Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 251115
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
615 AM CDT SAT APR 25 2015

.SYNOPSIS...
ISSUED AT 325 AM CDT SAT APR 25 2015

THE 07Z SURFACE ANALYSIS SHOWED A NUMBER OF SURFACE BOUNDARIES  ON
THE HIGH PLAINS. THERE ARE TWO THAT APPEAR TO BE OF MOST INTEREST
FOR THE FORECAST TODAY. ONE IS A DEWPOINT GRADIENT FROM EASTERN
SOUTH DAKOTA TO THE SOUTHERN NEBRASKA PANHANDLE. THE OTHER IS A
FRONT AND INVERTED TROUGH ACROSS MONTANA AND NORTHWEST WYOMING. THE
WYOMING SYSTEM WAS ASSOCIATED WITH LOW PRESSURE CENTERED ALONG THE
WYOMING-MONTANA BORDER AND ANOTHER NORTH OF RIVERTON.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 325 AM CDT SAT APR 25 2015

THE CONVERGENCE ALONG THE DEWPOINT BOUNDARY IN NORTHERN AND WESTERN
NEBRASKA WILL CONTINUE TO BE THE FOCUS FOR SCATTERED SHOWERS AND
THUNDERSTORMS IN NORTHEAST AND NORTH CENTRAL NEBRASKA THIS MORNING.
THE OTHER ARE OF INTEREST IS THE PRECIPITABLE WATER GRADIENT IN
WESTERN NEBRASKA WHICH WILL BE IN PLACE WHEN THE SYSTEM IN WYOMING
MAKES ITS WAY INTO NEBRASKA THIS AFTERNOON AND TONIGHT. WITH SOME
DAYTIME HEATING...875MB BASED LIFTED INDICES WILL DECREASE TO -3C TO
-4C. HOWEVER...AS HAS BEEN THE CASE THE PAST TWO DAYS...THE DEEP
0-6KM BULK SHEAR IS EXPECTED TO BE MARGINAL AS WILL BE THE AVAILABLE
CONVECTIVE POTENTIAL ENERGY...SO IF THERE IS ANY LARGE HAIL...IT
WILL BE VERY LOCALIZED. STILL...CONDITIONS ARE FAVORABLE FOR
THUNDERSTORM DEVELOPMENT IN THE NEBRASKA PANHANDLE AND THE WESTERN
SANDHILLS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 325 AM CDT SAT APR 25 2015

GUIDANCE CONTINUES TO ADVERTISE THE BREAKDOWN OF AN TRANSITORY UPPER
LEVEL RIDGE ON SUNDAY AS A TROUGH ADVANCES ACROSS THE INTER-MOUNTAIN
WEST.  THE TROUGH WILL ADVANCE ACROSS THE CENTRAL CONUS THROUGH
MID-WEEK AND CLOSE A LOW OFF OVER THE SOUTHERN PLAINS...BUT MID TO
LATE NEXT WEEK...UPPER TROPOSPHERIC RIDGING IS THEN PROGGED TO
SPREAD ATOP THE PLAINS.  THUS...UNSETTLED CONDITIONS ARE FORECAST
THROUGH THE MEDIUM RANGE...THEREAFTER TRENDING WARM AND DRY.

THE GREATEST CHANCES OF PRECIPITATION IN THE EXTENDED OCCUR ON
SUNDAY AS THE AFOREMENTIONED UPPER TROUGH  ADVANCES SOUTHEAST TOWARD
THE CENTRAL/SOUTHERN ROCKIES.  THE OVERALL TREND OF THE SYSTEM IS
SLOWING AND SOUTH...WHICH BREEDS UNCERTAINTY INTO THE POP FORECAST
LATE WEEKEND AND EARLY NEXT WEEK.  THE GENERAL IDEA REMAINS THE SAME
FROM THE PREVIOUS FORECAST IN THAT THE GREATEST CHANCES WILL REMAIN
ACROSS OUR WESTERN ZONES WHERE LOWER TROPOSPHERIC UPSLOPE WILL HELP
PROMOTE QPF...ALTHOUGH IT SHOULD BE NOTED THAT A BETTER CONTRIBUTION
OF OMEGA FROM THE SYSTEM WILL BE SOUTH AND WEST OF THE FORECAST
AREA...ESPECIALLY DURING THE SUNDAY NIGHT INTO MONDAY TIME PERIOD.
SO FOR THE FORECAST...WITH UNCERTAINTY...LEFT THE POP FORECAST
LARGELY ALONE SUNDAY...BUT TRENDED BACK CHANCES DURING THE OVERNIGHT
AND ON MONDAY.  THEREAFTER...INCREASING SUBSIDENCE ASSOCIATED WITH THE
AFOREMENTIONED UPPER RIDGE AND A RESULTANT LACK OF OMEGA LENDS A DRY
FORECAST INTO FRIDAY.

THE EASTERLY COMPONENT OF THE LOWER TROPOSPHERIC WIND LATE WEEKEND
AND ON MONDAY AT A MINIMUM WILL INCREASE CLOUDS ACROSS THE FORECAST
AREA. THE OVERCAST SKIES WILL COMBINE WITH THE REMNANTS OF A COOL
POST-FRONTAL AIRMASS TO KEEP HIGHS GENERALLY IN THE 60S...WITH LOWS
IN THE 40S AND POSSIBLY UPPER 30S MONDAY AND TUESDAY MORNING.
THERMAL ADVECTION AND SUBSIDENCE WILL WARM THE BL THEREAFTER...WITH
TEMPERATURES RESPONDING BY WARMING 5 DEGREES FAHRENHEIT OR SO
DAILY.  HIGHS BY LATE WEEK WILL BE PUSHING THE UPPER 70S TO LOWER
80S FOR MOST LOCATIONS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 610 AM CDT SAT APR 25 2015

LOW CLOUDS IN SOUTH DAKOTA AND EASTERN NEBRASKA WILL SPREAD
SOUTHWARD AND WESTWARD THIS MORNING. BY 15Z...THE LOW CLOUDS ARE
EXPECTED TO REACH A VTN-BBW-LXN LINE. CEILINGS NORTH AND EAST OF
THAT LINE ARE LIKELY TO BE AT OR BELOW 1000 FEET AGL WHILE...SOUTH
AND WEST OF THAT LINE...CEILINGS WILL BE 2000-3000 FEET AGL.

THIS AFTERNOON AFTER 21Z...SCATTERED THUNDERSTORMS ARE EXPECTED IN
THE WEST TO INCLUDE MRR...MHN AND OGA.

&&

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

$$

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





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