Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 301145
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
645 AM CDT TUE SEP 30 2014

.SYNOPSIS...
ISSUED AT 335 AM CDT TUE SEP 30 2014

H5 ANALYSIS FROM EARLIER THIS EVENING...HAS A VERY
ACTIVE PATTERN ACROSS NORTHERN PORTIONS OF NORTH AMERICA WITH CLOSED
LOWS OVER THE ALEUTIANS...NORTHERN ALASKA...AND NORTHERN PORTIONS OF
HUDSON BAY. ACROSS SOUTHERN CANADA AND THE LOWER 48...RIDGING WAS
PRESENT FROM EASTERN TX NORTH INTO SRN MANITOBA. SHORTWAVE TROUGHS
WERE PRESENT OVER THE NORTHERN GREAT LAKES...CENTRAL COLORADO AND
SWRN MONTANA. AS OF 3 AM CDT...WV IMAGERY HAS THE CENTRAL COLORADO
WAVE...NOW OVER SERN WYOMING. AT THE SURFACE...STRONG LOW PRESSURE
WAS PRESENT OVER CENTRAL PORTIONS OF THE NEBRASKA PANHANDLE. SHOWERS
AND THUNDERSTORMS CONTINUE ROUGHLY ALONG A LINE FROM AROUND BROKEN
BOW....TO NORTH CENTRAL CHERRY COUNTY. OTHER SHOWERS WERE LOCATED
OVER THE EASTERN PANHANDLE. ALL ACTIVITY WAS MOVING TO THE NORTH
NORTH NORTHWEST. AS OF 3 AM CDT...TEMPERATURES RANGED FROM 55 AT
OGALLALA AND IMPERIAL TO 65 AT ONEILL AND BROKEN BOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT TUE SEP 30 2014

THE MAIN FORECAST CHALLENGES TODAY ARE THE THREAT FOR
WINDS...ESPECIALLY OVER NORTHERN PORTIONS OF THE FORECAST
AREA...AS WELL AS PRECIPITATION CHANCES. LOW PRESSURE WILL TRACK
TO THE NORTH NORTHEAST INTO SWRN SD...THEN NORTH CENTRAL SD BY 00Z
WEDNESDAY. AS THIS SURFACE LOW TRACKS NORTH...STRONG WESTERLY
GRADIENT WINDS WILL DEVELOP ACROSS THE NORTHEASTERN NEBRASKA
PANHANDLE AND PORTIONS OF NORTH CENTRAL NEBRASKA LATER THIS
MORNING INTO THE AFTERNOON HOURS. BUFKIT FORECAST SOUNDINGS AT
PINE RIDGE AND VALENTINE ARE INDICATING WINDS JUST ABOVE THE
BOUNDARY LAYER APPG 45 TO 55 MPH THIS MORNING...DIMINISHING TO 40
TO 50 MPH THIS AFTERNOON. WITH THIS IN MIND...WILL HOIST A WIND
ADVISORY FOR SHERIDAN COUNTY...EAST TO CHERRY AND KEYA PAHA
COUNTIES. THE PRESSURE GRADIENT WILL RELAX ACROSS NORTHERN
NEBRASKA DURING THE LATE AFTERNOON HOURS...HOWEVER BUFKIT
SOUNDINGS CONTINUE TO INDICATE DECENT MIXING THROUGH EARLY
EVENING. WITH THIS IN MIND...WILL START THE ADVISORY AT 8 AM CDT
AND KEEP THE ADVISORY GOING THROUGH 7 PM CDT. PRECIPITATION
CHANCES ARE A SECOND FORECAST CHALLENGE TODAY. WRAP AROUND PCPN
WILL BE A THREAT OVER THE NORTHERN PANHANDLE AND WESTERN PORTIONS
OF NORTH CENTRAL NEBRASKA LATER THIS MORNING. WITH SURFACE
HEATING...WE COULD SEE SOME ISOLATED SHRAS AND TSRAS RE DEVELOP
UNDERNEATH THE COLD POOL ALOFT THIS AFTERNOON IN THESE SAME AREAS.
FURTHER SOUTH...WESTERLY WINDS WILL FORCE THE DRYLINE INTO
CENTRAL...THEN EASTERN NEBRASKA LATER THIS AFTERNOON. ALONG AND
EAST OF THIS LINE...THUNDERSTORMS ARE EXPECTED TO DEVELOP. ATTM
BASED ON THE LATEST NAM AND GFS SOLNS...THE GREATEST THREAT FOR
STORMS...WILL BE ACROSS THE FAR NORTHEASTERN ZONES...WITH THE
SEVERE THREAT BEING CONFINED TO EASTERN BOYD...EASTERN HOLT AND
WHEELER COUNTIES. ATTM...THE MAIN SEVERE MODE WILL BE WINDS AND
HAIL...AS THE TORNADO THREAT WILL BE FARTHER NORTH AND NORTHEAST
OVER SOUTH DAKOTA WHERE TURNING OF THE LOW LEVEL WINDS WILL BE
GREATEST. HIGHS TODAY WILL RANGE FROM THE LOWER 60S UNDER THE COLD
POOL IN THE NORTHWEST...TO THE UPPER 70S IN THE SOUTHWEST AND
EAST. DECENT SUBSIDENCE WILL DEVELOP TONIGHT BEHIND THE EXITING
DISTURBANCE...WHICH WILL LIFT FROM NORTHERN SOUTH DAKOTA INTO SRN
MANITOBA. DRY CONDITIONS TONIGHT...WILL BE TEMPORARY THOUGH...AS
ANOTHER UPPER LEVEL TROUGH OF LOW PRESSURE WILL APPROACH THE
REGION ON WEDNESDAY INTO WEDNESDAY NIGHT.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 335 AM CDT TUE SEP 30 2014

