Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 251211
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
711 AM CDT MON MAY 25 2015

.UPDATE...
ISSUED AT 708 AM CDT MON MAY 25 2015

FOG HAS STEADILY EXPANDED WEST WITH VISIBILITIES DOWN TO A 1/4
MILE FROM ONEILL TO SOUTH OF VALENTINE. A DENSE FOG ADVISORY IS IN
EFFECT UNTIL 10 AM CDT FOR THE NORTH CENTRAL.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 335 AM CDT MON MAY 25 2015

FORECAST CHALLENGE IS POPS. MODELS ARE IN GOOD AGREEMENT THAT THE
CLOSED UPPER LOW WILL DIVIDE AND BECOME AN OPEN WAVE TO LIFT OUT
THROUGH TONIGHT. WHILE MODELS ARE IN AGREEMENT HERE...EACH CREATE
DISTINCTIVE DIFFERENCE QPF PROJECTIONS IN THE NEAR TERM. THE
EVENTUAL EVOLUTION OF THE CLOSED LOW WILL INFLUENCE CONVECTION
TONIGHT WHERE HIGHER POPS GENERALLY MAINTAINED ACROSS THE NORTH.
TODAY TEMPERATURES WILL TREND UPWARDS WITH HIGH TEMPERATURES IN THE
60S TO LOWER 70S. AS THE UPPER LOW TRACKS NORTHEAST ISOLATED TO
SCATTERED THUNDERSTORMS ARE POSSIBLE THIS EVENING. THEN OVERNIGHT AS
BUILDING HEIGHTS PERSUE IN THE WEST SOME CLEARING TAKES PLACE ACROSS
THE WEST. TONIGHT COOLEST READINGS ACROSS THE WEST RANGING FROM THE
LOWER 40S IN THE EASTERN PANHANDLE TO MIDDLE 50S NORTH CENTRAL.

THE NORTH PLATTE...SOUTH PLATTE AND PLATTE RIVERS REMAIN HIGH WITH
THE ADDITIONAL RAINS SUNDAY TO MAINTAIN HIGHER FLOWS. SEE THE LATEST
RIVER AND FLOOD STATEMENTS FOR MORE DETAILS.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 335 AM CDT MON MAY 25 2015

AN UPPER LEVEL RIDGE AXIS OVER WILL BE POSITIONED OVER THE EASTERN
ROCKIES AND INTO THE HIGH PLAINS AT THE START OF THE LONG TERM
PERIOD ON TUESDAY. EXPECTING QUIETER WEATHER CONDITIONS AS
COMPARED TO MONDAY AS AN AREA OF SFC HIGH PRESSURE MOVES INTO THE
DAKOTAS AND SOUTHWARD INTO CENTRAL NEBRASKA. SOUTHERLY FLOW
GRADUALLY RETURNS TO WESTERN NEBRASKA LATE IN THE DAY. MODELS
CONTINUE TO SHOW ISOLATED STORMS DEVELOPING WEST OF THE CWA DURING
THE LATE AFTERNOON AND EVENING AND AS LOW LEVEL MOISTURE IS ADVECTED
INTO THE PANHANDLE. NOT TERRIBLY CONFIDENT IN THIS OUTCOME GIVEN THE
LACK OF UPPER LEVEL FORCING AND A WELL DEFINED SURFACE BOUNDARY TO
SERVE AS A FOCUS FOR CONVECTIVE INITIATION...BUT KEPT SLIGHT POPS
RUNNING FOR THE EASTERN PANHANDLE AND SOUTHWEST NEBRASKA GIVEN RUN
TO RUN PERSISTENCE IN THE MODELS.

UPPER LEVEL HEIGHT FALLS COMMENCE WEDNESDAY AS A TROUGH BEGINS TO
DIG SOUTHEAST OVER THE WESTERN CONUS. INCREASING DPVA ALOFT WILL
PROMOTE A DEEPENING LEE SIDE TROUGH OVER EASTERN COLORADO AND
WYOMING...AND INCREASING SOUTHERLY FLOW OVER MOST OF THE PLAINS.
STORMS BEGIN TO DEVELOP BY MID TO LATE AFTERNOON THE CAP WEAKENS IN
THE VICINITY OF THE AFOREMENTIONED LEE SIDE TROUGH. A FEW SEVERE
STORMS WILL BE POSSIBLE AS THE STORMS PUSH EAST GIVEN SURFACE BASED
CAPE VALUES AROUND 1500-2000 J/KG AND STEEP LAPSE RATES. HOWEVER
ADEQUATE DEEP LAYER SHEAR IS LACKING IN THE PRESENCE OF WEAK UPPER
LEVEL FLOW. STRENGTHENING UPPER LEVEL JET AFTER DARK WILL HELP KEEP
THUNDERSTORMS GOING AS THEY PUSH EAST INTO CENTRAL NEBRASKA
OVERNIGHT.

PRECIPITATION CHANCES INCREASE LATE IN THE WEEK AS THE WEST COAST
TROUGH SLOWLY MOVES THROUGH THE CENTRAL ROCKIES AND INTO THE PLAINS
BY THE WEEKEND. DEEP MOISTURE TRANSPORT FROM THE GULF ALONG WITH
UPPER LEVEL MOISTURE OFF THE EASTERN PACIFIC WILL PUSH PWAT VALUES
CLOSE TO 1.25 INCHES...AND POSSIBLY HIGHER...OVER WESTERN AND NORTH
CENTRAL NEBRASKA SO LOCALLY HEAVY RAINFALL WILL LIKELY BE A THREAT.
MODELS DIVERGE CONSIDERABLY ON THEIR THOUGHTS FOR THE WEEKEND.
EC/GEM SHOVE A COLD FRONT THROUGH THE AREA AND PUSHES IT WELL TO OUR
SOUTH...ADVECTING IN DRY CONDITIONS IN IT/S WAKE FOR SATURDAY AND
SUNDAY. THE GFS ALSO BRINGS THE COLD FRONT THROUGH BUT STALLS IT OUT
JUST TO OUR SOUTH...WHICH WOULD MEAN MORE PRECIPITATION CHANCES FOR
THE AREA OVER THE WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 630 AM CDT MON MAY 25 2015

CEILING WILL LOWER FROM THE SOUTH TO NORTH WHERE LOWER IFR CEILING
ARE FORECAST AT THE KVTN TERMINAL. FURTHER SOUTH DRIER AIR IN THE
MID LAYERS WILL BRING ABOUT IMPROVING CEILINGS THROUGH THE DAY.
MODELS ARE IN GOOD AGREEMENT WITH UPPER LOW TO MOVE NORTHEAST THAT
WILL BRING A CHANCE FOR ISOLATED TO SCATTERED THUNDESTORMS IN THE
AFTERNOON AT BOTH TERMINALS.


&&

.LBF WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NEZ005>010-
026>029.

&&

$$

UPDATE...KECK
SHORT TERM...KECK
LONG TERM...MARTIN
AVIATION...KECK






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