Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 212305
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
505 PM CST FRI NOV 21 2014

.SYNOPSIS...
ISSUED AT 355 PM CST FRI NOV 21 2014

AT 20Z WATER VAPOR IMAGERY SHOWED A LOW AMPLITUDE WAVE PATTERN
ACROSS MUCH OF THE CONUS...WHILE THERE WAS AN UPPER LEVEL LOW OVER
SOUTHERN CALIFORNIA AND WESTERN ARIZONA. FURTHER UPSTREAM...A BROAD
UPPER LEVEL TROUGH WAS SEEN ACROSS ALASKA AND THE NORTHERN PACIFIC.
AT THE SURFACE...A LARGE AREA OF HIGH PRESSURE ENCOMPASSED THE
EASTERN HALF OF THE COUNTRY AND WITH A WEAK SURFACE TROUGH ACROSS
THE NORTHERN AND HIGH PLAINS SOUTHERLY FLOW TOOK SHAPE INTO WESTERN
NEBRASKA. THE SHARP INVERSION AS SEEN IN THE 12Z KLBF SOUNDING
SHOWED TEMPERATURES BETWEEN 875MB AND 800MB AROUND 5-6C AND LAPS
SOUNDINGS SHOWED MIXING HAD OCCURRED TO THOSE LEVELS WHICH LED TO
TEMPERATURES IN THE 40S TO AROUND 60.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 355 PM CST FRI NOV 21 2014

THROUGH SATURDAY...THE UPPER LOW OVER THE SOUTHWEST WILL PROGRESS
EAST AND IS EXPECTED TO BE OVER TEXAS BY LATE IN THE DAY. THIS WILL
CAUSE THE SURFACE HIGH OVER THE EASTERN PART OF THE CONUS TO SHIFT
EAST AS WELL. CONCURRENTLY...A SYSTEM WILL MOVE ONSHORE OVER THE
PACIFIC NORTHWEST WHICH WILL DEVELOP A SURFACE LOW ON THE LEE SIDE OF
THE CANADIAN ROCKIES. THIS SURFACE PATTERN WILL KEEP THE LOW LEVEL
FLOW FROM THE SOUTH TO SOUTHWEST THROUGH THE PERIOD. THE PRESSURE
GRADIENT WILL NOT BE TIGHT ENOUGH OVERNIGHT TO KEEP THE WINDS UP SO
ANTICIPATING THE BOUNDARY LAYER INVERSION TO SET UP WITH WINDS
DROPPING OFF. SKIES SHOULD ALSO BE MOSTLY CLEAR TONIGHT SO LOOKING
AT GOOD RADIATIONAL COOLING TO DROP TEMPERATURES DOWN INTO THE TEENS
AND LOW 20S IN FAVORED COOL SPOTS...WHILE HIGHER TERRAIN MAY ONLY
DROP INTO THE MID AND UPPER 20S. FORECAST SOUNDINGS DO SHOW THE
SURFACE T/TD SPREAD NARROWING SIGNIFICANTLY BY MORNING...BUT THE
MOISTURE IS JUST AT THE SURFACE WITH NO DEPTH TO IT SO NOT LOOKING
AT ANY FOG POTENTIAL TONIGHT. ONE OTHER MENTION IS THE LARGE AREA OF
STRATUS/FOG ACROSS THE EASTERN TWO-THIRDS OF KANSAS TODAY. THE
MODELS DO LIFT IT TO THE NORTH OVERNIGHT BUT CURRENT RUNS KEEP THIS
MOISTURE JUST TO THE EAST OF THE LOCAL AREA. IF THE CLOUDS WOULD
COME FURTHER WEST THAN EXPECTED...THE CLOUD COVER AND TEMPERATURES
FORECAST WOULD BE IMPACTED.

THE MAIN CONCERN WITH SATURDAY WILL BE TEMPERATURES. 850MB
TEMPERATURES RAISE ANOTHER 5 DEGREES OR SO BY 21Z SATURDAY. WITH THE
SOUTHWEST WINDS CONTINUING AND A GOOD AMOUNT OF SUNSHINE EXPECTED
THINKING THE BOUNDARY LAYER SHOULD MIX QUITE EFFICIENTLY DURING THE
DAY. THE MODELS WERE WELL TOO COOL WITH HIGHS TODAY AND SO WENT
ABOVE MUCH OF THE DETERMINISTIC MODEL SOLUTIONS FOR HIGHS TOMORROW.
THE STATISTICAL GUIDANCE SEEMS TO HAVE FINALLY GOTTEN A HOLD OF THE
WARMER PATTERN AND DO WARM TEMPERATURES INTO THE 50S AND 60S FOR
SATURDAY. CONFIDENCE IS FAIRLY HIGH ON THE WARMER TEMPERATURE
FORECAST...BUT DO HAVE SOME CONCERNS THAT SOME AREAS MAY NOT BE WARM
ENOUGH YET.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 355 PM CST FRI NOV 21 2014

MID RANGE PERIODS (SATURDAY NIGHT THROUGH MONDAY)...

