Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 261005
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
405 AM CST FRI DEC 26 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM CST FRI DEC 26 2014

SATELLITE AND THE RUC INDICATE A CLOSED H500 MB LOW MOVING ACROSS
THE FOUR CORNERS. A DEFORMATION BAND OF SNOW EXTENDED FROM NRN
COLO INTO WY WHICH WAS SHOWING SIGNS OF WEAKENING. A NEW
DEFORMATION BAND WAS DEVELOPING ACROSS NRN NM AND THIS DISTURBANCE
IS FCST BY THE MODELS TO LIFT THROUGH THE FCST AREA TODAY AND
TONIGHT AFFECTING AREAS ALONG AND EAST OF A LINE FROM KIML-KOGA-
KTIF-KONL. THE MODEL CONSENSUS SUGGESTS THE BEST SNOWFALL...4 TO 6
INCHES...WOULD LIFT FROM HAYES CENTER TO NORTH PLATTE AND THEN
NORTHEAST THROUGH BURWELL AND ONEILL. ROCK AND HOLT COUNTY HAVE
BEEN ADDED TO THE WINTER WEATHER ADVISORY IN EFFECT UNTIL 06Z
TONIGHT.

THE MODEL QPF IS MOST TIGHTLY CLUSTERED OVER NORTH PLATTE AND MODEL
QPF SPREAD INCREASES EAST AND WEST OF THAT POINT. WE ARE EXPECTING
AROUND 0.25 TO 0.33 INCHES OF QPF FROM THIS DISTURBANCE. THE GFS WAS
THE FIRST MODEL TWO DAYS AGO TO INDICATE A SEMI CLOSED H700MB LOW
LIFTING NORTHEAST THROUGH THE FCST AREA. THE OTHER MODELS CARRIED
THIS DISTURBANCE EAST MOSTLY THROUGH KS AND SCNTL/ERN NEB. NOW ALL
THE MODELS ARE IN AGREEMENT LIFTING THIS LOW THROUGH THE FCST AREA.
THERE IS SOME WOBBLING GOING ON WHICH IS NORMAL. THE RAP IS A BIT
EAST OF THE MODEL CONSENSUS. BUT GIVEN THE PERFORMANCE OF THE MODELS
YESTERDAY FAVORING THE CNTL PANHANDLE VS THE RAP WITH THE CHEYENNE
DIVIDE...THE MODEL CONSENSUS WINS THE FCST. GIVEN THE MODEL
CONSENSUS AND A 15 TO 1 RATIO...4 TO 6 INCHES OF SNOW APPEARS
LIKELY. THE 06Z NAM CONTINUES TO INDICATE THESE AMOUNTS FROM
KIML-KLBF-KBUB-KONL BUT SHOWS 6 TO 8 INCHES FROM KBBW-KBUB-KONL.
THIS IS A TREND IN THE MODELS FOR SLOWER DEVELOPMENT AND THE NAM
ACTUALLY HAS A CLOSED H700MB LOW OVER KGRI AT 03Z THIS EVENING WHILE
THE MODEL CONSENSUS WAS SHOWS THIS LOW AS AN OPEN WAVE. IF THIS
TREND CONTINUES AND A CLOSED H700MB LOW WERE TO TRAVERSE THE FCST
AREA...THE CHANCE OF HEAVY SNOW WOULD INCREASE.

FOR NOW THE FCST IS FOR 3 TO 6 INCHES OF SNOW IN THE ADVISORY AREA.
THIS IS AN INCREASE OF 2 INCHES OVER THE PREVIOUS FORECAST.

PATCHY FREEZING DRIZZLE CONTINUES THIS MORNING ASSOCIATED WITH
TRAPPED MOISTURE BELOW A 700MB DRY INTRUSION. THIS DRIZZLE IS
EXPECTED TO CLEAR THE FCST AREA 12Z-15Z THIS MORNING AND A CHECK OF
THE NEDOR WEBSITE INDICATES ROADS IN CUSTER COUNTY ARE COMPLETELY
COVERED WITH ICE...UNTREATED AND NO TRAVEL IS ADVISED SO THE
ADVISORY WILL BEGIN EARLIER IN THIS AREA. WITH QUICKLY CHANGING
AND DETERIORATING CONDITIONS...WILL ADD ADDITIONAL COUNTIES TO THE
ADVISORY TO THE NORTHEAST AND ISSUE A FREEZING RAIN ADVISORY FOR
FAR NORTH CENTRAL NEBRASKA THROUGH THIS MORNING.

