Area Forecast Discussion
Issued by NWS North Platte, NE

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLBF 171151
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
651 AM CDT SUN AUG 17 2014

.SYNOPSIS...
ISSUED AT 347 AM CDT SUN AUG 17 2014

H5 ANALYSIS FROM EARLIER THIS EVENING HAD A DECENT CLOSED LOW
OVER SWRN SASKATCHEWAN...WITH A SECONDARY LOW OFF THE COAST OF
NORTHERN CALIFORNIA. FURTHER EAST...A CLOSED LOW WAS NOTED OVER
SRN QUEBEC WITH ADDITIONAL SHORTWAVES NOTED OVER EASTERN MISSOURI
AND OVER NRN TEXAS. EARLIER THIS EVENING...SHRAS AND TSRAS
DEVELOPED ALONG HIGHWAY 61 FROM NORTH OF OGALLALA TO GRANT. THIS
ACTIVITY SHIFTED SE AND DISSIPATED QUICKLY BY MID EVENING. AT THE
SURFACE...A WEAK SURFACE TROUGH OF LOW PRESSURE EXTENDED ALONG THE
FRONT RANGE OF WYOMING AND COLORADO. EAST OF THIS FEATURE...CALM
WINDS OR LIGHT EASTERLY WINDS WERE PRESENT ACROSS WESTERN AND
NORTH CENTRAL NEBRASKA. WITH CLEAR SKIES IN PLACE...3 AM
TEMPERATURES RANGED FROM 62 AT VALENTINE...TO 67 AT IMPERIAL.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 347 AM CDT SUN AUG 17 2014

TODAY AND TONIGHT...THE MAIN FORECAST CHALLENGE IS THUNDERSTORM
CHANCES AND THE THREAT FOR SEVERE STORMS LATER THIS AFTERNOON AND
INTO THE EVENING HOURS. LATER TODAY...AN UPPER LEVEL TROUGH WILL
APPROACH THE WESTERN DAKOTAS AND THE NEBR PANHANDLE. DOWNSTREAM OF
THIS FEATURE...STEEPENING LAPSE RATES...COUPLED WITH INCREASING
DIURNAL INSTABILITY DUE TO SURFACE HEATING...SHOULD LEAD TO SOME
THUNDERSTORM DEVELOPMENT IN THE NORTHWEST BY MID AFTERNOON. AS
THIS ACTIVITY MOVES EAST INTO DEEPER LOW LEVEL MOISTURE...MORE
ORGANIZED ACTIVITY WILL DEVELOP...ESPECIALLY OVER NORTH CENTRAL
NEBRASKA IN THE VICINITY OF A WEAK JET STREAK. UNLIKE THE PAST
COUPLE OF DAYS...BULK LAYER SHEAR WILL DOUBLE TO 30 TO 40 KTS
LATER TODAY...LEADING TO AN INCREASED THREAT FOR SEVERE
STORMS...ESPECIALLY IN CENTRAL AND EASTERN PORTIONS OF THE
FORECAST AREA WHERE SB CAPES OF 3000+ J/KG WILL BE ORIENTED EAST
OF A LINE FROM GORDON TO NORTH PLATTE. WEST OF THIS LINE...MUCH
DRIER BOUNDARY LAYER AIR WILL PUSH INTO THE PANHANDLE AND SWRN
NEBRASKA LATER THIS AFTERNOON...WITH SURFACE DEW POINTS RANGING
FROM THE LOWER 40S TO LOWER 50S. THIS DRIER AIR...WILL HELP TO
PROPEL HIGHS INTO THE MIDDLE 90S IN THE FAR SOUTHWEST THIS
AFTERNOON. FURTHER EAST IN THE MOIST BOUNDARY LAYER...HIGHS WILL
BE IN THE MID TO UPPER 80S. MINIMUM RELATIVE HUMIDITIES WILL REACH
20 TO 25 PERCENT IN THE FAR SOUTHWEST AND SERN PANHANDLE THIS
AFTERNOON...HOWEVER LIGHT WINDS SHOULD KEEP FIRE DANGER IN CHECK.
FOR TONIGHT...CONVECTION WILL RIDE EAST ACROSS NORTH CENTRAL
NEBRASKA ON THE NRN PERIPHERY OF AN INCREASING LOW LEVEL JET...THE
NOSE OF WHICH WILL PUSH INTO NERN NEBRASKA BY 12Z MONDAY.
THUNDERSTORMS ARE EXPECTED TO PUSH EAST OF THE AREA BY THIS TIME.
AS FOR THE SEVERE THREAT...THE MAIN THREATS WILL BE FROM LARGE
HAIL AND WINDS INITIALLY...SHIFTING TO A WIND THREAT INTO THE
OVERNIGHT. LOWS TONIGHT WILL RANGE FROM THE MID 50S IN THE
WEST...TO THE MIDDLE 60S IN THE EAST.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 347 AM CDT SUN AUG 17 2014

