Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 262033
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
333 PM CDT TUE MAY 26 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 331 PM CDT TUE MAY 26 2015

TRANSITORY RIDGE WILL CONTINUE TO SLIDE EAST AND REPLACED BY HEIGHT
FALLS BY WED MID DAY ALONG THE LEE OF THE ROCKIES. LARGE UPPER
TROUGH ACROSS THE ROCKIES WILL MOVE ONLY SLOWLY EASTWARD DURING THE
NEXT COUPLE OF DAYS...PUNCTUATED BY A LARGE PV ANOMALY DROPPING
SOUTHWARD OVER THE PAC NW AND ANOTHER PV ANOMALY MOVING EAST AT THE
BASE OF THE TROUGH ACROSS THE NRN BAJA. WEAKER PV ANOMALY CURRENTLY
LOCATED NEAR THE UT/CO BORDER ALSO SLIDING EAST AND WILL CONTRIBUTE
TO INCREASING THUNDERSTORM CHANCES ACROSS THE CENTRAL PLAINS WED.

SPECIFICALLY AND CLOSER TO HOME...WEAK SFC HIGH SETTLING IN OVER NRN
NEB WHILE STEEPER LAPSE RATES ALOFT ARE ALLOWING DAYTIME INSOLATION
TO QUICKLY GENERATE CU AND SUBSEQUENT SHOWERS ASSOCIATED WITH THE
EXITING UPPER LOW OVER NWRN IA. THESE SHOULD DIMINISH WITH SUNSET
ALLOWING CLEARING SKIES AFTER DARK. LARGER SCALE SUBSIDENCE
ASSOCIATED WITH THE AFOREMENTIONED TRANSITORY UPPER RIDGE LIMITING
VERTICAL DEVELOPMENT AND HENCE MAINLY SPRINKLES REACHING THE GROUND.
FURTHER WEST...UPSLOPE FLOW AROUND WEAK SFC HIGH AND FALLING HEIGHTS
LEADING TO ISOLATED THUNDERSTORM DEVELOPMENT PRIMARILY ASSOCIATED
WITH TERRAIN FEATURES. AGAIN THESE SHOULD DIMINISH WITH SUNSET...BUT
AS THE NEXT PV ANOMALY MOVES INTO THE REGION EARLY WED ADDITIONAL
THUNDERSTORMS ARE EXPECTED TO DEVELOP DURING THE MID TO LATE MORNING
HOURS OVER WESTERN NEB AND CONTINUE TO PROGRESS EASTWARD DURING THE
DAY WED. BECAUSE THE TIMING OF THIS SYSTEM DOES NOT COINCIDE WITH
PEAK HEATING...INSTABILITY ON WED WILL NOT BE THAT IMPRESSIVE THOUGH
SOME WEAK MID LEVEL INSTABILITY WILL BE PRESENT AS SRLY FLOW
INCREASES ALONG THE HIGH PLAINS. WHILE A FEW STORMS MAY REACH STRONG
LEVELS...WIDESPREAD SEVERE WEATHER IS NOT EXPECTED WED.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 331 PM CDT TUE MAY 26 2015

THE TRAJECTORY FROM THE TEXAS GULF COAST WILL CONTINUE BRINGING
MOISTURE INTO CENTRAL AND WESTERN NEBRASKA NORTH AND EAST OF THE DRY
LINE. THIS WILL HAVE HIGH PRECIPITABLE WATER VALUES (APPROACHING 1.0
INCH) OVER THE NEBRASKA SANDHILLS AND CENTRAL NEBRASKA AND
PERSISTENT MODERATE RAIN CAN BE EXPECTED. THE INSTABILITY...LIFTED
INDICES OF -2C TO -5C...WOULD SUPPORT AT LEAST A FEW EMBEDDED
THUNDERSTORMS AND LOCALIZED HEAVY RAIN.

