Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 082338 AAA
AFDLBF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
638 PM CDT TUE JUL 8 2014

.SYNOPSIS...
ISSUED AT 316 PM CDT TUE JUL 8 2014

H5 ANALYSIS THIS MORNING REMAINS LARGELY UNCHANGED FROM
24 HOURS AGO. A BROAD TROUGH OF LOW PRESSURE EXTENDED FROM THE HUDSON
BAY SWD INTO THE THE UPPER MIDWEST. A JET STREAK EXTENDED FROM
MANITOBA SEWD TO SRN WISCONSIN...AND INTO NORTHERN PORTIONS OF NEW
YORK. HT FALLS WERE MOST PREVALENT ACROSS THE UPPER MISSISSIPPI
VALLEY AND UPPER MIDWEST WITH 50 TO 90 METER FALLS NOTED FROM
OMAHA...EWD TO OHIO AND SRN MICHIGAN. UPSTREAM OF THE TROUGH...A LOW
AMPLITUDE RIDGE CONTINUES ACROSS THE WESTERN CONUS WITH BROAD NWRLY
FLOW NOTED OVER THE NRN ROCKIES...CENTRAL AND NORTHERN PLAINS. AT
THE SURFACE...HIGH PRESSURE WAS ANCHORED FROM NERN MONTANA...SSEWD
INTO NERN COLORADO. SKIES WERE PARTLY CLOUDY WITH SOME SCATTERED
CUMULUS CLOUDS NOTED ACROSS THE EASTERN HALF OF THE FORECAST AREA.
AS OF 3 PM CDT...TEMPERATURES RANGED FROM 78 AT VALENTINE TO 84 AT
NORTH PLATTE.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 316 PM CDT TUE JUL 8 2014

FORECAST CONCERN IN THE SHORT TERM DEALS WITH
CONVECTION CHANCES EARLY WEDNESDAY MORNING AND AGAIN LATE
AFTERNOON.  LOW LEVEL JET AND INCREASING H7 THETA-E WILL WORK IN
CONJUNCTION WITH AN APPROACHING MID LEVEL DISTURBANCE PASSING THROUGH
NORTHWEST FLOW TO SPARK OFF ELEVATED CONVECTION.  ISOLATED TO
SCATTERED COVERAGE CAN BE EXPECTED AFTER MIDNIGHT FROM NORTHWEST
NEBRASKA SOUTHEAST THROUGH MUCH OF THE CENTRAL SANDHILLS AND
EVENTUALLY INTO CUSTER COUNTY.  SEVERE WEATHER IS NOT ANTICIPATED AS
THE ATMOSPHERE REMAINS WEAKLY UNSTABLE THROUGH THE OVERNIGHT. STORMS
TO CONTINUE WEDNESDAYS AS THERE/S STRONG SUPPORT FROM THE NEAR/SHORT
TERM DETERMINISTIC SOLUTIONS THAT THIS ACTIVITY WILL SPREAD
SOUTHEAST THROUGH THE MORNING AND DISSIPATE BY EARLY AFTERNOON
OVER EASTERN PORTIONS OF THE CWA.

FOR OVERNIGHT LOWS TONIGHT...BC MET/MAV BLEND HAS BEEN ACCEPTABLE
COMPROMISE LATELY...GIVEN THIS BLEND...WILL GO WITH LOWS IN THE
MID TO UPPER 50S FOR MOST LOCATIONS.

WEDNESDAY AFTERNOON...LOW PRESSURE OFF THE LEE OF THE ROCKIES WILL HELP
ADVECT TD/S BACK INTO THE UPPER 50S TO LOWER 60S OVER MUCH OF THE
CENTRAL SANDHILLS AND POINTS SOUTH.  THE HIGHER BL MOISTURE COMBINED
WITH STRONG BOUNDARY LAYER HEATING AND STEEP 0-3KM LAPSE RATES OF
7.5-9.0 C/KM WILL PROMOTE A MODERATELY UNSTABLE ATMOSPHERE CAPABLE
OF PRODUCING STRONG TO SEVERE STORMS BY LATE AFTERNOON.  ESPECIALLY
SINCE THE ATMOSPHERE IS PROJECTED TO BE DEEPLY SHEARED WITH UPWARDS
TO 50KTS 0-6 KM BULK SHEAR BY 00Z THURSDAY.  LATEST GUIDANCE FAVORS
THIS ADDITIONAL STORM INITIATION NORTHEAST OF THE SURFACE
LOW...WHICH IS SHOWN TO BE CENTERED NEAR YUMA COUNTY COLORADO FROM
21-00Z.  HAVE CHANCE POP WORDING IN THE FORECAST FOR SOUTHWEST
NEBRASKA AFTER 21Z...WITH SLIGHT CHANCES ELSEWHERE.  IF STORMS ARE
REALIZED...LARGE HAIL AND DAMAGING WIND WOULD BE THE PRIMARY THREATS
AS LARGE LCL HEIGHTS WOULD MITIGATE THE SUPERCELLULAR TORNADO
THREAT.

