Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 010830
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
330 AM CDT MON JUN 1 2015

.SYNOPSIS...
ISSUED AT 329 AM CDT MON JUN 1 2015

AT 08Z...A TROUGH OF SURFACE LOW PRESSURE EXTENDED FROM MONTANA
THROUGH WYOMING INTO EASTERN COLORADO. ISOLATED SHOWERS OR
THUNDERSTORMS OCCURRING FROM EAST OF NORTH PLATTE THROUGH EAST OF
MCCOOK.  DEWPOINTS HAVE MOSTLY RISEN INTO THE LOWER 50S AND RANGE
AS HIGH AS 55 AT OGA AND 56 AT AIA. TEMPERATURES RANGING FROM 54 AT
AINSWORTH TO 60 AT NORTH PLATTE. WINDS GENERALLY LIGHT SOUTHEAST.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 329 AM CDT MON JUN 1 2015

TODAY AND TONIGHT...A TRANSITORY UPPER RIDGE AXIS WILL MOVE ONTO THE
CENTRAL HIGH PLAINS AS AN UPPER LEVEL EXTENDS ACROSS THE THE PACIFIC
NORTHWEST INTO THE DESERT SOUTHWEST. THIS WILL CREATE AMPLIFIED
SOUTHWESTERLY FLOW ALOFT INTO THE CENTRAL ROCKIES AND ADJACENT FRONT
RANGE. THE AXIS OF THIS UPPER TROUGH WILL LIFT NORTHEAST FROM THE
GREAT BASIN INTO THE CENTRAL ROCKIES TODAY. FAIRLY HIGH H85
DEWPOINTS NEAR 15C WILL EXIST FROM NWRN KS...SWRN NEBR AND THE NEBR
PNHDL. WITH HIGHS REACHING THE LOWER 80S IN THESE AREAS...SBCAPES TO
RANGE AS HIGH AS 500-1500J/KG. ISOLATED TO WIDELY SCATTERED
THUNDERSTORMS SHOULD DEVELOP ONTO THE FRONT RANGE OF CO AND WY THIS
AFTERNOON. STORM MOTION FCST TO BE 10KTS OR LESS. SOME OF THE
SHOWERS AND THUNDERSTORMS SHOULD MOVE THROUGH THE ERN PANHANDLE AND
SWRN NEBR THIS EVENING THEN DIMINISH EASTWARD AS INSTABILITY WANES.
STRONG STORMS ARE POSSIBLE THIS EVENING MAINLY WEST OF A MERRIMAN
THROUGH HAYES CENTER LINE WHERE A FEW STORMS COULD CONTAIN HAIL UP
TO NICKEL SIZE AND GUSTY WINDS. KEPT A SLIGHT CHANCE IN AFTER
MIDNIGHT ACROSS THE EASTERN HALF OF FA AS UPPER SUPPORT WEAKENS BUT
LOW LVL JET KICKS IN. STRATUS IS LIKELY TO DEVELOP LATE TONIGHT
ACROSS SWRN NEBR INTO THE CENTRAL SANDHILLS. LOWS MAINLY NEAR 60.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 329 AM CDT MON JUN 1 2015

PRIMARY FORECAST CHALLENGE FOR THE LONG TERM PERIOD IS THE POTENTIAL
FOR SEVERE WEATHER AND HEAVY RAINFALL ACROSS THE SANDHILLS REGION
FOR THE MIDDLE OF THE WEEK. TUESDAY MORNING A BROAD...LOW AMPLITUDE
TROUGH WILL BE WELL ESTABLISHED ACROSS THE WESTERN TWO-THIRDS OF THE
CONUS. A WEAK PV MAX EMBEDDED IN THE SOUTHWEST FLOW ALOFT MOVES
ACROSS THE NORTHERN ROCKIES AND INTO THE DAKOTAS BY LATE IN THE DAY.
AS THIS OCCURS A DEEP ELEVATED MIXED LAYER IS ADVECTED OFF THE
ROCKIES AND INTO THE CENTRAL PLAINS...AND A SURFACE TROUGH ACROSS
EASTERN COLORADO/WESTERN NEBRASKA DEEPENS AND BECOMES BETTER
DEFINED. EAST OF THE SURFACE TROUGH SOUTHERLY FLOW WILL FAVOR A WARM
BOUNDARY LAYER WITH MOIST DEWPOINTS OF 60-65F. THE RICH THETA-E AIR
NEAR THE SURFACE AND VERY STEEP LAPSE RATES ALOFT WILL LEAD TO A
STRONGLY UNSTABLE ENVIRONMENT CHARACTERIZED BY MLCAPE VALUES AOA
3000 J/KG. CONVECTIVE INITIATION BEGINS ALONG THE SURFACE TROUGH
DURING THE MID TO LATE AFTERNOON HOURS. STORMS WILL HAVE THE
POTENTIAL TO QUICKLY BECOME SEVERE GIVEN THE STRONG INSTABILITY AND
DEEP LAYER SHEAR OF 30-40 KTS. VERY LARGE HAIL WILL BE THE PRIMARY
SEVERE WEATHER THREAT WITH MODELS ADVERTISING AROUND 1500 J/KG
CONTRIBUTION TO SURFACE CAPE IN THE -10C TO -30C LAYER. A FEW
TORNADOES WILL ALSO BE POSSIBLE WITH ANY DISCRETE UPDRAFTS...MAINLY
DURING THE EARLY EVENING HOURS AS THE LOW LEVEL JET DEVELOPS AND
ENHANCES LOW LEVEL SRH. THE BEST CHANCE FOR THUNDERSTORMS...AND
POTENTIAL SEVERE WEATHER...WILL GENERALLY BE ALONG AND EAST OF AN
ARTHUR TO CODY LINE. FURTHER SOUTH AND WEST OF THE SURFACE
TROUGH...WEAKER UPPER LEVEL SUPPORT AND LOW LEVEL MOISTURE
CONVERGENCE WILL LIKELY LIMIT THE DEGREE OF THUNDERSTORM COVERAGE.
TUESDAY NIGHT THE LOW LEVEL JET WILL HELP MAINTAIN THUNDERSTORMS AS
THEY PUSH EAST...HOWEVER THE SEVERE WEATHER THREAT GRADUALLY
DIMINISHES AS INSTABILITY WANES.

