Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 251147
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
647 AM CDT SAT OCT 25 2014

.SYNOPSIS...
ISSUED AT 328 AM CDT SAT OCT 25 2014

H5 ANALYSIS FROM EARLIER THIS EVENING HAD A BROAD RIDGE
OF HIGH PRESSURE EXTENDING FROM NEW MEXICO NWD INTO THE NORTHERN
ROCKIES AND NORTHERN PLAINS. LOW PRESSURE WAS NOTED OFF THE
CALIFORNIA COAST...AS WELL AS THE CANADIAN MARITIMES. ACROSS
SOUTHERN AND CENTRAL CANADA...SHORT WAVES WERE NOTED OFF THE COAST
OF CENTRAL BRITISH COLUMBIA AND OVER FAR NRN SASKATCHEWAN. AT THE
SURFACE...WEAK HIGH PRESSURE WAS NOTED OVER NORTHWESTERN
NEBRASKA...WESTERN SOUTH DAKOTA AND NERN WYOMING. THIS FEATURE ALONG
WITH A SHORTWAVE TROUGH OVER NRN MINNESOTA...HAS FORCED A WEAK BACK
DOOR COLD FRONT INTO NORTHERN NEBRASKA OVERNIGHT. RADAR IMAGERY OVER
THE PAST 1 TO 2 HRS...SHOWS THE WIND SHIFT ACROSS THE CENTRAL AND
NORTHERN SANDHILLS. AS OF 3 AM CDT...THIS BOUNDARY HAD PUSHED SOUTH
INTO SOUTHERN CHERRY...SOUTHERN BROWN...SOUTHERN ROCK AND SOUTHERN
HOLT COUNTIES. UNDER CLEAR SKIES...TEMPERATURES AS OF 3 AM CDT
RANGED FROM 39 AT NORTH PLATTE TO 50 AT VALENTINE.

WARM AIR WILL CONTINUE ACROSS THE CNTL PLAINS THROUGH
SUNDAY FOLLOWED BY A STRONG COLD FRONT AND A RETURN TO SEASONAL
TEMPERATURES MONDAY AND TUESDAY. AFTER A BRIEF WARM UP
WEDNESDAY...ARCTIC HIGH PRESSURE MOVES INTO THE NRN PLAINS AND UPPER
MIDWEST AND BACKS INTO NEB PRODUCING COOLER WEATHER THURSDAY AND
FRIDAY.

THE MODELS SHOW NO BREAK DOWN IN THE DRY WEATHER PATTERN WHICH IS
NOW IN ITS 4TH WEEK. THE RIDGE ACROSS THE SWRN U.S. IS TOO STRONG
FOR THIS TIME OF YEAR.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SAT OCT 25 2014

THE MAIN FORECAST CHALLENGES OVER
THE NEXT 24 HOURS ARE TEMPERATURES TODAY...THEN THE POTENTIAL FOR FOG
TONIGHT. FOR TODAY...WEAK HIGH PRESSURE WILL TRACK ACROSS SOUTH
DAKOTA INTO NWRN IOWA. THE WEAK BACK DOOR FRONTAL BOUNDARY WILL
STALL ACROSS THE NORTHERN AND EASTERN CWA THIS AFTERNOON...LEADING
TO A DECENT SPREAD IN TEMPS FROM THE NORTHEASTERN CWA TO THE
SOUTHWEST. AS WAS THE CASE YESTERDAY...THE MAV GUIDANCE CONTINUES TO
BE WARMER WITH RESPECT TO HIGHS COMPARED TO THE MET GUIDANCE...WITH
A DECENT SPREAD NOTED WITH TDYS FORECAST NUMBERS. FOR HIGHS
TODAY...UTILIZED A BLEND BETWEEN THE MAV AND MET NUMBERS...WEIGHTED
MORE TOWARD THE WARMER MAV GUIDANCE AS IT DID MUCH BETTER WITH HIGHS
YESTERDAY. ALSO...BASED ON H85 TEMPS DEPICTED IN THE GFS AND NAM
SOLNS FOR THIS AFTERNOON...WEIGHTING HIGHS TOWARD THE WARMER MAV
NUMBERS SEEMED LIKE A BETTER FIT TO THE FCST H85 TEMPS. HIGHS TODAY
WILL RANGE FROM AROUND 73 IN THE NORTHEAST...TO 83 IN THE FAR
SOUTHWEST. FOR TONIGHT...RIDGING ALOFT WILL BEGIN TO TRANSITION EAST
INTO THE UPPER MISSISSIPPI VALLEY. FURTHER WEST...A TROUGH OF LOW
PRESSURE ALOFT WILL PUSH INTO WEST COAST OF THE CONUS. WITH
SOUTHWESTERLY FLOW ALOFT DEVELOPING ACROSS THE ROCKIES AND HIGH
PLAINS...A SURFACE TROUGH OF LOW PRESSURE WILL DEEPEN ALONG THE
FRONT RANGES OF COLORADO AND WYOMING...AS WELL AS THE NEBRASKA
PANHANDLE. SERLY WINDS WILL INCREASE OVERNIGHT EAST OF THE
DEVELOPING TROUGH AND WEST OF EXITING HIGH PRESSURE...PUSHING LOW
LEVEL MOISTURE INTO SOUTHERN AND EASTERN PORTIONS OF THE CWA
OVERNIGHT. BL RH WILL BEGIN TO APPROACH 100 PERCENT IN THE SERN AND
EASTERN CWA TOWARD 12Z SUNDAY. WITH DECENT RADIATIVE COOLING
EXPECTED SATURDAY EVENING...FOLLOWED BY LOW LEVEL MOISTURE ADVECTION
OVERNIGHT...WILL BE A GOOD SETUP FOR FOG IN THE SOUTH AND
SOUTHEASTERN AND EASTERN CWA OVERNIGHT TONIGHT. INHERITED FCST HAD
THIS MENTIONED AND ONLY MADE SOME MINOR ADJUSTMENTS SPATIALLY TOWARD
THE LATEST NAM12 BL RH FORECAST.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 328 AM CDT SAT OCT 25 2014

