Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 312323 AAA
AFDLBF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
623 PM CDT SUN MAY 31 2015

.SYNOPSIS...
ISSUED AT 305 PM CDT SUN MAY 31 2015

H5 ANALYSIS THIS MORNING HAS A CONTINUATION OF BROAD
WESTERLY FLOW ACROSS THE WESTERN CONUS WITH NUMEROUS EMBEDDED
SHORTWAVES EXTENDING FROM THE DAKOTAS...SWD INTO THE ARKLATEX.
UPSTREAM OF THE CENTRAL PLAINS...SHORTWAVES WERE NOTED OVER SWRN
CANADA...AS WELL AS OFF THE COAST OF CALIFORNIA AND OREGON. VISIBLE
SATELLITE IMAGERY THIS AFTERNOON HAS A BROAD AREA OF CONVECTIVE
CLOUD DEVELOPMENT ACROSS SERN WYOMING...AS WELL AS NWRN WYOMING.
ACROSS CENTRAL AND EASTERN NEBRASKA...A BROAD SHIELD OF CLOUD COVER
EXTENDED ALONG AND EAST OF HIGHWAY 83 FROM VALENTINE TO NORTH
PLATTE. LIGHT RAIN SHOWERS WERE PRESENT MAINLY ACROSS NORTHERN
NEBRASKA EARLIER THIS MORNING...AND HAVE SINCE WEAKENED AS THEY
TRACK EAST INTO NORTHEASTERN NEBRASKA. TEMPERATURES AS OF 2 PM CDT
RANGED FROM 62 AT ONEILL...TO 74 AT OGALLALA.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 305 PM CDT SUN MAY 31 2015

TONIGHT AND MONDAY.  A WEAK DISTURBANCE WILL WORK IN CONJUNCTION
WITH LIGHT EASTERLY UPSLOPE TARGETING A SURFACE TROUGH OVER THE
EASTERN PANHANDLE TO PROMOTE ISOLATED THUNDERSTORM DEVELOPMENT THIS
EVENING.  PROXIMITY SOUNDINGS FROM SOUTHWEST NEBRASKA AND THE
ADJACENT EASTERN PANHANDLE INDICATE MEAGER AMOUNTS OF AVAILABLE
CONVECTIVE ENERGY FOR STORM PRODUCTION BY LATE AFTERNOON
TODAY...WHICH THUS FAR THE CURRENT LAPS ANALYSIS HAS VERIFIED.  WHEN
STORMS INITIATE OFF THE HIGH PLAINS...EXPECT GARDEN VARIETY...OR
POSSIBLY A STRONG STORM OR TWO TO BE THE PREVAILING STORM
MODE...WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED OWING TO THE
WEAK DESTABILIZATION.  COVERAGE WILL INCREASE TO SCATTERED LATE THIS
EVENING AND INTO THE EARLY MORNING HOURS MONDAY AS THE ACTIVITY
MOVES ACROSS SOUTHWEST NEBRASKA AND ENCOUNTERS A 35-40 KT
LLJ....AGAIN HOWEVER...SEVERE WEATHER IS NOT ANTICIPATED AS THE
ATMOSPHERE STABILIZES WITH THE LOSS OF SOLAR RADIATION.

MONDAY...MID LEVEL RIDGE WILL SHIFT EAST ACROSS THE HIGH PLAINS INTO
WEST CENTRAL NEBRASKA DURING THE DAY.  INCREASING HEIGHTS AND WAA
FROM THE WEST WILL PUSH TEMPERATURES BACK INTO THE 80S FOR LOCATIONS
GENERALLY WEST OF HIGHWAY 83...70S TO THE EAST.  IN
ADDITION...STRONG SOUTHERLY BOUNDARY LAYER FLOW WILL CONTINUE TO
PUMP MOISTURE INTO THE REGION...WHICH WILL LEAD TO A CONSIDERABLE
INCREASE IN AVAILABLE CONVECTIVE ENERGY FOR THUNDERSTORM
DEVELOPMENT.  WITH THE STRONG INSTABILITY IN PLACE...SEVERE
THUNDERSTORMS CANNOT BE RULED OUT DURING THE AFTERNOON
HOURS...DESPITE THE RIDGING /ASSOCIATED SUBSIDENCE/ BUILDING ATOP
THE REGION...HOWEVER THE BETTER CHANCES OF STORMS COME JUST BEYOND
THE SHORT TERM PERIOD AS A NORTHERN ROCKIES/PLAINS TROUGH BREAKS THE
UPPER RIDGE DOWN...LEADING TO INCREASING DCVA/LARGE SCALE FORCING
FOR ASCENT ACROSS OUR WESTERN ZONES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 305 PM CDT SUN MAY 31 2015

