Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 210852
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
352 AM CDT SUN SEP 21 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT SUN SEP 21 2014

TODAY AND TONIGHT...PACIFIC HIGH PRESSURE ACROSS THE NRN HIGH
PLAINS WILL BUILD SOUTHEAST INTO THE MIDSOUTH TODAY AND TONIGHT.
LIGHT WINDS ARE EXPECTED TODAY. AS THE HIGH DROPS SOUTH TONIGHT A
LOW LEVEL JET WILL DEVELOP AND STRENGTHEN TO 30-40KT BY MONDAY
MORNING. THIS WOULD KEEP THE WRN ZONES WARMER THAN THE EAST
OVERNIGHT WITH 40S EAST AND 50S WEST.

HIGHS TODAY CONTINUE TO FOLLOW THE WARM SIDE OF THE MULTIMODEL
ENSEMBLE EXCEPT WEST WHERE MID AND HIGH CLOUDS WOULD KEEP HIGHS OFF
THE WARM SIDE. THE RAP...GEM AND ECM SUGGEST THE MID LEVEL
CLOUDS...NOT SHOWN IN THE OTHER MODELS...MAY BE ASSOCIATED WITH
FRONTOGENESIS. ISOLATED SHOWERS OR THUNDERSTORMS MAY DRIFT INTO WRN
NEB LATE TONIGHT WITH THE APPROACH OF AN UPPER LOW ACROSS THE NRN
ROCKIES.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 350 AM CDT SUN SEP 21 2014

...THE MAIN PLAYER FOR THE FORECAST THIS NEXT WEEK WILL BE HOW THE
UPPER LOW NOW OVER CALIFORNIA WILL MOVE ACROSS THE CENTRAL PART OF
THE CONUS.

AN UPPER LEVEL RIDGE SITTING FROM THE SOUTHWEST INTO THE CENTRAL
PLAINS WILL HELP TO STEER THE PATH OF THE CALIFORNIA UPPER LOW OVER
THE NEXT WEEK AS IT TRIES TO PROGRESS EASTWARD. MODELS ARE IN GOOD
AGREEMENT WITH THE NOW CLOSED LOW OPENING UP BY MONDAY AS IT MOVES
TOWARDS THE CENTRAL ROCKIES. THEN THROUGH MONDAY NIGHT THE SYSTEM
WILL PROGRESS EASTWARD...WITH THE UPPER LOW CENTER LOOKING TO PASS
SOMEWHERE ACROSS SOUTH DAKOTA. THE SYSTEM WILL THEN MORPH INTO A
RATHER AMPLIFIED SHORTWAVE TROUGH...WHICH BY WEDNESDAY WILL EXTEND
FROM THE NORTHERN PLAINS INTO TEXAS. THE TROUGH WILL BE SLOW TO MOVE
OUT OF THE REGION...MEANWHILE THE PATTERN ACROSS THE PACIFIC AND
WESTERN CONUS BECOMES VERY AMPLIFIED AS A DEEP LONGWAVE TROUGH MOVES
TOWARDS THE WESTERN CONUS...FURTHER AMPLIFYING THE RIDGE OVER THE
WESTERN HALF OF THE CONUS. THIS RIDGE WILL BUILD INTO THE PLAINS BY
LATER IN THE WEEK...ENDING THE NORTHWEST INFLUENCE LOCALLY.
AGAIN...MODELS HAVE GOOD AGREEMENT IN HOW THIS WILL PLAY OUT SO
HAVE FAIR CONFIDENCE IN THIS FORECAST PACKAGE.

MOISTURE WILL INCREASE AS THE SOUTHERLY FLOW STRENGTHENS
THROUGHOUT THE DAY MONDAY AS THE UPPER LEVEL SYSTEM MOVES TOWARD
THE REGION. BY MONDAY AFTERNOON...PRECIPITABLE WATER VALUES LOOK
TO INCREASE TO AN INCH OR GREATER ACROSS MUCH OF THE FORECAST AREA
WHICH IS 125-175 PERCENT OF NORMAL. THE DEEP LIFT AND MOISTURE IS
SLIGHTLY DELAYED FROM PRIOR FORECAST RUNS SO DID SLOW BRINGING
PRECIPITATION EASTWARD ON MONDAY. THROUGH THE NOON HOUR...AREAS
EAST OF HIGHWAY 83 SHOULD STAY DRY WITH SLIGHT CHANCES TO THE
WEST. RAIN CHANCES WILL INCREASE THROUGH THE AFTERNOON...WITH THE
HIGHEST CHANCES ACROSS THE LOCAL AREA COMING MONDAY NIGHT AS THE
LOW LEVEL JET PICKS UP...COINCIDENTALLY WHEN THE BETTER LIFT FROM
THE UPPER SYSTEM IS PASSING BY. THERE ISN/T AN EXTRAORDINARY AMOUNT
OF CAPE TO WORK WITH...BUT THERE WILL BE ENOUGH TO HAVE
THUNDERSTORM MENTIONS IN THE FORECAST. ALSO...AS SHEAR INCREASES
WITH THE WINDS PUSHING AROUND THE UPPER LEVEL SYSTEM CANNOT RULE
OUT A FEW STRONG OR PERHAPS EVEN SEVERE STORMS MONDAY AFTERNOON
AND EVENING.

