Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 290003 AAA
AFDLBF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
703 PM CDT SUN SEP 28 2014

.SYNOPSIS...
ISSUED AT 322 PM CDT SUN SEP 28 2014

AT 19Z...WATER VAPOR IMAGERY INDICATED A DEEP TROUGH ACROSS THE
WESTERN CONUS WITH A CLOSED LOW ROTATING OVER NEVADA. ALSO...A
SHORTWAVE TROUGH WAS SEEN IN THE NORTHERN STREAM PUSHING ACROSS
MANITOBA AND SASKATCHEWAN. BROAD RIDGING WAS SEEN OVER THE EASTERN
TWO THIRDS OF THE COUNTRY...WHILE A WEAK UPPER LOW CONTINUES TO
SPIN OVER IOWA. WITH THE UPPER LOW OVER IOWA...THE WARM AIR ALOFT
HAS BEEN FUNNELED NORTH ACROSS THE HIGH PLAINS AND INTO THE
DAKOTAS WITH THE WARM AIR ADVECTION ONGOING WITH THE SOUTHERLY
FLOW ON THE DOWNSTREAM SIDE OF THE WESTERN TROUGH. AT THE
SURFACE...LOW PRESSURE WAS SEEN OVER EASTERN COLORADO WHICH
EXTENDED NORTHEAST ACROSS THE NEBRASKA PANHANDLE...THROUGH EASTERN
SOUTH DAKOTA AND INTO MINNESOTA. AN EXTENSIVE AREA OF STRATUS WAS
OBSERVED THROUGH THE DAY ON THE NORTH SIDE OF THE
FRONT...ENCOMPASSING MUCH OF NORTH DAKOTA...WESTERN SOUTH
DAKOTA...THE FAR NORTHERN NEBRASKA PANHANDLE AND MUCH OF WYOMING
AS A COOLER AIRMASS PUSHED SOUTH ASSOCIATED WITH THE CANADIAN
SHORTWAVE TROUGH. LOCATIONS UNDER THE STRATUS SAW LITTLE WARMING
THROUGH THE DAY AS MID AFTERNOON TEMPERATURES REMAINED IN THE
UPPER 50S. THE REST OF THE FORECAST AREA SAW SIGNIFICANT WARMING
WITH TEMPERATURES IN THE 80S. IN ADDITION...GOOD MIXING AND STEEP
LAPSE RATES HAVE LED TO BREEZY SOUTHERLY WINDS AND DEVELOPMENT OF
A CUMULUS FIELD OVER PORTIONS OF THE AREA.

THE LARGE UPPER LEVEL LOW SWIRLY ACROSS THE WRN U.S. THIS AFTN
WILL LIFT THROUGH THE ROCKIES AND INTO THE NRN PLAINS BY TUESDAY.
A STRONG PACIFIC FRONT WILL SWEEP THE FCST AREA MONDAY NIGHT AND
TUESDAY PRODUCING HEAVY RAIN ACROSS WRN NEB WITH LIGHTER AMOUNTS
EAST. COOLER WEATHER PREVAILS TUESDAY THROUGH SUNDAY.

&&

.UPDATE...
ISSUED AT 658 PM CDT SUN SEP 28 2014

UPDATED TO INCREASE ISOLATED THUNDERSTORM COVERAGE AREA OVER
NORTHERN NEBRASKA ALONG BOUNDARY. MOST OF THIS SHOULD GO AWAY WITH
THE HEATING OF THE DAY AND THEN BEGIN ANEW AS A WAVE MOVES OUT OF
THE ROCKIES.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 322 PM CDT SUN SEP 28 2014