HIGHS FOR WEDNESDAY ARE A BLEND OF AVAILABLE NUMERICAL
GUIDANCE...BUT THEN NUDGED SLIGHTLY COOLER WHERE MORNING/EARLY
AFTERNOON CLOUDS AND SHOWERS ARE EXPECTED /NORTH CENTRAL NEBRASKA/.
HIGHS WERE NUDGED UP A TOUCH ACROSS SOUTHWEST NEBRASKA WHERE FULL
SUN IS ANTICIPATED.  THUS A TEN DEGREE RANGE OF HIGH TEMPERATURES IS
POSSIBLE...WITH LOWER 80S ACROSS NORTH CENTRAL NEBRASKA AND EASTERN
PORTIONS OF THE CWA...LOWER 90S FOR OUR FAR SOUTHWEST.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 316 PM CDT TUE JUL 8 2014

WEDNESDAY NIGHT THROUGH FRIDAY NIGHT...THROUGH THE END
OF THE WEEK...THE MAIN FORECAST CHALLENGE WILL BE THE THREAT FOR
THUNDERSTORMS EACH DAY AS WE CONTINUE TO BE IN NORTHWESTERLY FLOW
ALOFT. FOR WEDNESDAY NIGHT...CONVECTION IS EXPECTED TO BE ONGOING
ACROSS THE PANHANDLE...EASTERN COLORADO AND EASTERN WYOMING BY WEDS
EVENING INVOF A SURFACE TROUGH OF LOW PRESSURE AND INSTABILITY AXIS.
THIS ACTIVITY WILL TRANSITION TO THE SOUTHEAST WEDS NIGHT WITH NWRLY
WINDS ALOFT...AND SHOULD HAVE A DECENT CHANCE OF SUSTAINING ITSELF
OVERNIGHT THANKS TO A LOW LEVEL JET WHICH IS FOCUSED ACROSS
SOUTHWESTERN AND SOUTH CENTRAL NEBRASKA. WITH THIS IN MIND...I HAVE
PAINTED MY HIGHEST POPS ACROSS THE SRN HALF OF THE CWA FOR WEDS
NIGHT WITH SLIGHT CHANCES ACROSS THE NORTH. ATTM...CONFIDENCE IN
PCPN IS LOW...ESPECIALLY IN THE NORTH AS LITTLE OR NO TS INITIATION
IS EXPECTED OVER SOUTH CENTRAL SD WEDS EVE.

ANOTHER ROUND OF THUNDERSTORMS WILL BE POSSIBLE ON THURSDAY AS A
SECOND SHORTWAVE TRACKS ACROSS THE CENTRAL AND NORTHERN ROCKIES.
CONVECTION WILL BE ENHANCED INITIALLY ALONG A SURFACE TROUGH
ANCHORED OVER WESTERN NEBRASKA...EASTERN WYOMING...AND WESTERN SOUTH
DAKOTA. ATTM...INITIATION IS EXPECTED OVER NORTHWESTERN NEBRASKA AND
SWRN SD INVOF OF THE WEAKEST CAPPING. WITH INITIATION FURTHER NORTH
THURSDAY...MOST OF THE FORECAST AREA SHOULD SEE BETTER CHANCES FOR
PCPN THURSDAY NIGHT GIVEN THE WEST NORTHWESTERLY STEERING WINDS. IN
ADDITION...THE MODELS DEVELOP A STRONGER LOW LEVEL JET THURSDAY
NIGHT...WHICH WILL HELP TO SUSTAIN THUNDERSTORMS OVERNIGHT.

FRIDAY WILL BE DRY WITH A SURFACE FRONT SOUTH OF THE FORECAST
AREA...HOWEVER BY FRIDAY NIGHT...ANOTHER UPPER LEVEL DISTURBANCE
WILL APPROACH THE CENTRAL AND NORTHERN ROCKIES. AS THIS APPROACHES
THE HIGH PLAINS FRIDAY EVENING...ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA.

SATURDAY THROUGH TUESDAY...AFTER FRIDAY NIGHT...THE UPPER AIR
PATTERN WILL AMPLIFY ACROSS THE CONUS AS A DEEP TROUGH OF LOW
PRESSURE DROPS SOUTH INTO THE GREAT LAKES AND UPPER MIDWEST. RIDGING
WILL AMPLIFY ACROSS THE WESTERN CONUS WHICH WILL PUT THE FORECAST
AREA IN NORTHWESTERLY FLOW ALOFT FOR EARLY NEXT WEEK. CONVECTION
WILL CONTINUE TO INITIATE OVER THE FRONT RANGES OF COLORADO AND
WYOMING...HOWEVER STEERING WINDS WILL KEEP THE BEST CHANCES FOR
PRECIPITATION ACROSS THE WEST AND SOUTHWEST EARLY NEXT WEEK. AS WE
HEAD INTO THE MIDDLE AND END OF NEXT WEEK...THE ECMWF AND GFS SOLNS
DIVERGE IN THEIR SOLUTIONS A BIT. THE ECMWF AMPLIFIES THE PATTERN
FURTHER WITH A DEEP TROUGH OF LOW PRESSURE ACROSS THE EASTERN CONUS
AND A RIDGE WHICH RETROGRADES WEST TO ALONG THE WEST COAST OF THE
CONUS BY THE END OF THE WEEK. IF THIS SOLN WAS TO PLAY OUT...HIGHS
MAY STRUGGLE TO GET OUT OF THE LOWER 70S NEXT WEEK. FOR
NOW...LIMITED HIGHS TO THE UPPER 70S TO AROUND 80 NEXT TUESDAY AS
THE GFS IS ADVERTISING A LOWER AMPLITUDE PATTERN LATE NEXT WEEK
WHICH IS INDICATIVE OF WARMER TEMPS COMPARED TO THE ECMWF.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 638 PM CDT TUE JUL 8 2014

VFR IS EXPECTED ALL AREAS OVERNIGHT AND WEDNESDAY.

A WEAK DISTURBANCE ACROSS MT WILL MOVE INTO NCNTL NEB AND PRODUCE
SCATTERED SHRA AND ISOLATED THUNDERSTORMS 06Z-18Z. THEREAFTER
ISOLATED STRONG OR SEVERE STORMS MAY DEVELOP ACROSS SWRN NEB ALONG
AND WEST OF A LINE FROM KAIA-KMCK.

&&

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

$$

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






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