROSS
CENTRAL OK AND NRN TX -- WILL MOVE EWD ACROSS MS VALLEY THIS
EVENING AND TONIGHT AS PRIMARY SURFACE CYCLONE EJECTS NEWD OVER WI.
ALTHOUGH SYNOPTIC WARM FRONT IS ANALYZED OVER NERN MO/SRN IL...MORE
RELEVANT FEATURE IS MARINE/WARM FRONT NOW EXTENDING FROM W LA
MESOLOW SEWD ACROSS NERN GULF.

--- LOWER SABINE REGION TO GA AND FL PANHANDLE ---
SEVERE THREAT DOES NOT APPEAR EXTREME OR DENSELY CONCENTRATED
YET...BUT DOES COVER A BROAD EXPANSE OF LOWER MS VALLEY/DELTA AND
GULF COAST STATES.  SEVERE RISK REMAINS CONDITIONAL ENOUGH THAT
CATEGORICAL RISK IS KEPT AS SLGT.  HOWEVER...INCREASING MOISTURE
UNDER STRENGTHENING FLOW ALOFT SUGGEST THAT MORE CONCENTRATED FOCI
WOULD WARRANT UPGRADE.

COMBINATION OF DIURNAL HEATING AND WAA WILL EFFECTIVELY SHIFT
MARINE FRONT INLAND ACROSS MUCH OF MS AND PORTIONS AL TODAY...
BENEATH SUSTAINED TO INCREASING DEEP-LAYER SHEAR.  MESOSCALE
BOUNDARIES AWAY FROM OR INTERSECTING MARINE FRONT COULD SERVE AS
CONVECTIVE INITIATORS AS WELL.  SEVERE WIND THREAT SHOULD PERSIST
WITH ONGOING MCS AS IT MOVES EWD ACROSS LA/MS REMAINDER
MORNING...AND ISOLATED SUPERCELLS AND BOWING LINE SEGMENTS MAY
DEVELOP IN WEAKLY CAPPED AIR MASS PRECEDING THE MCS.  SRH 300-500
OBSERVED AND FORECAST ACROSS THIS REGION -- ALONG WITH 45-60 KT 0-6
KM AGL SHEAR AND MIN SR FLOW EXCEEDING 15 KT FOR SOME REASONABLE
CELL MOTIONS -- ALL SUGGEST POTENTIAL FOR A FEW SUPERCELL
TORNADOES.  LARGE HAIL IS LIKELY AS WELL -- HIGHEST PROBABILITIES
BEING WITH ROTATING TSTMS AHEAD OF LINE.

--- AR TO LOWER OH VALLEY ---
SURFACE ANALYSIS SHOWS MID TO UPPER 50S SURFACE DEW POINTS  A SHORT
DISTANCE UPSTREAM IN NERN TX/NRN LA...AND 12Z RAOBS SHOWED STEEP
MID LEVEL LAPSE RATES REMAIN UPSTREAM AS WELL.  THESE FACTORS ALONG
WITH INCREASING MID LEVEL FLOW SUGGEST SEVERE RISK REMAINS FOR THIS
REGION -- DESPITE HINDRANCE OF IDEAL RETURN FLOW BY LARGE AREA OF
CONVECTION NOW IN SERN AR AND LA.  DIURNAL HEATING AND LIFT INVOF
FRONT SHOULD CONTRIBUTE TO THREAT FOR SEVERE TSTMS WITH LARGE HAIL
AND DAMAGING GUSTS OVER AR/SERN MO/WRN TN REGION THIS AFTERNOON
...POSSIBLY AS FAR N AS SRN IL/INDIANA AROUND 21Z-03Z TIME FRAME.

..EDWARDS.. 03/12/01