Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 252324 AAA
AFDLBF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
524 PM CST TUE NOV 25 2014

.SYNOPSIS...
ISSUED AT 258 PM CST TUE NOV 25 2014

H5 ANALYSIS FROM THIS MORNING HAS CLOSED LOW OVER
NORTHERN PORTIONS OF HUDSON BAY WITH A LONGWAVE TROUGH EXTENDING
SOUTH INTO FAR SOUTHERN TEXAS. EAST OF THE TROUGH...A 70 TO 110KT
JET STREAK EXTENDED FROM BROWNSVILLE TX...NE INTO THE MID
ATLANTIC...NEW ENGLAND AND THE CANADIAN MARITIMES. WEST OF THE
TROUGH...50 TO 100 METER HT RISES WERE NOTED ACROSS THE FOUR CORNERS
THIS MORNING. OVER WESTERN CANADA...A NICE SHORTWAVE WAS PRESENT
ACROSS SRN ALBERTA AND SRN SASKATCHEWAN...WHILE AT THE SURFACE...LOW
PRESSURE WAS PRESENT OVER FAR NORTHEASTERN MONTANA. A SURFACE TROUGH
EXTENDED SWD INTO EASTERN COLORADO FROM THE SFC LOW. A WARM FRONT
EXTENDED EAST INTO SERN ND WITH AN ARCTIC COLD FRONT EXTENDING NW OF
THE SURFACE LOW INTO SOUTHERN PORTIONS OF ALBERTA. ABUNDANT MID AND
HIGH LEVEL MOISTURE CONTINUES TO STREAM INTO THE NWRN CONUS PER WV
IMAGERY...AND THIS HAS LED TO OVERCAST SKIES ACROSS WESTERN AND
NORTH CENTRAL NEBRASKA TODAY. AS OF 2 PM CST...TEMPERATURES RANGED
FROM 40 AT THEDFORD TO 47 AT IMPERIAL.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 258 PM CST TUE NOV 25 2014

THE ALBERTA CLIPPER CONTINUES TO MOVE ACROSS THE AREA TONIGHT. THE
INITIAL TROUGH HAS SPARKED A FEW ISOLATED FLURRIES/SPRINKLES ACROSS
NW NEBRASKA. RADAR RETURNS SUGGEST MORE ACROSS MUCH OF WESTERN
NEBRASKA...HOWEVER A 20 PLUS DEGREE T/TD SPREAD IN ASSOCIATION WITH
A DRY LOWER LEVEL HAS RESULTED IN LITTLE REACHING THE GROUND. TOP
DOWN SATURATION WILL TAKE PLACE TONIGHT...AS SFC TEMPS COOL...WHICH
SHOULD RESULT IN MORE PRECIP REACHING THE GROUND. HOWEVER THE FIRST
WAVE WILL BE PUSHING ACROSS N CENTRAL...WITH A SECOND WAVE ACROSS
THE PANHANDLE AND FAR WESTERN NEBRASKA. EXPECT SNOW TO BE THE
PRIMARY P TYPE AS TEMPS FALL INTO THE 30S THEN 20S AND 850MB TEMPS
BELOW ZERO. COULD BRIEFLY SEE A MIX AS SFC TEMPS START IN THE LOWER
40S. ANOTHER CONCERN WILL BE THE INCREASE OF NW WINDS BEHIND THE
MAIN COLD FRONT. LOCAL GUSTS AT TIMES TO 30 TO 40 MPH.

LINGERING LIGHT SNOW CHANCES ACROSS THE EASTERN PANHANDLE IN THE
MORNING...THEN DIMINISH FROM SOUTH TO NORTH AS DRY AIR GETS DRAW IN
FROM THE WEST. CAA WILL HOLD TEMPS DOWN WITH HIGHS ONLY IN THE
MID/UPPER 20S ACROSS NORTH CENTRAL...WHILE LOWER 30S ACROSS THE NW
AND UPPER 30S TO AROUND 40 IN THE SW. WINDS WILL BE STRONGEST IN THE
MORNING THEN DECREASING AS THE DAY GOES ON.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 258 PM CST TUE NOV 25 2014