SUNDAY THROUGH TUESDAY MORNING...TWO FEATURES WILL AFFECT THE MAX
TEMPERATURE FORECAST SUNDAY. ONE IS THE COLD FRONT MOVING IN FROM
THE WEST AND THE OTHER IS THE POTENTIAL FOR FOG SUNDAY MORNING WHICH
COULD SHORTEN THE HEATING CYCLE BY 1 TO 2 HOURS. THE NAM IS THE
FLAGSHIP MODEL FOR FOG FORECASTING. LOW PRESSURE ON THE NRN HIGH
PLAINS IS EXPECTED TO DRAW MOISTURE NORTH AND WEST LATE SATURDAY
NIGHT. BOUNDARY LAYER WINDS BECOME LIGHT SUNDAY MORNING WITH A TROF
OVER THE FCST AREA. DRY AIR ALOFT SHOULD PRODUCE AT LEAST PATCHY FOG
ACROSS THE SOUTHWEST AND INTO PARTS OF NCNTL NEB. BURNOFF SHOULD
OCCUR 15Z-16Z.

THE LATEST 00Z SOUNDING IN NORTHWEST FLOW FRIDAY EVENING SHOWED A
MIXING HEIGHT TO 750 MB AT LBF. DENVER MIXED TO 550MB AND SET A NEW
RECORD HIGH. RAPID CITY MIXED TO 800 MB. THE FORECAST FOLLOWS THE
LATEST LOCAL CLIMO FOR A HIGH IN THE LOWER 80S CNTL AND WEST...70S
IN THE NORTHWEST WITH COOL AIR MIXING DOWN...70S ARE FORECAST IN THE
EAST ALONG A PLUME OF RICH BOUNDARY LAYER MOISTURE. THERE IS SOME
COOL AIR MOVING INTO THE CNTL ZONES DURING THE AFTN WHICH WOULD
LIMIT WARMER READINGS.

THE PACIFIC FRONT MOVES THROUGH SUNDAY NIGHT AND IT IS WEAK. WINDS
DROP OFF TO LESS THAN 10 MPH AND ONLY INCREASE TO 15 TO 20 MPH
MONDAY. THE PACIFIC HIGH SHOULD BE ACROSS THE CNTL ROCKIES TUESDAY
MORNING AND PRODUCING LOWS IN THE 20S ACROSS WRN NEB.

RAIN CHANCES WITH THE APPROACH OF A -20C TO -25C COLD POOL ALOFT
MONDAY LOOK PALTRY. THE ECM WAS THE WETTEST MODEL WITH POCKETS OF
QPF UP TO 0.15 OF AN INCH CENTERED OVER THE SANDHILLS. THE MODELS
SHOW A SERIOUS SHORTAGE OF MOISTURE IN THE 850-700 MB LEVELS. IT
LOOKS LIKE THE COLD FRONT SUNDAY NIGHT HAS DRIVEN THE MOISTURE SOUTH
AND THE COLD AIR IN THE LOWER LEVELS IS INSUFFICIENT TO COOL
SOUNDING PROFILES TO ANYWHERE NEAR SATURATION.

WEDNESDAY THROUGH FRIDAY...THE ECM...GFS AND GEF MODELS ARE IN VERY
GOOD AGREEMENT PULLING DOWN ARCTIC HIGH PRESSURE THROUGH THE NRN
PLAINS AND UPPER MIDWEST. THIS WOULD BACK INTO THE FCST AREA
THURSDAY. LOW PRESSURE ON THE NRN HIGH PLAINS WILL FOCUS THE WARMER
TEMPERATURES ACROSS WRN NEB...60S FOR HIGHS WHILE THE EAST REMAINS
IN THE 50S. THE ECM AND GFS SUGGEST STRATUS COULD FORM FRIDAY
MORNING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 646 AM CDT SAT OCT 25 2014

FOR THE KLBF TERMINAL...CLEAR SKIES ARE LIKELY OVER THE NEXT 24
HOURS WITH SOUTHEASTERLY WINDS AT UNDER 10 KTS. THERE IS A SMALL
THREAT FOR PATCHY FOG IN THE VICINITY OF THE KLBF TERMINAL
OVERNIGHT TONIGHT. WITH THE THREAT BEING SMALL ATTM...WILL FORGO
MENTION IN THE 12Z TAF. FOR THE KVTN TERMINAL...CLEAR SKIES ARE
LIKELY OVER THE NEXT 24 HOURS WITH WINDS FROM THE SOUTHEAST AT
UNDER 10 KTS.

&&

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

$$

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






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