Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 020512
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1212 AM CDT TUE SEP 2 2014

.SYNOPSIS...
ISSUED AT 321 PM CDT MON SEP 1 2014

AT 19Z...WATER VAPOR IMAGERY SHOWED A BROAD LONGWAVE TROUGH ACROSS
THE CENTRAL PART OF THE COUNTRY...WITH AND EMBEDDED SHORTWAVE TROUGH
MOVING OUT OF WYOMING AND INTO WESTERN NEBRASKA WITH SCATTERED
THUNDERSTORM ACTIVITY ASSOCIATED WITH IT ACROSS EASTERN
WYOMING...SOUTHWEST SOUTH DAKOTA AND NORTHWEST NEBRASKA. AT THE
SURFACE...WEAK FLOW WAS OBSERVED WITH HIGH PRESSURE LOCATED OVER THE
NORTHERN AND CENTRAL PLAINS. OFF AND ON SUNSHINE MOST PLACES HAS
ALLOWED TEMPERATURES TO CLIMB INTO THE 70S...AS A COOL AIRMASS
/850MB TEMPERATURES FROM 12Z SOUNDINGS AROUND 13C/ WAS SITUATED
ACROSS THE REGION.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 321 PM CDT MON SEP 1 2014

THUNDERSTORMS WILL BE POSSIBLE THROUGH THIS EVENING AS THE SHORTWAVE
TROUGH TO THE WEST OF THE LOCAL AREA PROGRESSES EASTWARD. THE
SHORTWAVE...ALONG WITH ADDITIONAL LARGE SCALE LIFT FROM THE AREA
BEING ON THE LEFT EXIT REGION OF AN UPPER LEVEL JET STREAK MOVING
INTO THE HIGH PLAINS FROM THE NORTHERN ROCKIES WILL COMBINE WITH
MARGINAL INSTABILITY /IN THE FORM OF 1500 J/KG MU CAPE/ TO HELP THE
DEVELOPMENT OF SHOWERS AND STORMS. LAPS SOUNDINGS AS OF 19Z SHOW THE
BOUNDARY LAYER HAS MIXED OUT...CREATING STEEP LOW LEVEL LAPSE RATES
ACROSS ALL OF WESTERN AND CENTRAL NEBRASKA...LEADING TO INVERTED-V
TYPE SOUNDINGS. STORMS HAVE BEEN ON THE INCREASE IN COVERAGE OVER
THE LAST HOUR...AND WILL EXPECT THIS ACTIVITY TO CONTINUE AND
INCREASE OVER THE NEXT FEW HOURS. EFFECTIVE SHEAR ACROSS THE AREA IS
MARGINAL...AT 25 TO 30KTS AND WITH MU CAPE ONLY ON THE ORDER OR 1000
TO 1500 J/KG...JUST NOT EXCITED ABOUT THE POTENTIAL FOR STRONG
STORMS. IF AN ISOLATED CELL IS ABLE TO GET A MORE INTENSE
UPDRAFT...COULD GET A PULSE TYPE STRONG TO SEVERE STORM WITH
DAMAGING WINDS BEING THE MAIN THREAT. THE SHORTWAVE WILL PASS INTO
EASTERN NEBRASKA AFTER MIDNIGHT AND WITH THE LARGE-SCALE FLOW
TURNING TO SUBSIDENCE BEHIND THE WAVE AND WITH THE AREA MOVING INTO
THE RIGHT EXIT REGION OF THE UPPER LEVEL JET STREAK...EXPECT SHOWERS
AND STORMS TO EXIT THE LOCAL AREA SHORTLY AFTER MIDNIGHT.

WITH SUBSIDENCE IN PLACE AND HIGH PRESSURE BUILDING IN AT THE
SURFACE...SKIES ARE EXPECTED TO CLEAR BY MORNING AND WITH LIGHT
WINDS...LOOKING AT ANOTHER CHILLY NIGHT ACROSS THE AREA. THE COOLER
TEMPERATURES WILL BE ACROSS THE WESTERN SANDHILLS AND INTO VALLEYS
ACROSS SOUTHWEST NEBRASKA WHERE SKIES WILL CLEAR EARLIER AND
RADIATIONAL COOLING IS HIGHEST WITH THE SETTLING BOUNDARY LAYER AIR.
LOOKING FOR LOWS IN THE 40S IN THESE AREAS...WITH LOW 50S ELSEWHERE.

