Severe Thunderstorm Warning 158, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
245 AM CDT WED JUN 24 1998

FORECAST CHALLENGE TO BE TEMPERATURES AND POPS TODAY...

VISFOG IMAGERY LOOP THROUGH 0615Z INDICATES AREA OF STRATUS EXPANDING
INTO THE PLATTE VALLEY AND SPREADING WEST. IR IMAGERY SHOWING FEW
CLOUDS ALOFT SO STRATUS DECK SHOULD BE BRIEF INTO THE EARLY MORNING
HOURS AND QUICKLY BURNING OFF. WV LOOP INDICATES NEXT UPPER DISTURBANCE
MOVING ACROSS UTAH AND WITH AVN MODEL BETTER DEPICTING IN 00Z MODEL
OUTPUT. KLNX 88D NOT SHOWING ANY RETURN OVER THE WRN AND NCNTRL NEB
ATTM.

TODAY MODELS ARE SHOWING DIFFERENCES IN TIMING AND POSITION WITH SERIES
OF 5H WAVES TO EJECT NE THROUGH THE PERIOD. PREFER COMBINATION OF
ETA/AVN SOLUTION THROUGH THE PERIOD. FOR TODAY WAA INCREASES AT MID
LEVELS WITH 7H TEMPERATURES SUFFICIENTLY WARM TO CAP ANY TSTM
DEVELOPMENT TILL LATE AFTN. BEST CHC FOR ISOLD TSTM APPEAR OVER THE
PANHANDLE WHERE DRYLINE WILL BE THE FOCUS AND HIGHEST POPS IN NCNTRL
SECTIONS AS SFC LOW MOVE EAST. DWPT MACRO SHOWED DRIER AIR TO MOVE INTO
THE WEST THIS AFTN WITH DWPTS AT OR ABOVE THE MID 50S OVR PORTIONS OF
NCNTRL. MEAN RH REMAINS LOW WITH ANY CONVECTION WHICH DEVELOPS OVERALL
MOISTURE LIMITED WEST. CAPES INCREASE TO ABOVE 1500 J/KG OVER THE
NCNTRL AFTER 18Z WITH SFC LOW CIRCULATION TO ADVECT HIGHER THETA-E
MOISTURE TO THE NW. THETA-E RIDGE AXIS EXTENDS WEST ACROSS SRN SOUTH
DAKOTA BY EVENING WITH TSTMS DEVELOPING MOVING EAST NORTHEAST. VVELS BY
EVENING SHOWED A MAXIMUM LIFT OVER NCNTRL SECTIONS WITH 94O ON TARGET.
WILL GO CLOSE TO AVN GUIDANCES FOR TEMPERATURES.

TONIGHT SUBSIDENCE INCREASES WEST WITH MAIN LIFT AND CONVERGENCE TO
SHIFTING EAST OF FA. DUE TO QUESTIONABLE FRONTAL LOCATION...MORE A DWPT
FRONT WILL LEAVE LOW POPS IN NCNTRL. MODELS SHOWING DIFFERENCE IN
LONGWAVE TROUGH OVER THE WEST COAST BY THIS TIME AND ETA MODEL
PERFERRED. WEAKER WAVES TO MOVE THROUGH AND LOW MEAN RH TO CONTINUE.
OVERNIGHT LOWS NEAR 60.

THURSDAY HOT AND DRY CONDITIONS EXPECTED AS 7H TEMPS WARM WITH 16 DEG C
ISOTHERM EXTENDING NORTH INTO SWRN NEB. DRYLINE REMAINS IN THE WEST
WITH BEST CHC OF TSTMS TO FORM BY LATE AFTN ACROSS NRN FA.
THURSDAY WEAK WAVE TO MOVE EAST DURING THE MORNING FOR FEW CLOUDS THEN
SUNNY CONDITIONS. IF AVN MODEL VARIFIES BEST WILL BE VERY HOT DAY AS
WESTERLY FLOW ALOFT INCREASING WARMING ALOFT.

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

CCF
LBF UU 089/059 092/066 095 -10
IML UU 090/060 095/065 097 -10
VTN UU 090/056 095/065 097 22-
ONL UU 090/062 091/065 092 23-

TLW

NEZ004>010-022>029-035>038-056>059-069>071-251200-

SEVERE WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1133 AM CDT (1033 AM MDT) WED JUN 24 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 MAY BE NEEDED IN PARTS OF NORTH CENTRAL
NEBRASKA LATE THIS AFTERNOON AND TONIGHT...

THERE IS A SLIGHT CHANCE OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON
AND TONIGHT IN PARTS OF NORTH CENTRAL NEBRASKA. THE GREATEST RISK FOR
THUNDERSTORMS WILL BE EAST OF A VALENTINE...DUNNING AND BROKEN BOW LINE.
ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL ALSO BE POSSIBLE
FURTHER WEST BUT STORMS WHICH DEVELOP ARE EXPECTED TO REMAIN BELOW
SEVERE LIMITS.

A SURFACE LOW WILL MOVE NORTHEAST INTO CENTRAL NEBRASKA TODAY WITH THE
ASSOCIATED WARM FRONT LIFTING NORTH. AREAS NORTH AND EAST OF THE LOW
CENTER WILL BECOME INCREASINGLY UNSTABLE DURING THE AFTERNOON AS SURFACE
HEATING INCREASES. THUNDERSTORMS SHOULD DEVELOP IN THE VICINITY OF THE
WARM FRONT LATE THIS AFTERNOON. A DISTURBANCE ALOFT WILL ALSO BE MOVING
ACROSS THE AREA AND SHOULD FURTHER INTENSIFY THE THUNDERSTORMS SO THAT A
FEW STORMS COULD REACH SEVERE LEVELS. ALTHOUGH SOME LARGE HAIL WILL BE
POSSIBLE...THE MAIN THREAT APPEARS TO BE DAMAGING WINDS SINCE AVAILABLE
MOISTURE IS LIMITED.

FS