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000
FXUS63 KLBF 020534 AAB
AFDLBF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1134 PM CST SUN DEC 1 2013

.SYNOPSIS...
ISSUED AT 252 PM CST SUN DEC 1 2013

DEEP UPPER LEVEL LOW ALONG THE COAST OF BRITISH COLUMBIA WILL
MOVE SOUTH THROUGH WASHINGTON STATE MONDAY AND EJECT A LEAD SHORT
WAVE DISTURBANCE THROUGH THE NRN PLAINS TUESDAY.

UPSTREAM...A VERY STRONG UPPER LEVEL BLOCKING RIDGE ACROSS ALASKA
HAS GENERATED A 1049 MB ARCTIC HIGH WHICH WILL BUILD TO AROUND 1052
MB AS IT MOVES SOUTH TONIGHT AND THEN WEAKEN AS IT SPREADS OUT
ACROSS THE NRN AND CNTL PLAINS NEXT WEEK.

THIS ARCTIC HIGH WILL PRODUCE SUBZERO HIGHS ACROSS NORTH DAKOTA FOR
SEVERAL DAYS WITH HIGHS IN THE SINGLE DIGITS...TEENS AND LOWER 20S
ACROSS WRN AND NCNTL NEBRASKA WEDNESDAY THROUGH SUNDAY.

THE MAIN PROBLEM WITH THIS FORECAST IS THE TEMPERATURE FORECAST BOTH
AHEAD AND BEHIND THE ARCTIC FRONT. TODAYS MODEL RUNS SHOW THE STORM
MOVING THROUGH THE NRN PLAINS TUESDAY IS DEEPER AND THIS WILL SEND
THE ARCTIC FRONT THROUGH THE FCST AREA SOONER.

THE SNOW CHANCES ARE IN PLACE TUESDAY AND WEDNESDAY ACROSS
NORTHERN NEBRASKA AT 30 TO 40 PERCENT. THE ARCTIC SURGE SHOWN BY
THE MODELS IS FASTER AND DRIER BUT SOME MODELS SHOW A DISTURBANCE
MOVING ACROSS THE FCST AREA TUESDAY PRODUCING SIGNIFICANT SNOWFALL
ACROSS NRN NEB.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 252 PM CST SUN DEC 1 2013

AS SURFACE LOW PRESSURE DEEPENS OVERNIGHT ACROSS SOUTHEAST
MONTANA...WEST WINDS WILL CONTINUE THROUGH THE NIGHT ACROSS WESTERN
AND NORTH CENTRAL NEBRASKA.  THESE WINDS WILL HELP KEEP TEMPERATURES
MILD...WITH LOWS RANGING FROM THE MID 20S TO LOWER 30S.

SURFACE LOW PRESSURE MIGRATES TO FAR SOUTHWEST SOUTH
DAKOTA/NORTHWEST NEBRASKA MONDAY.  A FAVORABLE WEST TO SOUTHWEST
CHINOOK WIND EVENT IS EXPECTED TO THE SOUTH OF THIS LOW PRESSURE
CENTER ACROSS MUCH OF WESTERN AND NORTH CENTRAL NEBRASKA.  A VERY
MILD/WARM DAY IS ANTICIPATED...WITH HIGHS REACHING THE MID 50S TO
MID 60S.  THERE IS POTENTIAL FOR TEMPERATURES TO BE EVEN
WARMER...PERHAPS UPPER 60S IN A FEW LOCALS...BUT PERSISTENT MID AND
HIGH LEVEL CLOUDS WILL LIKELY HINDER WARMING A FEW DEGREES.  IF
CLOUD COVER ENDS UP BEING LESS...THEN THOSE WARMER HIGHS COULD BE
REALIZED.  FOR NOW...VERY DENSE CLOUD COVER IS NOTED ACROSS THE
PACIFIC NORTHWEST...WITH THE FLOW ALOFT TO CARRY THESE CLOUDS TOWARD
OUR AREA.  WILL SIDE WITH A BIT COOLER HIGHS AND MORE CLOUD COVER
FOR NOW.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 252 PM CST SUN DEC 1 2013

MONDAY NIGHT THROUGH WEDNESDAY...
A VERY STRONG THERMAL RIDGE WILL BE MOVING ACROSS THE FCST AREA
MONDAY NIGHT WITH A SOLID BANK OF MID LEVEL CLOUDS. THE H850 TEMPS
OF 10C TO 15C AND MID LEVEL CLOUDS SHOULD LIMIT LOWS TO THE UPPER
20S TO NEAR 30. NOTE THE NAM IS DEEPENING THE NORTH DAKOTA LEAD
SHORT WAVE AND DRIVING THE ARCTIC FRONT INTO THE FCST AREA BY
MIDNIGHT MONDAY WHICH WOULD PRODUCE EVENING LOWS FOLLOWED BY A SHARP
DROP OFF IN TEMPS.

