Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 251145
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
645 AM CDT TUE AUG 25 2015

.SYNOPSIS...
ISSUED AT 354 AM CDT TUE AUG 25 2015

H5 ANALYSIS FROM EARLIER THIS EVENING HAD PERSISTENT HIGH
PRESSURE OVER THE FOUR CORNERS WITH A RIDGE EXTENDING NWD INTO
CENTRAL SASKATCHEWAN. EAST OF THE RIDGE...LOW PRESSURE WAS NOTED
OVER EASTERN ONTARIO WITH A TROUGH EXTENDING SWD INTO THE MIDDLE
OHIO VALLEY. LOW PRESSURE WAS ALSO LOCATED WEST OF THE ALASKA
PANHANDLE WITH A TROUGH EXTENDING SW INTO THE NORTHEASTERN
PACIFIC. CURRENT WV IMAGERY HAS A VERY WEAK SHORTWAVE LIFTING SE
FROM THE BLACK HILLS INTO THE NEBR PANHANDLE AND THIS WAS NOTHING
MORE THAN SOME DISSIPATING UPPER LEVEL CLOUDINESS. A STRONGER
SHORTWAVE WAS MOVING WEST NORTHWEST ACROSS NRN MEXICO...ON THE
SWRN PERIPHERY OF THE FOUR CORNERS HIGH. THIS IS THE SYSTEM WHICH
WILL LIFT TO THE NORTHWEST...NORTH...THEN EAST ACROSS THE CENTRAL
ROCKIES WEDNESDAY NIGHT INTO THURSDAY...IMPACTING THE DAKOTAS AND
NEBR WITH INCREASED CHANCES FOR PCPN. CURRENTLY AT THE
SURFACE...AN ELONGATED AREA OF HIGH PRESSURE EXTENDED FROM EASTERN
ND...SWD INTO THE MID AND LOWER MISSOURI VALLEY. WEST OF THIS
FEATURE...A SURFACE TROUGH OF LOW PRESSURE EXTENDED FROM CENTRAL
MT...SSEWD INTO EASTERN WYOMING AND THE FRONT RANGE OF COLORADO.
WITH THE EXCEPTION OF SOME HIGH CLOUDS OVER NORTHWESTERN
NEBRASKA...SKIES WERE MAINLY CLEAR WITH 3 AM READINGS RANGING FROM
52 AT BROKEN BOW TO 65 AT IMPERIAL.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 354 AM CDT TUE AUG 25 2015

OVER THE NEXT 24 HOURS...SRLY WINDS WILL BEGIN TO INCREASE AS
HIGH PRESSURE DRIFTS EAST AND LEE SIDE TROUGHING DEEPENS OFF TO
THE WEST. WITH THE INCREASED SRLY WINDS...THE MODELS HAVE LATCHED
ONTO INCREASING LOW LEVEL MOISTURE ADVECTION INTO THE WESTERN HALF
OF THE CWA THIS AFTERNOON. IN ADDITION TO INCREASED MOISTURE
ADVECTION...LOW LEVEL WAA WILL INCREASE AS WELL...ALBEIT...NOT
NEARLY AS STRONG AS SEEN YESTERDAY. AS FOR HIGHS THIS
AFTERNOON...THERE WAS GOOD AGREEMENT BETWEEN THE MET AND MAV
GUIDANCE THIS AFTERNOON AS THEY HAD AN IDENTICAL 88 FOR A HIGH AT
NORTH PLATTE. DECIDED TO UNDERCUT THIS SLIGHTLY GIVEN THE DEGREE
OF LOW LEVEL MOISTURE ADVECTION TDY. ATTM FEEL INCREASED MOISTURE
WILL HOLD MAX TEMPS BACK SLIGHTLY THIS AFTERNOON. THE INCREASED
MOISTURE AND TEMPERATURE ADVECTION THIS AFTERNOON...WILL LEAD TO
SB CAPES OF 1700-2300 J/KG IN THE WESTERN HALF OF THE CWA THIS
AFTERNOON. DECENT BULK LAYER SHEAR EXISTS AS WELL. HOWEVER...FCST
SOUNDINGS INDICATE A STRONG CAPPING INVERSION ACROSS THE FORECAST
AREA TODAY...SO A DRY FCST WILL BE CONTINUED. THIS CAPPING EXTENDS
WELL WEST OF THE FORECAST AREA...AND GIVEN THE NW MID LEVEL
WINDS...ANY FRONT RANGE CONVECTION...SHOULD LIFT WELL OFF TO THE
SW OF THE FORECAST AREA THIS AFTN AND EVE. FOR TONIGHT...SKIES
WILL BE MOSTLY CLEAR...WITH SOME INCREASING HIGH CLOUDINESS
POSSIBLE IN THE NWRN CWA. LOWS WILL RANGE FROM THE MID 50S IN THE
EAST...WHERE DRIER BOUNDARY LAYER AIR IS EXPECTED...TO AROUND 60
IN THE WEST AND NORTHWEST DUE TO A COMBINATION OF INCREASED LOW
LEVEL MOISTURE...AND INVADING HIGH CLOUDS FROM THE NORTHWEST.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 354 AM CDT TUE AUG 25 2015

