Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 181735
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1235 PM CDT SAT OCT 18 2014

.SYNOPSIS...
ISSUED AT 343 AM CDT SAT OCT 18 2014

HAND ANALYSIS OF THE 06Z MSL DATA SHOWED A WEAK FRONT ACROSS
MINNESOTA AND NORTH DAKOTA. ANOTHER WEAK FRONT WAS INDICATED IN A
TEMPERATURE DISCONTINUITY ACROSS NEBRASKA FROM NEAR SIOUX CITY
THROUGH GRAND ISLAND AND LEXINGTON TO CHADRON. THE WATER VAPOR
IMAGERY SHOWED A PROMINENT POTENTIAL VORTICITY INTRUSION ASSOCIATED
WITH THE SURFACE FRONT ACROSS NEBRASKA. THERE WAS ALSO A TROUGH
ACROSS EASTERN WYOMING AND NORTHEAST COLORADO.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT SAT OCT 18 2014

DRY WEATHER IS EXPECTED TO CONTINUE TODAY AND TONIGHT WITH
SEASONABLE TEMPERATURES. WIND WILL RETURN TO THE SOUTH AS THE LEE
SIDE TROUGH CONTINUES TO DEVELOP. IT WILL BE A LITTLE BREEZY AS THE
TROUGH DEEPENS AND THE GRADIENT STRENGTHENS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 343 AM CDT SAT OCT 18 2014

THE PRIMARY FORECAST CHALLENGES THROUGH THIS PERIOD WILL BE
TEMPERATURES THROUGH THE PERIOD AND WITH RAIN AND THUNDERSTORM
POTENTIAL FOR MID-WEEK.

THE LATEST 18.00Z MODEL SUITE IS IN PRETTY GOOD AGREEMENT FOR MUCH
OF THE NEXT WEEK...HOWEVER DO START SEEING SOME DIVERGENCE IN THE
SOLUTIONS BY LATE IN THE PERIOD /THURSDAY NIGHT INTO FRIDAY/. THE
UPPER LEVEL PATTERN WILL STAY QUITE AMPLIFIED AS THE LONGWAVE
TROUGH OVER THE GREAT LAKES MIGRATES EAST INTO THE NORTHEASTERN
CONUS AND THE LARGE SYSTEM OVER THE GULF OF ALASKA AND NORTH
CENTRAL PACIFIC MOVES TOWARDS THE WEST COAST. AS THE PACIFIC
SYSTEM MOVES CLOSER...THE RIDGING NOW CENTERED OVER THE ROCKY
MOUNTAINS WILL BUILD EASTWARD ACROSS THE PLAINS PROVIDING THE
OPPORTUNITY FOR ABOVE NORMAL TEMPERATURES. DRY AIR WILL TAKE
RESIDENCE ACROSS THE AREA AS A COLD FRONT WILL MOVE THROUGH THE
REGION SUNDAY PUSHING THE MOISTURE ACROSS THE AREA SOUTHWARD. WITH
PLENTIFUL SUNSHINE THROUGH TUESDAY...LOOKING FOR GOOD BOUNDARY
LAYER MIXING TO TAKE PLACE...AND WITH 850MB TEMPERATURES
INCREASING TO 13C- 16C...SHOULD SEE HIGH TEMPERATURES INTO THE 70S
FOR THE ENTIRE FORECAST AREA FOR SUNDAY THROUGH TUESDAY. WITH THE
DRY AIR TAKING PLACE BY SUNDAY NIGHT AND WITH LIGHT WINDS
EXPECTED FOR MUCH OF THE AREA...LOWERED MINIMUM TEMPERATURES FROM THE
PRIOR FORECAST. LEFT LOWS IN THE LOW TO MID 40S OVER NORTH CENTRAL
NEBRASKA AS IT LOOKS POSSIBLE FOR WINDS TO CONTINUE TO BLOW
THROUGH THE NIGHT TO KEEP A BIT OF MIXING ONGOING.