MID RANGE...MONDAY NIGHT THROUGH WEDNESDAY...THUNDERSTORM CHANCES
ARE THE MAIN FORECAST CHALLENGE IN THE MID RANGE...FOLLOWED BY THE
THREAT FOR HEAVY RAIN IN THE EXTENDED PERIODS. CONVECTION IS
EXPECTED TO INITIATE IN THE WESTERN NEBRASKA PANHANDLE LATE MONDAY
AFTERNOON INVOF OF A SURFACE TROUGH AND DRYLINE. THIS ACTIVITY WILL
BEGIN TO PUSH INTO THE EASTERN PANHANDLE EARLY MONDAY EVENING.
SEVERE POTENTIAL WILL BE FAIRLY LIMITED MONDAY EVENING AS BULK SHEAR
FALLS FROM AROUND 35 KTS AT 00Z TO AROUND 25 KTS AT 06Z TUES. SHEAR
WILL WEAKEN AS WELL FROM WEST TO EAST...SO THE STRONG TSRA THREAT
WILL REMAIN GENERALLY WEST OF HIGHWAY 83...CONFINED TO MONDAY
EVENING. OVERNIGHT...WE COULD SEE SOME CONVECTION SUSTAIN ITSELF AS
IT TRACKS INTO CENTRAL AND EASTERN NEBRASKA AS A LOW LEVEL JET
DEVELOPS OVERNIGHT. HOWEVER...WILL LITTLE OR NO BOUNDARY LAYER
FOCUS...WILL KEEP POPS CAPPED AT A SLIGHT CHANCE. ADDITIONAL POPS
WERE INTRODUCED IN THE NRN PANHANDLE LATE MONDAY NIGHT AS A
SECONDARY SHORTWAVE LIFTS FROM NORTHEASTERN WYOMING INTO THE BLACK
HILLS. ANOTHER ROUND OF CONVECTION IS EXPECTED TO DEVELOP TUESDAY
AFTERNOON INVOF THE SURFACE TROUGH/DRYLINE...ORIENTED ACROSS THE
CENTRAL PANHANDLE. CONVECTIVE ENERGY IS HIGH TUESDAY
AFTERNOON/EVENING WITH CAPES APPG 4000 J/KG INVOF OF THE SURFACE
TROUGH...HOWEVER BULK SHEAR IS FAIRLY WEAK ON THE ORDER OF 20 TO 25
KTS...SO HEAVY RAIN WILL BE THE MAIN SEVERE THREAT. HOWEVER
MARGINALLY SEVERE HAIL CANNOT BE RULED OUT AS CAPES IN THE -10 TO
-30C ARE AROUND 1400 J/KG. ON TUESDAY NIGHT INTO WEDNESDAY...A WEAK
FRONTAL BOUNDARY/WIND SHIFT LINE WILL PUSH ACROSS WESTERN AND NORTH
CENTRAL NEBRASKA. THIS FEATURE WILL BE ORIENTED JUST OFF TO THE EAST
AND SOUTHEAST OF THE AREA. ATTM...THE GREATEST SEVERE THREAT IS OVER
SWRN NEBRASKA...WHICH IS IN CLOSET PROXIMITY TO THE NORTHERN
PERIPHERY OF THE FRONTAL BOUNDARY...ALSO WHERE CAPES AND BULK SHEAR
IS MOST FAVORABLE FOR SEVERE STORMS. FURTHER NORTH...BULK SHEAR
WEAKENS SUBSTANTIALLY. HOWEVER DEEP EASTERLIES AND ABUNDANT MOISTURE
WITH PWATS OF 1.25 TO 1.75 INCHES WILL LEAD TO A THREAT FOR HEAVY
RAIN...AND WITH THE MID LEVEL FLOW ORIENTED PARALLEL TO THE
FRONT...WE COULD SEE SOME TRAINING OF THUNDERSTORMS ACROSS SWRN
NEBRASKA WEDS AFTN/NIGHT WHICH COULD ENHANCE OUR FLOODING THREAT.
WILL CONTINUE TO HIGHLIGHT THIS THREAT FOR HEAVY RAIN IN THE HWO.