STRONG SHORTWAVE ALOFT WILL BE CRESTING THE TOP OF THE UPPER LEVEL
RIDGE ACROSS THE WY/MT AREA DURING THE DAY WEDNESDAY.  AHEAD OF THIS
FEATURE...STRONG SOUTHERLY LOW LEVEL FLOW WILL PROMOTE STRONG MOIST
WARM AIR ADVECTION INTO CENTRAL/WESTERN NEBRASKA. BOUNDARY LAYER DEW
POINTS IN THE 60S WILL COMBINE WITH STEEP MID LEVEL LAPSE RATES AND
CREATE VERY UNSTABLE CONDITIONS BY WEDNESDAY AFTERNOON. HOWEVER WITH
UPPER LEVEL FORCING STILL WEST OF THE AREA AND LITTLE IN THE WAY OF
LOW LEVEL CONVERGENCE FOR SURFACE BASED STORM FORMATION...WILL KEEP
THE DAY WEDNESDAY DRY. WEDNESDAY NIGHT COULD BE A DIFFERENT STORY.
STRONG SOUTHERLY LOW LEVEL JET WILL VEER TO SOUTHWEST AFTER
MIDNIGHT. DECENT ELEVATED INSTABILITY DEVELOPS ACROSS MAINLY NORTH
CENTRAL INTO NORTHEAST NEBRASKA AFTER MIDNIGHT. IT IS UNCLEAR
HOWEVER IF UPPER LEVEL FORCING WILL BE STRONG ENOUGH TO DEVELOP
STORMS ABOVE THE CAPPED BOUNDARY LAYER...BUT SOME POTENTIAL IS THERE
ESPECIALLY ACROSS NORTHERN NEBRASKA. WILL CARRY LOW CHANCE POPS IN
THAT AREA...WITH DECREASING CHANCES SOUTHWARD.

SHORTWAVE/UPPER LEVEL LOW MOVES EAST-SOUTHEAST FROM MT/WY AND
CROSSES SD/NE THURSDAY AND THURSDAY NIGHT. THE ENSEMBLE MEAN H700MB
UPPER LOW TRACK HAS BEEN CONSISTENTLY ACROSS SOUTH DAKOTA...AND THAT
IS WHERE THE BEST CHANCE FOR RAIN WILL RESIDE. THERE WILL BE AN AREA
OF SURFACE LOW PRESSURE AND ASSOCIATED SURFACE TROUGH THAT MOVES
EASTWARD ACROSS OUR FORECAST AREA DURING THE DAY THURSDAY INTO
THURSDAY NIGHT. SOME CHANCE OF TSTM DEVELOPMENT ALONG AND AHEAD OF
THIS SURFACE TROUGH...AND WILL KEEP THE 30 TO 50 PERCENT CHANCES FOR
RAINFALL GOING FROM PREVIOUS FORECAST.

FRIDAY INTO THE WEEKEND AND THE FIRST OF NEXT WEEK...UPPER LEVEL
RIDGE OF HIGH PRESSURE BUILDS NORTHWARD ONCE AGAIN AND EXPANDS
ACROSS THE CENTRAL PLAINS. WILL CONTINUE THE DRY FORECAST AND
SEASONABLY WARM TEMPERATURES IN THE FORECAST.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 644 AM CDT TUE AUG 25 2015

EXPECT CLEAR SKIES ACROSS WESTERN AND NORTH CENTRAL NEBRASKA OVER
THE NEXT 24 HOURS. WINDS WILL BE FROM THE SOUTH OR SOUTHEAST AT
AROUND 10 KTS THROUGH 12Z WEDNESDAY.

&&

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

$$

SYNOPSIS...CLB
SHORT TERM...CLB
LONG TERM...TAYLOR
AVIATION...CLB


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