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000
FXUS63 KLBF 080238 AAB
AFDLBF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
838 PM CST SAT DEC 7 2013

.SYNOPSIS...
ISSUED AT 311 PM CST SAT DEC 7 2013

AN ACTIVE...HIGHLY MERIDIONAL...H5 PATTERN CONTINUES ACROSS THE
CONUS THIS MORNING WITH A CLOSED LOW LOCATED OVER NRN OREGON. A
SECOND STRONG SHORTWAVE TROUGH WAS LOCATED OVER WRN
ONTARIO...WITH A THIRD SYSTEM LOCATED OVER EASTERN PORTIONS OF
THE NW TERRITORIES OF CANADA. THE CLOSED LOW OVER NRN
OREGON...HAS MIGRATED SOUTHEAST AND WAS LOCATED ACROSS SERN
OREGON AS OF 18Z PER WV IMAGERY. AT THE SURFACE...HIGH PRESSURE
WAS LOCATED OVER FAR NERN NEBRASKA. SRLY WINDS HAVE INCREASED
ACROSS WESTERN NEBRASKA THIS AFTERNOON ON THE BACK SIDE OF THE
HIGH AND WERE BLOWING AS HIGH AS 27 MPH AT IMPERIAL. TEMPERATURES
AS OF 2 PM CST RANGED FROM 9 ABOVE AT IMPERIAL AND OGALLALA...TO
ZERO AT VALENTINE. RADAR RETURNS FROM NERN COLORADO ARE
INDICATING SOME LIGHT SNOW...WHICH HAS BEGUN TO MOVE INTO SWRN
NEBRASKA AS OF 2 PM CST. VISBYS AS OF 2 PM CST HAD DROPPED DOWN
TO 1 1/4 MILES AT NORTH PLATTE.

&&

.UPDATE...
ISSUED AT 838 PM CST SAT DEC 7 2013

TEMPS HAVE BEEN FALLING OFF VERY SLOWLY MOST AREAS EXCEPT ACROSS
THE NORTHWEST WHERE BETTER...ALTHOUGH MARGINAL...RADIATIONAL
COOLING IS OPERATING. THE LOW CLOUDS ARE BLANKETING THE LOSS OF
HEATING FROM THE GROUND.

ALSO RERAN THE SNOW FCST USING THE GEM...SREF AND NAM WHICH WERE
WETTER THAN THE GFS AND ECM. THE CARR METHOD SUGGESTED 20 TO 1
SNOW WATER RATIOS WHICH PRODUCES SLIGHTLY HIGHER SNOW TOTALS THAN
THE PREVIOUS FCST. THIS PUT UP TO 4 INCH IN HOLT COUNTY BY SUNDAY
AFTERNOON AND 2 INCHES IN THE PLATTE VALLEYS.

CONDITIONS ARE QUITE FAVORABLE FOR SNOW GROWTH WITH VERTICAL
MOTION THE LIMITING FACTOR. THE UPSLOPE FLOW WITH THE SOUTHEAST
WINDS IS A WILD CARD THOUGH AS THE MODELS OFTEN MISS THIS FEATURE.
JUST A FEW HUNDRED FEET OF LIFT ON THE SAND HILLS IN THIS TYPE OF
ENVIRONMENT CAN MAKE THE DIFFERENCE BETWEEN 2 INCHES AND 4 INCHES.
FOR EXAMPLE...THE ROADS IN TRYON PER NEDOR CAMS ARE NEARLY COVERED WHILE
HWY 83 AND I-80 IN NORTH PLATTE ARE MOSTLY CLEAR.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 311 PM CST SAT DEC 7 2013

