Severe Thunderstorm Warning 20, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
215 PM CDT FRI MAY 8 1998

...TRYING TO RESOLVE TIMING AND EXTENT OF PCPN ASSOCIATED WITH MINORS
ROTATING ARND UPR LVL SYSTEM CONTINUE TO THE THE MAIN FORCAST PROBLEM...

12Z UPR AIR ANAL PLACED SYSTEM OVER NORTHWEST SD AND WAS STACKED NEARLY
VERTICAL FROM H7 UP THROUGH H3.  SATL STILL INDICATES VERY LITTLE MVMT
WITH PERHAPS A SLIGHT WESTWARD DRIFT MORE IN LINE WITH NGM PROG.  DIRTY
SFC HIGH STILL RIDGING DOWN INTO STATE.  TSTMS FIRING ON BOUNDARY IN
NORTHEAST CO AND WILL HAVE TO BE WATCHED AS THEY MOVE TOWARD CWA.  LNX
WSR-88D WITH EXTENSIVE SHWRS AND A FEW TSTMS OVER MUCH OF FORECAST AREA
AND A NICE FIT TO QG FORCING IN THE 850/700 LAYER ON NGM GRIDDED DATA.

MODELS AGAIN SIMILAR IN THE EARLY PERIODS WITH THE BROAD FEATURES BUT
SIGNIFICANT DIFFERENCES ARE IN THE DETAILS AND PREFER NGM AT LEAST THRU
THE EARLY PERIODS IN THE WAY IT HANDLES QG/VVEL FORCING FIELDS. ETA
DYNAMICS ARE QUICKLY PUSHED WEST AND SOUTH OUT OF FORECAST AREA AND
CONSIDERING CURRENT TRENDS AND WITH SLOW MOVEMENT OF NORTHERN SYSTM THIS
APPEARS UNLIKELY.  NGM KEEPS DECENT QG FORCING OVER AT LEAST WESTERN
HALF OF FORECAST AREA THROUGH ABOUT 30 HRS WHICH MAY BE A BIT OVERDONE.
NGM ALSO WITH LAYER VVELS AND INSENTROPIC LIFT OVER THE SAME AREA FOR
THE SAME TIME SO IF NGM IS CORRECT DECENT POPS JUSTIFIED THROUGH SAT
OVER AT LEAST WESTERN PART OF CWA.

IN THE LONGER TERM MODELS TAKE NORTHERN SYSTEM FAR ENOUGH WEST AND
NORTH THAT IT SHOULD NO LONGER BE A CONCERN.  THE UPR LVL SYSTEM IN THE
SOUTHERN STREAM WILL BRUSH SRN NE BUT NOT BE A BIG PLAYER. THE SRN
PLAINS SURFACE LOW BY 12Z INTENSIFIES OVR WESTERN OK WITH EASTERLY FLOW
ACROSS ALL OF STATE...ETA APPEARS TOO FAST WITH THIS FEATURE...AND THEN
MOVES EAST WITH TIME. LAYER MEAN RH BEGINS TO DECREASE THIRD AND FORTH
PERIODS AND WOULD EXPECT SOME BREAK IN CLOUDS SAT NGT AND SOME SUNSHINE
SUNDAY.

FAN/FWC NUMBERS CLOSE AND NO REASON TO ARGUE MUCH ALTHO MAY UNDERCUT
SLIGHTLY.

WORK ZONES WILL FOLLOW SHORTLY FOR YOUR CONSIDERATION.

PRELIMINARY GUIDANCE FOR COORDINATION ONLY.  OFFICIAL FORECASTS ARE
CONTAINED WITHIN PRODUCT OMAZFPNE...

CCF NUMBERS:

LBF WE 042/059 040/070 044 21+532
OGA WE 043/060 042/072 045 21+532
IML WE 044/062 041/072 045 215532
VTN WE 041/059 040/071 043 215432
ANW WE 040/060 040/071 044 21+32-
ONL EB 039/064 038/072 044 2133--
BBW WE 043/062 040/072 044 21+431

BOWMAN

NEZ004>010-022>029-035>038-056>059-069>071-091200-

SEVERE WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1035 AM CDT (935 AM MDT) FRI MAY 8 1998

THIS OUTLOOK PERTAINS TO THE FOLLOWING NEBRASKA COUNTIES...

ARTHUR     BLAINE     BOYD       BROWN      CHASE      CHERRY
CUSTER     DEUEL      FRONTIER   GARDEN     GARFIELD   GRANT
HAYES      HOLT       HOOKER     KEITH      KEYA PAHA  LINCOLN
LOGAN      LOUP       MCPHERSON  PERKINS    ROCK       SHERIDAN
THOMAS     WHEELER

...STORM SPOTTER ACTIVATION IS NOT EXPECTED TODAY OR TONIGHT...

A NEARLY STATIONARY WEATHER DISTURBANCE ALOFT LOCATED OVER WESTERN
SOUTH DAKOTA WILL CONTINUE TO BRING SCATTERED SHOWERS AND AN ISOLATED
THUNDERSTORM TO A LARGE PART OF WESTERN NEBRASKA TODAY AND TONIGHT WITH
THE SHOWERS REACHING INTO NORTH CENTRAL NEBRASKA BY LATE TODAY AND
TONIGHT.  THERE WILL CONTINUE TO BE A CHANCE OF SHOWERS AND POSSIBLY A
THUNDERSTORM INTO SATURDAY ACROSS THE OUTLOOK AREA.

A COOL AND RELATIVELY STABLE AIRMASS ASSOCIATED WITH A WEAK RIDGE OF
HIGH PRESSURE AT THE SURFACE...AND LACK OF SIGNIFICANT SUNSHINE DURING
THE DAY...WILL MINIMIZE THE THREAT OF STRONG THUNDERSTORM ACTIVITY OVER
THE OUTLOOK AREA.  THEREFORE...NO SEVERE WEATHER IS EXPECTED THROUGH AT
LEAST SATURDAY MORNING.

WERT