Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 221524
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1024 AM CDT FRI AUG 22 2014

.UPDATE...
ISSUED AT 1010 CDT CDT FRI AUG 22 2014

SHOWERS AND THUNDERSTORMS CONTINUE LATE THIS MORNING IN SOUTHWEST
NEBRASKA...GENERALLY ALONG THE I-80 AND I-76 CORRIDORS. THIS BAND
WILL SLOWLY NUDGE NORTH AS MID LEVEL WAA CONTINUES IN RESPONSE TO
A PV MAX EJECTING OUT OF THE DESERT SOUTHWEST. VIS SATELLITE SHOWS
CLEARING SKIES ACROSS NORTHWEST KANSAS...PUSHING INTO SOUTHWEST
NEBRASKA. THIS SHOULD SET THE STAGE FOR ADEQUATE HEATING AND BUILD
UP OF SFC INSTABILITY LATER TO FUEL WIDESPREAD THUNDERSTORM
DEVELOPMENT BY MID TO LATE AFTERNOON. TWO AREAS OF HEAVY
PRECIPITATION ARE LIKELY AS THE UPPER LEVEL LOW AND A SURGE OF
MONSOONAL MOISTURE MOVES OVER THE CENTRAL PLAINS THIS EVENING INTO
TONIGHT...PUSHING PWATS TO OVER TWO STANDARD DEVIATIONS ABOVE
NORMAL. FIRST AREA OF CONCERN WOULD BE FROM SOUTHWEST INTO
CENTRAL NEBRASKA AS CONVECTION DEVELOPS AND MOVES NORTHEAST OF A
SFC WARM FRONT NEAR THE KS-NE BORDER. THIS CONVECTION SHOULD
REMAIN ROBUST AND SUSTAINED THROUGH THE NIGHT AS THE LLJ
STRENGTHENS AND SUPPLIES AMPLE WAA AND MOISTURE TRANSPORT INTO THE
AREA. THE SECOND AREA OF CONCERN IS ACROSS THE WESTERN SANDHILLS
WHERE A DEFORMATION ZONE WILL SET UP TO WEST SIDE OF THE SFC LOW
PRESSURE MOVING INTO THE CENTRAL SANDHILLS OVERNIGHT. ISENTROPIC
ANALYSIS SHOWS STRONG UPSLOPE THETA-E ADVECTION IN THE LOW TO MID
LEVELS THROUGH 9Z TONIGHT. OVERALL...WOULD NOT BE SURPRISED TO SEE
NUMEROUS REP ROTS OF 1" OF RAINFALL WITH HIGHER AMOUNTS POSSIBLE
WITHIN AREAS OF SUSTAINED DEEP CONVECTION.

SEVERE WEATHER WILL ALSO BE POSSIBLE ACROSS MUCH OF THE FORECAST
AREA LATE THIS AFTERNOON AND INTO THE EVERY OVERNIGHT HOURS. MID
LEVEL LAPSE RATES WILL CONTINUE TO STEEPEN IN CONCERT WITH
STRENGTHENING UPPER LEVEL FLOW AS THE SOUTHWEST UPPER LEVEL LOW
APPROACHES THE AREA. AT THIS TIME LARGE HAIL AND STRONG DAMAGING
WINDS LOOK TO BE THE PRIMARY THREATS. A SMALL WINDOW FOR A
TORNADO OR TWO WILL EXIST DURING THE EVENING HOURS AS LOW LEVEL
SHEAR INCREASES IN CONJUNCTION WITH A STRENGTHENING LOW LEVEL JET.
THE MOST FAVORABLE AREA LOOKS TO BE JUST NORTH OF THE WARM FRONT
NEAR THE KS-NE BORDER AND SOUTH OF I-80. THE TORNADO THREAT DOES
REMAIN UNCERTAIN THOUGH AS STORMS WILL LIKELY HAVE A HIGH DEGREE
OF PRECIP LOADING GIVEN THE VERY MOIST ENVIRONMENT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 359 AM CDT FRI AUG 22 2014

MODELS IN FAIR AGREEMENT THIS MORNING WITH NAM HAVING A BETTER
HANDLE ON ONGOING PRECIPITATION. WILL LEAN TOWARDS NAM SOLUTION.
STRONG WAVE IN BOTTOM OF TROUGH TO THE WEST ENTERING FOUR CORNERS
EARLY THIS MORNING. THIS FEATURE TO EJECT ACROSS THE ROCKIES WITH
SURFACE LOW DEVELOPING OVER EASTERN COLORADO...WESTERN KANSAS TODAY.
THIS LOW TO MOVE NORTH ACROSS WESTERN NEBRASKA LIFTING A WARM
FRONTAL BOUNDARY NORTH ACROSS THE AREA. ONGOING CONVECTION EARLY
THIS MORNING AS SEEN IN KLNX RADAR. LATER THIS MORNING AS THE WAVE
TO THE SOUTHWEST EMERGES ONTO THE PLAINS CONVECTION NORTH OF SURFACE
BOUNDARY OVER SOUTHWEST NEBRASKA. ABUNDANT MOISTURE IN PLACE WITH
PWATS LAST NIGHT IN THE NEIGHBORHOOD OF 150% TO 175% OF NORMAL
AROUND 2 STANDARD DEVIATIONS. HAVE INTRODUCED MODERATE RAIN AND
UPPED QPF FIELDS. FAIRLY WARM TEMPERATURES ALOFT AT 850MB
TEMPERATURES ON THE ORDER OF 20C THROUGH THE AFTERNOON AND COOLING
THROUGH THE EVENING. FAVORABLE HODOGRAPHS AND BULK SHEAR IN THE
VICINITY OF THE FRONT THIS AFTERNOON AROUND 30 TO 40 KTS. LOW LEVEL
JET WILL KICK IN LATE IN THE AFTERNOON AS UPPER WAVE MOVES TOWARDS
THE CENTRAL PLAINS. HIGHS TODAY ONLY IN THE 80S. BEST DYNAMICS
BETWEEN 23/00Z AND 23/03Z OVER SOUTHWEST NEBRASKA ALONG THE FRONT
WITH SBCAPES 3 TO 4 THOUSAND J/K. ONGOING THREAT OVER NIGHT AS
SURFACE LOW MOVES NORTH ACROSS WESTERN NEBRASKA. EASTERN NEBRASKA
PANHANDLE MAY SEE SIGNIFICANT RAINFALL IN DEFORMATION ZONE AS MAIN
ENERGY WITH UPPER LOW AND UPGLIDE PRODUCE FAVORABLE LIFT. MODELS
HAVE SYSTEM EXITING NORTHERN NEBRASKA THROUGH THE MORNING ON
SATURDAY. LOWS FRIDAY NIGHT IN THE 60S.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 359 AM CDT FRI AUG 22 2014

