Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 222315
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
615 PM CDT WED APR 22 2015

.SYNOPSIS...
ISSUED AT 311 PM CDT WED APR 22 2015

UPPER AIR PATTERN OVER NORTH AMERICA LARGE AREA OF LOW PRESSURE AND
BROAD CYCLONIC FLOW CENTERED JUST NORTH OF THE GREAT LAKES. FURTHER
WEST AN UPPER LEVEL RIDGE WAS TRACKING ACROSS THE NORTHERN ROCKIES
OVER THE TOP OF ANOTHER LARGE AREA OF LOW PRESSURE SPINNING OFF THE
SOUTHWEST COAST OF CALIFORNIA.

CLOSER TO THE CWA SKIES WERE MOSTLY CLEAR IN THE PRESENCE OF A DRY
AIR MASS AND DEEP LAYER SUBSIDENCE. AS OF 20Z AN AREA OF SFC HIGH
PRESSURE WAS CENTERED OVER NORTHEAST KS...SOUTHERLY WINDS OF 10 TO
15 MPH TO MUCH OF WESTERN AND NORTH CENTRAL NEBRASKA. TEMPERATURES
WERE GENERALLY NEAR TO JUST BELOW NORMAL IN THE MID 50S TO LOW 60S.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 311 PM CDT WED APR 22 2015

QUIET CONDITIONS ARE EXPECTED THE REST OF THE AFTERNOON AND EVENING
AS SKIES REMAIN MOSTLY CLEAR. TONIGHT THE SFC HIGH PRESSURE
CURRENTLY CENTERED IN NORTHWEST KS WILL SLIDE FURTHER EAST...AND
THE SOUTHERLY FLOW WILL BEGIN TO ADVECT LOW LEVEL MOISTURE UP THE
HIGH PLAINS AND INTO SOUTHWEST NEBRASKA. THE AMOUNT OF MOISTURE
STILL REMAINS IN QUESTION AS MODEL GUIDANCE IS NOT IN AGREEMENT WITH
AS MUCH AS 5C SPREAD IN THE 0.5 KM DEWPOINT FIELDS OVER SOUTHWEST
NEBRASKA BY 12Z THURSDAY. THIS IS MOST LIKELY DUE TO THEIR
RESPECTIVE HANDLING OF THE DEEP CONVECTION GENERATED OVER THE TX
PANHANDLE/WESTERN OK THIS EVENING. A MODEL BLEND FALLS IN LINE WITH
THE LATEST SREF SOLUTION WHICH STILL SHOWS HIGH PROBABILITY OF A
STRATUS DECK MOVING INTO OUR SOUTHWEST ZONES...PRIMARILY ALONG AND
WEST OF HWY 83. A WEAK SHORTWAVE EJECTING OUT OF CO WILL MAY
BE ENOUGH TO TRIGGER A FEW SPRINKLES IN THIS VICINITY DURING THE
MORNING HOURS.

THE UPPER LEVEL RIDGE AND WARMER TEMPERATURES ALOFT MOVE EASTWARD
TOWARD THE CENTRAL CONUS ON THURSDAY...HOWEVER EXPANDING CLOUD COVER
FROM THE SOUTH AND WEST MAY HINDER SFC TEMPERATURES. SOUTHERLY
WINDS INCREASE IN RESPONSE TO A DEEPENING LEE SIDE SFC TROUGH. THIS
SHOULD PROMOTE AMPLE MIXING IN BL AND WITH WARM AIR ALOFT
TEMPERATURES STILL MAKE IT TO NEAR NORMAL IN THE LOW TO MID 60S FOR
THE AFTERNOON HOURS.