AS AN UPPER TROUGH EMERGES ONTO THE NRN AND CNTRL HIGH PLAINS
SATURDAY NIGHT...A COLD FRONT WILL MOVE INTO WRN NEBR AFTER
MIDNIGHT. THIS MAY ALSO BRING A FEW RAIN OR SNOW SHOWERS TO
SHERIDAN OR WRN CHERRY COUNTY. ON THE BACKSIDE OF UPPER TROUGH...A
SLIGHT CHANCE FOR RAIN OR SNOW SHOWERS IN THE NCTRL SUNDAY AFTN.
NORTHWEST WINDS WILL ALSO INCREASE TO 20 TO 35 MPH ACROSS THE
WESTERN SANDHILLS INTO SOUTHWEST NEBR BY SUNDAY AFTN. A COOLDOWN
FOR SUNDAY. ONLY MINOR CHANGES TO PREVIOUS FORECAST HIGHS FROM
LOWER 40S FAR NRN AREAS TO NEAR 50 FAR SOUTH. AS A CLOSED UPPER
LOW MOVES FROM MINNESOTA INTO THE GREAT LAKES SUNDAY NIGHT INTO
MONDAY...HAVE CONTINUED A SLIGHT CHANCE FOR SNOW SHOWERS ACROSS
PORTIONS OF NCTRL NEBR. WILL ALSO REMAIN WINDY THROUGH THIS PERIOD
DUE TO A RATHER TIGHT H7 AND SURFACE PRESSURE GRADIENT. COLDER AIR
WILL BE DRAWN INTO THE NORTHEASTERN HALF OF THE FA ESPECIALLY. H85
TEMPS WILL ONLY RECOVER TO -9C AT ONL AND 0C AT IML. CORRESPONDING
HIGH TEMPS MIXED DOWN BRING 42 AT IML AT 28 AT ONL.

EXTENDED PERIODS (MONDAY NIGHT THROUGH FRIDAY)...

THE UPPER FLOW PATTERN WILL BECOME STRONGLY MERIDIONAL BY WEDNESDAY
AS A STRONG UPPER RIDGE MOVES ACROSS THE WESTERN U.S. AND A
TROUGH DEEPENS ACROSS THE EASTERN U.S. WESTERN NEBRASKA WILL BE
CAUGHT BETWEEN THE COLD AIRMASS TO THE EAST AND MILD AIR TO THE
WEST. A RATHER SIGNIFICANT WARMUP TO PREVIOUS HIGH
TEMPERATURES...ESPECIALLY ACROSS THE SWRN HALF OF FA. THE GOOD
AGREEMENT BETWEEN THE 12Z GFS AND 00Z AND 12Z ECMWF PLACES
CONFIDENCE MUCH HIGHER THAN THE PAST SEVERAL MODEL RUNS. THE
TANDEM BREAKDOWN OF UPPER RIDGING OVER ALASKA AND WEAKENING OF
THE NORTH ATLANTIC RIDGE CENTERED AROUND 10 WEST LONGITUDE
SUPPORTS A PROGRESSIVE SYNOPTIC FLOW AND ABOVE NORMAL TEMPERATURES
ACROSS THE NRN AND CNTRL HIGH PLAINS THURSDAY AND FRIDAY. PRIOR TO
SOME ARCTIC AIR COMING DOWN WEDNESDAY INTO THURSDAY...HIGHS
TUESDAY WILL BE SEASONABLE FROM THE LOWER 40S NORTH TO THE UPPER
40S FAR SOUTH. THEN HIGHS WEDNESDAY TO CONTRAST FROM 32 AT ONL TO
48 AT IML AND HIGHS THANKSGIVING DAY FROM 28 AT ONL TO 42 AT IML.
FRIDAY HIGHS TO WARM TO THE UPPER 30S NORTHEAST TO UPPER 40S
SOUTHWEST. THERE WILL BE A SLIGHT CHANCE FOR SNOW SHOWERS TUESDAY
NIGHT INTO WEDNESDAY NIGHT. NOTHING HOWEVER SUGGESTS THIS SHOULD
BECOME ANY HAZARD TO EARLY HOLIDAY TRAVEL.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 503 PM CST FRI NOV 21 2014

UNLIMITED FLIGHT CONDITIONS ARE EXPECTED THROUGH SATURDAY EVENING.
WIND 210-250 WILL INCREASE TO 12-16G18-22KT LATE SATURDAY MORNING
TO EARLY AFTERNOON 17-19Z.

&&

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

$$

SYNOPSIS...BROOKS
SHORT TERM...BROOKS
LONG TERM...ROBERG
AVIATION...SPRINGER






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