Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 180444
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1144 PM CDT WED SEP 17 2014

.SYNOPSIS...
ISSUED AT 300 PM CDT WED SEP 17 2014

H5 ANALYSIS FROM THIS MORNING HAD A CLOSED LOW OVER
HUDSON BAY WITH A TROUGH OF LOW PRESSURE EXTENDING SWD INTO EASTERN
CANADA. ACROSS THE CONUS...BROAD WEST NORTHWESTERLY FLOW WAS PRESENT
FROM THE EASTERN SEABOARD...WEST TO THE NORTHERN ROCKIES WHERE A
RIDGE EXTENDED NWD INTO THE NORTHWEST TERRITORIES OF CANADA. OFF THE
PACIFIC COAST...A TROUGH OF LOW PRESSURE WAS NOTED. THE REMNANTS OF
ODILE WERE LOCATED OVER SERN AZ WITH A LARGE CIRRUS SHIELD EXTENDING
NEWD INTO NEW MEXICO...SRN COLORADO...THE TEXAS PANHANDLE...SWRN
KANSAS AND WESTERN OKLAHOMA. ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA...DENSE FOG DEVELOPED EARLIER THIS MORNING ACROSS
LINCOLN...HAYES...FRONTIER...CUSTER AND EASTERN PORTIONS OF KEITH
COUNTY. THIS FOG BURNED OFF AROUND 11 AM THIS MORNING. IN ITS
PLACE...MAINLY CLEAR SKIES WERE PRESENT THIS AFTERNOON. AT THE
SURFACE...A STATIONARY FRONT EXTENDED ACROSS THE PANHANDLE...INTO
NWRN KS...WHERE IT EXTENDED EAST INTO SWRN MO. NORTH AND EAST OF
THIS FEATURE...LIGHT EASTERLY WINDS HAVE DEVELOPED. TEMPERATURES AS
OF 3 PM CDT...RANGED FROM 79 AT AINSWORTH TO 88 AT THEDFORD AND IMPERIAL.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 300 PM CDT WED SEP 17 2014

A WARM FRONT AT H850 MB WILL LIFT SLOWLY FROM SOUTHWEST TO NORTHEAST
ACROSS NEBRASKA TONIGHT THROUGH THURSDAY. ELEVATED INSTABILITY WILL
INCREASE ALONG AND AHEAD OF THE BOUNDARY FROM SOUTH
CENTRAL...SOUTHWEST AND INTO CENTRAL NEBRASKA LATE THIS EVENING
THROUGH THURSDAY MORNING. MEANWHILE A WEAK SHORTWAVE...CURRENTLY
OVER WYOMING...WILL MOVE EAST ACROSS THE REGION OVERNIGHT. AS THIS
OCCURS...EXPECT ISOLATED SHOWERS AND THUNDERSTORMS TO DEVELOP IN THE
AREA OF ELEVATED INSTABILITY. THE OTHER STORY WILL BE THE CONTINUED
BOUNDARY LAYER ADVECTION OF GULF MOISTURE INTO THE REGION FROM THE
SOUTH...WITH AREAS OF FOG AND LOW STRATUS CLOUDS REDEVELOPING
OVERNIGHT. THE SATURATED LAYER IS A BIT MORE THICK TONIGHT INTO
THURSDAY MORNING...AROUND 1500 FEET OR SO. WITH THE THICKER
LAYER...ANTICIPATING THE STRATUS WILL BE SLOWER TO ERODE/BURN OFF
THURSDAY MORNING...AND COULD LINGER INTO THE EARLY AFTERNOON HOURS
ACROSS CENTRAL AND SOUTHWEST NEBRASKA. FOR THIS REASON HAVE LOWERED
HIGHS INTO THE MID TO UPPER 70S IN THESE AREAS...WITH 80S ELSEWHERE.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 300 PM CDT WED SEP 17 2014

