Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 232013
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
313 PM CDT SAT AUG 23 2014

.SYNOPSIS...
ISSUED AT 313 PM CDT SAT AUG 23 2014

H5 ANALYSIS FROM THIS MORNING HAS RIDGING ACROSS THE
MISSISSIPPI VALLEY FROM THE GULF COAST NWD INTO THE WESTERN GREAT
LAKES. FURTHER EAST...DECENT SHORTWAVES WERE NOTED OVER LAKE ONTARIO
AND NOVA SCOTIA. FURTHER WEST...A TANDEM OF SHORTWAVES WERE LOCATED OVER
THE INTERMOUNTAIN WEST. THE FIRST OVER WESTERN COLORADO AND A SECOND
OVER EASTERN IDAHO...WHILE ANOTHER SHORTWAVE WAS UPSTREAM OVER THE
ALASKA PANHANDLE. WV IMAGERY AS OF 1 PM CDT...INDICATED SHORTWAVE
ENERGY IN ASSOCIATION WITH THE WAVE OVER WESTERN COLORADO HAD BEGUN
TO EMERGE ACROSS CENTRAL COLORADO AND HAS LED TO INCREASING
CLOUDINESS ALONG THE FRONT RANGE OF COLORADO. OVER THE NEXT COUPLE
OF HRS...SHRAS AND TSRAS ARE EXPECTED TO DEVELOP ON THE LEE SIDE OF
THE ROCKIES INVOF THE FRONT RANGES OF COLORADO AND WYOMING. FURTHER
WEST...A CLOSED LOW REMAINS IN PLACE OVER EASTERN IDAHO ATTM WITH A
BROAD AREA OF CLOUDS AND SHOWERS ACROSS MONTANA...NORTH DAKOTA AND
NORTHERN SOUTH DAKOTA. ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA...ABUNDANT CLOUDINESS WAS PRESENT OVER MOST OF THE AREA
WITH THE EXCEPTION OF FAR SWRN NEBRASKA AND THE EASTERN NEBRASKA
PANHANDLE WHERE CLOUDS HAVE SCATTERED OUT OVER THE PAST 1 TO 2
HOURS. AT THE SURFACE...A TANDEM OF LOW PRESSURE CENTERS WERE
PRESENT ACROSS SERN WYOMING AND A SECOND OVER SOUTH CENTRAL SD. A
WARM FRONT EXTENDED FROM SERN WYOMING INTO EASTERN SOUTH
DAKOTA...WHILE A COLD FRONT EXTENDED SSWD INTO THE CENTRAL ROCKIES.
UNDER PARTLY TO MOSTLY CLOUDY SKIES...TEMPERATURES AS OF 3 PM
CDT...RANGED FROM 72 AT AINSWORTH...TO 82 AT BROKEN BOW.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 313 PM CDT SAT AUG 23 2014

