Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 142117
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
317 PM CST SUN FEB 14 2016

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 316 PM CST SUN FEB 14 2016

THE MAIN FORECAST CHALLENGE THROUGH MONDAY AFTERNOON IS
PRECIPITATION. A MID LEVEL SHORTWAVE AND A SURFACE TROUGH WILL
TRAVERSE THE FORECAST AREA LATE THIS EVENING WHILE ANOTHER SYSTEM
APPROACHES NORTHWEST NEBRASKA MONDAY AFTERNOON.

THIS EVENING AND TONIGHT...THE 12Z MODEL SUITE ALONG WITH HRRR AND
RAP GENERALLY AGREE WITH PREVIOUS FORECAST PACKAGE...SO MADE MINOR
ADJUSTMENTS TO PRECIPITATION AND TEMPERATURES. WEAK RADAR ECHOES
OVER PARTS OF NORTHERN NEBRASKA AND THE PANHANDLE TODAY HAVE BEEN
THE RESULT OF MID LEVEL CLOUDS AND VIRGA...VERIFIED BY WEB CAMERAS
AND SURFACE OBS. THE GFS...ECM...AND NAM SHOW SUFFICIENT 500-700 HPA
FRONTOGENESIS ACROSS THE FORECAST AREA THIS EVENING...BUT FORECAST
SOUNDINGS INDICATE CONTINUED LOW LEVEL DRY AIR...ESPECIALLY ACROSS
SOUTHWEST NEBRASKA. THE RAP AND NAM BRING SATURATION AS LOW AS
850HPA ACROSS THE NORTH WHILE THE HRRR SHOWS SCATTERED LIGHT SHOWERS
NORTH AND FAR SOUTHWEST. DESPITE THE DRY AIR IN THE SOUTH...RAP
FORECAST SOUNDINGS SUGGEST AMPLE LOW LEVEL LIFT TO SUPPORT A LIGHT
SHOWER IF EVAPORATIVE COOLING OCCURS. KEPT SCHC MENTION GENERALLY
ACROSS THE NORTHERN THIRD OF THE FORECAST AREA AND SPRINKLES/
FLURRIES FOR THE REMAINDER. THE TEMPERATURE PROFILE GENERALLY
SUPPORTS RAIN AS 0-2KFT AGL TEMPS AND SFC WET BULB REMAIN ABOVE
FREEZING. HOWEVER...DID MENTION RASN AFTER 03Z AS SATURATION AND
LIFT OCCUR IN THE DGZ. MOST OF THE FORCING AND LOW/MID LEVEL
MOISTURE MOVE EAST AFTER 06Z WHEN ALL SNOW WOULD BE BETTER
SUPPORTED. KEPT MIN TEMPS ABOVE MOS GUIDANCE TO ACCOUNT FOR
CLOUDS...850HPA TEMPS ABOVE 0C...AND WINDS STAYING NEAR 10 KTS.

MONDAY...TRENDED MAX TEMPS UP A DEGREE OR TWO TO FOLLOW THE ECM AND
MAV MORE CLOSELY. DESPITE INCREASING CLOUD COVER THROUGH THE
DAY...WAA AT 850HPA AND DOWNSLOPING WINDS SHOULD OVERCOME. THE NEXT
WAVE OF MOISTURE ENTERS NORTHWEST NEBRASKA EARLY AFTERNOON...BUT LOW
LEVEL DRY AIR MAY HANG ON THROUGH LATE AFTERNOON OR EARLY EVENING.
ISENTROPIC LIFT IS MORE EVIDENT WITH THIS SYSTEM...ESPECIALLY ACROSS
THE NORTH. INCLUDED SCHC AS EARLY AS 18Z FAR NORTHWEST...BUT BETTER
CHANCE OCCURS AFTER 00Z AS LOW LEVEL MOISTENING AND LIFT INCREASE.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 316 PM CST SUN FEB 14 2016

MONDAY NIGHT THROUGH WEDNESDAY...A FAIRLY POTENT UPPER LEVEL
DISTURBANCE NEAR OR JUST OVER THE COAST OF CNTL BRITISH COLUMBIA
WILL MOVE RAPIDLY THROUGH THE MISSOURI BASIN MONDAY NIGHT. THE PTYPE
IS RAIN SHOWERS AS THE FCST AREA WILL BE ON THE SRN OR WARM SIDE OF
THE DISTURBANCE. LOWS TUESDAY MORNING FALL INTO THE LOWER 30S.
COOLING ALOFT COULD PERHAPS PRODUCE A MIX BUT THE PREDOMINATE PTYPE
IS RAIN.

THE MORNING RUN OF THE ECM SHOWS SHOWERS AS FAR SOUTH AS INTERSTATE
80 WITH THIS SYSTEM. THE MODEL CONSENSUS IS ALONG OR NORTH OF
NEBRASKA HIGHWAY 2. THE ECM SHOWS MUCH MORE ROBUST 700-500MB
MOISTURE BUT VERY MODEST SATURATION IN THE 850-700MB LAYER.