THURSDAY NIGHT THROUGH SATURDAY...THE MAIN FORECAST
CHALLENGE IS PRECIPITATION CHANCES FRIDAY NIGHT IN ASSOCIATION WITH
AN APPROACHING FRONTAL BOUNDARY. FOR THURSDAY NIGHT AND
FRIDAY...SURFACE LOW PRESSURE WILL DEEPEN ACROSS SOUTHWESTERN SOUTH
DAKOTA IN ADVANCE OF AN APPROACHING NORTHERN STREAM SHORTWAVE. THIS
WILL LEAD TO INCREASED SOUTHERLY WINDS THURSDAY NIGHT. THE INCREASED
WINDS SHOULD ALLEVIATE THE FOG THREAT...HOWEVER...LINGERING LOW
LEVEL MOISTURE PER H850-H900 RH FIELD...MAY ALLOW CLOUDS TO PERSIST
AT LEAST INTO THE LATE EVENING HRS IN THE EASTERN CWA. WITH THIS IN
MIND...WILL LINGER SOME CLOUD COVER IN THE EAST INTO THE LATE
EVENING HOURS. WITH A WELL MIXED BOUNDARY LAYER EXPECTED
OVERNIGHT...LOWS WILL BE MILD WITH READINGS IN THE LOWER 60S
EXPECTED. ON FRIDAY...A PRE FRONTAL TROUGH OF LOW PRESSURE WILL
APPROACH NORTHWESTERN NEBRASKA. SOUTH AND EAST OF THIS
FEATURE...DRIER...SOUTHWESTERLY WINDS WILL IMPACT THE FORECAST AREA
FRIDAY AFTERNOON. WITH H85 TEMPS IN THE LOWER TO MIDDLE 20S...HIGHS
FROM THE MIDDLE 80S TO LOWER 90S LOOK PLAUSIBLE. ATTM...WILL KEEP
HIGHS LIMITED TO THE UPPER 80S...ESPECIALLY OVER SWRN NEBRASKA...TO
ACCOUNT FOR CIRRUS IN ASSOCIATION WITH THE REMNANTS OF ODILE. FRIDAY
NIGHT INTO SATURDAY...A COLD FRONT WILL PASS THROUGH THE FORECAST
AREA OVERNIGHT FRIDAY NIGHT. UPPER LEVEL SUPPORT FOR PCPN WILL
ARRIVE LATE EVENING AND INTO THE OVERNIGHT BEHIND THE FRONT...WHICH
THE MODELS HAVE TRENDED SLOWER WITH WITH TDYS RUNS. WITH THIS IN
MIND...DECIDED TO SLOW DOWN THE PROGRESSION OF PRECIPITATION CHANCES
FRIDAY NIGHT INTO SATURDAY MORNING. THIS LED TO A DRY FORECAST
FRIDAY EVENING IN THE SOUTHWESTERN CWA WITH THE BEST PRECIPITATION
CHANCES FOR NORTH PLATTE BEING AFTER MIDNIGHT FRIDAY NIGHT INTO
EARLY SATURDAY MORNING. AS FOR POPS...DECIDED TO SCALE THESE BACK
SOME...ESPECIALLY IN THE SOUTHWESTERN CWA AS UPPER LEVEL SUPPORT IS
STRONGEST IN THE EASTERN DAKOTAS AND NORTHEASTERN NEBRASKA...WHICH
IS WHERE THE BEST LOW LEVEL MOISTURE RESIDES. AS FOR THE REMNANTS OF
ODILE...THE LATEST MODEL SOLNS...TRACK THIS SYSTEM ACROSS SRN KS
LATE FRIDAY NIGHT INTO SATURDAY. ITS ONLY IMPACTS MAY BE SOME HIGH
CLOUDINESS ON THE NORTHERN PERIPHERY OF THIS SYSTEM...WHICH MAY
LIMIT HIGH TEMPS SOME FRIDAY AND SATURDAY.

SATURDAY NIGHT THROUGH WEDNESDAY...BENIGN WEATHER CONDITIONS ARE
EXPECTED BEHIND THE FRONT SATURDAY NIGHT INTO MONDAY. AFTER
MONDAY...THE THREAT FOR PCPN WILL INCREASE AS A POSSIBLE TROUGH OF
LOW PRESSURE LIFTS ACROSS THE INTERMOUNTAIN WEST...EMERGING ONTO THE
NORTHERN PLAINS MONDAY NIGHT INTO TUESDAY. THIS MODEL SCENARIO IS IN
STARK CONTRAST TO THE PAST SEVERAL DAYS MODEL RUNS...WHICH BUILDS A
LARGE RIDGE ACROSS THE WESTERN CONUS. SIMPLY PUT...WITH THE LARGE
MODEL CHANGE NOTED THIS MORNING...FORECAST CONFIDENCE IN DAYS 5
THROUGH 7 IS LOW. ON THIS NOTION...WILL KEEP TEMPS AT OR NEAR
SEASONAL LEVELS AND POPS RIGHT AROUND CLIMO.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1143 PM CDT WED SEP 17 2014

ONCE AGAIN...THE FORECAST ISSUE TONIGHT AND EARLY THURSDAY IS THE
LIKELIHOOD OF CEILING AND/OR VISIBILITY BELOW INSTRUMENT THRESHOLDS.
CONSENSUS AMONG THE SHORT RANGE MODEL OUTPUT IS THAT INSTRUMENT OR
LOW INSTRUMENT METEOROLOGICAL CONDITIONS ARE LIKELY IN A LARGE PART
OF WESTERN NEBRASKA ALONG AND SOUTH-WEST OF A VTN-ANW-BBW LINE.
THOUGH IT MAKES LITTLE DIFFERENCE IN THE FLIGHT CATEGORY...THE OTHER
QUESTION IS...FOG OR STRATUS? CURRENT INDICATIONS ARE THAT THE WIND
SPEED WILL BE 5-10KT AND THAT WOULD FAVOR LOW STRATUS VERSUS FOG.
THEREFORE...OUR CONFIDENCE IS HIGH THAT CEILING AT OR BELOW 500 FEET
AGL WILL DEVELOP AFTER 09Z FOR MHN...OGA AND LBF AND CONFIDENCE IS
NOT HIGH THAT INSTRUMENT CONDITIONS WILL DEVELOP FOR VTN...TIF AND
BBW. FOR THIS FORECAST ISSUANCE...WE WILL INCLUDE CEILING BELOW 500
FEET AND VISIBILITY 2-3SM FOR LBF AND CEILING JUST ABOVE 1000 FEET
AGL AND VISIBILITY 3-5SM FOR VTN. THE LOW CLOUDS WILL BE SLOW TO
SCATTER OUT. CURRENT INDICATIONS FROM SHORT RANGE MODELS AND
CONDITIONAL CLIMATOLOGY WOULD INDICATE SCATTERING BETWEEN 16Z AND
18Z.

THOUGH THIS IS BEYOND THE 24 HOUR FORECAST WINDOW...INSTRUMENT
METEOROLOGICAL CONDITIONS ARE AGAIN POSSIBLE THURSDAY NIGHT.

&&

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

$$

SYNOPSIS...CLB
SHORT TERM...TAYLOR
LONG TERM...CLB
AVIATION...SPRINGER






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