FOR TONIGHT...ALTHOUGH THE PRIMARY SYSTEM REMAINS OFF TO THE
WEST...SOME OF THE MODELS ARE SHOWING A WEAK IMPULSE OF MID LEVEL
ENERGY BREAKING OFF FROM THE MAIN SYSTEM AND MOVING INTO WESTERN
NEBRASKA THIS EVENING. SOME ENHANCED LIFT FROM THIS ENERGY...ALONG
WITH THE NOSE OF THE LOW LEVEL JET PUSHING OVER THE COLD FRONT
OVER NORTHWEST NEBRASKA COULD LEAD TO DEVELOPMENT OF SHOWERS AND
ISOLATED THUNDERSTORMS IN THE VICINITY OF THE FRONT. CONFIDENCE
ISN/T HIGH YET THAT ACTIVITY WILL DEVELOP...BUT DIDN/T WANT TO
LEAVE A DRY FORECAST AS THE SET-UP LOOKS FAVORABLE SO ADDED IN
SLIGHT CHANCES FOR THE EVENING HOURS. THE WHOLE UPPER LEVEL SYSTEM
STARTS TO MIGRATE EAST OVERNIGHT AND WITH LARGE SCALE LIFT
INCREASING AS MORE ENERGY MOVES OUT OF THE SOUTHWEST AND THE UPPER
JET PUSHES INTO AREAS TO THE WEST EXPECT COVERAGE OF PRECIPITATION
TO INCREASE BY 12Z OVER THE PANHANDLE.

THERE SHOULD BE A BREAK MONDAY MORNING AS THE FIRST WAVE OF SHOWERS
AND THUNDERSTORMS PUSHES NORTH AND OUT OF THE AREA. THE UPPER LEVEL
TROUGH STARTS TO OPEN UP DURING THE DAY MONDAY AND START TO TAKE ON
A NEGATIVE TILT AND CONTINUE TO MOVE TOWARDS THE CENTRAL PLAINS. BY
00Z TUESDAY THE TROUGH AXIS EXTENDS FROM NORTHWEST WYOMING INTO
NORTHERN NEW MEXICO. DURING THE AFTERNOON...STRONG SOUTHERLY FLOW
WILL BE ONGOING...PUSHING DIRECTLY INTO WESTERN NEBRASKA. AT THE
SAME TIME...THE UPPER LEVEL JET STREAK WILL BE LOCATED FROM NORTHERN
NEW MEXICO INTO SOUTHEAST WYOMING...PUTTING THE LOCAL AREA /OR THE
WESTERN PORTIONS ANYWAY/ INTO THE RIGHT EXIT REGION AND IN THE
FAVORED AREA FOR LARGE SCALE LIFT. ANTICIPATING STORMS TO DEVELOP
AROUND EARLY TO MID AFTERNOON ACROSS WESTERN NEBRASKA AS EVERYTHING
BEGINS TO COME TOGETHER. ALTHOUGH INSTABILITY LOOKS TO BE LIMITED
WITH MU CAPES AROUND 1000 J/KG AND DEEP LAYER SHEAR IN THE 30-40KT
RANGE...THE STRENGTH OF THE SYSTEM AND THE AMOUNT OF LIFT ASSOCIATED
WITH IT SHOULD BE ENOUGH TO PRODUCE SOME STRONG STORMS...MAINLY OVER
THE SOUTHERN PANHANDLE AND INTO FAR SOUTHWEST NEBRASKA. SOUTHERLY
WINDS WILL BE BREEZY...AND AS FORECAST SOUNDINGS ARE SHOWING MIXING
TO NEAR 750MB...GUSTS IN THE AFTERNOON SHOULD BE IN THE AREA OF
30-35 KTS AT TIMES. THIS WILL ALSO LEAD TO WARM TEMPERATURES OVER
THE SOUTHEAST HALF OF THE FORECAST AREA WHICH WILL SEE AMPLE
SUNSHINE. HIGHS IN THESE AREAS SHOULD AGAIN REACH INTO THE LOW 80S.
THE WESTERN AREAS WILL LIKELY BE A BIT COOLER...IN THE 70S.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 322 PM CDT SUN SEP 28 2014

MONDAY NIGHT THROUGH WEDNESDAY...THE MODELS ARE IN BETTER AGREEMENT
TRENDING TOWARD THE DEEP GFS SOLN AND HAVE CONVERGED ON THE SLOWER
TIMING OF THE HEAVY CONVECTION WHICH IS EXPECTED TO DEVELOP ACROSS
WRN NEB MONDAY EVENING AND SPLIT OFF FROM THE UPPER LOW AS IT
MOVES EAST THROUGH NCNTL NEB EARLY TUESDAY MORNING. THUS A FULL
MODEL BLEND WAS USED FOR QPF AND POPS WHICH PRODUCES AROUND AN
INCH OF RAIN IN THE WEST AND AS LITTLE AS 1/4 INCH IN THE EAST.
THE HEAVIEST RAIN IS EXPECTED ACROSS NORTHWEST NEBRASKA...NEAR THE
TRACK OF THE H7 LOW.