THE THREE GUIDANCE DATA SETS ARE VERY CLOSE FOR HIGHS TUESDAY IN THE
LOWER 40S TO MID 50S. SOME MIDLEVEL COOLING IN THE MORNING WILL HAVE
TO BE OVERCOME. H850MB TEMPERATURES SHOULD RISE TO 0C TO 8C BY LATE
AFTERNOON. A MIX OF SUN AND CLOUDS WAS INDICATED IN THE MODELS.

THERMAL RIDGING CONTINUES TO BUILD TUESDAY NIGHT AND WEDNESDAY WITH
H850MB TEMPERATURES RISING TO 5C TO 10C. THIS SUPPORTS LOWS IN THE
UPPER 20S TO LOWER 30S AND HIGHS IN THE 50S TO NEAR 60. GENERALLY
CLEAR SKIES ARE EXPECTED DURING THIS TIME. SOME HIGH CIRRUS MAY BE
OVERHEAD IN THE AFTERNOON.

WEDNESDAY NIGHT THROUGH SUNDAY...THURSDAY IS THE BIG DAY. WEST-
SOUTHWEST WINDS ARE UNIDIRECTIONAL TO 700MB AND H850MB TEMPERATURES
RISE TO 15C TO 20C. HIGHS WILL EASILY RISE INTO THE 60S. THE GFS AND
ECM SHOW A LONG WAVE TROF FLUSHING WARM AIR ACROSS THE ROCKIES AND
INTO THE CNTL PLAINS. HIGH CLOUDINESS ASSOCIATED WITH A BAROCLINIC
LEAF POSITIONED ACROSS THE NRN PLAINS AND MIDWEST COULD PLACE THE
FCST AREA IN NEARLY FULL SUN. LATER FORECASTS MAY RAISE HIGHS A BIT.
A BLEND OF GUIDANCE PLUS BIAS CORRECTION WAS THE BASIS FOR THE
TEMPERATURE FORECAST.

A KINK SHOWED UP IN THE FORECAST THURSDAY NIGHT ASSOCIATED WITH A
PACIFIC COLD FRONT FRIDAY. 700MB WINDS INCREASE TO 60 TO 75 KTS
AHEAD OF THE FRONT IN THE ECM AND GFS. COUPLED WITH A PV1.5 ANOMALY
AND 6 HR PRESSURE RISES OF 12-16MB...A PERIOD OF STRONG OR HIGH WIND
GUSTS COULD DEVELOP THURSDAY NIGHT. LATER FORECASTS WILL MONITOR
THIS POTENTIAL WIND EVENT.

LOW PRESSURE TRACKS INTO THE UPPER MIDWEST FRIDAY AND THIS SHOULD
SEND A PACIFIC COLD FRONT THROUGH THE FCST AREA. H850MB TEMPERATURES
COOL TO 5C TO 10C SUPPORTING HIGHS IN THE 50S TO AROUND 60.
DOWNSLOPING WEST NORTHWEST WINDS NEAR 25 TO 30 MPH WILL CONTINUE TO
SUPPORT DEEP VERTICAL MIXING.

ZONAL FLOW ALOFT IS IN PLACE SATURDAY AND A NEW SFC LOW FORMS ON THE
NRN HIGH PLAINS. NO SIGNIFICANT WARMING OR COOLING IS SHOWN AT
H850MB BUT WEAK WINDS SUGGEST A SHALLOWER MIXING HEIGHT. THE
FORECAST FOR HIGHS IN THE 50S WOULD APPEAR THE BEST FIT.

SOME SORT OF COLD FRONT IS SHOWN BY THE GFS...ECM AND GFS ENSEMBLE
SATURDAY NIGHT COOLING HIGHS INTO THE 40S TO AROUND 50 SUNDAY. THE
MODELS ARE IN GOOD AGREEMENT WITH A DOUBLE BARREL HIGH PRESSURE
SYSTEM OVER SCNTL CANADA AND THE CNTL ROCKIES. THIS WOULD PUT THE
BRAKES ON ANY SORT ARCTIC AIR AS THE MILDER PACIFIC HIGH ACROSS THE
ROCKIES DOMINATES THE COLDER ARCTIC AIR.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1125 AM CST SUN FEB 14 2016

VFR CONDITIONS WILL CONTINUE FOR MOST OF WESTERN NEBRASKA THROUGH
MIDDAY MONDAY...AND STRATUS OVER NORTHERN/EASTERN NEBRASKA
AFFECTING KONL WILL SLOWLY LIFT THIS AFTERNOON. A FEW LIGHT RAIN
SHOWERS WILL MOVE THROUGH THE AREA THIS EVENING...BUT VISBY OR CIG
RESTRICTIONS ARE NOT ANTICIPATED. AMBIENT SURFACE WINDS WILL
GENERALLY STAY AROUND 10 KTS OUT OF THE WEST THROUGH THE FORECAST
PERIOD.

&&

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

$$

SHORT TERM...SNIVELY
LONG TERM...CDC
AVIATION...SNIVELY


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