THE MODELS INDICATE DRY AIR WILL WORK EAST TO HIGHWAY 83 AFTER
MIDNIGHT ALLOWING FOR A FEW TO SEVERAL HOURS OF MODEST RADIATIONAL
COOLING. LOWS TONIGHT ALONG AND WEST OF HIGHWAY 83 SHOULD FALL TO
NEAR OR BELOW ZERO IN MANY AREAS.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 358 AM CST FRI DEC 26 2014

PRIMARY FORECAST CONCERNS FOR THIS PERIOD DEALS WITH TEMPERATURES
AS A COLDER AIRMASS STAYS IN PLACE ACROSS THE REGION...THEN WITH
AN INTRUDING ARCTIC COLD FRONT EARLY NEXT WEEK WHICH BRINGS AN
AIRMASS INTO THE AREA THAT IS COLDER YET ALONG WITH CHANCES FOR
SNOW.

MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE EVOLUTION OF THE UPPER
LEVEL PATTERN THROUGH THE NEXT WEEK WHICH LEADS TO SLIGHTLY ABOVE
AVERAGE CONFIDENCE IN THE FORECAST. THAT BEING SAID...THERE ARE
DIFFERENCES IN DETAILS OF INDIVIDUAL SHORTWAVE TROUGHS MOVING ACROSS
THE AREA WHICH DOES PROVIDE SOME UNCERTAINTY FOR PORTIONS OF THE
FORECAST.

BY SATURDAY MORNING THE SHORTWAVE TROUGH THAT WILL PUSH UP THROUGH
KANSAS AND EASTERN NEBRASKA WILL BE ON ITS WAY EAST OF THE REGION
WHILE A WEAK SHORTWAVE COMING OUT OF THE NORTHERN STREAM WILL PASS
ACROSS THE FORECAST AREA THROUGH THE DAY SATURDAY. BEHIND THIS
SHORTWAVE SUBSIDENCE WILL BE INCREASING WHICH SHOULD LEAD TO
CLEARING SKIES THROUGH THE DAY. HIGH PRESSURE AT THE SURFACE WILL
DRIFT TO THE SOUTHEAST THROUGH THE DAY AND SATURDAY NIGHT. SO
LOOKING FOR DECREASING WINDS...BUT AS IT WILL BE CENTERED SOUTH AND
EAST OF THE LOCAL AREA THE PRESSURE GRADIENT MAY KEEP WINDS FROM
GOING CALM. EVEN WITH LIGHT WINDS...THE CLEAR SKIES WILL PROMOTE
RADIATIONAL COOLING SATURDAY NIGHT SO COULD GET FAIRLY
COLD...ESPECIALLY IN AREAS WHERE THERE IS FRESH SNOW COVER. MODIFIED
THE PRIOR FORECAST ONLY SLIGHTLY AS IT SEEMED TO HAVE A DECENT
HANDLE ON THE COLDER TEMPERATURES.

WEAK RIDGING BRINGS TEMPERATURES UP SLIGHTLY FOR SUNDAY...BUT WITH
THE AIRMASS REMAINING COLD WITH 850MB TEMPERATURES AT -1C TO -6C
TEMPERATURES WILL LIKELY STAY NEAR OR BELOW FREEZING. THE ONGOING
FORECAST WILL KEEP HIGHS IN THE MID TO UPPER 20S. LOOKING FOR THE
ARCTIC FRONT MENTIONED EARLIER TO START PUSHING INTO NORTHERN
NEBRASKA BY 12Z MONDAY MORNING. THIS IS WHERE SOME DIFFERENCES LIE
THOUGH...MAINLY WITH THE TIMING OF THE SHORTWAVES THROUGH THE AREA.
THE GFS IS A BIT QUICKER TO MOVE THINGS THROUGH AND TOOK A SLOWER
APPROACH WHICH IS SHOWN BY BOTH THE ECMWF AND GEM. THE SYSTEM IN
QUESTION IS CURRENTLY OVER THE NORTHERN PACIFIC...MOVING TOWARDS THE
GULF OF ALASKA. THE MODELS DO AGREE THAT THIS SYSTEM WILL MOVE INTO
THE PACIFIC NORTHWEST SATURDAY NIGHT THE WILL DIG DOWN THE PACIFIC
COAST AND BECOME CLOSED OFF TUESDAY NIGHT INTO WEDNESDAY. AS THIS
OCCURS AN ADDITIONAL SHORTWAVE TROUGH THAT IS CURRENTLY PART OF THE
ORIGINAL SYSTEM WILL GET CAUGHT UP IN THE NORTHERN STREAM AND WILL
MOVE DOWN THROUGH THE NORTHERN AND CENTRAL PLAINS TUESDAY. THE
INITIAL COLD FRONT WILL MOVE ACROSS THE FORECAST AREA MONDAY
MORNING...WHICH DROPS 850MB TEMPERATURES DOWN TO NEAR -15C BY 18Z
MONDAY. THE PRESSURE GRADIENT WILL TIGHTEN BEHIND THE FRONT SO
ANTICIPATING WINDS TO INCREASE FOR MONDAY. THERE WILL ALSO BE A
CHANCE FOR SNOW BEHIND THE FRONT...HOWEVER WITH A GENERAL LACK OF
MOISTURE NOT EXPECTING QPF AMOUNTS TO BE SIGNIFICANT. THE BEST LIFT
IS SEEN ACROSS THE NORTHERN PART OF THE FORECAST AREA SUNDAY
NIGHT...THEN WEAKENS ACROSS THE CENTRAL AND EASTERN PART OF THE
AREA. SO WILL KEEP THE TREND FOR HIGHER PRECIPITATION CHANCES OVER
THE NORTHERN ZONES FOR EARLY MONDAY MORNING THEN TRANSITION TO THE
WESTERN HALF ON MONDAY...THEN TO THE SOUTHERN PART OF THE FORECAST
AREA FOR MONDAY NIGHT. AGAIN...QPF AMOUNTS DON/T LOOK TO BE TOO MUCH
SO AT MOST EXPECT A COUPLE INCHES OF SNOW.