THE FOCUS OF THE EXTENDED DISCUSSION IS ON COOL UNSETTLED
CONDITIONS MID-WEEK...BUT THEREAFTER A WARMING AND DRYING TREND IS
ANTICIPATED.

THE LONG RANGE MODELS ARE IN GOOD AGREEMENT DEPICTING SPLIT UPPER
FLOW ACROSS THE WESTERN AND CENTRAL CONUS ON WEDNESDAY.  THE PATTERN
WILL FAVOR THE PASSAGE OF A MID LEVEL TROUGH AND ATTENDANT COLD
FRONT...WHICH WILL SERVE AS A FOCUS FOR SHOWER AND STORM DEVELOPMENT
WEDNESDAY AFTERNOON THROUGH MIDDAY THURSDAY.  WITH FORMIDABLE
DYNAMICS AND MOISTURE IN PLACE...MODEL GENERATED QPF RAMP UP LATE
WEDNESDAY INTO EARLY THURSDAY.  THE GFS...NAM...AND ECMWF ALL
GENERATE RAINFALL AMOUNTS OF A HALF INCH OR GREATER OVER A LARGE
PORTION OF THE FORECAST AREA...WITH THE CONSENSUS OF THE HEAVIEST
QPF OCCURRING GENERALLY DURING THE 06Z-12Z TIME PERIOD THURSDAY
ACROSS THE HEART OF THE SANDHILLS.  A FAIR BIT OF COOLING ALOFT
ASSOCIATED WITH THE TROUGH IS ANTICIPATED AS WELL...THUS A
CONVECTIVE ELEMENT IS POSSIBLE.  BUFR SOUNDINGS SHOW SUFFICIENT CAPE
FOR THUNDER THROUGH 06Z THURSDAY ACROSS MUCH OF THE SANDHILLS AND
POINTS SOUTH.

THE NORTHERN STREAM WILL REMAIN ACTIVE AS WELL...FORCING AN
ADDITIONAL TROUGH AND STRONG COLD FRONT THROUGH THE NORTHERN PLAINS
LATE WEEK.   THE GFS AND ECMWF ARE DIFFERING IN THE AMOUNT OF
COOLING...BUT BOTH SHOW SUB 0C H85 TEMPS BY 12Z FRIDAY MORNING.
LOWER TO MID 30S SFC LOWS ARE POSSIBLE FRIDAY AND ESPECIALLY
SATURDAY MORNING.  A SIDE NOTE...THE ECMX MOS GUIDANCE IS SUGGESTING
26 AND 29 FAHRENHEIT AT NORTH PLATTE AND VALENTINE RESPECTIVELY
SATURDAY MORNING.  FROST WILL BE A CONCERN.

BEYOND SATURDAY MORNING...RISING HEIGHTS AND WAA ASSOCIATED WITH A
BUILDING WESTERN CONUS RIDGE WILL HELP PUSH TEMPERATURES UP FOR THE
WEEKEND AND EARLY NEXT WEEK.  A WEAK FRONT MAY COOL HIGHS SUNDAY A
FEW DEGREES COMPARED TO SATURDAY...BUT WITH THAT...HIGHS THIS
WEEKEND AND EARLY NEXT WEEK SHOULD REMAIN SEASONAL /IN THE LOWER TO
MID 70S/ WITH LOWS IN THE 40S. RAIN CHANCES REMAIN ABSENT FROM THE
FORECAST THIS WEEKEND AND BEYOND AS WIDESPREAD KINEMATIC FORCING FOR
PRECIPITATION IS LACKING.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 645 AM CDT TUE SEP 30 2014

TRONG WINDS ARE LIKELY OVER NORTHERN NEBRASKA TODAY. AT THE KVTN
TERMINAL...SOUTHWESTERLY WINDS WILL GUST UP TO 35 KTS THIS
AFTERNOON...DIMINISHING TO AROUND 10 KTS TONIGHT. WINDS MAY GUST UP
TO 25 KTS AT THE KLBF TERMINAL THIS AFTERNOON...BEFORE DIMINISHING
TO UNDER 10 KTS TONIGHT. SKIES WILL BE MOSTLY CLOUDY AT THE KVTN
TERMINAL WITH CIGS RANGING FROM 3000 TO 7000 FT AGL THIS MORNING.
CIGS WILL INCREASE TO 10000 FT AGL THEREAFTER. FOR THE KLBF
TERMINAL...EXPECT GIGS AROUND 25000 FT AGL TODAY...LOWERING TO 12000
FT AGL TONIGHT.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR
NEZ004>006-094.

&&

$$

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





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