Severe Thunderstorm Warning 74, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
223 PM CDT MON JUN 18 2001

...FORECAST CHALLENGE TO BE POPS TONIGHT...

THE COLD FRONT WAS PROGRESSING SOUTHEAST AT 1 PM CDT THROUGH THE
NORTHWEST...TO NEAR AN ONL TO OGA LINE WITH A SURFACE PREFRONTAL
TROUGH EXTENDING ACROSS THE SOUTHWEST. MOISTURE REMAINS LIMITED WITH
12Z LBF SOUNDING DRY. SOME CLOUDS INCREASING BEHIND COLD FRONT INTO
THE NORTHWEST WITH VISIBLE SATELLITE IMAGERY SHOWING CUMULUS FIELD
FORMING IN THE NORTHEAST. RADAR MOSAIC QUIET WITH NO RETURNS OVER
FORECAST AREA.

MODELS IN GOOD AGREEMENT WITH FRONT TO PROGRESS SOUTHEAST WITH ETA
APPEARING A COUPLE HOURS FAST COMPARED TO FRONTS CURRENT POSITION.
WILL USE BLEND OF ETA AND AVN WITH DEGREE OF MOISTENING MAIN
CONSIDERATIONS FOR THUNDERSTORMS THIS EVENING.

BY 6 PM CDT THE COLD FRONT IS PROGGED TO BE SOUTHEAST OF THE
FORECAST AREA WITH COOLER AIR TO FILTER IN ON THE NORTH WINDS.
BEST FORCING WILL BE TO THE NORTH AND SOUTHEAST WITH AN ISOLATED
THUNDERSTORM POSSIBLE IN THE EXTREME SOUTHWEST OTHERWISE LOOKING
RATHER DRY TONIGHT AS HIGH PRESSURE RIDGES SOUTHEAST. COLD AIR
STRATOCUMULUS FORMING OVER WESTERN SOUTH DAKOTA WILL WILL SPREAD
INTO THE NORTHWEST BUT WITH THE LOSS OF HEATING THIS EVENING CLOUDS
SHOULD DISSIPATE WITH CLOUD SHIELD TO ASSOCIATED WITH H7 WAVE
TO CLIP THE NORTHEAST OTHERWISE PARTLY CLOUDY ACROSS THE WEST WITH
CLOUD DEBRIS FROM CONVECTION WHICH MAY FIRE OVER NORTHEAST COLORADO
TO SPREAD DOWNSTREAM WITH MOSTLY CLOUDY FOR THE EXTREME SOUTHWEST.
THREAT FOR PRECIP ENDS AFTER MIDNIGHT CDT IN THE EXTREME SOUTHWEST
WITH TEMPERATURES TO DROP TO NEAR AVN MOS GUIDANCES.

TUESDAY LOW LEVEL CONVERGENCE INCREASES TO THE SOUTH AS FRONT
PUSHES SOUTH AND WASHES OUT WITH A WEAK REFLECTION OF BOUNDARY
ACROSS KANSAS. FORCING GREATEST ACROSS SOUTHEAST NEBRASKA INTO
NORTHEAST KANSAS. UPSLOPE FLOW MOST PRONOUNCED TO THE SOUTH WITH
SOUTHERN TIER ZONES BROKE OUT FOR BLENDING WITH REMAINDER OF FORECAST
AREA UNDER INCREASING SUBSIDENCE AS SURFACE HIGH BUILDS SOUTHEAST.
USED BLEND OF GUIDANCES AS CLOUD COVERAGE WILL DETERMINE DEGREE OF
WARMING WITH EAST UPSLOPE FLOW TO KEEP READINGS ON THE COOL SIDE.