.LONG RANGE...THURSDAY THROUGH SUNDAY...THE THREAT FOR RAIN WILL
CONTINUE INTO THURSDAY AND THURSDAY NIGHT...AS THE FORECAST AREA
REMAINS ON THE NORTHERN SIDE OF THE WARM FRONTAL BOUNDARY ACROSS
KANSAS. LOW LEVEL EASTERLIES AND ABUNDANT MOISTURE WILL CONTINUE TO
BE PRESENT ACROSS THE FORECAST AREA WITH A DECENT SHOT OF MODERATE
TO HEAVY RAIN ONCE AGAIN. CONDS WILL DRY OUT TEMPORARILY FRIDAY INTO
SATURDAY AS THE WARM FRONT WASHES OUT AND SRLY WINDS AND STRONG LOW
LEVEL WAA RETURNS TO THE REGION. AT THE SAME TIME...A CLOSED LOW
WILL BEGIN TO TRACK INTO SRN CALIFORNIA...WHICH WILL AMPLIFY THE
RIDGE ACROSS THE CENTRAL CONUS. THIS FEATURE WILL COME ASHORE ON
SATURDAY...WITH AN INCREASED THREAT FOR RAIN ONCE AGAIN SATURDAY
NIGHT/SUNDAY. HEAVY RAIN MAY BE AN ISSUE ONCE AGAIN AS THE GFS SOLN
ACTUALLY TAPS INTO TROPICAL MOISTURE OFF THE BAJA CA COAST...AND
PUSHES THIS NORTHEAST INTO THE ROCKIES AND PLAINS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 623 PM CDT SUN MAY 31 2015

AT SOME POINT TONIGHT...06Z-09Z...MVFR/IFR CIGS AND VSBY SHOULD
DEVELOP ALONG AND EAST OF HIGHWAY 61. SOME MODELS ARE VERY
FAST...THE RAP...WHICH OTHERS ARE SLOW...THE SREF. THE NAM WAS IN
THE MIDDLE AND WAS THE BASIS FOR THE FORECAST.

A DISTURBANCE ACROSS ERN WY THIS EVENING WILL MOVE EAST
OVERNIGHT...PERHAPS TRIGGERING ISOLATED SHRA AND TSTM COVERAGE
WHICH WOULD DISSIPATE OR MOVE EAST OF THE FCST AREA 09Z-12Z.

VFR IS EXPECTED ALL AREAS BY 18Z. TSTM CHANCES INCREASE ALONG OR
NEAR HIGHWAY 61 FROM 21Z ONWARD. STORM COVERAGE 21Z-00Z WOULD
LIKELY BE ISOLATED BUT SEVERE OR STRONG

&&

.HYDROLOGY...
ISSUED AT 305 PM CDT SUN MAY 31 2015

CURRENT FLOOD WARNINGS FOR THE PLATTE...SOUTH PLATTE AND NORTH
PLATTE RIVER SYSTEMS REMAIN IN PLACE.  RIVER LEVELS ALONG THE PLATTE
AND SOUTH PLATTE RIVER BASINS ARE FORECAST TO SLOWLY DECREASE IN THE
COMING WORK WEEK...HOWEVER THE FORECAST CALLS FOR AN INCREASING
THREAT OF HEAVY RAINFALL NEXT WEEK.  HEAVY RAINFALL ACCUMULATIONS
COULD EFFECT RIVER LEVELS.  PLEASE CHECK THE LATEST WARNING
INFORMATION FOR CURRENT CRESTS AND TIMES.

&&

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

$$

SYNOPSIS...CLB
SHORT TERM...JACOBS
LONG TERM...CLB
AVIATION...CDC
HYDROLOGY...JACOBS





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