Hail in Nebraska, April 24, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
253 PM CDT THU APR 24 2008

...FORECAST CHALLENGE IS SEVERE POTENTIAL AND PRECIPITATION CHANCES
OVER THE NEXT 48 HOURS...

.SYNOPSIS...18Z SURFACE ANALYSIS HAS A QUASI STATIONARY FRONT
EXTENDING FROM KONL TO KIML. THIS FEATURE EXTENDS TO THE SW INTO
EASTERN COLORADO...THEN NORTH ALONG THE FRONT RANGE OF COLORADO AND
WYOMING. SURFACE LOW PRESSURE LOCATED NEAR KCYS AND IN SERN
COLORADO. ABUNDANT STRATUS HAS PERSISTED IN THE POST FRONTAL
ENVIRONMENT TDY OFF TO THE NORTH OF NORTH PLATTE RIVER VALLEY. THIS
STRATUS HAS HAD A HARD PUSHING FURTHER SOUTH THANKS TO SLIGHTLY
DRIER AIR AND CLEAR SKIES IN SWRN AREAS. WV IMAGERY AT MIDDAY INDICATING
A TANDEM OF UPPER LEVEL DISTURBANCES. THE FIRST IS EXITING ERN SD
ATTM WITH ANOTHER OFF TO THE SOUTH WEST...CURRENTLY CROSSING THE SRN
ROCKIES ATTM. THIS FEATURE IS EXPECTED TO FIRE OFF CONVECTION WITHIN
THE NEXT 2 TO 4 HOURS OVER SWRN NEBR AND NERN COLORADO. TEMPERATURES
AT 18Z RANGED FROM 72 AT KIML...TO 44 AT KVTN.

.DISCUSSION...

.SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)...MAIN FORECASTING
CHALLENGES IN THE NEXT 72 HOURS LIE WITH SEVERE POTENTIAL
TONIGHT...THEN PRECIPITATION CHANCES SATURDAY AND SATURDAY NIGHT.
FOR TONIGHT...BEFORE MENTIONED WAVE WILL ENTER ERN COLORADO IN THE
NEXT 2-4 HOURS...AND IS EXPECTED TO INITIATE CONVECTION OVER ERN
COLORADO...INTO THE SRN NEBRASKA PANHANDLE. SURFACE LOW PRESSURE
WILL STRENGTHEN OVER ERN COLORADO BETWEEN 21 TO 00Z THIS
AFTERNOON...WHICH WILL BACK SURFACE WINDS AND TEMPORALLY LIFT THE
STATIONARY FRONT NORTHWARD. CONVERGENCE ALONG THIS FEATURE AS WELL
AS DECENT BACKED WINDS WILL BE FAVORABLE FOR ISOLATED TORNADOES AND
VERY LARGE HAIL. THE MAIN THREAT AS IT STANDS...IS ALONG AND SOUTH
OF INTERSTATE 80. FURTHER NORTH...IN THE COLD SECTOR...LARGE HAIL IS
EXPECTED WITH A LIMITED TORNADO THREAT. AREA OF MAIN CONCERN HERE IS
SOUTH OF HIGHWAY 2 AND NORTH OF INTERSTATE 80. SCATTERED CONVECTION
WILL ORGANIZE INTO A MCS LATE THIS EVENING OFF TO THE SOUTHEAST.
BEST POTENTIAL FOR AN MCS LIES ACROSS SOUTH CENTRAL NEBR AND
NCENTRAL KS...WHERE FOCUS OF H85 SRLY LOW LEVEL JET IS LOCATED AND
DEEPEST MOISTURE LIES.

LATER TONIGHT...ADDITIONAL PRECIPITATION EXPECTED OVER NRN AREAS AS AN
UPPR LVL TROF OF LOW PRESSURE SLIDES ACROSS THE DAKOTAS AND NRN
NEBRASKA. BOTH THE GFS AND NAM ARE COLD ENOUGH FOR SNOW IN THE POST
FRONTAL ENVIRONMENT ACROSS THE NRN CWA...HOWEVER ACCUMULATIONS
SHOULD BE MINIMAL DUE TO WARM GROUND CONDS AND EXPECTED LOWS IN THE
LWR TO MID 30S. WILL CONTINUE TO WORD FCST AS RAIN/SNOW DUE TO TEMPS
IN THE 30S. ON SATURDAY NIGHT...ANOTHER EMBEDDED DISTURBANCE WILL MOVE
THROUGH THE REGION. STRONG MID LEVEL FRONTOGENESIS...COMPLIMENTED
WITH DECENT ISENTROPIC LIFT AT THE 295K LVL...WILL SPREAD ACROSS THE
NORTHERN CWA ON SATURDAY AND SATURDAY NIGHT. INCREASED POPS IN NRN
AREAS TO ACCOUNT FOR THE PARAMETERS LISTED ABOVE AND TO COME IN LINE
WITH SURROUNDING OFFICES. AFTER SATURDAY...A CLEARING TREND WILL
COMMENCE AS THE TROF EXITS TO THE EAST AND A RIDGE BEGINS TO SLOWLY
BUILD INTO THE CENTRAL CONUS.