A PACIFIC FRONT WILL MOVE THROUGH THE REGION ON TUESDAY WHICH WILL
SWITCH WINDS TO THE WEST...AND THUS CUTTING OFF THE SOUTHERLY
FLOW. A FAIRLY STRONG PV ANOMALY ROTATING AROUND THE UPPER LOW
WILL MOVE ACROSS NEBRASKA TUESDAY AFTERNOON...AND WITH GOOD LIFT
AND AND MOISTURE IN PLACE SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO MOVE INTO THE STATE FROM THE WEST BY THE AFTERNOON HOURS.
ALTHOUGH THE AIRMASS WON/T BE TERRIBLY COOL...CLOUD COVER AND
PRECIPITATION WILL KEEP TEMPERATURES DOWN ON MONDAY AND
TUESDAY...WITH HIGHS IN THE 70S /MAYBE TO AROUND 80/.

FOR THE END OF THE WEEK...ALTHOUGH THE MID-WEEK SYSTEM MOVES EAST
AND RIDGING ALOFT BUILDS IN...THE MODELS ARE NOW SHOWING THE
UPPER LOW CIRCLING AROUND THE RIDGE OVER THE NORTH CENTRAL PART OF
THE CONUS AND MAKES ITS WAY BACK INTO THE CENTRAL PLAINS. THIS
WOULD KEEP THE WARMER AIR UNDER THE RIDGE PREDOMINANTLY WEST AND
NORTH OF THE AREA...AS THE AXIS WILL LIE FROM BAJA CALIFORNIA
THROUGH THE CENTRAL ROCKIES AND INTO THE DAKOTAS. ALTHOUGH THERE
COULD BE A FEW SHOWERS AND MAYBE THUNDERSTORMS...THE LIFT ISN/T
TOO SUBSTANTIAL UNTIL GETTING CLOSER TO SUNDAY SO PRECIPITATION
CHANCES HAVE BEEN LIMITED IN THE OUTER PERIODS OF THE FORECAST AT
THIS TIME.

AS FOR TEMPERATURES THROUGH THE MIDDLE AND LAST PARTS OF THE
WEEK...WITH THE WARMER AIR UNDER THE RIDGE STAYING WEST...AND THE
COOLER AIR STAYING ACROSS THE GREAT LAKES INTO OHIO RIVER REGIONS
WILL KEEP TEMPERATURES NEAR NORMAL MOST DAYS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1224 AM CDT SUN SEP 21 2014

SHORT RANGE PROJECTIONS DO NOT INDICATE ANY POTENTIAL FOR FG/BR
TONIGHT OR EARLY SUNDAY. IF THE TEMPERATURES WERE TO GET INTO THE
LOWER 40S...PATCHY FOG COULD FORM IN VALLEYS AND OTHER LOW-LYING
AREAS IN CENTRAL AND SOUTHWEST NEBRASKA (BBW...LBF...OGA...MHN AND
TIF. CURRENT INDICATIONS...CONSIDERING DEWPOINTS AROUND THE
AREA...ARE THAT TEMPERATURES WILL REMAIN IN THE 45 TO 50 RANGE IN
THOSE AREAS. HOWEVER...NEAR THE NEBRASKA-SOUTH DAKOTA BORDER (ONL...
ANW AND VTN) TEMPERATURES MAY FALL TO AROUND 40. FOR FOG TO FORM IN
THAT AREA...TEMPERATURES WOULD PROBABLY NEED TO FALL INTO THE
UPPER 30S. SINCE THE PROBABILITY OF INSTRUMENT CONDITIONS IN
FG/BR...WE WILL NOT INCLUDE IT IN THE TERMINAL FORECASTS FOR VTN OR
LBF.


&&

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

$$

SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...CDC






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