Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 260840
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
340 AM CDT SUN APR 26 2015

.SYNOPSIS...
ISSUED AT 340 AM CDT SUN APR 26 2015

HAND ANALYSIS OF THE 07Z MSL DATA SHOWED AN INVERTED TROUGH FROM A
LOW IN SOUTHEAST SASKATCHEWAN TO A LOW IN SOUTHEAST COLORADO. THERE
WAS ALSO LOW PRESSURE CENTERED OVER SOUTHWEST WYOMING. ALL THREE LOW
PRESSURE SYSTEMS HAD UPPER SUPPORT INDICATED IN THE WATER VAPOR
IMAGERY. THE WYOMING AND SASKATCHEWAN LOWS HAD MATURING VORTICES
WHILE THE COLORADO LOW HAD A POTENTIAL VORTICITY INTRUSION.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT SUN APR 26 2015

SHOWERS AND ISOLATED THUNDERSTORMS ARE STILL EXPECTED WITH THE
INVERTED TROUGH IN THE WESTERN NEBRASKA SANDHILLS AND THE PANHANDLE.
WITH LIFTED INDICES AT OR ABOVE 4C...IT IS UNLIKELY THAT ANY THUNDER
WILL DEVELOP. THE UPWARD MOTION WITH THE INVERTED TROUGH IS ALSO
WEAK...SO PRECIPITATION AMOUNTS AND COVERAGE WILL NOT BE HIGH.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 340 AM CDT SUN APR 26 2015

THE DETERMINISTIC DATA CONTINUES TO ADVERTISE POSSIBLE UNSETTLED
CONDITIONS FOR OUR FAR WEST EARLY DURING THE EXTENDED PERIODS AS A
NORTHERN STREAM SHORTWAVE TROUGH ADVANCES ALONG THE US/CANADA BORDER
AND A CLOSED LOW DRIFTS EAST ONTO THE SOUTHERN PLAINS.  THE PATTERN
HOWEVER TRANSITIONS BY MID-WEEK AS UPPER TROPOSPHERIC RIDGING
AMPLIFIES ACROSS THE PLAINS INTO CENTRAL CANADA.  THIS WILL PROVIDE
FOR A WIDESPREAD WARMUP AND FOR GENERALLY DRY CONDITIONS.  LATE IN THE
EXTENDED...THERE IS SUPPORT FROM THE LONG RANGE SOLUTIONS THAT A
NORTHERN STREAM SHORTWAVE WILL BREAKDOWN THE CENTRAL CONUS RIDGE AND
FORCE A COLD FRONT THROUGH THE REGION.  THUS...SLIGHTLY COOLER
TEMPERATURES ARE THEN FORECAST FOR FRIDAY AND POSSIBLY THE WEEKEND.

PRECIPITATION CHANCES ARE LESS THAN IDEAL FOR WEST CENTRAL NEBRASKA
BEYOND 12Z MONDAY...BUT ARE NOT TOTALLY DISCOUNTED.  WE WILL CARRY A
SLIGHT CHANCE MENTION MONDAY ACROSS OUR FAR NORTHWEST TO ACCOUNT FOR
WEAK LOWER TROPOSPHERIC UPSLOPE GENERATED QPF WHICH POSSIBLY MAY BE
ENHANCED BY THE PASSAGE OF THE NORTHERN PLAINS SHORTWAVE.  BUT AT
THIS POINT THE BETTER OMEGA IS PROGGED TO BE NORTH AND WEST OF THE
FORECAST AREA...SO IF PRECIPITATION IS REALIZED...IT WOULD BE
LIGHT.  THE SHOWERS MAY CONTINUE INTO THE EVENING HOURS POSSIBLY
SPREADING QPF INTO THE SANDHILLS REGION ON TUESDAY AS THE WAVE
ADVANCES THROUGH THE NORTHERN PLAINS.  FOR WEDNESDAY THROUGH MIDDAY
THURSDAY...INCREASING SUBSIDENCE ASSOCIATED WITH THE AFOREMENTIONED
UPPER RIDGE AND A RESULTANT LACK OF OMEGA WILL PROMOTE DRY AND
WARMING CONDITIONS.  HIGHS BY MID-AFTERNOON THURSDAY WILL CLIMB BACK
INTO THE UPPER 70S TO LOWER 80S FOR MOST LOCATIONS.

THE MODELS CAME IN STRONGER/QUICKER WITH A PROPOSED NORTHERN STREAM
SHORTWAVE...WHICH IS SHOWN TO DRAG A COLD FRONT THROUGH THE PLAINS
EARLY FRIDAY MORNING.  THE MODEL CONSENSUS INDICATES SOME RETURN
OF LOWER TROPOSPHERIC MOISTURE BACK ACROSS THE HIGH PLAINS...WITH
THE GFS INDICATING LATE AFTERNOON TO OVERNIGHT TSTORM ACTIVITY
THURSDAY INTO FRIDAY.  THE EC IS LESS AMBITIOUS WITH THE STORM
DEVELOPMENT AND GENERALLY IS PREFERRED AT THIS POINT.  BOTH INDICATE
THE GREATER CHANCES WILL REMAIN NORTH OF THE FORECAST AREA.  AN
ADDITIONAL DISTURBANCE COULD BRING CHANCES OF STORMS BACK TO THE
AREA THIS WEEKEND...HOWEVER AS WITH THE POTENTIAL THURS-FRI
SYSTEM...THE MODELS HAVE STRUGGLED WITH CONSISTENCY...SO CONFIDENCE
IS LOW ATTM.

FOR THOSE CONCERNED WITH OVERNIGHT LOWS AND THE POTENTIAL DAMAGE TO
YOUNG COLD-SENSITIVE PLANTS...MODEL GUIDANCE INDICATES NEAR FREEZING
TEMPERATURES NEAR THE CONFLUENCE OF THE N/S PLATTE RIVER AND
POSSIBLY ACROSS CENTRAL CUSTER COUNTY TUESDAY MORNING.  ATTM...THE
CONSENSUS KEEPS MINIMUM READINGS JUST ABOVE 0C.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1207 AM CDT SUN APR 26 2015

THUNDERSTORMS HAVE DISSIPATED OVER WESTERN NEBRASKA WITH SCATTERED
RAINSHOWERS FROM MERRIMAN TO OGALLALA. IN AREAS OF SHOWERS VFR
CEILINGS AND VISIBILITIES. STRATUS CONTINUES TO PUSH WEST AND NORTH
FROM THE EAST. LEADING EDGE OF STRATUS MVFR CEILINGS...DROPPING INTO
IFR CATEGORIES FURTHER TO THE SOUTH AND EAST. SOME SPOTTY REPORTS OF
FOG IN MVFR CATEGORIES. SHOWERS WILL DISSIPATE THROUGH THE EARLY
MORNING HOURS WITH AN AREA OF RELATIVELY DRY AIR AT THE SURFACE.
SOME BR IS EXPECTED TO DEVELOP AFTER 09Z AND LAST THROUGH 13Z TO 15
Z TIME FRAME WITH MVFR CATEGORIES FOR VISIBILITY. LOW CLOUDS TO HANG
IN MOST OF THE DAY WITH CEILINGS RISING INTO VFR CATEGORIES THROUGH
THE AFTERNOON.


&&

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

$$

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








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