AS THE TRAJECTORY CONTINUES INTO THURSDAY...PRECIPITABLE WATER
VALUES WILL APPROACH 1.5 INCH. THE 800MB BASED LIFTED INDICES OF -4C
TO -7C WILL PROBABLY SUPPORT GREATER COVERAGE OF THUNDERSTORMS.
WITH 25-30KT BULK SHEAR (0-6KM) THURSDAY AFTERNOON AND 2500-3000J/KG
CONVECTIVE POTENTIAL...THE UPDRAFT MAY BE OFFSET ENOUGH TO ALLOW A
STRONG UPDRAFT TO PERSIST. IN ADDITION...THE LOW LEVEL WIND PROFILE
MAY PRODUCE A ROTATING UPDRAFT. THEREFORE...THE DEVELOPMENT OF A
SEVERE SUPER CELL IS POSSIBLE...ESPECIALLY SOUTH OF INTERSTATE
80.

AS A COOL FRONT BACKS AGAINST THE MOUNTAINS SATURDAY NIGHT...THE
POTENTIAL FOR PRECIPITATION DIMINISHES UNTIL RETURN FLOW BRINGS THE
FRONT BACK EAST AND BEGINS BRINGING MOISTURE BACK TO THE HIGH
PLAINS. THAT COULD BE AS LATE AS NEXT TUESDAY NIGHT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1237 PM CDT TUE MAY 26 2015

VFR CONDITIONS EXPECTED AT KLBF AND KVTN FOR THE FCST PERIOD. WEAK
HIGH PRESSURE BUILDING INTO THE REGION WILL ALLOW FOR LIGHTER WINDS
THROUGH THE AFTERNOON WITH A WEAK UPSLOPE DEVELOPING IN THE
PANHANDLE. AS CLOUDS CLEAR SOME REDEVELOPMENT OF CU IS LIKELY AND
MAY PRODUCE SPRINKLES BUT UNDER TRANSITORY UPPER RIDGING VERY
LITTLE LARGE SCALE FORCING IS EXPECTED THROUGH EVENING. INCREASING
TSRA CHANCES IN THE PANHANDLE AND SOUTHWESTERN NEB DURING THE
MORNING WED SHOULD STAY EAST OF TAF SITES UNTIL BEYOND THE FCST PERIOD.


&&

.HYDROLOGY...
ISSUED AT 331 PM CDT TUE MAY 26 2015

NORTH PLATTE RIVER SLOWLY COMING UP AT LISCO AND LEWELLEN WITH
UPSTREAM RELEASES AND RAINFALL OF THE LAST FEW DAYS. PLEASE SEE
FLOOD STATEMENTS PERTAINING TO THE NORTH PLATTE RIVER AT LISCO AND
LEWELLEN FOR FURTHER DETAILS. AT THIS TIME LOOKS LIKE MCCONAUGHY
SHOULD BE ABLE TO HOLD MOST OF THE UPSTREAM RELEASES...AND THEREFORE
IMPACTS NOT AS APPARENT FURTHER DOWNSTREAM.

THE SOUTH PLATTE RIVER WILL BE COMING UP ONCE AGAIN WITH RAINFALL
OVER THE BASIN IN NORTHEAST COLORADO AND THE CONTINUED SNOW MELT IN
THE ROCKIES. ADDITIONAL RAINFALL...SOME WHICH COULD BE HEAVY...IS
POSSIBLE MID WEEK AND EARLY THIS WEEKEND. SOUTH PLATTE RIVER CRESTS
ARE EXPECTED IN THE WEDNESDAY AND THURSDAY TIME FRAME FROM ROSCOE TO
NORTH PLATTE AND THE THURSDAY TO FRIDAY TIME FRAME AT BRADY. CHECK
WITH LATEST WARNING INFORMATION FOR CRESTS AND TIMES.

&&

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

$$

SHORT TERM...JWS
LONG TERM...SPRINGER
AVIATION...JWS
HYDROLOGY...JWS





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