Severe Thunderstorm Warning 66, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
311 PM CDT MON JUN 9 2003

...FORECAST CHALLENGE WILL BE DRYLINE MOVING EAST AND IMPACT FROM
FRONTAL SYSTEM TONIGHT...

AREA OF LOW PRESSURE CENTERED SOUTH OF PHP WILL CONTINUE TO MOVE
EAST THIS EVENING WITH ASSOCIATED WARM FRONT EXTENDING SOUTHEAST
FROM SOUTH OF VTN...AND FET AT 19Z. DEWPOINTS IN THE LOWER 60S
NOSING NORTH TO THE BBW AREA WITH DRYLINE INTO FAR WESTERN NEB
EXTENDING SOUTHWEST ACROSS OGA. RADAR MOSAIC SHOWING RETURNS MAINLY
NORTHEAST AND SOUTHWEST OF FORECAST AREA AT THIS TIME.

USING BLEND OF WSETA AND MESOETA IN THE NEAR TERM--
THUNDERSTORMS TO DEVELOP RAPIDLY AFTER 21Z AS DRY LINE EDGES EAST
TO A VTN TO LBF LINE. WV IMAGERY SHOWING SEVERAL WEAK WAVES
MOVING EAST WITH BETTER MOISTURE AND DYNAMICS ACROSS THE CENTRAL
AS LOW 60S DEWPOINTS SPREAD NORTHEAST TO VTN TO ANW LINE. BY 00Z AN
APEX ACROSS THE NORTH CENTRAL WILL BE THE FOCUS FOR THUNDERSTORMS
SOME POSSIBLY SEVERE WITH THE MEAN WIND CARRYING STORMS EAST BY OUT
OF THE NORTH CENTRAL BY 03Z THEN ISOLATED OR SCATTERED STORMS IN THE
SOUTHWEST UNTIL MIDNIGHT. AFTER MIDNIGHT SYSTEM WILL BE TO THE
EAST WITH SUBSIDENCE TAKING OVER FOR PARTLY CLOUDY SKIES OVERNIGHT.

TUESDAY HIGH PRESSURE WILL DOMINATE THE PATTERN UNTIL EVENING.
THEN AS SURFACE RIDGE AXIS BUILDS EAST DURING THE EVENING EAST WINDS
INCREASING UPSLOPE FLOW WITH STEEP LAPSE RATES AND SUFFICIENT
MOISTURE FOR SLIGHT CHANCE FOR THUNDERSTORMS AS UPPER LEVEL
DISTURBANCES MOVE EAST DURING THE EVENING AND H85 SOUTH JET TO 35
KNOTS KICKS IN.

WEDNESDAY MODEL DIFFER IN TIMING WAVES TO THE EAST WITH A SCHC
TRW INCLUDED AS FRONTAL BOUNDARY MOVES SLOWLY EAST WITH BEST FORCING
SEEN FOR OVERNIGHT CONVECTION ACROSS THE SOUTHWEST. THURSDAY HIGH
PRESSURE WILL RIDGE SOUTHWEST WITH MODELS VARYING POSITION AND
TIMING OF DISTURBANCES MOVING EAST WITH POPS RETAINED.

MODELS HAVING DIFFICULT TIME RESOLVING EMBEDDED WAVES IN THE
SOUTHERN STREAM IN THE EXTENDED PERIOD. 06Z GFS MORE SOUTH THAN
00Z AND ECMWF RUNS WITH TREND TO PUSH POTENTIAL CONVECTION SOUTH
ACROSS THE PLAINS. WILL LEAVE FRIDAY AND SATURDAY POPS AS IS AS WEAK
WIND REGIME NOT PROVIDING SUFFICIENT CONFIDENCE TO REMOVE AT THIS
TIME. CLOUDS AND POTENTIAL PRECIP WILL HOLD TEMPERATURES DOWN FRIDAY
BUT WILL BLEND AS NEEDED. SATURDAY THE H5 RIDGE AXIS WILL SHARPEN
WITH H5 TROF AXIS EXTENDING NORTHWEST INTO SOUTHWEST NEBRASKA SUNDAY
FOR CLOUDS BUT NO MENTION OF WX SUNDAY AS THUNDERSTORMS THAT DO FORM
SHOULD BE MOVING SLOW AND TO A SOUTHEAST DIRECTION OUT OF CWA. MONDAY
REX FORMATION FORMS EAST AND H25 JETSTREAM WILL BE WELL NORTH AND
WEST. MONDAY ISOLATED CONVECTION THAT FORMS ON THE HIGH PLAINS WILL
BE SLOW MOVING AND POTENTIAL IMPACT THE EXTREME WEST AND PANHANDLE
BUT WILL LEAVE OUT FOR NOW.