TUESDAY NIGHT INTO WEDNESDAY THE UPSLOPE FLOW BECOMES MORE
PRONOUNCED WITH SURFACE HIGH TO REBUILD BACK TO THE NORTHWEST. H85
SOUTHERLY WINDS WILL SPREAD LOW LEVEL MOISTURE BACK TO THE
NORTHWEST WITH CLOUDY SKIES AND A CHANCE OF LIGHT RAIN IN THE
PANHANDLE AND EXTREME SOUTH. CONDENSATION PRESSURE DEFICITS LOWER
WITH LOWS CLOUDS TO SPREAD NORTHWEST...MAINLY SOUTH OF VTN TO
BARTLETT LINE. TEMPERATURES TO BE HELD DOWN BY EXTENSIVE CLOUD
COVERAGE GOING INTO WEDNESDAY WITH GUIDANCE CLOSE AND FOLLOWED.

WEDNESDAY NIGHT THE BEST CHANCE FOR STORMS AGAIN IN THE WEST AS H7
WAVE DROPS SOUTHEAST. UPSLOPE FLOW REMAINS INTACT WITH MOISTURE
PRESENT AS DIVERGENCE ALOFT INCREASES. WILL INTRODUCE CHANCE OF
THUNDERSTORMS MAINLY ACROSS THE SOUTH. LOWS DROPPING INTO THE MID
40S.

A DRY EXTENDED LOOKS ON TAP AS THE H5 TROUGH SWINGS SOUTHEAST
THROUGH THE OHIO VALLEY THURSDAY WITH THE UPPER RIDGE TO STRENGTHEN
WEST AND BUILD EAST ACROSS THE PLAINS THROUGH SATURDAY. THEN AS H5
LOW FORMS AND CUTS OFF OVER NORTHERN GEORGIA AND ALABAMA SUBSIDENCE
INCREASES OVER THE PLAINS AS THE H5 CLOSED SYSTEM MOVES WEST.
MOISTURE RETURN FROM THE GULF APPEARS LIMITED WITH FOCUS TO THE EAST
SUNDAY NIGHT INTO MONDAY BUT NOT SeUFFICIENT TO INCLUDE MENTION OF
RAINFALL. TEMPERATURES WILL TREND UPWARDS INTO THE LOW TO MID 90S
THROUGH SATURDAY THEN POSSIBLY A COOLDOWN INTO THE 80S SUNDAY AND
MONDAY AFTER A FRONT MOVES EAST ON SATURDAY.

.LBF...NONE.

KECK

NEZ004>010-022>029-035>038-056>059-069>071-182045-

SEVERE WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1112 AM CDT MON JUN 18 2001

...STORM SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON AND
TONIGHT ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...

THERE IS A CHANCE FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND INTO
THE EVENING HOURS OVER PORTIONS OF WESTERN AND NORTH CENTRAL
NEBRASKA. THE GREATEST THREAT FOR SEVERE WEATHER THIS AFTERNOON AND
EVENING WILL BE EAST OF A HAYES CENTER TO NORTH PLATTE TO
AINSWORTH LINE. THUNDERSTORMS WHICH DO DEVELOP WEST OF THIS LINE
SHOULD REMAIN BELOW SEVERE LIMITS THROUGH THIS EVENING. LARGE HAIL
AND DAMAGING WINDS WILL BE THE GREATEST THREAT.

A COLD FRONT WILL SLIDE SOUTH OVER WESTERN AND NORTH CENTRAL
NEBRASKA THIS AFTERNOON. ALONG AND EAST OF THE FRONT...STRONG
SOUTHERLY WINDS WILL CONTINUE TO PUMP GULF MOISTURE NORTHWARD. WITH
A LIFTING MECHANISM IN PLACE...THUNDERSTORMS ARE POSSIBLE ALONG THE
FRONT.

BY LATE TONIGHT...AN UPPER LEVEL DISTURBANCE WILL MOVE INTO
SOUTHWESTERN PORTIONS OF THE OUTLOOK INCREASING THE
CHANCE FOR THUNDERSTORM DEVELOPMENT. THE THREAT OF SEVERE WEATHER
WILL BE SOUTH OF AN OGALLALA...TO NORTH PLATTE...TO BROKEN BOW LINE.
THE MAIN THREAT FROM THESE THUNDERSTORMS WILL BE FROM LARGE HAIL.

CLB