DEEPENING SURFACE LOW OVER EASTERN COLORADO WILL LEAD TO EASTERLY
UPSLOPE WINDS OVER THE CWA FOR WEDNESDAY. SEVERE STORM THREAT
INCREASES ONCE AGAIN IN SOUTHWEST NEBRASKA WHERE UNSTABLE CONDITIONS
WILL DEVELOP BY LATE AFTERNOON. LARGE HAIL WILL BE THE PRIMARY
THREAT...BUT A TORNADO OR TWO WILL ALSO BE POSSIBLE...ESPECIALLY IN
THE VICINITY OF THE SURFACE WARM FRONT/TRIPLE POINT AS THE LOW LEVEL
JET INCREASES BY EARLY EVENING. MAINTAINED LIKELY POPS FOR THE
ENTIRE FORECAST AREA AFTER 00Z AS MODELS CONTINUE TO SHOW WIDESPREAD
QPF AND THE POTENTIAL FOR LOCALLY HEAVY RAINFALL. WARM FRONT HANGS
UP ACROSS CENTRAL KANSAS ON THURSDAY. EASTERLY UPSLOPE FLOW AND
ABUNDANT MOISTURE TO THE NORTH OF THE FRONT WILL LEAD TO ANOTHER DAY
OF SHOWER AND THUNDERSTORM CHANCES ACROSS THE CWA...HOWEVER THE
SEVERE THREAT SHOULD BE LOW.

FRIDAY LOOKS DRIER AS AN AREA OF UPPER LEVEL HIGH PRESSURE BECOMES
ESTABLISHED OVER EASTERN NEW MEXICO/WEST TEXAS. THE BREAK FROM
PRECIPITATION CHANCES IS SHORT LIVED AS BOTH THE GFS AND EURO BOTH
DEVELOP A STRONG TAP OF MOISTURE OFF THE PACIFIC BY THE END OF THE
WEEK...WITH DEEP MOISTURE ROUNDING THE TOP OF THE RIDGE AND INTO THE
EASTERN ROCKIES AND HIGH PLAINS. THIS MAY KEEP THE THREAT FOR
MODERATE TO HEAVY RAINFALL IN THE PICTURE FOR THE WEEKEND.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1131 PM CDT SUN MAY 31 2015

THE MODELS CONTINUE TO INDICATE STRATUS AND IFR/MVFR CIGS. LIFR
CIGS MAY DEVELOP ALONG OR WEST OF HIGHWAY 61. FLIGHT CONDITIONS
SHOULD IMPROVE TO VFR/MVFR AROUND 18Z WITH VFR ALL AREAS BY 21Z.

ISOLATED TO LOW END SCATTERED TSTMS...SOME SEVERE...MAY DEVELOP
ACROSS THE PANHANDLE 21Z-00Z WHICH WOULD MOVE EAST AND DECAY
BETWEEN HIGHWAY 61 AND HIGHWAY 83 MONDAY EVENING.

&&

.HYDROLOGY...
ISSUED AT 329 AM CDT MON JUN 1 2015

CURRENT FLOOD WARNINGS FOR THE PLATTE...SOUTH PLATTE...AND NORTH
PLATTE RIVER SYSTEMS REMAIN IN PLACE. RIVER LEVELS SHOULD REMAIN
FAIRLY STEADY OR SLOWLY FALL ALONG THE SOUTH PLATTE AND PLATTE RIVER
SYSTEMS THROUGH THE END OF THIS WEEK. WHILE ROSCOE AND BRADY WILL
CONTINUE TO REMAIN ABOVE FLOOD STAGE...THE STAGE AT NORTH PLATTE HAS
CURRENTLY FALLEN TO NEAR FLOOD STAGE AND IS FORECAST TO FALL
SLIGHTLY BELOW FLOOD STAGE TODAY. RIVER LEVELS ALONG THE NORTH
PLATTE RIVER UPSTREAM OF LAKE MCCONAUGHY ARE FORECAST TO REMAIN ABOVE
FLOOD STAGE AND RISE SLIGHTLY THROUGH THE END OF THE WEEK. THE STAGE
AT LEWELLEN IS CURRENTLY NEAR THE MODERATE FLOOD STAGE OF 8.5 FEET.

THE POTENTIAL FOR HEAVY RAINFALL WILL EXIST THIS WEEK AND COULD LEAD
TO LOCALIZED FLASH FLOODING AND THIS RUNOFF COULD CAUSE RIVER LEVELS
TO RISE IN SOME AREAS. PLEASE CHECK THE LATEST FLOOD WARNING
FORECASTS.


&&

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

&&

$$

SYNOPSIS...ROBERG
SHORT TERM...ROBERG
LONG TERM...MARTIN
AVIATION...CDC
HYDROLOGY...ROBERG






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