.LBF...NONE.

KECK

NEZ004>010-022>029-035>038-056>059-069>071-094-101030-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORTH PLATTE NE
305 PM CDT MON JUN 9 2003

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

.DAY ONE...TONIGHT.

MOISTURE HAS RETURNED TO THE OUTLOOK AREA ON SOUTHERLY WINDS
ROTATING AROUND A LOW PRESSURE SYSTEM IN WEST CENTRAL NEBRASKA. THIS
ADDED MOISTURE AND PLENTY OF SUNSHINE HAS ALLOWED THE ATMOSPHERE TO
BECOME VERY UNSTABLE. AS THE LOW PRESSURE IN WESTERN NEBRASKA
CONTINUES TO LIFT TO THE NORTHEAST...IT WILL DRAG A SURFACE TROUGH
AND COLD FRONT ACROSS WESTERN NEBRASKA WHILE...LIFTING A BOUNDARY
ACROSS NORTH CENTRAL NEBRASKA. ADDED LIFT FROM AN UPPER LEVEL
DISTURBANCE WITH INTERACT WITH THESE BOUNDARIES AND THUNDERSTORM
DEVELOPMENT WILL BE POSSIBLE...WITH A FEW OF THESE STORMS POSSIBLY
REACHING SEVERE LIMITS. THE GREATEST RISK FOR SEVERE WEATHER WILL BE
EAST OF A MERRIMAN TO NORTH PLATTE LINE THROUGH THIS EVENING. THE
MAIN THREATS WITH ANY STORM THAT REACHES SEVERE LEVELS WILL BE LARGE
HAIL. HOWEVER...ISOLATED TORNADOES WILL BE POSSIBLE MAINLY OVER
NORTHEAST PORTIONS OF THE OUTLOOK AREA...EAST OF HIGHWAY 183 AND
NORTH OF HIGHWAY 91.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

ON TUESDAY...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTH
AND WEST OF A LINE FROM VALENTINE TO OGALLALA. THUNDERSTORMS WILL
FIRE IN THE AFTERNOON ACROSS THE FRONT RANGE OF THE ROCKIES WHERE
THE HIGHER INSTABILITY WILL EXIST. AS THESE STORMS MOVE EASTWARD
INTO WESTERN PORTIONS OF THE OUTLOOK AREA DURING THE LATE AFTERNOON
AND EARLY EVENING HOURS...THEY MAY BE STRONG ENOUGH TO PRODUCE LARGE
HAIL.

FOR THE REST OF THE FORECAST...THUNDERSTORMS ARE POSSIBLE IN WESTERN
AND NORTH CENTRAL NEBRASKA EACH DAY WEDNESDAY THROUGH SATURDAY. AT
THIS TIME...A FEW STORMS THAT DEVELOP ON WEDNESDAY MAY REACH SEVERE
LEVELS...MAINLY WEST OF HIGHWAY 83.

.SPOTTER INFORMATION STATEMENT...

STORM SPOTTER ACTIVATION WILL PROBABLY BE NECESSARY IN NORTHEAST
PORTIONS OF THE OUTLOOK AREA THIS EVENING. SPOTTERS SHOULD ONCE
AGAIN BE READY FOR ACTIVATION TUESDAY AND WEDNESDAY.

DP