Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 282004
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
304 PM CDT TUE JUL 28 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 303 PM CDT TUE JUL 28 2015

TONIGHT AND TOMORROW.  LOW TEMPERATURES ARE THE PRIMARY FORECAST
CONCERN OVER THE NEXT 24 HOURS.  A POST FRONTAL AIRMASS CONTINUES TO
ADVECT EAST ACROSS THE FORECAST AREA TODAY.  COOLER AND DRIER
CONDITIONS PREVAIL...AND WILL CONTINUE OVERNIGHT.  MODEL GUIDANCE
INDICATES TD/S REMAINING IN THE UPPER 40S DURING THE PRE-DAWN
HOURS...AND WITH CLEAR SKIES FORECAST...MORNING LOWS WILL BE
UNSEASONABLY COOL.  NUMERICAL GUIDANCE SUGGESTS MORNING LOWS AT KLBF
NEAR 50F...WHICH IS A DEGREE ABOVE THE RECORD LOW OF 49.  BUT AT
THIS TIME WE FEEL THE RECORD IS SAFE AS NUMERICAL GUIDANCE AS OF
LATE HAS HAD TROUBLE COMPENSATING FOR THE INCREASED LOWER
TROPOSPHERIC MOISTURE WE/VE SEEN.  THUS HEDGED OUR LOWS UP A DEGREE
OR TWO FOR MOST PLACES...WHICH SUGGESTS LOWS IN THE PLATTE RIVER
VALLEY IN THE LOWER 50S.

HIGH PRESSURE BUILDS TO THE EAST THROUGH THE DAY ON
WEDNESDAY...SETTING UP AN EVENTUAL RETURN TO SOUTHERLY FLOW.  HIGHS
WILL WARM A FEW DEGREES...WITH MOST READINGS IN THE MID 80S.  THE
ATMOSPHERE WILL REMAIN STABLE...LIMITING ANY THUNDER CHANCES
WEDNESDAY.  HOWEVER IF A ROUGE STORM WERE TO FORM...THE MOST LIKELY
LOCATION WILL BE ACROSS THE FAR EASTERN PANHANDLE WHERE INCREASING
THETA BUILDS NORTHEAST FROM THE HIGH PLAINS.  AS OF NOW CHANCES FOR
AN STORM IS LESS THAN 10%...SO WILL FORGO ANY MENTION OF
PRECIPITATION.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 303 PM CDT TUE JUL 28 2015

EDNESDAY NIGHT THROUGH FRIDAY...THE NAM AND GFS SUGGEST SUFFICIENT
LOW LEVEL FORCING IN THE FORM OF A FRONTAL BOUNDARY AND STEEP LAPSE
RATES FOR ISOLATED AFTN SHOWERS AND THUNDERSTORMS THURSDAY AND
FRIDAY. A CHECK ON THE MODEL SOUNDINGS WOULD SUGGEST OTHERWISE BUT
GIVEN THE COOL AIR ALOFT ISOLATED POPS ARE IN PLACE IN ACROSS A
SMATTERING OF WRN AND NCNTL NEB.

THE WEAK FRONT DRAPED ACROSS THE SANDHILLS FRIDAY MAY HOLD HIGHS TO
THE UPPER 80S ACROSS NRN NEB WITH NEAR 90 SOUTH. UPPER 80S TO AROUND
90 WILL HOLD ALL AREAS FOR THURSDAY.

K INDICES IN BOTH MODELS SURGE INTO THE 40S DURING THE PEAK AFTN
HEATING PERIOD THURSDAY AND FRIDAY INDICATING STEEP LAPSE RATES. THE
SOUNDINGS SHOW VERY LIMITED MOISTURE THURSDAY SO THE FORECAST POPS
ARE ISOLATED. MOISTURE IN THE NAM INCREASES SMARTLY FRIDAY WITH
AMBIENT PWAT OF 1.33 INCHES. IF THE NAM IS NOT TOO FAST WITH THE
MOISTURE RETURN PROCESS THEN ISOLD POPS ARE WARRANTED AT THE
MINIMUM. IN FACT...THE 2500J/KG MLCAPE...BULK SHEAR OF 30 TO 40 KT
CALCULATED TO 450 MB AND H700MB TEMPERATURES LESS THAN 10C WOULD
SUPPORT THE POTENTIAL FOR SUPERCELL DEVELOPMENT. SO WE WILL BE
LOOKING AT THE DAY 3 SEVERE WEATHER OUTLOOK FROM SPC TONIGHT.

SATURDAY THROUGH TUESDAY...THE UPPER LEVEL RIDGE ACROSS THE MIDSOUTH
WILL RETROGRADE WEST INTO THE DESERT SW AND THEN AMPLIFY NORTH INTO
THE ROCKIES. THIS PLACES THE FCST AREA IN NORTHWEST FLOW ALOFT. THE
GFS AND ECM BOTH PIN THE STRONGEST HEATING AT 700MB ACROSS THE
ROCKIES AND WRN REACHES OF CNTL HIGH PLAINS SUGGESTING A WEAK
CAP...LESS THAN 14C...WOULD REMAIN ACROSS THE FCST AREA. THE POP
FORECAST IS ISOLATED GIVEN THE UNCERTAIN FORCING ALOFT AND PWAT
AROUND 1 INCH. WEAK COLD FRONTS APPEAR TO BE BACKING INTO THE FCST
AREA IN THE GFS AND ECM MODELS PREVENTING GREATER MOISTURE RETURN.

SUNDAY COULD BE THE WARMEST DAY AS THE UPPER LEVEL RIDGE BUILDS EAST
A BIT WITH HIGHS IN THE 90S. OTHERWISE UPPER 80S TO NEAR 90 APPEAR
TO BE THE OPERATIVE FORECAST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1236 PM CDT TUE JUL 28 2015

VFR ANTICIPATED ACROSS ALL AREA TERMINALS THROUGH THE 18Z TAF
PERIOD. MODEL GUIDANCE CONTINUES TO INDICATE GUSTY NORTHWEST
WINDS PERSISTING THROUGH THE AFTERNOON ACROSS WEST CENTRAL
NEBRASKA...BUT WEAKENING THIS EVENING AND OVERNIGHT AS SURFACE
HIGH PRESSURE BUILDS INTO THE REGION. FORECAST CONFIDENCE IS HIGH.

&&

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

$$

SHORT TERM...JACOBS
LONG TERM...CDC
AVIATION...JACOBS



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