Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 281749
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1149 AM CST FRI NOV 28 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM CST FRI NOV 28 2014

TODAY AND TONIGHT...A CHECK ON UPPER LEVEL MOISTURE IN THE
NAM...GFS AND RAP MODELS INDICATES AN INCREASE TODAY. UPPER LEVEL
WINDS ALSO INCREASE BY 10 TO 15 KT. THIS WOULD SUGGEST THE
POTENTIAL FOR CIRRUS DEVELOPING OFF THE LARAMIE RANGE WHICH WOULD
SPREAD EAST DURING THE AFTN. THE AMOUNT OF COVERAGE RANGES FROM
TOTALLY OVERCAST IN THE GFS TO NEARLY NONE IN THE RAP. THE
TEMPERATURE FORECAST USES A MIDDLE OF THE ROAD APPROACH FOR PARTLY
CLOUDY CONDITIONS. THE RAP AND NAM ALSO SHOW A WEAK COLD FRONT
DROPPING THROUGH NRN NEBRASKA THIS AFTN WHICH WOULD KEEP THE NORTH
MOSTLY IN THE 50S FOR HIGHS. SOUTH OF THE FRONT...DESPITE THE HIGH
CLOUDS...DEEPER MIXING IS EXPECTED WHICH SHOULD SEND HIGHS INTO
THE 60S TO LOWER 70S...NEAR RECORD.

TONIGHT...THE MODELS SHOW THE UPPER LEVELS DRYING OUT WHICH WOULD
BE ALL FOR CLEARING...LIGHT WINDS AND RADIATIONAL COOLING THE IN
THE N/S PLATTE VALLEYS. THE HIGHLANDS STAY MIXED. LOWS TONIGHT
RANGE FROM THE LOWER 20S IN THE VALLEYS TO UPPER 30S ACROSS THE
SANDHILLS.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 358 AM CST FRI NOV 28 2014

FORECAST CONCERNS DEAL WITH TEMPERATURES AND WINDS...AND FIRE
WEATHER POTENTIAL FOR SATURDAY. THE NEXT WEEK LOOKS LARGELY DRY
ALTHOUGH IT IS POSSIBLE FOR A FEW SNOW SHOWERS /FLURRIES/ WITH
LITTLE OR NO ACCUMULATION SATURDAY NIGHT INTO MONDAY MORNING.

MODELS HAVE DECENT AGREEMENT THROUGH THE PERIOD NOW SO CONFIDENCE
IS IMPROVING WITH THE SENSIBLE WEATHER CONDITIONS FOR THIS
FORECAST CYCLE.

THE PERIOD BEGINS WITH A VERY ANOMALOUSLY WARM DAY FOR SATURDAY.
VERY LITTLE RUN TO RUN CHANGES HAVE BEEN NOTICED ACROSS THE AREA
SO GOOD CONFIDENCE ON A VERY WARM DAY. THE IMPENDING STRONG COLD
FRONT WILL STAY UP OVER SOUTH DAKOTA THROUGH 00Z SUNDAY WITH THE
SURFACE PATTERN SHOWING WESTERLY WINDS ACROSS NEBRASKA. THE
WESTERLY COMPONENT OF THE WINDS WILL GIVE THE AIR IN THE BOUNDARY
LAYER WARMING DOWNSLOPE CONDITIONS. THE MODELS AREN/T PARTICULARLY
STRONG WITH THE WINDS AS THE PRESSURE GRADIENT IS QUITE WEAK BUT
DEEPER MIXING INTO THE AFTERNOON SHOULD PROVIDE BREEZY CONDITIONS
IN PLACES. THE STRONGER WINDS AT THE TOP OF THE MIXED LAYER ARE
ACROSS NORTHERN NEBRASKA AT 20 TO 30KTS. GOING SOUTH...THE
SOUTHERN PART OF THE STATE SEES WINDS AT THE SAME LEVEL ONLY AT 10
TO 15KTS. HAVE INCLUDED THE HIGHER WINDS OVER THE NORTHERN AREAS
AND LOWER WINDS ACROSS THE SOUTH IN THE FORECAST TODAY. LOOKING
INTO HIGHS...MINIMAL CHANGES WERE MADE TO ONGOING FORECAST. THIS
LEAVES HIGHS IN THE 60S...WITH LOW 70S OVER THE SOUTHERN PART OF
THE STATE. STANDARDIZED ANOMALIES CONTINUE TO SHOW TEMPERATURES AT
850MB AT 2-3 STANDARD DEVIATIONS ABOVE NORMAL. THINKING THIS WILL
BE CLOSE TO THE HEIGHT OF THE MIXED LAYER...LIKELY HIGHER OVER THE
HIGHER TERRAIN IN THE WESTERN PART OF THE FORECAST AREA SO
AGAIN...ONGOING TEMPERATURES LOOK APPROPRIATE WHICH WILL BE NEAR
RECORD READINGS. THE OTHER CONCERN WITH SATURDAY WILL BE NEAR
CRITICAL FIRE WEATHER POTENTIAL. THE WARM TEMPERATURES AND DRY AIR
IN PLACE WILL DROP RELATIVE HUMIDITY DOWN BELOW 20
PERCENT...MAINLY FROM SOUTHWEST NEBRASKA INTO THE EASTERN
SANDHILLS. AT THIS TIME...THE STRONGER WINDS DON/T LOOK TO
COINCIDE WITH THE DRIER CONDITIONS SO NOT ANTICIPATING THE NEED
FOR FIRE WEATHER HEADLINES DESPITE THE WARM AND DRY CONDITIONS.