THERE IS STILL A BROAD SPREAD IN THE TIMING AND INTENSITY OF THE
ARCTIC FRONT. THIS IS A DIRECT RESULT OF THE STRENGTH OF THE SHORT
WAVE MOVING THROUGH NORTH DAKOTA. IF THIS WAVE IS AS STRONG AS THE
NAM SHOWS THEN HIGHS TUESDAY MIGHT ONLY REACH THE 20S IN MANY AREAS.
THE SLOWEST MODEL WAS THE 12Z GFS WITH HIGHS TUESDAY RANGING FROM 29
AT RUSHVILLE TO 60 AT STOCKVILLE. THE NAM...GFS...SREF...GEM AND ECM
WHERE ALL BLENDED TOGETHER AT THE 18Z FORECAST POINT FOR HIGHS IN
THE LOWER 20S NORTHWEST TO LOWER 40S IN THE SOUTHEAST TUESDAY.

THE SURGE OF DRY ARCTIC AIR AND WEAK TO NO DYNAMICS HAS TAKEN IT
TOLL ON POPS USING THE NAM...SREF...GFS AND GEF MODELS. THE GEM AND
ECM HAVE PERKED UP THOUGH. THOSE MODELS FEATURE A WEAK LEAD SHORT
WAVE MOVING THROUGH NORTH DAKOTA BUT CARRY SIGNIFICANT ENERGY
THROUGH NEBRASKA AS A RESULT. THE FORECAST USES A 4 MODEL BLEND FOR
30 TO 40 POPS ACROSS NRN NEB TUESDAY.

H850 MB TEMPS WEDNESDAY HOVER AT -15C TO -20C FOR HIGHS MOSTLY IN
THE TEENS. WIND CHILL READINGS TUESDAY NIGHT FALL TO -10F ACROSS THE
NORTHWEST AND REMAIN BELOW ZERO WEDNESDAY. THE DEEP STORM ACROSS THE
NORTH DAKOTA AND THE UPPER MIDWEST TUESDAY AND WEDNESDAY WILL
PRODUCING STRONG NORTHWEST WINDS ACROSS THE FCST AREA...15 TO 25 MPH
WITH GUSTS TO AROUND 30 MPH.

WEDNESDAY NIGHT THROUGH SUNDAY...
H850 MB TEMPS NEARLY FLAT LINE AT -15C TO -20C. A SLIGHT UPWARD
TREND IS INDICATED IN TIME SERIES PLOTS AT KLBF AND KVTN. THE ARCTIC
HIGH BUILDS ACROSS THE SOON TO BE SNOW FIELD ACROSS THE NRN PLAINS
AND SPREADS OUT. THE AIR MASS WILL MODIFY SOMEWHAT DOWN HERE BUT THE
HIGH WILL REJUVENATE EACH NIGHT ACROSS THE NRN PLAINS.

THE ARCTIC HIGH WILL MOVE OFF SUNDAY SETTING UP SOUTH WINDS. THE
ECM AND GFS SHOW A WEAK DISTURBANCE LIFTING OUT THE WRN U.S. LONG
WAVE TROF FOR A SLIGHT CHANCE OF SNOW SATURDAY NIGHT THROUGH SUNDAY.
WHAT THIS REALLY REPRESENTS IS A LEAD WAVE PRECEDING AN ARCTIC HIGH
WITH ITS ORIGIN IN SIBERIA. LIGHT SNOW IS POSSIBLE AHEAD OF THIS
HIGH WHICH MOVES IN A WEEK FROM MONDAY.

OTHERWISE...HIGHS SHOULD BE MOSTLY IN THE TEENS. LOWS ARE
PROBLEMATIC. WINDS GO LIGHT FRIDAY AND SATURDAY MORNING SO MINS WERE
LOWERED A FEW DEGREES. THE REAL QUESTION IS SNOW COVER. 2 INCHES OF
SNOW COVER WOULD MAKE THE DIFFERENCE BETWEEN 2 BELOW AND 12 OR MORE
BELOW. THE SAME FOLLOWS FOR HIGHS. 2 INCHES OF SNOW RESULT IN A 10
DEGREE MARK DOWN IN TEMPS BOTH DAY AND NIGHT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1134 PM CST SUN DEC 1 2013

VISUAL FLIGHT RULES ARE EXPECTED THROUGH THE NEXT 24 HOURS. LIGHT
WEST WINDS TONIGHT WILL INCREASE THROUGH THE EARLY MORNING
HOURS INTO THE DAY ON MONDAY. SCATTERED TO BROKEN CLOUDS EXPECTED
OVER NIGHT AOA 8K FT.

&&

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

$$

SYNOPSIS...CDC
SHORT TERM...TAYLOR
LONG TERM...CDC
AVIATION...POWER