COMPLEX WEATHER SYSTEM TO IMPACT THE AREA TONIGHT AND TOMORROW.
INITIAL BAND OF LIGHT SNOW LIFTING NE EARLY THIS EVENING.
VISIBILITIES HAVE BEEN DROPPING CLOSE TO A MILE...HOWEVER
ACCUMULATION WILL BE LESS THAN HALF AN INCH. ADDITIONAL CHANCES
FOR LIGHT SNOW CONTINUE THIS EVENING AHEAD OF THE MAIN SHORT
WAVE. THE MAIN WAVE ARRIVES LATER TONIGHT...WITH WATER VAPOR
SHOWING A DECENT PLUM OF MOISTURE ASSOCIATED WITH THIS. DEPTH OF
THE DENDRITIC GROWTH ZONE IS GOOD...HOWEVER OMEGA /LIFT/ IS
LIMITED. MODELS SHOW FRONTOGENESIS BAND STRONGEST LATE TONIGHT
INTO THE MORNING HOURS. TOP DOWN SATURATION SHOULD ADD IN THE
PRODUCTION OF LIGHT TO BRIEFLY MODERATE SNOW. MODELS IN GENERAL
PRODUCING A TENTH TO 0.15 OF AN INCH OF QPF. SNOW RATIO AROUND 18
TO 1 WOULD RESULT IN A SWATCH OF 2 TO 3 INCHES. LOWEST AMOUNTS OF
AROUND 1 INCH ACROSS THE NW PART OF NEB.

MEANWHILE COLD TEMPS AGAIN TO BE AN ISSUE. HEAVY SNOW PACK AREAS
HAVE ONLY WARMED TO AROUND ZERO...AND WILL NOT MAKE IT OUT OF THE
SINGLE DIGITS. CLOUDS WILL LIMIT COOLING TONIGHT...COMPARED TO
THE LAST COUPLE OF NIGHTS WHERE 15 TO 25 BELOW ZERO WAS
COMMON...HOWEVER THE SNOW PACK AND COLD START SHOULD ALLOW FOR
TEMPS TO FALL TO THE SINGLE DIGITS BELOW ZERO. ELSEWHERE WITH OUT
THE SNOW PACK...LOWS IN THE SINGLE DIGITS ABOVE ZERO. WINDS
OVERNIGHT GENERALLY 5 TO 15 MPH...WHICH WILL CREATE ONLY SOME
MINOR BLOWING SNOW...HOWEVER WINDS CHILLS IN THE 10 TO 25 BELOW
ZERO RANGE. DECIDED TO HOLD OFF ON ISSUING ANOTHER ADIVISORY
ACROSS THE NW ZONES...DUE TO UNCERTAINTY STILL WITH THE SNOW.
WANTING TO SEE THE 00Z RUN TO SEE IF THE SNOW BAND MAY SHIFT OR
AMOUNTS INCREASE /WHICH CAN NOT BE RULED OUT/ IN WHICH ONE COULD
JUSTIFY A WINTER WX ADVISORY FOR MARGINAL WIND CHILLS AND SNOW.

TOMORROW AFTERNOON SNOW WILL BE ENDING WEST TO EAST WITH COLD
HIGH PRESSURE FILLING IN BEHIND THE SYSTEM. HIGHS STRUGGLE TO
AROUND 10 TO THE MID TEENS.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 311 PM CST SAT DEC 7 2013