MID RANGE...WEDNESDAY NIGHT THROUGH FRIDAY...THE MAIN
FORECASTING CHALLENGES IN THE MID RANGE ARE FZDZ/LIGHT PCPN CHANCES
WEDNESDAY NIGHT...AND THEN TEMPERATURES. FOR WEDNESDAY NIGHT...A
WARM FRONT WILL LIFT FROM THE PANHANDLE INTO CENTRAL PORTIONS OF THE
FORECAST AREA. WAS INITIALLY CONCERNED ABOUT A FREEZING DRIZZLE
THREAT AS WARMER AIR ALOFT LIFTS OVER AN ARCTIC AIR MASS IN PLACE
FROM WEDNESDAY. ALSO...MODEL LAYER RH FROM H850 TO H900 IS DECENT
ACROSS NORTH CENTRAL NEBRASKA OVERNIGHT WEDS NIGHT. LOOKING AT CROSS
SECTIONS AND BUFKIT SOUNDINGS ACROSS NORTHERN NEBRASKA...THE THERMAL
PROFILE IS SOMEWHAT FAVORABLE FOR FREEZING PCPN THURSDAY
MORNING...HOWEVER...RH/S IN THE H850 TO H900 LAYER NEVER SATURATE
DURING THE PERIOD. IN ADDITION...GFS AND NAM BUFKIT SOUNDINGS DO NOT
INDICATE ANY FAVORABLE LIFT IN THIS MOIST LAYER. WITH THIS IN
MIND...WILL HOLD OFF ON ANY MENTION OF PCPN OR FZDZ WEDS NIGHT
ACROSS NORTH CENTRAL PORTIONS OF THE FORECAST AREA. WILL ADVISE THE
ONCOMING SHIFT TO WATCH THIS HOWEVER AS TRAVEL IMPACTS ARE POSSIBLE
THANKSGIVING MORNING. THROUGH MIDDAY THURSDAY...THE COLD FRONT WILL
PUSH INTO EASTERN SOUTH DAKOTA. SRLY WINDS WILL INCREASE WEST OF THE
EXITING WARM FRONT WITH A NICE WARMUP ON TAP ACROSS THE WESTERN HALF
OF THE FORECAST AREA. FURTHER EAST...LATER TIMING OF THE WARM FRONT
WILL HOLD HIGHS BACK IN THE UPPER 30S AND 40S. WEST OF HIGHWAY 83
AND SOUTH OF THE INTERSTATE...HIGHS WILL REACH THE 50S...WITH NEAR
60 POSSIBLE AROUND IMPERIAL. WITH LIGHT WESTERLY WINDS FORECAST
THURSDAY NIGHT...DECIDED TO UNDERCUT GUIDANCE A TAD BASED ON THE
LIGHT WINDS AND DRY BOUNDARY LAYER. THIS LED TO LOWS IN THE 20S WITH
LOWS AROUND 20 IN THE PLATTE VALLEY. ON FRIDAY...TEMPERATURES WILL
WARM TO THE MID 50S IN THE NORTHEAST AND MAY APPROACH 70 IN THE FAR
SOUTHWEST. TEMPS WERE TRENDED UP SLIGHTLY FROM THE INHERITED
FORECAST BASED ON HIGHER H85 TEMPS IN THIS MORNINGS GFS AND NAM
RUNS.

LONG RANGE...FRIDAY NIGHT THROUGH TUESDAY...TEMPERATURES ARE THE
MAIN FORECAST CHALLENGE IN THE LONG RANGE PERIODS...AS THE TIMING OF
AN ARCTIC FRONT FRIDAY NIGHT/SATURDAY IS STILL IN DOUBT. LOOKING AT
THE LATEST GFS AND ECMWF RUNS...BOTH MODELS HAVE THE LEADING EDGE OF
THE ARCTIC AIR ACROSS NORTHERN NEBRASKA BY 00Z SATURDAY. THIS MODEL
TREND IS IN CONTRAST WITH THE PREVIOUS RUNS OF THESE RESPECTIVE
MODELS...AS THE GFS WAS ABOUT 12 HRS FASTER WITH THE FRONT COMPARED
TO THE ECMWF. THE MAIN RUN TO RUN DIFFERENCE WITH THE GFS BETWEEN THIS
MORNINGS AND LAST NIGHTS RUN IS THE NEW GFS DROPS ARCTIC AIR INTO
THE NORTHERN CWA SATURDAY MORNING...LIFTING IT NORTH IN THE
AFTERNOON...WHICH IS HARD TO BELIEVE GIVEN THIS TIME OF YEAR. SO THIS
LEADS TO CONTINUED DOUBTS ON WHERE THE FRONT WILL BE LOCATED BY PEAK
HEATING SATURDAY. WITH THIS IN MIND...DIDN`T MAKE ANY LARGE SCALE
CHANGES TO THE TEMP FCST ON SATURDAY. ATTM PROPOSED FCST HAS HIGHS
RANGING FROM THE LOWER 40S IN THE FAR NORTH TO THE LOWER 60S IN THE
SOUTH. THE ARCTIC FRONT WILL PUSH THROUGH THE FORECAST SATURDAY
NIGHT WITH MUCH COLDER TEMPS ARRIVING FOR SUNDAY AND MONDAY.
ATTM...THE FRONTAL PASSAGE SHOULD BE A DRY ONE AS THE MID LEVEL
FRONT AND ASSOCIATED LIFT WILL REMAIN OVER SOUTH DAKOTA SATURDAY
NIGHT. HIGHS SUNDAY WILL BE IN THE 20S...WITH 30S FOR MONDAY.
READINGS WILL REBOUND BACK INTO THE 40S AND 50S TUESDAY AS RIDGING
DEVELOPS EAST OF A WEST CONUS TROUGH.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 524 PM CST TUE NOV 25 2014

INDICATIONS ON RADAR...THE NAM...HRRR AND RAP MODELS SUGGEST THE
BEST CHANCE OF MVFR/IFR CIGS/VSBY IN SNOW WOULD OCCUR ACROSS WRN
NEB TONIGHT AS AN AREA OF SNOW SPREADS SOUTH-SOUTHEAST THROUGH THE
PANHANDLE AND SWRN NEB. OTHERWISE MVFR CIGS ARE EXPECTED ALONG AND
NORTH OF NEBRASKA HIGHWAY 2 THROUGH 15Z-17Z WITH VFR DEVELOPING
ALL AREAS THEREAFTER.

&&

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

$$

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






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