THE BIG PUSH OF COLDER AIR WILL COME WITH THE TUESDAY SHORTWAVE
TROUGH MOVES IN. MODELS AREN/T QUITE AS COLD AS PRIOR RUNS WERE BUT
STILL DROP 850MB TEMPERATURES DOWN TO -20C OR COLDER FOR TUESDAY.
LOOKING AT ENSEMBLE GUIDANCE...ITS COMING INTO BETTER AGREEMENT FROM
YESTERDAYS RUN...AS THE 26.00 RUN FROM THE GFS ENSEMBLE NOW IS ONLY
GIVING A SPREAD OF 10 DEGREES FOR HIGHS RATHER THAN 30 AS WAS SEEN
YESTERDAY. IT DOES STILL LOOK LIKE TUESDAY AND TUESDAY NIGHT WILL BE
THE COLDEST PERIODS OF THE WEEK...HOWEVER THERE IS CONSIDERABLE
DIFFERENCES IN GOING THROUGH THE WEEK IN HOW MUCH AND WHERE THE COLD
AIR WILL BE SO ALTHOUGH HAVE HIGH CONFIDENCE THAT TEMPERATURES WILL
BE COLD...AND BELOW NORMAL...HOW MUCH BELOW NORMAL WILL REMAIN IN
QUESTION AT THIS TIME AND HAVE JUST KEPT THE TEMPERATURE TREND GOING
DOWNWARD IN THE FORECAST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1133 PM CST THU DEC 25 2014

ONE UPPER LEVEL DISTURBANCE WILL LIFT NORTH OF THE FORECAST AREA
OVERNIGHT...AND A SECOND WILL APPROACH SOUTHWESTERN AND CENTRAL
NEBRASKA FRIDAY MORNING INTO FRIDAY EVENING. FOR THE KLBF
TERMINAL...SOME PATCHY FREEZING DRIZZLE AND FOG IS POSSIBLE
THROUGH 10Z. CIGS WILL BE AROUND 1200 FT AGL...HOWEVER...THEY MAY
DROP AS LOW AS 800 FT AGL WITH ANY DRIZZLE OR FOG. LIGHT SNOW IS
POSSIBLE AFTER 14Z FRIDAY...AND WILL PERSIST OFF AND ON THROUGH
FRIDAY EVENING. VISBYS WILL GENERALLY BE AROUND 3SM WITH
SNOW...HOWEVER SOME MODERATE INTENSITY SNOW IS POSSIBLE LATE
MORNING FRIDAY WITH VISBYS DOWN TO 1SM AND CIGS AS LOW AS 900 FT
AGL. A SECONDARY SHOT OF LIGHT TO MODERATE INTENSITY SNOW IS
POSSIBLE FRIDAY EVENING WITH VISBYS AS LOW AS 1.5SM WITH CIGS AS
LOW AS 1000 FT AGL. FOR THE KVTN TERMINAL...LIGHT SNOW IS POSSIBLE
OVERNIGHT WITH VISBYS DOWN TO 3SM AND CIGS AS LOW AS 1200 FT AGL.
ON FRIDAY...BROKEN TO OVERCAST CIGS OF 1500 TO 2000 FT AGL ARE
POSSIBLE BY FRIDAY AFTERNOON...LIGHT SNOW WILL BE POSSIBLE WITH
VISBYS AS LOW AS 2SM.


&&

.LBF WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 9 AM CST /8 AM MST/ THIS MORNING TO
MIDNIGHT CST /11 PM MST/ TONIGHT FOR NEZ025-026-036-037-057>059-
069>071.

WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR
NEZ027>029-038.

FREEZING RAIN ADVISORY UNTIL 9 AM CST THIS MORNING FOR NEZ006-
007.

WINTER WEATHER ADVISORY UNTIL NOON CST /11 AM MST/ TODAY FOR
NEZ004-005-022>024-035-056-094.

WINTER WEATHER ADVISORY UNTIL 9 AM CST THIS MORNING FOR NEZ009-
010.

WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT CST TONIGHT
FOR NEZ009-010.

&&

$$

SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...CLB








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