UPPER LEVEL LOW/TROUGH TO PUSH ACROSS THE CENTRAL/NORTHERN
ROCKIES ON SATURDAY AND ONTO THE PLAIN BY SUNDAY. MEANWHILE RIDGE
STRETCHES FROM THE SOUTHERN PLAINS TO THE OHIO RIVER VALLEY. BY
SATURDAY THE STRONG DISTURBANCE SHOULD BE NORTH OF THE
CWA...HOWEVER A SECOND WEAKER WAVE WILL BE ROTATING AROUND THE
UPPER LEVEL LOW. THIS WILL BRING THE CHANCE FOR ADDITIONAL
SHOWERS...ALTHOUGH NOT AS HEAVY RAIN PRODUCING AS THE PWATS DROP
CLOSER TO SEASONAL. SATURDAY NIGHT WILL SEE A COLD FRONT PUSH
ACROSS THE AREA WITH YET ANOTHER CHANCE FOR STORMS. MOISTURE
THROUGH THE COLUMN NOT AS IMPRESSIVE AS BEFORE SO CONTINUE TO
TREND DOWN POPS.

BEHIND THE FRONT WILL BE DECREASING CLOUDS. TEMPS SHOULD BE COOLER
ALTHOUGH ONLY SLIGHTLY AS MORE SUN WILL OFFSET THE COLD ADVECTION.
MODELS HAVE SHIFTED THE DISTURBANCE TRACK TO THE NORTH AND IT
LOOKS MORE LIKELY SUNDAY WILL BE DRY. SUNDAY NIGHT INTO MONDAY IS
A DIFFERENT STORY AS MODELS IN GOOD AGREEMENT WITH ANOTHER TROUGH
DIGGING ACROSS THE NORTHERN ROCKIES WITH A WAVE AHEAD OF THIS NEXT
TROUGH. MOISTURE RETURN STILL IN QUESTION...SO LOWER POPS FOR NOW
ON SUNDAY NIGHT...AND INCREASING FOR MONDAY.

TUESDAY WILL SEE ANOTHER WAVE MOVE ACROSS THE AREA WITH CONTINUED
CHANCES FOR RAIN. CLOUDS AND PRECIP WILL HELP TO HOLD TEMPS DOWN
THROUGH MID WEEK.

BY THURSDAY MODELS SHOWING SOME AGREEMENT WITH THE RIDGE
REBUILDING ACROSS THE PAC COAST. THE EC HOWEVER NOW HAS A LOW
OVER THE CENTRAL ROCKIES THAT SLOWLY PUSHES EAST. THE GFS DOES NOT
HAVE THIS FEATURE. THIS CREATE SIGNIFICANT DIFFERENCES IN WHAT ONE
WOULD EXPECTED. THE GFS WOULD BE DRIER AND WARMER...HOWEVER THE EC
WOULD FAVOR COOLER AND LOW POPS. THIS IS A SHIFT FROM THE PAST FEW
RUNS AS THE GFS WAS THE COOLER SOLUTION. THUS HIGH UNCERTAIN FROM
MID WEEK ON...SO STAY TUNED TO LIKELY CHANGES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1122 PM CDT THU AUG 21 2014

VFR IS EXPECTED ALL AREAS THROUGH 18Z. THEREAFTER...SCATTERED
STRONG TO SEVERE STORMS DEVELOP ACROSS SWRN NEB AND LIFT NORTH
THROUGH THE FCST AREA. STORM ACTIVITY COULD STILL BE ONGOING
ACROSS NRN NEB AT 06Z FRIDAY NIGHT.

THE AREA OF SHOWERS ACROSS NERN COLO WAS SHOWING LIGHTNING. THIS
HAS DIMINISHED. THESE SHOWERS ARE EXPECTED TO MOVE INTO WRN NEB
LATER TONIGHT AND PERHAPS PERSIST FRIDAY MORNING.


&&

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

&&

$$

UPDATE...MARTIN
SHORT TERM...POWER
LONG TERM...MASEK
AVIATION...CDC





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