THE COLD FRONT WILL PLOW SOUTH THROUGH THE FORECAST AREA SATURDAY
NIGHT. THIS FRONT WILL DROP TEMPERATURES DRAMATICALLY WITH 850MB
VALUES LOWERING FROM 13-18C AT 00Z SUNDAY TO -17C TO -10C BY 00Z
MONDAY. THIS WILL KEEP THE DIURNAL TEMPERATURE CHANGE VERY MINIMAL
ON SUNDAY AND TEMPERATURES WILL ONLY RAISE INTO THE 20S FOR MUCH
OF THE AREA. ALSO THINKING WINDS WILL INCREASE BEHIND THE FRONT
AND HAVE TRENDED THE FORECAST ACCORDINGLY FOR SATURDAY NIGHT AND
SUNDAY. NEARLY UNIDIRECTIONAL WINDS FROM THE NORTH-
NORTHWEST...STRONG COLD AIR ADVECTION...GOOD SUBSIDENCE...AND A
TIGHT PRESSURE GRADIENT ALL ARE GOOD INGREDIENTS FOR BREEZY TO
STRONG WINDS.

THE MODELS ARE INDICATING SOME FRONTOGENETICAL FORCING ALONG THE
FRONT SATURDAY NIGHT. MOISTURE ISN/T VERY IMPRESSIVE AND REALLY
NOT MUCH LIFT IN THE LAYER SO JUST ADDED IN SOME FLURRIES FOR NOW
IN AREAS. THEN...ON SUNDAY NIGHT AS THE SURFACE HIGH BUILDS
SOUTHEAST INTO EASTER SOUTH DAKOTA RETURN FLOW WILL BE IN PLACE
FROM WESTERN KANSAS INTO THE NEBRASKA PANHANDLE. THIS WILL BRING
SOME INCREASED MOISTURE INTO LEVELS BELOW 700MB. ALTHOUGH THE
MOISTURE DOES INCREASE...THE LIFT IN THE LAYER ISN/T VERY
IMPRESSIVE SO DIDN/T HAVE THE CONFIDENCE TO ADD MEASURABLE SNOW
IN THE FORECAST YET AND JUST INCLUDED SOME FLURRIES FOR PORTIONS OF
THE PANHANDLE SUNDAY NIGHT.

MONDAY MORNING WILL BE QUITE COLD AS THE REGION IS INFLUENCED BY
THE COLD AIR /850MB TEMPERATURES AT -12C TO -14C AND A SURFACE HIGH
CENTERED OVER THE DAKOTAS. THE AIRMASS IN PLACE WOULD SUGGEST LOWS
BELOW ZERO ARE CERTAINLY POSSIBLE WHERE WINDS DECOUPLE COMPLETELY
AND BECOME CALM. THIS MAY STAY IN AREAS DIRECTLY UNDER THE SURFACE
HIGH OVER SOUTH DAKOTA SO KEPT LOWS IN THE SINGLE DIGITS AT THIS
TIME THOUGH DID DROP THEM A FEW DEGREES.

THE NEXT WORK WEEK LOOKS TO BE A YO-YO IN TEMPERATURES WITH COLD
CONDITIONS MONDAY AND WEDNESDAY AND A BIT WARMER FOR TUESDAY AND
THURSDAY. THE HIGH DEPARTS MONDAY NIGHT WITH FAIRLY STRONG RETURN
FLOW OCCURRING INTO TUESDAY TO PUSH OUT THE COLD AIR MASS WITH A
RETURN OF CLOSE TO NEAR NORMAL TEMPERATURES IN THE 40S MOST
PLACES. ANOTHER COLD FRONT WILL THEN MOVE THROUGH THE NORTHERN
PLAINS AGAIN TUESDAY NIGHT AND MODELS HAVE COME INTO BETTER
AGREEMENT IN ITS TIMING AND OTHER DETAILS. THIS FRONTAL PASSAGE
LOOKS TO BE DRY AT THIS TIME BUT IT WILL BRING ANOTHER REINFORCING
SHOT OF COLDER AIR...ALTHOUGH NOT NEARLY AS COLD AS THE SUNDAY
SYSTEM. THEN THURSDAY LOOKS TO BRING STRONG WARM AIR ADVECTION
BACK TO PERHAPS GET TEMPERATURES BACK ABOVE NORMAL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1120 AM CST FRI NOV 28 2014

SCATTERED TO BROKEN HIGH CLOUDINESS WILL CONTINUE TO STREAM EAST
ACROSS THE REGION THIS AFTERNOON INTO TONIGHT. VFR CONDITIONS WILL
PREVAIL WITH WEST WINDS 5 TO 15 KTS. LOCAL GUSTS TO 25 KTS ARE
POSSIBLE THIS AFTERNOON ACROSS NORTHERN NEBRASKA.

&&

.FIRE WEATHER...
ISSUED AT 317 AM CST FRI NOV 28 2014

TODAY...DEWPOINTS WHERE DERIVED FROM 50 PERCENT OF
THE VERY DRY RAP MODEL AND 50 PERCENT OF THE OTHER MODELS. THIS
PRODUCES RH VALUES BETWEEN 15 AND 20 PERCENT SOUTH OF INTERSTATE 80.
WINDS SHOULD BE LIGHT IN THIS AREA AS THE RAP SHOWS A SFC TROF
SETTING UP ACROSS THE SOUTH. SO VERY HIGH FIRE DANGER IS EXPECTED
BUT WINDS ARE LIGHT GUSTING TO JUST 20 MPH.

&&

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

$$

SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...TAYLOR
FIRE WEATHER...CDC





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