SPC Day 1 Thunderstorm Outlook Issued 20Z 20030621


ZCZC SPCSWODY1 ALL
ACUS01 KWNS 212009
SPC AC 212007

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

VALID 212000Z - 221200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM
10 NE INL 20 N SUX 10 SE P28 20 W LTS 50 S CDS 60 ESE LBB
30 SE LBB 15 S LBB 15 WNW LBB 40 WNW PVW 35 W AMA 40 ENE LAA
40 NNW GLD 15 NW SNY 40 SSE DGW 35 N CPR 60 E WRL 40 ENE SHR
15 E 4BQ 55 WSW DIK 55 NNE ISN.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 NE CRP 15 NNE AUS
50 WNW TPL 20 S BWD 50 SW BWD 20 WSW JCT 40 SSE DRT ...CONT...
65 WNW MRF 45 W INK 40 N HOB LAA 30 NE LIC 50 W AKO 25 N 4FC
45 NW GJT 35 NNW MLF 40 SW ELY 50 E U31 40 SSE BAM 20 ENE BAM
45 NNE EKO 45 SSE TWF 30 SE BYI 30 SW PIH 50 E SUN 55 SSW 27U
40 WSW S80 40 NE EPH 30 N 4OM ...CONT... 20 NNE ELO 35 N FOD
15 ESE EMP 20 S BVO MLC 25 ENE PRX 35 NNE SHV 30 ESE MLU
15 SSE MEI 45 S CSG 25 S SAV.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 N ART 30 NNW GFL
30 S RUT 10 SSW PVD ...CONT... 10 E ORF 20 WSW RIC 40 W SHD
40 W EKN 20 WNW HLG 20 WSW ERI.

...ND/MN/SD/NEB/KS/NW TX/W OK
CONVECTION IS DEVELOPING ALONG A COLD FRONT POSITIONED ACROSS NWRN
SD/WRN ND. AXIS OF MODERATELY UNSTABLE AIR EXISTS AHEAD OF THE
CONVECTION WITH SFC DEWPOINTS IN THE MID 60S AND MLCAPE AROUND 1500
J/KG. AS A SHORTWAVE TROUGH EVIDENT ON WV IMAGERY COMES OUT OF NRN
WY LATE THIS AFTERNOON...STORM COVERAGE WILL INCREASE AS IT SPREADS
NEWD ACROSS ERN WY/NWRN SD/SRN AND CNTRL ND. AS THE LOW-LEVEL JET
INTENSIFIES THIS EVENING...CONVECTION DEVELOPMENT SHOULD INCREASE
ACROSS WRN AND CNTRL NEB. A BROAD BAND OF MID-LEVEL SW FLOW IS
PRESENT ACROSS THE REGION WITH MAXIMUM SPEEDS AROUND 50 KT ORIENTED
PARALLEL TO THE SFC BOUNDARY. THIS COINCIDED WITH THE STRONGEST
DEEP LAYER SHEAR WHICH SHOULD BE SUFFICIENT FOR ISOLATED
SUPERCELLS. ORIENTATION OF THE CLOUD LAYER FLOW SUGGESTS DAMAGING
WIND GUSTS WILL BE POSSIBLE. LARGE HAIL WILL ALSO BE A THREAT WITH
LAPSE RATES AROUND 8.5 C/KM. ISOLATED TORNADOES WILL BE POSSIBLE
ESPECIALLY IF SUPERCELLS CAN GET ROOTED IN THE BETTER LOW-LEVEL
MOISTURE ACROSS SCNTRL ND/CNTRL SD/CNTRL NEB. LATER THIS
EVENING...AN MCS MAY DEVELOP AND MOVE ACROSS THE ERN DAKOTAS/WRN MN
WITH A THREAT FOR ISOLATED SEVERE STORMS LATE TONIGHT.
 
FARTHER S ACROSS KS/NW TX/OK...THE CAPPING INVERSION WAS NOT
PARTICULARLY STRONG HOWEVER...CONVECTIVE DEVELOPMENT IS MORE
CONDITIONAL DUE TO THE WEAK FORCING PRESENT. ABUNDANT LOW-LEVEL
MOISTURE EXISTS ALONG THE MOIST AXIS WITH LOWER TO MID 70F SFC
DEWPOINTS ACROSS CNTRL-NWRN OK. IF UPDRAFTS DEVELOP...CONVECTION
SHOULD REMAIN ISOLATED. DEEP LAYER SHEAR IN THE REGION WAS STRONG
DUE TO A LOW TO MID-LEVEL JET OVER NWRN OK AND DUE TO THE BACKED
BOUNDARY LAYER FLOW. SFCOA SHOWED 0-6 KM SHEAR AROUND 50 KT
SUGGESTING THE STORMS WILL BE SUPERCELLULAR. BACKED SFC WINDS AND
THE AMOUNT OF LOW-LEVEL SHEAR SUGGEST ISOLATED TORNADOES WILL BE
POSSIBLE IF STORMS CAN DEVELOP. ISOLATED LARGE HAIL/DAMAGING WINDS
WILL ALSO BE POSSIBLE WITH ANY SUPERCELL THAT DEVELOPS.  
 
..BROYLES.. 06/21/03

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