.LONG TERM (MONDAY THROUGH THURSDAY)...FAIRLY BENIGN PATTERN NOTED
AFTER MONDAY WITH H5 RIDGING BUILDING INTO THE CENTRAL CONUS WITH
WARMER TEMPS NOTED. AFTER MIDWEEK...THE GFS AND ECMWF SOLNS DIVERGE
SOMEWHAT. BOTH MODELS AMPLIFY THE PATTERN AFTER MIDWEEK WITH A TROF
AND CLOSED SYSTEM DEVELOPING ACROSS THE CENTRAL ROCKIES BY DAY 5.
WHERE THE MODELS DIVERGE IS THE TRACK OF THE SYSTEMS DAYS 6 AND 7.
THE GFS SOLN LIFTS THE BULK OF THE ENERGY ACROSS THE DAKOTAS AND NRN
NEBRASKA...WHILE THE ECMWF IS FURTHER SOUTH AND PHASED WITH THE
HUDSON BAY LOW...WHICH IN ITSELF IS MUCH FARTHER SOUTH COMPARED TO
THE GFS. IN LIGHT OF THIS...AM FAVORING THE GFS SOLN FOR NOW WITH
HIGHS GENERALLY IN THE 60S FRO WEDNESDAY AND THURSDAY. HAVE
INTRODUCED POPS ON DAYS 6 AND 7 AS THE WRN TROF LIFTS ACROSS THE NRN
PLAINS...HOWEVER THEY ARE NOT AS HIGH AS HPC GUIDANCE SUGGESTS.

&&

.AVIATION...

TERMINALS LBF AND VTN WILL BE IMPACTED BY A RANGE OF CONDITIONS AS A
LOW PRESSURE CENTER FORMS OVER SOUTHEAST COLORADO AND TRACKS
NORTHEAST ALONG A SEMI STATIONARY FRONT THAT CURRENTLY EXTENDS
NORTHEAST THROUGH CENTRAL NEBRASKA. STRATUS AND FOG SPREAD INTO THE
NORTH REDUCING CEILING AND VISIBILITIES AT THE VTN TERMINAL TO LIFR
AND IFR CONDITIONS THAT WILL LIFT THIS EVENING TO VFR BRIEFLY THIS
EVENING BEFORE RETURNING TO MVFR BY 10Z OVERNIGHT. FURTHER SOUTH VFR
CONDITIONS WILL BE SEEN THROUGH 02Z THEN DETERIORATE AS A STRONG
UPPER LEVEL DISTURBANCE CROSSES THE SOUTHWEST THAT IS EXPECTED TO
INITIATE STRONG TO SEVERE THUNDERSTORMS THROUGH THE EVENING.
OVERNIGHT CLOUDS AND CEILINGS ARE EXPECTED TO THEN DROP TO MVFR OR
IFR CONDITIONS OVERNIGHT INTO FRIDAY MORNING.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...NONE

.AVIATION...KECK
.SHORT AND LONG TERM...BUTTLER

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
310 PM CDT THU APR 24 2008

NEZ004>010-022>029-035>038-056>059-069>071-094-252015-
SHERIDAN-EASTERN CHERRY-KEYA PAHA-BOYD-BROWN-ROCK-HOLT-GARDEN-
GRANT-HOOKER-THOMAS-BLAINE-LOUP-GARFIELD-WHEELER-ARTHUR-MCPHERSON-
LOGAN-CUSTER-DEUEL-KEITH-PERKINS-LINCOLN-CHASE-HAYES-FRONTIER-
WESTERN CHERRY-
310 PM CDT THU APR 24 2008 /210 PM MDT THU APR 24 2008/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WESTERN AND
NORTH CENTRAL NEBRASKA.

.DAY ONE...TONIGHT.

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER
PORTIONS OF CHASE...HAYES...LINCOLN...CUSTER...AND FRONTIER
COUNTIES THIS EVENING. FURTHER NORTHWEST THERE IS A SLIGHT RISK OF
SEVERE THUNDERSTORMS OVER THE REMAINDER OF WESTERN AND NORTH
CENTRAL NEBRASKA.

A NEARLY STATIONARY BOUNDARY FROM NEAR IMPERIAL TO BROKEN BOW
WILL BE THE FOCUS OF THUNDERSTORM DEVELOPMENT AS AN UPPER LEVEL
WAVE MOVES OUT OF THE NORTHERN ROCKIES. CONDITIONS ARE FAVORABLE
FOR THE DEVELOPMENT OF SUPERCELLS WITH LARGE HAIL AND ISOLATED
TORNADOES. ALTHOUGH MOST OF WESTERN AND NORTH CENTRAL NEBRASKA IS
OUTLOOKED FOR SEVERE POTENTIAL THE MAIN AREA OF CONCERN WILL BE
OVER SOUTHWEST NEBRASKA ALONG THE BOUNDARY FROM IMPERIAL TO BROKEN
BOW.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE NEEDED THROUGH TONIGHT.

&&

THIS PRODUCT IS NOW AVAILABLE...ALONG WITH OTHER WEATHER...
HYDROLOGICAL AND CLIMATOLOGICAL INFORMATION...AT
HTTP://WWW.WEATHER.GOV/NORTHPLATTE

WFO LBF