12Z MONDAY AND BEYOND. THE SYNOPTIC PATTERN DURING THE EXTENDED
PERIOD GENERALLY FAVORS THE MAINTENANCE OF A MEAN WESTERN CONUS
TROUGH WHILE A STRONG ANTICYCLONE RESIDES OVER THE SOUTHEASTERN
STATES. ZONAL FLOW IS SHOWN TO PREVAIL INITIALLY ATOP THE CENTRAL
PLAINS...BUT SLOWLY GIVE WAY TO SOUTHWEST FLOW LATE IN THE WEEK AS
THE TROUGH SLOWLY TRACKS EAST. DESPITE DIFFERENCES IN THE LONGER
RANGE DETERMINISTIC OUTPUT...THIS OVERALL PATTERN FAVORS THE
PERIODIC PASSAGE OF SHORTWAVES...WHICH MAY PROVIDE FOR ADDITIONAL
PRECIPITATION CHANCES DURING MUCH OF THE EXTENDED PERIOD. ATTM
CONFIDENCE IN TIMING OF THESE SHORTWAVE IMPULSE IS LOW...THUS WILL
NOT VARY FROM THE CR PROCEDURE TONIGHT.

AFTER SHOWERS AND STORMS EARLY ON MONDAY...DRYING CONDITIONS SHOULD
PREVAIL FOR MUCH OF THE DAY AND THROUGH EARLY TUESDAY AS LOW
AMPLITUDE SHORTWAVE RIDGING BUILDS EAST ATOP THE PLAINS.  HOWEVER
TUESDAY EVENING/EARLY WEDNESDAY BOTH THE GFS AND EC DEVELOP A
CONVECTIVE SIGNAL WITH THE APPROACH OF A SW IMPULSE.  INITIALLY
/TUESDAY AFTERNOON/ STORMS WILL FAVOR AN AREA OF MOISTURE
CONVERGENCE ALONG THE SURFACE FRONT AND JUST NORTH OF A SFC LOW IN
NORTHEAST COLORADO/SW NEB.  AMPLE CONVECTIVE POTENTIAL ENERGY OF 2000
J/KG OR MORE WILL WORK WITH 0-6KM BULK SHEAR OF 30-40KTS TO PROMOTE
ROTATING UPDRAFTS CAPABLE OF SEVERE HAIL ACROSS THIS AREA.  A WIND
THREAT WILL BE LIKELY AS WELL...ESPECIALLY ACROSS SOUTHWEST NEB LATE
AFTERNOON WHERE BUFR SOUNDINGS INDICATE INVERTED-V ATMOSPHERIC
PROFILES.  THIS ACTIVITY IS SHOWN TO PROGRESS EAST INTO THE
OVERNIGHT WITH A STRONG LOW LEVEL JET.  IT SHOULD BE NOTED HOWEVER
THAT THE GFS REMAINS ON THE STRONG SIDE WITH THE LLJ AND IS
AMBITIOUS IN DEVELOPING DEEP BL MOISTURE AS COMPARED WITH THE
ECMWF.  WITH PWATS SHOWN BY THE GFS TO INCREASE TO OR NEAR
2"...HEAVY RAINFALL WOULD BE ANTICIPATED WITH THE GFS PROJECTED
CONVECTIVE COMPLEX OVERNIGHT.

HUMID AND UNSTABLE CONDITIONS RETURN FOR WEDNESDAY WITH THE THREAT
OF ADDITIONAL STORMS BY EVENING.  FOCUS FOR STORM DEVELOPMENT IS NOT
AS CERTAIN AS FROM THE PREVIOUS DAY...AND CONSIDERING BULK SHEAR
VALUES DECREASE...WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED.

THE NEXT BEST SHOT AT WIDESPREAD STORMS/QPF COMES FRIDAY INTO
SATURDAY WITH THE GFS/EC LIFTING A FAIRLY SIGNIFICANT SW THROUGH THE
PLAINS.  AGAIN THIS APPEARS TO BE A CASE WHERE A DEFINED SURFACE
BOUNDARY INTERACTS WITH THE SHORTWAVE AND ABUNDANT TROPOSPHERIC
MOISTURE.  SEVERE WEATHER MAY BE POSSIBLE AS WELL.

TEMPERATURES THROUGH THE EXTENDED PERIODS ARE ANTICIPATED TO BE
RATHER MONOTONOUS...WITH HIGHS MAINLY IN THE UPPER 80S TO LOWER
90S...LOW IN THE UPPER 50S TO MID 60S.  THERE MAY BE A STRONG COLD
FRONT LATE IN THE EXTENDED WHICH WOULD COOL TEMPERATURES FOR NEXT
WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 649 AM CDT SUN AUG 17 2014

FOR THE KLBF TERMINAL...EXPECT MAINLY CLEAR SKIES THROUGH MID
AFTERNOON. SCATTERED SKIES AROUND 8000 FT AGL WILL DEVELOP BY MID
AFTERNOON WITH THUNDERSTORMS IN THE VICINITY OF THE TERMINAL FROM
00Z TO 05Z MONDAY. SKIES WILL CLEAR THEREAFTER. FOR THE KVTN
TERMINAL...SKIES WILL BE MOSTLY CLEAR THIS MORNING WITH AN INCREASED
THREAT FOR THUNDERSTORMS AFTER MID AFTERNOON. CIGS MAY DIP TO AROUND
7000 FT AGL IN THE VICINITY OF THUNDERSTORMS. SKIES WILL CLEAR
OVERNIGHT AT THE KVTN TERMINAL.

&&

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

$$

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






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.