Severe Thunderstorm Warning 139, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
235 PM CDT SUN AUG 4 2002

...FCST CHALLENGE CONCERNS THREAT OF TSTMS TNGT THRU MON EVNG FLWD
BY EXTENT OF HTG FOR RMNDR OF FCST PD...

1800 ANALYSIS PLACED QSTNRY SFC LOW PRES NR KMCK WITH QSTNRY SFC FNT
EXTDG NEWD JUST S OF LBF CWA. TRAILING SFC TROF EXTD SWWD FM SFC LOW
TO BTWN KGLD AND KHLC. TEMPS OVR SRN HLF OF NEB NOW IN LWR 90S AND
APPROACHING CONVECT TEMPS. LTST SATL SHW DVLPG LN OF TCU ALNG TROF
AXIS...WITH ACCAS DVLPG NR AND N OF SFC LOW AND QSTNRY FNT. WDLY
SCT-SCT ELEVATED CONVECTION CONTD OVR NCNTRL NEB IN VCNTY OF EXITING
SHRT WV TROF.

PLACEMENT OF SFC LOW AND QSTNRY FNT TO PLAY CRITICAL ROLE IN WX OVR
LBF CWA TNGT INTO MON EVNG. CONFLUENCE OF LOW LVL AIR AND POOLING OF
SFC DEW PNTS ALNG AND N OF FNTL BOUNDARY COMBINING WITH DAYTIME SFC
HTG SHD SUPPORT DVLPMNT OF SCT TSTMS LTE THIS AFTN AND ON MON.

DYNAMIC SUPPORT SHD COME FM PLACEMENT OF UPR RDG TO SE OF LBF
CWA...ALLOWING CONTD STREAM OF WK SHRT WV TROFS TO ROTATE ARND
PERIPHERY OF UPR HIGH AND THRU WRN AND NRN HI PLNS. H7 TEMPS OVR LBF
CWA RMN JUST COOL ENF TO ALLOW WK CAP TO BE BKN EACH AFTN...WITH
ELEVATED CONVECTION TO CONT DURG OVRNGT HRS AS LLJ PROVIDES ADTNL
LIFT FOR ELEVATED TSTMS N OF SFC FNT.

AS UPR RDG SLOWLY BACKS WWD INTO CNTRL HI PLNS AND BACK INTO LBF
CWA...TEMPS FM H7-H5 GRDLY RISE. SFC WNDS ALSO VEER INTO A MORE SLY
DIRECTION AS SFC FNT LIFTS N OF AREA AS WRMFNT...THEREBY ENDING
UPSLOPE FLOW AND ALLOWING DRIER LOW LVL AIR FM OFF WRN HI PLNS TO
ADVECT NEWD. COMBO OF THE ABV WL END THE THREAT OF PCPN AND SET THE
STAGE FOR ANOTHER ROUND OF HOT AND DRY WX FOR ALL OF LBF CWA BY LTR
MON NGT...CONTG INTO AT LEAST FRI...WHEN ANOTHER PSBL WEAKENING OF
UPR RDG OCCURS...OPENING THE DOOR TO WDLY SCT PCPN PROVIDED THAT UPR
TEMPS COOL AND SFC FNT IS ABLE TO PUSH SEWD INTO CNTRL PLNS.

ETA RMNS THE PREFERRED MODEL OF CHOICE FOR THIS FCST PD DUE TO ITS
BTR LOW LVL RESOLUTION AND AVNS TENDENCY TO GENERATE COPIOUS AMNTS
OF QPF IN AREA WHERE NO PCPN HAS FALLEN AND WHERE RECORD DROUGHT
CONTS.

LONGER RANGE MRF HIGHLY QUESTIONABLE FOR FRI-SUN PCPN THREAT
CONSIDERING ITS SEEMINGLY PREMATURE ERROSION OF UPR RDG OVR CNTRL
PLNS AS UPR LOW APPROACHES FM NW. ECMF APPEARS TO BE MORE REALISTIC
IN  MAINTAINING STRENGTH OF BROAD UPR RDG OVR CNTRL PLNS...SPCLY
SINCE NO STG ERN PACIFIC RDG EXISTS WHICH WUD SUPPORT A SEWD PUSH OF
OF COOLER AIR ALFT INTO THE NRN PLAINS. WL THEREFORE MAINTAIN A
PERSISTENCE FCST FOR EXTENDED PDS OF THE FCST TIL THE ABV SCENERIO
BCMS MORE DEFINED.

.LBF...NONE.

WERT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORTH PLATTE, NE
814 PM CDT SUN AUG 4 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0810 PM    2 E COMSTOCK              NE   1.75 INCH HAIL
08/04/02   CUSTER

IZZI