Area Forecast Discussion
Issued by NWS North Platte, NE

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284
FXUS63 KLBF 300906
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
406 AM CDT SAT APR 30 2016

.SYNOPSIS...
ISSUED AT 406 AM CDT SAT APR 30 2016

POTENT UPPER LEVEL LOW SPINNING THIS MORNING ACROSS EAST CENTRAL
COLORADO. EXCELLENT MOISTURE TRANSPORT FROM THE GULF/EAST PACIFIC
AHEAD OF THE LOW...AND WRAPS INTO WESTERN NEBRASKA. DYNAMIC COOLING
HAS CAUSED RAIN TO CHANGE OVER TO SNOW ACROSS SOUTHWEST NEBRASKA AND
THE SOUTHERN SANDHILLS...WHERE TEMPS ARE IN THE LOWER 30S. ELSEWHERE
MID TO UPPER 30S AND RAIN TO A RAIN/SNOW MIX EXPERIENCED.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT SAT APR 30 2016

UPPER LEVEL LOW WILL CONTINUE TO SLOWLY DRIFT TO THE EAST THEN
NORTHEAST TODAY AND TONIGHT. EXPECT THE DYNAMIC COOLING TO CONTINUE
AROUND THE LOW...WHICH EXPANDS TO THE NORTH WITH MOST OF THE
SANDHILLS BECOMING A RAIN/SNOW MIX AND PRIMARILY ALL SNOW THIS
MORNING. AS TEMPS WARM A COUPLE OF DEGREES FOR THE
AFTERNOON...PRECIP WILL BECOME MORE A MIX OR A LEAST A LITTLE MORE
MELTING AT THE SURFACE. TEMPS TONIGHT WILL COOL BACK WITH A CHANGE
OVER TO MOSTLY SNOW ACROSS WESTERN NEB. WILL NEED TO MONITOR THE
EASTERN ZONES FOR POSSIBLE CHANGE...BUT CURRENT THOUGHT IS JUST WARM
ENOUGH FOR RAIN. AREAS WITH A WINTER HEADLINE...BOTH THE
WARNING/ADVISORY...WILL CONTINUE TO SEE SNOW...ALTHOUGH SOME OF THE
NORTHERN SECTIONS MAY NOT RECORD MUCH FOR ACCUMULATION...WILL NOT
CHANGE ANY OF THE HEADLINES AT THIS TIME. ALSO WATCHING THE FLOODING
POTENTIAL ACROSS SOUTHWEST INTO CENTRAL NEB. GENERALLY HALF TO ONE
INCH HAS FALLEN ACROSS THIS AREA...WHICH HAS A FAIRLY SATURATED
GROUND FROM PREVIOUS RAINFALL. WILL CONTINUE THE AREAL FLOOD WATCH
AND MONITOR CLOSELY. ONE THING OF CONCERN IS THE DRY SLOT THAT HAS
WORKED INTO SW NEB. MODELS ARE STRUGGLING TO HANDLE THIS DRY AIR.
THE MODELS ARE FILLING IN THIS DRY SLOT...WHICH MY GUT SAYS SEEMS TO
BE TO QUICKLY IN THE MODELS...SO HAVE SCALED BACK THE
FORECAST...ALTHOUGH IT MAY NEED TO BE SCALED BACK MORE.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 406 AM CDT SAT APR 30 2016

MID RANGE...SUNDAY AND MONDAY... MAIN FORECAST CHALLENGES ARE
TEMPERATURES AND PRECIPITATION AS THE UPPER LOW MOVES EAST OF THE
STATE AND IS FOLLOWED BY A BUILDING RIDGE OVER THE INTERMOUNTAIN
WEST.