ON TUESDAY...THE MODELS ARE INDICATING THE UPPER LEVEL TROUGH OVER
THE PACIFIC OCEAN WILL HAVE MOVED ONSHORE AND LIFT INTO THE ROCKY
MOUNTAINS. THIS WILL PUSH THE SURFACE HIGH THAT WILL HAVE RESIDED
OVER THE LOCAL AREA FOR THE EARLY PART OF THE WEEK EASTWARD WHILE
A SURFACE TROUGH DEVELOPS ALONG THE LEE SIDE OF THE ROCKIES. THIS
WILL CAUSE SOUTHERLY RETURN FLOW TO SET UP BY THE END OF THE DAY.
MODELS ARE SHOWING GOOD FLOW COMING INTO THE NORTHERN AND CENTRAL
PLAINS FROM THE GULF OF MEXICO WHICH WILL INCREASE DEWPOINTS
ACROSS THE FORECAST AREA INTO THE UPPER 40S TO AROUND 50 DEGREES.
THE CURRENT TRAJECTORY OF THE MORE MOIST AIR WOULD BRING THESE
HIGHER DEWPOINTS MAINLY INTO THE NEBRASKA PANHANDLE AND OTHER
PARTS OF WESTERN NEBRASKA. IN ADDITION TO THE INCREASE OF MOISTURE
IN THE BOUNDARY LAYER...THE ENTIRE COLUMN WILL SEE A GOOD INCREASE
IN MOISTURE AS PRECIPITABLE WATER VALUES INCREASE TO AN INCH OR
MORE...WHICH IS ABOUT 200 PERCENT OF NORMAL. WHEN INTERROGATING
MOISTURE TRANSPORT FOR WEDNESDAY...THERE IS A FOCUS OF MOISTURE
CONVERGENCE OVER WESTERN NEBRASKA BY WEDNESDAY AFTERNOON AS THE
UPPER LEVEL TROUGH MAKES ITS WAY ACROSS THE PLAINS. FORECAST CROSS
SECTIONS ARE ALSO SHOWING A VERY STRONG OMEGA SIGNAL BY WEDNESDAY
AFTERNOON AND FORECAST SOUNDINGS ARE SHOWING PARTS OF THE FORECAST
AREA WITH AT LEAST SOME INSTABILITY. WITH THE LARGE SCALE LIFT IN
PLACE FROM THE APPROACHING SHORTWAVE TROUGH...THE MOISTURE
CONVERGENCE...AND THE INSTABILITY IN PLACE...FEEL THE MENTION OF
THUNDERSTORMS SHOULD CONTINUE BUT MAINLY FROM WEDNESDAY AFTERNOON
THROUGH THE EVENING HOURS. THAT BEING SAID...THE INSTABILITY ISN/T
REAL GREAT WITH LESS THAN 1K J/KG...SO KEPT MENTION OF JUST
ISOLATED THUNDERSTORMS AT THIS TIME. ALSO...PRECIPITATION CHANCES
DID GET RAISED SLIGHTLY FOR WEDNESDAY AND WEDNESDAY NIGHT AS GOOD
MODEL AGREEMENT LED TO INCREASED CONFIDENCE ON TIMING.

THE SYSTEM MOVES THROUGH QUITE QUICKLY...HOWEVER THERE ARE
DIFFERENCES IN JUST HOW QUICK. THE GEM IS THE SLOWEST
SOLUTIONS...WITH THE GFS SLIGHTLY FASTER...AND THE ECMWF THE
QUICKEST TO MOVE THE SYSTEM EAST. FEEL THAT THE PRECIPITATION WILL
BE EAST OF THE LOCAL AREA BY THURSDAY MORNING...BUT ACCOUNTING FOR
SOME CHANGES IN THE FORECAST MODELS DID KEEP SOME LOW CHANCES IN
THE FORECAST FOR THE DAYTIME THURSDAY. MAY BE ABLE TO REFINE THESE
CHANCES IN THE NEXT FORECAST CYCLE.

AFTER THIS SYSTEM GETS OUT OF THE REGION...ANOTHER UPPER LEVEL
RIDGE IS SET TO BUILD INTO THE CENTRAL PART OF THE COUNTRY. SO
AFTER A DAY OR SO OF SOME COOLER /NEAR NORMAL/
TEMPERATURES...LOOKING FOR ANOTHER WARM-UP WITH DRY CONDITIONS
INTO NEXT WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1235 PM CDT SAT OCT 18 2014

VFR FLIGHT RULES ANTICIPATED FOR ALL WESTERN AND NORTH CENTRAL
NEBRASKA TERMINALS THROUGH THE 18Z TAF CYCLE. THE ONE EXCEPTION
CONTINUES TO BE FAR NORTH CENTRAL NEBRASKA /KONL TERMINAL/ WHERE
PERSISTENT DECK OF STRATUS REMAINS...THIS DECK IS BREAKING AND
SHOULD CLEAR AOB 19Z. OTHERWISE THE MODELS HINT AT THE POSSIBILITY
OF GROUND FOG AT KLBF AND POSSIBLY KVTN...HOWEVER THIS OUTCOME IS
NOT CERTAIN AND WILL BE LEFT OUT OF THE OFFICIAL TAF FOR NOW.

&&

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

$$

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








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