Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 292323 AAA
AFDLBF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
622 PM CDT WED OCT 29 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 305 PM CDT WED OCT 29 2014

SFC HIGH PRESSURE WILL CONTINUE TO BUILD EAST THIS EVENING AND
OVERNIGHT ALLOWING FOR LIGHT WESTERLY DOWNSLOPING FLOW...HOWEVER A
DRY FRONT WILL CROSS WESTERN NEBRASKA EARLY THURSDAY RESULTING IN
BREEZY NORTHWEST FLOW. MODEL GUIDANCE INDICATES COOLER HIGHS FOR
THURSDAY AS H85 TEMPERATURES ARE SHOWN TO FALL SOME 5-6C BEHIND
THE FRONT. BASED OFF OF NUMERICAL GUIDANCE...HIGHS WILL RANGE FROM
THE LOWER 50S ACROSS OUR NORTHERN BORDER...TO THE LOWER 60S OVER
THE FAR SOUTH. LOWS THURSDAY MORNING WILL BE SEASONAL...WITH LOWER
30S PREVAILING IN FAVORED RIVER BASINS AND ACROSS THE WEST...UPPER
30S ELSEWHERE. THE SHORT TERM MODELS CONTINUE TO SUGGEST A DRY
FORECAST THROUGH THURSDAY AS UPPER RIDGING BUILDS FROM THE WEST.
THERE ARE INDICATIONS OF A QUICK HITTING SHORTWAVE DIVING SOUTH
ACROSS THE NORTHERN PLAINS OVERNIGHT...BUT ANY ASSOCIATED QPF WITH
THE SYSTEM REMAINS NORTH OVER THE DAKOTAS WHERE BETTER MOISTURE
EXISTS. INCREASING CLOUD COVER WOULD BE EXPECTED HOWEVER OVER
NORTH CENTRAL NEBRASKA.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CDT WED OCT 29 2014

THE FORECAST FOR FRIDAY AND SATURDAY CONTINUES TO BE AN INTERESTING
PROBLEM. THE RUN-TO-RUN TREND IN THE STATISTICAL GUIDANCE FOR
TEMPERATURES FRIDAY SEEMS TO HAVE STABILIZED WITH HIGH TEMPERATURES
MAINLY IN THE 40S OVER CENTRAL AND WESTERN NEBRASKA AND LOWS FRIDAY
MORNING IN THE UPPER TEENS TO LOWER 20S. THIS WILL BE ABOUT AS COLD
AS THE AREA HAS EXPERIENCED THIS SEASON SO FAR. SINCE THE SOURCE OF
THE AIRMASS IS ALONG THE COAST OF THE ARCTIC OCEAN...WHERE CURRENT
TEMPERATURES ARE IN THE SINGLE DIGITS TO BELOW ZERO FAHRENHEIT AND
THE SPEED OF TRANSIT IS RAPID...THERE MAY NOT BE A LOT OF
MODIFICATION AND THE STATISTICAL OUTPUT IS REASONABLE. THE CENTER OF
THE AIRMASS WILL BE WELL EAST OF NEBRASKA BUT CIRCULATION AROUND
THE SYSTEM WILL GIVE A TRAJECTORY OF THE COLDEST AIR ACROSS THE
CENTRAL PLAINS AND COMING INTO SOUTH CENTRAL AND SOUTHWEST NEBRASKA
FROM THE SOUTH. THOUGH IT MAY SEEM COUNTER-INTUITIVE...THE STRONG
SOUTH FLOW WILL BRING COLD AIR INTO THE AREA. AS THE HIGH MOVES OFF
INTO SOUTHERN GREAT LAKES...THE SOUTH FLOW WILL AGAIN COME FROM WEST
TEXAS AND BRING MUCH WARMER TEMPERATURES INTO CENTRAL AND WESTERN
NEBRASKA BY SUNDAY.

WITH THE THE ARCTIC AIR INTERACTING WITH A WELL-DEVELOPED LEESIDE
TROUGH...THE PRESSURE GRADIENT WILL RESULT IN QUITE WINDY CONDITIONS
LATE SATURDAY MORNING TO EARLY EVENING. THE SUSTAINED WIND SPEED
SHOULD BE WELL BELOW 40 MPH THOUGH THE GUSTS COULD EXCEED 50
MPH.

A STRONG PACIFIC FRONT COMES ACROSS THE ROCKIES AND ONTO THE PLAINS
SUNDAY NIGHT AND MONDAY. A CROSS SECTION ACROSS THE TEMPERATURE
GRADIENT SHOWS DECENT SYSTEM-RELATIVE ISENTROPIC LIFT AND THE
AGEOSTROPHIC VERTICAL CIRCULATION AND THETA-E INDICATES STRONG
FRONTOGENESIS IN A FAIRLY UNSTABLE 300-315K (700-400MB) LAYER. THE
UNDERLYING DRY LAYER SATURATES FAIRLY QUICKLY. THUS...THE STRONG
FORCING AND QUICK SATURATION SHOULD RESULT IN LIGHT PRECIPITATION
OVER THE NEBRASKA SANDHILLS SUNDAY NIGHT AND POSSIBLY INTO MONDAY.
SINCE THAT IS STILL MORE THAN 120 HOURS OUT...THE PROBABILITY
NUMBERS SHOULD BE KEPT LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 622 PM CDT WED OCT 29 2014

VFR IS EXPECTED ALL AREAS TONIGHT THROUGH THURSDAY.

A PACIFIC COLD FRONT MOVES THROUGH TONIGHT. THE FRONT IS CURRENTLY
MOVING THROUGH WRN NEB. WINDS THURSDAY MORNING SHOULD INCREASE TO
34018G27KT AND CONTINUE STRONG DURING THE AFTN. A SECOND COLD
FRONT...AN ARCTIC FRONT CURRENTLY NEAR REGINA SASKATCHEWAN...WILL BE
MOVING INTO NCNTL NEB THURSDAY AFTN.

&&

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

$$

SHORT TERM...JACOBS
LONG TERM...SPRINGER
AVIATION...CDC






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