SHOWERS AND THUNDERSTORMS CHANCES ENTER THE FORECAST NEAR THE END OF
THE PERIOD AS ANOTHER SHORTWAVE TROUGH EJECTS EAST OF OUT OF THE
CENTRAL ROCKIES. TRIMMED BACK AND SLOWED DOWN THE INHERITED POPS FOR
THURSDAY AFTERNOON AS LATEST MODEL RUNS KEEP MOST QPF WEST OF THE
CWA THROUGH 00Z FRIDAY. THE BEST CHANCE FOR SHOWER AND THUNDERSTORM
INITIATION BY MID TO LATE AFTERNOON WILL IN THE PANHANDLE AND
NORTHEAST CO WHERE THE BEST CONVERGENCE AND INSTABILITY RESIDES.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 311 PM CDT WED APR 22 2015

AN UPPER LONG WAVE LOCATED FROM SRN CALIF INTO WRN UTAH THURSDAY
EVENING WILL BE PRECEDED BY A WEAK LEAD DISTURBANCE. THIS
DISTURBANCE WILL EJECT NORTHEAST FROM THE TROUGH THURSDAY NIGHT
INTO FRIDAY. MODELS REMAIN WEAKER WITH THIS FEATURE COMPARED TO A
COUPLE OF DAYS AGO...AND HAVE HELD HIGHEST POPS THROUGH FRIDAY TO
40 PERCENT. HIGHS FRIDAY SHOULD REACH INTO THE MID TO UPPER 60S
WITH MORNING STRATUS EXPECTED TO BURN OFF. AS MAIN UPPER TROUGH
MOVES INTO THE CENTRAL PLAINS FRIDAY NIGHT...A FEW
MODELS...ESPECIALLY THE ECMWF...CLOSE THE SYSTEM OVER ACROSS
NEBR/KS. DID INCREASE POP THEN TO 40 TO 50 PERCENT. ON
SATURDAY...WRN NEBR WILL BECOME IN BETWEEN SYSTEMS WITH ONLY A
SLIGHT CHANCE FOR SHOWERS.

A STRONGER UPPER TROUGH WILL DIG SOUTHEAST FROM BRITISH COLUMBIA
INTO THE GREAT BASIN ON SATURDAY. THE GFS ENSEMBLE MEAN H5 HEIGHT
CLOSES OFF A LOW EAST OF THE FOUR CORNERS REGION WHILE THE ECMWF
IS SOUTHEAST. THE GFS ENSEMBLE TRACK THE LOW EAST ACROSS OKLA
WHILE THE ECMWF EAST ACROSS NRN TX. THE HIGHEST POPS LOOK TO BE
SATURDAY NIGHT AND SUNDAY ACROSS OUR WRN ZONES AT 40 TO 50 PERCENT
WHICH WILL OCCUR AHEAD OF THE SYSTEM. POPS LOWER CONSIDERABLY AS
CLOSED LOW TRACKS EAST TO OUR SOUTH AND WRN NEBR REMAINS UNDER THE
INFLUENCE OF NRN STREAM TROUGH. HIGHS SATURDAY THROUGH TUESDAY
LOOK TO RANGE AROUND 60 WARMING TO THE MID AND UPPER 60S BY
WEDNESDAY AS UPPER RIDGE BEGINS TO BUILD INTO THE REGION.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 615 PM CDT WED APR 22 2015

LOW LEVEL MOISTURE WILL FLOW NORTH FROM THE TEXAS PANHANDLE AND
WESTERN KANSAS OVERNIGHT...AND WILL APPROACH SOUTHWESTERN NEBRASKA
BY 12Z THURSDAY. CLOUDS WILL INCREASE THURSDAY MORNING WITH CIGS
OF 2500 TO 5000 FT AGL POSSIBLE AT THE KLBF TERMINAL THROUGH 00Z
FRIDAY. SKIES WILL BEGIN TO CLOUD OVER AT THE KVTN TERMINAL
THURSDAY AFTERNOON...WITH CIGS OF 5000 FT AGL POSSIBLE AFTER 20Z.
WINDS WILL BE FROM THE SOUTH OR SOUTH SOUTHEAST OVER THE NEXT 24
HOURS WITH SPEEDS UNDER 10 KTS TONIGHT...INCREASING TO 10 TO 20
KTS THURSDAY.

&&

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

$$

SYNOPSIS...MARTIN
SHORT TERM...MARTIN
LONG TERM...ROBERG
AVIATION...CLB





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