FOR TUESDAY...THE UPPER LEVEL FLOW STARTS TO BECOME MORE
ZONAL...WHICH WILL START TO BRING WARMER AND MORE SEASONABLE AIR
INTO THE REGION. A GENERAL LACK OF ANY SOURCE OF LIFT AND MOISTURE
SHOULD LEAVE TUESDAY BEING A QUIET WEATHER DAY WITH MOSTLY CLEAR
SKIES AND WARMING TEMPERATURES. FORECAST SOUNDINGS FROM THE NAM SHOW
THE CLOSEST T/TD SPREAD OF 10C AROUND 700MB TUESDAY AFTERNOON WHICH
SUGGESTS SUNNY SKIES. WITH THE INCREASE IN WARM AIR AS 850MB
TEMPERATURES WARM BACK INTO THE 17-24C RANGE BY LATE TUESDAY
AFTERNOON...EFFICIENT MIXING OF THE BOUNDARY LAYER WOULD SUGGEST
HIGHS REACHING THE UPPER 70S THROUGH MID 80S.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 321 PM CDT MON SEP 1 2014

TUESDAY NIGHT THROUGH THURSDAY...

WARM AIR ADVECTION WILL CONTINUE WEDNESDAY WITH AN EXPANSIVE
THERMAL RIDGE ACROSS THE CENTRAL PLAINS. H85 TEMPS TO RANGE FROM
25 TO 30C. SOUTHERLY WINDS WILL BRING DEWPOINTS UP INTO THE
MID/UPPER 60S EAST AND SOUTHEAST WHILE FALLING TO THE UPPER
40S/LOWER 50S NORTHWEST DURING THE AFTN. HIGHS FORECAST NEAR
PREVIOUS FCST OF 92-95 DEGREES MOST LOCATIONS. UPPER FLOW ALSO
BECOMES SOUTHWEST AS POSITIVELY TILTED TROUGH MOVES ACROSS
SOUTHERN CANADA AND THE PAC NW. THIS WILL BRING A COLD FRONT
INTO WESTERN NEBRASKA WEDNESDAY NIGHT. THIS NOW AGREED UPON BY
ALL MODELS. THIS WILL BRING A COOLDOWN THURSDAY TO THE MID 70S
NORTHWEST TO THE LOWER 80S FAR SOUTH. BREEZY NORTH WINDS 15 TO 30
MPH BEHIND THE FRONT.

THURSDAY NIGHT THROUGH MONDAY...

RELATIVELY COOL TEMPERATURES WILL PERSIST FRIDAY INTO SATURDAY AS
HIGHS RANGE AROUND 70. A SLIGHT CHANCE FOR SHOWERS THURSDAY NIGHT
INTO FRIDAY NIGHT. AN UPPER TROUGH WILL DROP INTO THE WESTERN
CONUS AS A SURFACE TROUGH DEVELOP ALONG THE LEE OF THE ROCKIES.
THIS WILL BRING A RETURN SOUTHERLY FLOW SUNDAY AND MONDAY WITH
HIGHS WARMING TO THE MID/UPPER 70S SUNDAY UPPER 70S/LOWER 80S BY
MONDAY. A DRY FORECAST SATURDAY THROUGH MONDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1209 AM CDT TUE SEP 2 2014

FOR THE 06Z TAF CYCLE...VFR SHOULD PREVAIL FOR MOST AREA TERMINALS
OVERNIGHT AND TOMORROW.  HOWEVER...GIVEN THE RECENT RAINFALL OVER
MUCH OF THE AREA...WOULD NOT BE TOO SURPRISED TO SEE SOME PATCHY
LOW FOG...WHICH COULD IMPACT EITHER KLBF OR KVTN. GUIDANCE DOES
HINT AT THIS AT KLBF AROUND 12Z...AND PATCHY SHALLOW MIST/FOG HAD
FORMED OVER THE FIELDS NEAR LBF. SO...WE WILL INCLUDE BR MENTION
WITH 5SM IN VTN AND 3SM BCFG AT LBF. OTHERWISE GUIDANCE
INDICATES WINDS SWITCHING TO SOUTHERLY FOR ALL AREA TERMINALS BY
EARLY AFTERNOON...BUT WIND SPEEDS TO REMAIN LIGHT.

&&

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

$$

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





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