MODELS REMAIN IN GOOD AGREEMENT
WITH THE PROJECTIONS OF A PV ANOMALY LIFTING NORTHEAST FROM FAR
SOUTHWESTERN WYOMING TOWARD THE NORTHERN PLAINS THIS EVENING AND
OVERNIGHT.  RECENT OBSERVATIONS INDICATE THAT THE LOW STRATUS IS
DISSIPATING EARLY THIS AFTERNOON...LEADING TO THE EVENTUAL
DESTABILIZATION OF THE LOWER TROPOSPHERE.  AS HEIGHTS FALL WITH THE
APPROACH OF THE PV MAX/ATTENDANT COLD FRONT...STORMS ARE ANTICIPATED
TO FORM INVOF OF THE HIGH PLAINS SURFACE LOW/FRONTAL BOUNDARY AND
POSSIBLY DRIFT EAST ACROSS THE SANDHILLS REGION OF NEB OVERNIGHT.
THE LATEST PROJECTIONS FROM THE RAP AND HRRR SHOWS THAT DESPITE THE
MORNING CLOUDS...LOW TO MID LEVEL LAPSE RATES HAVE INCREASED
SOME...YIELDING A WEAKLY UNSTABLE ATMOSPHERE ACROSS WESTERN PORTIONS
OF THE CWA /CONTINUED CLEARING WILL ALLOW FOR FURTHER
DESTABILIZATION/.  THE PROJECTED INSTABILITY /UPWARDS TO 1000 J/KG
ML CAPE/ COMBINED WITH 0-6KM BULK SHEAR OF 30KTS OR SO WILL PROMOTE
THE POSSIBILITY OF STRONG TO LOW END SEVERE STORMS THIS EVENING AND
OVERNIGHT.  ANOTHER AREA TO WATCH FOR SEVERE STORMS WILL BE ACROSS
NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AS A SECONDARY WARM FRONT
LIFTS NORTH TOWARD THE SOUTHEAST SOUTH DAKOTA.  ABUNDANT INSTABILITY
AND SUFFICIENT SHEAR WOULD PROMOTE RAPID STORM DEVELOPMENT CAPABLE
OF LARGE HAIL AND DAMAGING WIND GUSTS.

THE HEAVY RAIN THREAT WILL BE NOTICEABLY LESS TONIGHT AS BUFR
SOUNDINGS REVEAL A MUCH LESSER INFLUENCE FROM WARM RAIN
PROCESSES...BUT WITH PWATS AT OR SLIGHTLY ABOVE AVERAGE...BRIEF
HEAVY RAINFALL IS STILL POSSIBLE.

THE COLD FRONT CLEARS THE CWA EARLY ON SUNDAY WITH RAIN CHANCES
POSSIBLY LINGERING ACROSS OUR FAR EAST THROUGH 15Z...OTHERWISE A
SLIGHTLY COOLER AIRMASS IS ANTICIPATED WITH HIGHS RANGING FROM THE
MID 70S ACROSS OUR FAR NORTHWEST...TO LOW TO MID 80S SOUTH OF THE
INTERSTATE 80 CORRIDOR.  WITH MOISTURE LACKING AND A STABLE AIRMASS
ANTICIPATED SUNDAY AFTERNOON...STORM CHANCES SHOULD BE KEPT AT BAY
UNTIL AT LEAST 00Z MONDAY.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 331 PM CDT SAT AUG 23 2014

SUNDAY NIGHT THROUGH TUESDAY...THE MAIN FORECASTING
CHALLENGE CONTINUES TO BE PRECIPITATION CHANCES AND THE THREAT FOR
HEAVY RAIN AS A TROUGH AND SEMI STATIONARY FRONTAL BOUNDARY PERSISTS
ACROSS THE CENTRAL ROCKIES AND PLAINS DURING THE PERIOD. FOR SUNDAY
NIGHT...AFTER RELATIVELY QUIET WEATHER CONDS SUNDAY...MID LEVEL WAA
WILL INCREASE ALONG THE FRONT RANGE DURING THE
EVENING...TRANSITIONING EAST ACROSS THE CENTRAL PLAINS OVERNIGHT
SUNDAY NIGHT INTO EARLY MONDAY. AT THE SAME TIME...A NICE H250 JET
STREAK WILL LIFT ACROSS NWRN NEBRASKA INTO SOUTH DAKOTA PLACING
WESTERN AND NORTH CENTRAL NEBRASKA IN THE RIGHT REAR QUAD OF THIS
FEATURE. ENHANCED LIFT ACROSS THE FORECAST AREA...WILL LEAD TO A
SHARP INCREASE IN THE THREAT OF PCPN SUNDAY NIGHT INTO MONDAY. IN
THE LOWER LEVELS...A FRONTAL BOUNDARY WILL BE ANCHORED ACROSS SRN
NEBRASKA SUNDAY NIGHT WITH THE NOSE OF A H85 LOW LEVEL JET
POSITIONED ACROSS SWRN NEBRASKA. INHERITED FCST HAD THE HIGHEST POPS
ACROSS SRN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT INTO MONDAY
MORNING AND APPEARS ON TRACK ATTM. PRECIPITATION CHANCES WILL
DECREASE SOMEWHAT MONDAY AS MID LEVEL FORCING PUSHES EAST INTO THE
MID MISSOURI VALLEY. BY MONDAY NIGHT...ANOTHER STRONG UPPER LEVEL
DISTURBANCE WILL PUSH ACROSS THE CENTRAL PLAINS...LEADING TO
INCREASED CHANCES FOR RAIN MONDAY NIGHT...AS WELL AS TUESDAY NIGHT. LOW
LEVEL EASTERLY WINDS AND ABUNDANT MID AND UPPER LEVEL MOISTURE
TRANSPORT FROM THE SOUTHWEST IN ASSOCIATION WITH HURRICANE MARIE
COULD LEAD TO HEAVY RAIN ACROSS THE CENTRAL PLAINS BEGINNING MONDAY
NIGHT AND POSSIBLY PERSISTING INTO TUESDAY NIGHT. FURTHER SUPPORT
FOR HEAVY RAIN IS EVIDENT IN FCST PWATS RANGING FROM 1.5 TO 2.0
INCHES MONDAY NIGHT THROUGH TUESDAY NIGHT.

