Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 221113
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
513 AM CST THU JAN 22 2015

.SYNOPSIS...
ISSUED AT 358 AM CST THU JAN 22 2015

ANALYSIS OF THE 08Z MSL DATA SHOWED HIGH PRESSURE CENTERED IN
NORTHWEST NEBRASKA BETWEEN VALENTINE AND ALLIANCE. ALSO...HIGH
PRESSURE WAS LOCATED ALONG THE IDAHO-WYOMING BORDER NEAR
YELLOWSTONE PARK AND OVER NORTHWEST COLORADO NEAR CRAIG. A
BOUNDARY WAS DISCERNIBLE ON THE HIGH PLAINS OF MONTANA AND WYOMING
AND A FRONT WAS STRETCHED ACROSS NORTHWEST MISSOURI...KANSAS AND
SOUTHEAST COLORADO. AUTOMATIC SURFACE OBSERVATIONS AND 11-3.9
MICRON IMAGERY SHOWED CLOUDS OVER THE EASTERN THIRD OF NEBRASKA
AND IN A FEW LOCATIONS OVER THE NEBRASKA SANDHILLS. DARKENING IN
THE WATER VAPOR IMAGERY INDICATED THE LOCATION OF THE POLAR FRONT
ACROSS NORTHERN KANSAS WITH A STRONG POTENTIAL VORTICITY ANOMALY
NEAR THE FOUR CORNERS REGION IN THE SOUTHWEST U.S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM CST THU JAN 22 2015

AS THE SURFACE HIGH PRESSURE MOVES OFF TO THE EAST TODAY...
CLOUDINESS IN EASTERN NEBRASKA WILL DECREASE AND RETURN FLOW ALONG
THE LEE SIDE TROUGH WILL BRING SLIGHTLY WARMER TEMPERATURES TO
CENTRAL AND WESTERN NEBRASKA TODAY AND TONIGHT. THE DEVELOPING
UPPER LOW IN THE SOUTHWEST WILL KEEP MOISTURE AND CLOUDINESS OUT OF
CENTRAL AND WESTERN NEBRASKA THIS AFTERNOON AND TONIGHT.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 358 AM CST THU JAN 22 2015

FORECAST CHALLENGES LIE MAINLY WITH TEMPERATURES AND WINDS
THROUGHOUT THE PERIOD...WITH ALSO A LOOK AT CHANCES FOR
PRECIPITATION SATURDAY NIGHT INTO SUNDAY.

MODELS ARE IN DECENT AGREEMENT SO CONFIDENCE IN THE FORECAST ON THIS
PACKAGE IS GOOD. THE PERIOD BEGINS WITH THE UPPER LEVEL PATTERN
BEING FAIRLY AMPLIFIED WITH A DEEP TROUGH OVER THE EASTERN HALF OF
THE CONUS....WITH STRONG RIDGING OVER THE WESTERN CONUS. THIS PUTS
THE LOCAL AREA IN NORTHWEST FLOW WITH SEVERAL SHORTWAVE TROUGHS
PROJECTED TO PUSH ACROSS THE FORECAST AREA. THERE IS SOME
TRANSITION OF THE PATTERN GOING THROUGH THE MIDDLE PORTION OF NEXT
WEEK AS RIDGING BUILDS EAST INTO THE PLAINS AS THE NEXT LARGE
TROUGH HEADS ACROSS THE EASTERN PACIFIC.

ON FRIDAY...TEMPERATURES ALOFT WILL BE WARMING AS 850MB
TEMPERATURES RISE ABOVE 0C ACROSS THE ENTIRE FORECAST AREA. THIS
WON/T LEAD TO REAL WARM TEMPERATURES...BUT WILL BE WARMER THAN
WHAT IS EXPECTED FOR TODAY. A WEAK FRONTAL BOUNDARY WILL PASS
ACROSS THE AREA EARLY FRIDAY AND WITH A STRENGTHENED SURFACE
PRESSURE GRADIENT...EXPECT WINDS TO INCREASE THROUGH THE DAY.
ADDITIONALLY...A MIXED BOUNDARY LAYER TO 875MB-850MB SHOULD
TRANSPORT STRONGER WINDS TO THE SURFACE IN THE AFTERNOON. WINDS AT
THESE LEVELS ARE BEING SHOWN AROUND 30KTS BY FORECAST MODELS SO
NOT EXPECTING A WINDY DAY...JUST BREEZY AT TIMES. THESE WINDS AND
THE MIXED LOW LEVELS WILL ALSO HELP THE WARMING AS THE WARMER AIR
ALOFT MIXES TO THE SURFACE. WENT ON THE HIGHER END OF FORECAST
GUIDANCE AS THE MODELS HAVE TENDED TO BE A BIT TOO COOL IN MOST
INSTANCES THROUGH THE PAST WEEK AND WOULD EXPECT THIS TREND TO
CONTINUE. NOT EXPECTING THE BOUNDARY LAYER TO DECOUPLE FRIDAY NIGHT
IN MOST AREAS SO TEMPERATURES SHOULD STAY ON THE WARMER SIDE.