MID RANGE...SUNDAY NIGHT THROUGH TUESDAY...THE MAIN FORECASTING
CHALLENGE IN THE MID RANGE IS TEMPERATURES. FOR SUNDAY
NIGHT...ARCTIC HIGH PRESSURE WILL BUILD INTO THE BLACK HILLS AND
THE NEBRASKA PANHANDLE BY 12Z MONDAY. LIGHT WESTERLY WINDS AND
MOSTLY CLEAR SKIES ARE EXPECTED BEHIND SUNDAYS EXITING SHORTWAVE
TROUGH. WITH FRESH SNOW COVER EXPECTED FROM WHAT ACCUMULATES
TONIGHT AND SUNDAY...TEMPERATURES WILL TANK SUNDAY NIGHT. LOWS IN
THE INHERITED FCST WERE LOWERED SIGNIFICANTLY...AND ARE NOW MORE
TOWARD THE MUCH COLDER MAV GUIDANCE. FOR NORTH PLATTE THE NEW
FORECAST LOW OF -9 MAY NEED TO BE MODIFIED EVEN FURTHER DOWNWARD
IF THE SURFACE HIGH IS FASTER AND FURTHER EAST. FOR NOW...FEEL
THIS IS A GOOD PLACE TO START AND HAS GOOD FORECAST CONTINUITY
WITH THE NEIGHBORING OFFICES. ON MONDAY...HIGH PRESSURE WILL MOVE
INTO CENTRAL AND EASTERN KANSAS...LEADING TO WESTERLY WINDS
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. HIGHS MONDAY WILL
CONTINUE TO BE COLD...WITH READINGS IN THE TEENS EXPECTED AS WE
RECYCLE ARCTIC AIR ON THE NORTHERN PERIPHERY OF THE HIGH. ON
MONDAY NIGHT INTO TUESDAY...A CLIPPER WILL TRACK ACROSS NORTH
DAKOTA INTO NRN MINNESOTA. GUSTY WINDS MAY BE AN
ISSUE...PARTICULARLY ACROSS NORTHERN AND EASTERN NEBRASKA MONDAY
NIGHT INTO TUESDAY AND BLOWING SNOW MAY NEED TO BE ADDRESSED IN
LATER FORECASTS. TEMPERATURES ON MONDAY NIGHT AND TUESDAY WILL BE
MILDER AS WE WILL STAY MIXED MONDAY NIGHT AND TUESDAY. BASED ON
H85 TEMPS AND DECENT MIXING...HIGHS SHOULD BE IN THE 20S ON
TUESDAY.

TUESDAY NIGHT THROUGH SATURDAY...AFTER WEDNESDAY...THE MID RANGE
MODEL SOLUTIONS TREND FROM THE HIGHLY MERIDIONAL FLOW...TOWARD A
MORE ZONAL PATTERN THROUGH THE END OF THE WEEK. THE LATEST EURO
SOLN EVEN BUILDS A LARGE RIDGE ACROSS THE WESTERN CONUS TOWARD
THE END OF NEXT WEEKEND AND EARLY THE FOLLOWING WEEK. FOR
THURSDAY...FRIDAY AND SATURDAY...TEMPERATURES WILL TREND MORE
TOWARD SEASONAL NORMS WITH HIGHS IN THE 30S AND LOWS IN THE
SINGLE DIGITS TO TEENS. DRY CONDITIONS ARE EXPECTED FOR THE
REMAINDER OF THE EXTENDED FORECAST AS THE STORM TRACK WILL BE
WELL NORTH OF THE AREA.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 534 PM CST SAT DEC 7 2013

AREAS OF IFR ARE EXPECTED THIS EVENING AS BANDS OF LIGHT TO
BRIEFLY MODERATE SNOW LIFT NORTHEAST THROUGH THE FCST
AREA...MAINLY ALONG AND EAST OF HIGHWAY 83.

THIS SNOW WAS ASSOCIATED WITH THE WESTERN U.S. STORM SYSTEM WHICH
WILL LIFT THROUGH WRN AND NCNTL NEB SUNDAY. IFR COULD BECOME
WIDESPREAD SUNDAY AS THE MEAT OF THE STORM CROSSES THE FCST AREA.
THIS IFR IS EXPECTED TO AFFECT AREAS ALONG AND EAST OF HIGHWAY 83
FOR THE MOST PART BUT SWRN NEB FROM ROUGHLY KIML-KOGA AND EAST
COULD ALSO BE AFFECTED.

A WIND SHIFT FROM THE NORTHWEST WILL DEVELOP AS THE STORM MOVES
EAST OF THE FCST AREA. THIS WOULD LIKELY MARK THE BEGINNING OF VFR
WHICH WOULD SPREAD FROM WEST TO EAST DURING THE MID TO LATE
AFTERNOON.


&&

.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...CDC
SYNOPSIS...CLB
SHORT TERM...MASEK
LONG TERM...CLB
AVIATION...CDC