SUNDAY... BUMPED MAX TEMPS UP A DEGREE ACROSS THE AREA TO ACCOUNT
FOR WEAK WAA. MODELS CONSISTENT WITH H85 TEMPS RISING FROM NEAR 0C
SAT PM TO AROUND 2C SUNDAY. RETAINED POPS SOUTH OF HWY 20 IN THE
MORNING AS LOW LEVEL MOISTURE STICKS AROUND. FGEN FORCING SLOWLY
DIES OFF AND DRY AIR FILTERS IN FROM THE NORTH... BUT LIFT BELOW
700HPA SHOULD BE ENOUGH TO SUPPORT A LIGHT SHOWER. CUT OUT POPS IN
THE AFTERNOON AS NAM AND GFS FORECAST SOUNDINGS INTRODUCE DRY AIR IN
THE LOWEST 200HPA AND ISENTROPIC DOWNGLIDE TAKES OVER... MOST
NOTABLY AT 295K. THE NEXT WAVE OF MOISTURE ARRIVES SUNDAY EVENING AS
A WEAK LOW/MID LEVEL LOW PASSES THROUGH THE SOUTHERN PLAINS. KEPT
SCHC POPS SOUTH OF I-80 OVERNIGHT THROUGH 12Z MONDAY. WITH THE BULK
OF THE MOISTURE GENERALLY BELOW DGZ AND CONFINED SFC-650HPA... NOT
AS CONFIDENT FOR ALL SNOW. FREEZING LINE OCCURS AROUND 1KFT AGL IN
NAM SOUNDINGS AT KIML AND SFC TEMPS DOWN TO AROUND 35F... DID KEEP
RASN MENTION.

MONDAY... TRENDED MAX TEMPS UP SLIGHTLY FOR CONTINUED WAA WITH H85
TEMPS APPROACHING 8C. SLOWLY CLEARED CLOUDS OUT FROM NORTH TO SOUTH
DUE TO OVERALL SUBSIDENCE... ABUNDANT DRY AIR IN THE MID LEVELS...
AND DOWNSLOPING H85 FLOW. ONE FEATURE TO NOTE IS THE EURO DROPS A H5
LOW INTO THE AREA LATE EVENING. NAM AND GFS KEEP THE AREA UNDER THE
CONTROL OF HIGH PRESSURE AND HAVE OPTED FOR THIS SOLUTION. LOOKING
WELL UPSTREAM ON WATER VAPOR... CANNOT FIND A SIGNAL OF A PV OR
VORTMAX.

LONG RANGE...TUESDAY THROUGH FRIDAY... OTHER THAN THE EURO UPPER LOW
DISCREPANCY TO BEGIN THE PERIOD... WESTERN NEBRASKA PRIMARILY LIES
WITHIN NORTHWEST FLOW ALOFT WITH THE RIDGE SITUATED OVER THE
ROCKIES. THE GFS IS SLIGHTLY FASTER WITH THE H5 RIDGE AXIS BISECTING
THE CWA EARLY FRIDAY VERSUS LATE FRIDAY/EARLY SATURDAY IN THE EURO.
NEVERTHELESS... THE POTENTIAL IMPACT IS WHEN THE NEXT CLOSED LOW CAN
BRING MOISTURE INTO THE AREA LATE FRIDAY OR SATURDAY. IN THE
MEANTIME... A WARMING TREND AND FAIR CONDITIONS WILL BE THE MAIN
STORY. H85 TEMPS OVER THE SANDHILLS RISE FROM NEAR 12C TUESDAY TO
AROUND 15C WEDNESDAY. SOUTHERLY RETURN FLOW RESUMES THURSDAY AHEAD
OF THE THERMAL RIDGE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1148 PM CDT FRI APR 29 2016

FOR THE KLBF TERMINAL...EXPECT MAINLY IFR CIGS OVER THE NEXT 24
HOURS WITH PERIODS OF RAIN. SOME SNOW IS POSSIBLE FROM 8Z THROUGH
15Z SATURDAY WITH VISBYS DROPPING DOWN TO 1SM. OTHERWISE...VISBYS
IN ASSOCIATION WITH RAIN WILL BE IN THE 3 TO 5SM RANGE. FOR THE
KVTN TERMINAL...EXPECT IFR CIGS OVER THE NEXT 24 HOURS WITH LIGHT
RAIN EXPECTED. VISBYS WILL RANGE FROM 3 TO 5SM.



&&

.LBF WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 AM CDT /MIDNIGHT MDT/ SUNDAY FOR
NEZ005-025-036-037-056>058.

FLOOD WATCH UNTIL 1 PM CDT THIS AFTERNOON FOR NEZ038-059-070-071.

WINTER STORM WARNING UNTIL 1 AM CDT /MIDNIGHT MDT/ SUNDAY FOR
NEZ004-022>024-035-094.

&&

$$

SYNOPSIS...MASEK
SHORT TERM...MASEK
LONG TERM...SNIVELY
AVIATION...BUTTLER



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