WEDNESDAY THROUGH SATURDAY...LINGERING PCPN CHANCES ARE THE MAIN
FORECAST CHALLENGE IN THE LONG RANGE PERIODS. BY WEDNESDAY INTO
THURSDAY...THE PERSISTENT UPPER LEVEL TROUGH ACROSS THE
ROCKIES...WILL CROSS THE CENTRAL PLAINS INTO THE MISSISSIPPI VALLEY.
THE LATEST GFS SOLN IS 24 HRS FASTER COMPARED TO THE ECMWF IN
LIFTING THIS FEATURE EAST OF THE AREA. THE GFS IS DRY AFTER WEDS
WITH THE TROUGH OVER MISSOURI VALLEY BY 12Z THURSDAY...WHILE THE
ECMWF HAS THIS FEATURE OVER THE SAME AREA BY 12Z FRIDAY. INHERITED
FCST WAS DRY WEDS NIGHT AND INTRODUCED POPS FOR THIS PERIOD AS BOTH
MODELS HAVE TRENDED SLOWER. WILL HOLD OFF ON INTRODUCING POPS FOR
THURSDAY FOR NOW AND WAIT FOR THE MODELS TO COME INTO BETTER
AGREEMENT. AFTER UNSEASONABLY COOL HIGHS IN THE 70S FOR WEDNESDAY
AND THURSDAY...HIGHS WILL REBOUND BACK INTO THE 80S FOR THURSDAY AND
FRIDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1236 PM CDT SAT AUG 23 2014

MVFR OR LOWER STRATUS CONTINUES TO IMPACT MOST AREA TERMINALS
EARLY THIS AFTERNOON...BUT THE LATEST NEAR TERM GUIDANCE INDICATES
SOME DISSIPATION BACK TO VFR BY MID TO LATE AFTERNOON FOR MOST
TERMINALS. THUNDERSTORMS ARE ANTICIPATED OVER MUCH OF THE
SANDHILLS REGION THIS EVENING AND OVERNIGHT...FIRST FORMING OVER
THE HIGHER TERRAIN OF WESTERN NEBRASKA...THEN SPREADING NORTHEAST
OVERNIGHT. BRIEF HEAVY RAINFALL...HAIL AND ERRATIC WIND WOULD
ACCOMPANY ANY STORM THAT DEVELOPS. OTHERWISE DRIER AIR TO FOLLOW
THE STORMS SHOULD ALLOW FOR WIDESPREAD VFR THROUGH THE REMAINDER
OF THE 18Z TAF PERIOD.


&&

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

$$

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





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