Severe Thunderstorm Warning 256, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
250 PM CDT FRI AUG 8 2003

...18Z SYNOPSIS...
     THE GOES DERIVED TOTAL PRECIPITABLE WATER (TPW) AND LIFTED
INDICES SHOW THE STRONGEST INSTABILITY AND DEEP MOISTURE ACROSS THE
NEBRASKA PANHANDLE WEST OF A MERRIMAN-OGALLALA LINE. THE VISIBLE GOES
IMAGERY AND THE RADAR MOSAIC BOTH SHOW CONVECTION DEVELOPING SOUTH
AND EAST OF BROKEN BOW. HAND ANALYSIS SHOWED A SURFACE DEWPOINT
BOUNDARY APPROXIMATELY FROM RAPID CITY THROUGH SCOTTSBLUFF TO LAMAR
WITH DEWPOINTS AOA 60F EAST OF THE BOUNDARY. THIS FEATURE PRETTY MUCH
COINCIDES WITH THE TIGHT TPW GRADIENT. ANOTHER BOUNDARY WAS
DETECTABLE OVER SOUTHWEST NEBRASKA IN THE INFRA-RED IMAGERY FROM
SIDNEY THROUGH OGALLALA TO ABOUT WELLFLEET.

...MODELS...
     THE ETA CONTINUES SHOWING DECENT CONTINUITY WITH THE PREVIOUS
RUN AND IS SIMILAR TO THIS MORNINGS GFS IN ITS TREATMENT OF THE
SOUTHWEST UPPER HIGH. SO, MY CONFIDENCE I HIGH IN THE ETA SOLUTION
FOR DAYS 1, 2, AND 3.

FORECAST FOR TONIGHT...
     SURFACE BASED CAPES OF 2000J/KG IN THE LAPS PLOT WERE IN THE
SOUTHWEST AND WESTERN PART OF THE NORTH PLATTE FORECAST AREA SOUTH
AND WEST OF A LINE FROM LISCO THROUGH ARTHUR TO IMPERIAL. I WOULD
EXPECT CONVECTIVE INITIATION IN THAT GENERAL AREA ALONG THE SECOND
ABOVE MENTIONED BOUNDARY. SO, FOR TONIGHT, I WILL GO WITH SCATTERED
THUNDERSTORMS IN THE SOUTHEAST PANHANDLE AND THE SOUTHWEST COUNTIES
FROM ARTHUR THROUGH CHASE TO HAYES. OTHER ADJUSTMENTS MAY BE
REQUIRED IF RADAR AND SATELLITE WARRANT.
     OTHERWISE, FOR THE REST OF THE FORECAST, I WILL USE A BLEND OF
THE ETA AND ETA MOS AIR-BRUSHED ALONG THE EDGES FOR CONSISTENCY.

EXTENDED...TUESDAY THROUGH FRIDAY
     GFS AND ECMWF ARE IN GOOD AGREEMENT AND HAVE SHOWN SOME
CONSISTENCY ON PLACEMENT OF UPPER RIDGE AND AND UPPER LOW
OFF THE NORTHWEST COAST.  I HAVE HIGH CONFIDENCE IN THEM AS
BOTH SHOW VERY LITTLE MOVEMENT WITH THE UPPER LOW WHICH I
AGREE WITH AS THE SYSTEM APPEARS TO BE STACKED ALONG WITH THE
PRESENCE OF BLOCKING PATTERN SET UP NEAR THE GULF OF ALASKA.
EXTENDED APPEARS DRY WITH RIDGE AXIS MOVING JUST EAST OF THE CWA.

.LBF...NONE.

SPRINGER/BANNAN

NEZ004>010-022>029-035>038-056>059-069>071-094-091030-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORTH PLATTE NE
359 PM CDT FRI AUG 8 2003

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

.DAY ONE...TONIGHT.

THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE ACROSS ALL OF THE OUTLOOK
AREA THROUGH THE EARLY MORNING HOURS. SEVERE WEATHER IS NOT
ANTICIPATED WITH THESE STORMS AS WARMER TEMPERATURES AND WEAK WINDS
ALOFT WILL LIMIT THE INSTABILITY OF THE ATMOSPHERE. HOWEVER SMALL
HAIL...AND BRIEF WIND GUSTS UP TO 40 MPH WILL BE POSSIBLE WITH THE
STRONGEST STORMS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE ATMOSPHERE WILL BECOME MODERATELY UNSTABLE BY LATE SATURDAY
AFTERNOON ACROSS THE ENTIRE OUTLOOK REGION. A STRONGER UPPER LEVEL
DISTURBANCE MOVING OUT WYOMING...COMBINED WITH STRONGER WINDS
ALOFT...AND A SURFACE LOW MOVING INTO SOUTHERN SOUTH DAKOTA...WILL
LEAD TO SCATTERED THUNDERSTORM DEVELOPMENT. THOUGH STRONG TO SEVERE
STORMS WILL BE POSSIBLE OVER THE ENTIRE OUTLOOK AREA...THE AREA OF
GREATEST CONCERN WILL BE NORTH OF AN OSHKOSH TO BROKEN BOW LINE.
LARGE HAIL WILL BE THE PRIMARY THREAT ALONG WITH WIND GUSTS UP TO
AND OVER 60 MPH.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED ACROSS THE OUTLOOK REGION SATURDAY
AFTERNOON AND EVENING...BUT IS NOT ANTICIPATED TONIGHT.

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