SPC SUGGESTED SEVERE WEATHER MAY DEVELOP LATE MONDAY. WE ARE
MISSING A TRIPLE PT AND A HOT PROD OF WARM AIR ADVECTION. LINEAR
SEVERE CONVECTIVE DEVELOPMENT IS AND HAS BEEN ADVERTISED BY THE
NAM AND NOW THE ARF/NMM SOLNS ACROSS WRN NEB. THE MODELS SUGGEST
STRONG OR SEVERE WEATHER COULD LAST UNTIL 03Z-06Z MONDAY NIGHT.

WIND ADVISORY CONDITIONS MAY DEVELOP ACROSS NRN NEB TUESDAY AFTN AS
THE PV ANOMALY FORCES 45 TO 55 KT H700MB WINDS DOWNWARD TOWARD THE
SURFACE. THE GFS WAS THE STRONGEST WITH 40+ MPH SFC WINDS BUT THE
OTHER MODELS WERE CLOSER TO 30 MPH AND KEPT THOSE STRONGER WINDS
FARTHER NORTH. GIVEN THE STRENGTH OF THIS SYSTEM...ANYTHING IS
POSSIBLE WITH THE WIND SPEEDS WHICH WILL DEPEND ON THE TIMING AND
THE TRACK OF THE H700MB LOW TUESDAY.

SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE TUESDAY ACROSS NRN
NEB. THIS RAIN IS ASSOCIATED WITH THE UPPER LEVEL COLD POOL ACROSS
THE NRN PLAINS. SCATTERED SHOWERS ARE POSSIBLE WEDNESDAY AS A COLD
FRONT MOVES THROUGH THE FCST AREA.

THE TEMPERATURE FORECAST IS SIMILAR BOTH DAYS WITH 60S IN THE
NORTHWEST AND 70S ELSEWHERE.

THURSDAY THROUGH SUNDAY...THE MODELS CONTINUE TO SHOW TWO COLD FRONT
PASSING THROUGH WEDNESDAY AND THURSDAY NIGHT...A LITTLE FASTER THAN
YESTERDAYS MODEL RUNS OF THE GFS AND ECM. IT STILL APPEARS THAT WINDS
SHOULD BE SUFFICIENTLY STRONG FRIDAY NIGHT TO PREVENT A LIGHT FREEZE
AND THE MODELS SHOW SOME WEAK SHOWER ACTIVITY WITH COLD FRONT
WEDNESDAY.

LOW PRESSURE WILL MOVE THROUGH SRN CANADA SATURDAY AND SUNDAY
DRAWING WARM AIR OFF THE ROCKIES INTO THE FCST AREA. HIGHS IN THE
60S THURSDAY AND FRIDAY ARE EXPECTED TO RISE INTO THE 70S SATURDAY
AND SUNDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 658 PM CDT SUN SEP 28 2014

SOME ISOLATED STORMS ALONG A STATIONARY BOUNDARY OVER NORTHERN
NEBRASKA AND THEN LATER TONIGHT STORMS WILL MOVE OFF THE FRONT
RANGE OF THE ROCKIES INTO THE NEBRASKA PANHANDLE. HAVE CONTINUED
VCSH FOR KVTN TAF SITE OVER NIGHT WITH THE FRONTAL BOUNDARY CLOSE.
VFR CIGS AND VISIBILITIES EXPECTED. SOME MVFR CEILINGS POSSIBLE
OVER NORTHWEST NEBRASKA THROUGH THE EARLY MORNING HOURS WITH
SCATTERED THUNDERSTORMS MOVING IN.

&&

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

$$

UPDATE...POWER
SYNOPSIS...BROOKS/CDC
SHORT TERM...BROOKS
LONG TERM...CDC
AVIATION...POWER






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