BEGINNING EARLY SATURDAY MORNING...THE TRAIN OF WEAK SHORTWAVE
TROUGHS START MOVING OVER THE RIDGE AND DOWN TOWARDS THE BASE OF
THE TROUGH...AND IN MOST INSTANCES LOOK TO PASS OVER THE LOCAL
AREA. THAT BEING SAID...THERE ARE SOME DIFFERENCES IN TIMING
BETWEEN THE MODELS OF THESE WEAK IMPULSES OF ENERGY. EACH LOOK TO
BRING AN ENHANCED PV ANOMALY ACROSS THE AREA AND SUBSIDENCE BEHIND
THE FEATURE WITH STRENGTHENING WINDS ON THE BACKSIDE. MOST OF
THESE SHORTWAVE TROUGHS WILL PASS BY THE AREA DRY AS THERE WILL BE
LIMITED MOISTURE TO WORK WITH AND BELIEVE CLOUDS WILL BE THE
EXTENT OF WHAT WILL OCCUR WITH THEM. THERE IS ONE EXCEPTION...A
STRONGER SYSTEM WILL MOVE ACROSS THE AREA SATURDAY NIGHT INTO
SUNDAY WHERE THERE LOOKS TO BE ENOUGH MOISTURE TO DEVELOP
PRECIPITATION...MAINLY ACROSS NORTHERN AND NORTHEAST NEBRASKA. THE
BEST LIFT IS SEEN BETWEEN 00Z AND 06Z SUNDAY WITH SUBSIDENCE
QUICKLY TAKING OVER AFTER 06Z. LIMITED CHANCES FOR RAIN TO THIS
TIME FRAME. TEMPERATURE PROFILES INDICATE IT WILL BE WARM ENOUGH
TO HAVE THE MENTION OF JUST RAIN SO THAT HAS BEEN CHANGED FROM
WHAT WAS A RAIN/SNOW MIX FROM THE PRIOR FORECAST.

BACK TO TEMPERATURES AND WINDS...THE TREND WILL BE FOR WARMING
TEMPERATURES EACH DAY. THERE MAY BE A BIT OF COLD ADVECTION ON
SUNDAY BEHIND THE SHORTWAVE TROUGH...BUT THE MAIN IMPACTS WITH
THIS COOLER AIR WILL BE OVER EASTERN NEBRASKA. AND WITH THE
EXPECTATIONS OF DEEP MIXING ON SUNDAY IN THE WAKE OF THE
SYSTEM...HAVE KEPT THE FORECAST ON THE WARM SIDE WITH MID TO UPPER
50S IN PORTIONS OF THE FORECAST AREA. CONTINUE WITH THE COOLER
OVER THE NORTHERN PANHANDLE AND WESTERN SANDHILLS WITH SOME
INFLUENCE CONTINUING FROM SOME SNOWCOVER STILL BUT WOULD
ANTICIPATE THIS INFLUENCE WILL BE LESSER BY DAY GOING INTO NEXT
WEEK. THE MODELS ARE STARTING TO SHOW THE LOW LEVELS MIXING DURING
THE AFTERNOONS...BUT DON/T BELIEVE IT IS DEEP ENOUGH AS MOST DAYS
BOTH THE GFS AND NAM ARE ONLY MIXING TO 875MB-850MB. HAVE SEEN
PRIOR DAYS WHERE MIXING UP TO 700MB HAS OCCURRED SO WOULD
ANTICIPATE THIS TREND CONTINUING THROUGH THE FORECAST PERIOD AS
WELL.

GOING INTO MONDAY THROUGH WEDNESDAY...THE RIDGE BUILDS EAST AND
INTO THE PLAINS. THIS WILL LIMIT ANY INFLUENCE FROM SHORTWAVE
SYSTEMS AS THE TRACK WILL PUSH EAST OF THE REGION. THE MODELS
CONTINUE TO SHOW A SIGNIFICANT WARM-UP WITH 850MB TEMPERATURES
INCREASING TO 10C TO 15C ACROSS THE FORECAST AREA BY TUESDAY. THE
FORECAST CONTINUES TO GO UP THESE DAYS...BUT MAY STILL BE TOO COOL
WITH UPPER 50S AND LOW 60S IN THE FORECAST. AS CONFIDENCE ON
TEMPERATURES REACHING THESE VALUES INCREASES...THE FORECAST WILL
BE MODIFIED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 508 AM CST THU JAN 22 2015

LOCALIZED SHALLOW FOG IS EXPECTED THIS MORNING IN THE PLATTE RIVER
VALLEY...APPROXIMATELY ALONG A LXN-LBF-OGA LINE. THE COVERAGE WILL
BE LIMITED AND WILL NOT BE INCLUDED IN THE TERMINAL FORECAST FOR
LBF. OTHERWISE...CEILING AND VISIBILITY WILL BE UNLIMITED IN
CENTRAL AND WESTERN NEBRASKA TODAY AND TONIGHT WITH WEST TO
SOUTHWEST WIND AT LESS THAN 10KT.

&&

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

$$

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





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