Heavy Snow in Nebraska, February 27, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
155 AM CST TUE FEB 27 2001

GENERAL PATTERN CONTINUES WITH SPLIT FLOW.  RIDGE OFF BC...LARGE LOW
OFF THE COAST OF CA...UPPER LEVEL TROF ALONG US-CAN BORDER...AND
BROAD RIDGE IN THE EAST. SCATTERED ENERGY OVER TX-AZ-OK-CO-KS AND
MO EJECTED FROM LOW OFF CA COAST IS RESPONSIBLE FOR CURRENT RADAR
ECHOES. KLNX IS DOWN...SO RELYING ON SPOTTERS...METARS AND IR
SATELLITE FOR ANY SNOWFALL IN THE CWA.  HIGHER AMPLITUDE SPLIT FLOW
PROGGED BY THURSDAY AS LARGE LOW DEVELOPS OVER SE CANADA...FORCING
WEAK RIDGE OVER CENTRAL CAN AS CLOSED LOW COMES ASHORE NEAR SAN
DIEGO.

SNOW STILL LOOKS LIKE A GOOD BET THIS MORNING FOR SOUTHERN TIER
COUNTIES WHERE SNOW ADVISORY IS IN PLACE. NOT SURE ANY OF PANHANDLE
WILL MEET ADVISORY CRITERIA AS BETTER FORCING SHIFTS SOUTH TO
BORDER OF KS.  SEE HEAVY SNOW DISCUSSION. WILL WAIT FOR LATEST ETA
RUN TO ASSESS SNOW ADVISORY. AS STRONG SFC HIGH SINKS SOUTHEAST INTO
NORTHEAST NEB BY 00Z WED...MUCH OF SOUTHERN PARTS OF CWA REMAIN IN
NORTH OR NORTHEAST FLOW...AND THEREFORE LIGHT SNOW STILL POSSIBLE
UNTIL THEN. AS HIGH PUSHES FURTHER SOUTHWEST...SNOW SHUTS OFF
COMPLETELY BY 06Z WED OVER CWA. SO WILL INCLUDE WORDING FOR SOUTHERN
ZONES OF LIGHT SNOW TAPERING TO FLURRIES TONIGHT. HIGH WILL BE
CLEARING OUR SKIES FROM NORTH TO SOUTH...MAKING FOR A VERY COLD START
WEDNESDAY. WILL HAVE TO DOWN TREND SOME TEMPS FROM PREVIOUS FORECAST
FOR TUESDAY NIGHT LOW DUE TO CLEARING/GOOD RADIATIONAL COOLING.

AS HIGH CONTINUES SOUTHWARD TOWARD TX...UPPER LEVEL FLOW DEVELOPS A
COL OVER MUCH OF WRN NEB WED. WEST WINDS AND DOWNSLOPE TO BEGIN WED
BY 12Z ACROSS AREA. MECHANICAL MIXING WILL BE WEAK...SO WARM UP NOT
AS GREAT AS IT COULD BE. EXPECT IT WILL BE FURTHER HINDERED IN SOUTH
3 COUNTIES IF THEY GET AS MUCH SNOW AS THEY ARE PROGGED TO TODAY.
GOING FORECAST OF 25 TO 30 IS ALREADY BELOW GUIDANCE FOR IML AREA...
AND THINK THIS WILL BE A GOOD RANGE FOR WEDNESDAY HIGH. WEDNESDAY
ETA ALSO LOOKS LESS CLOUDY THAN PREVIOUS FORECAST WOULD INDICATE.
AVN STILL QUITE MOIST.  WILL GO WITH SUNNIER ETA SINCE SURFACE
HIGH SHOULD PROVIDE ENOUGH SUBSIDENCE TO ERODE CLOUDS. LAPSE RATES
NOT VERY STEEP EXCEPT IN SOME SOUTH AND WEST ZONES. WILL CALL IT
PARTLY SUNNY FOR THOSE AREAS AS LOW LEVEL MOISTURE COULD BE ADEQUATE
TO PRODUCE CU WITH AFTERNOON HEATING. OK WITH GOING TEMPS.

EXTENDED...UPPER LEVEL FLOW FLATTENS OUT BY 00Z SAT AS UPPER
LEVEL CLOSED LOW OPENS AND EJECTS OVER TX PANHANDLE.
MEANWHILE..LARGE UPPER LEVEL LOW IN NORTHERN BC DEVELOPS TROUGH
ALONG PACIFIC NW AND INLAND.  RETURN FLOW SETS UP ALONG HIGH PLAINS
00Z SAT...WHICH WOULD SUGGEST BETTER CHANCES THAN MRF CURRENTLY
INDICATES FOR FRIDAY NIGHT. SFC LOW PROGGED TO REMAIN NEARLY
STATIONARY OVER SE COLORADO UNTIL 00Z SUN...CONTINUING TO PUMP IN
GULF MOISTURE. SFC HIGH SITTING NORTH OF GREAT LAKES REGION IS
THE CAUSE OF THE STALL OUT. AS PAC NW TROUGH CROSSES ROCKIES...ENTERS
AREA SUNDAY ENHANCING CHANCES. BY MONDAY IT APPEARS SYSTEM HAS
WASHED OUT UNDER INFLUENCE OF STRONG HIGH PRESSURE BOTH AT SFC AND
ALOFT AS UPPER LEVEL RIDGE SHIFTS TOWARD HIGH PLAINS. IF CURRENT
RIDGE VERIFIES...THEN TEMPS MONDAY COULD ALSO BE MILD.  MRF HAS
BEEN TRYING TO WARM US UP IN OUT PERIODS FOR SEVERAL RUNS...ONLY TO
BE A BUST...SO WILL DOWNPLAY ANY WARMUP FOR NOW. LATEST GUIDANCE
APPEARS TO CONCUR.

.LBF...ZONES 056-058-069>071 8SNOW ADVISORY TODAY. MAY END UP
       DROPPING ZONES 056-058 DEPENDING ON 06Z ETA RUN.

SLM