Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 212009

Area Forecast Discussion
National Weather Service North Platte NE
309 PM CDT Sat Oct 21 2017

.SHORT TERM...(This evening through Sunday)
Issued at 309 PM CDT Sat Oct 21 2017

Tonight and tomorrow.  PV anomaly and area of FGEN will continue
east of the forecast area this evening.  Increasing subsidence to
follow, which will limit clouds for the overnight and as winds
weaken, a solid radiational cooling event is expected.  The latest
guidance trended lower by 2-4 degrees, which would suggest mid 20s
along the Platte River valley and northwest Nebraska, upper 20s to
lower 30s elsewhere.  This is near seasonal norms.  One place to
watch will be LBF where guidance is showing lows a cool as the lower
20s.  A transitory ridge will build across the western States
resulting in dry and warm conditions for Sunday.  A westerly
component of the lower tropospheric wind will help push highs back
into the 70s for most locations.  The warm temperatures will allow
for near critical relative humidity with readings in the lower 20s
over most places.  The wind does not look overly strong, so fire
headlines are not anticipated.

.LONG TERM...(Sunday night through Saturday)
Issued at 309 PM CDT Sat Oct 21 2017

After a warm up Sunday, another strong Pacific high pressure system
will build through the Central Plains Monday and Tuesday. An arctic
cold front is expected to move through the Central Plains Thursday.

Winds aloft Monday increase to around 75kt at h500mb and 50-60kts at
h700mb. 500m AGL winds increase to 25 to 30 kt which equates to 25
to 30 mph at the sfc. The forecast uses consensus model output
statistics from the NAM and GFS models for northwest winds 20 to
35 mph. gusts could reach 40 to 45 mph. The models suggest speeds
decrease to 15 to 25 mph Tuesday as the upper level jet moves off
east. Note trop heights fall to around 500mb Monday which could
force the stronger winds aloft down closer to the ground. It is
too early to predict if high wind criteria will be met but the
situation Monday will be monitored closely in later forecasts.

The next significant weather feature arrives in the form of an
arctic cold front Thursday. H850mb temperatures fall to 0C to -5C by
Friday morning with the cold air lasting through Saturday.
Deterministic model data indicates apparent temperatures in the
teens and 20s Friday and Saturday mornings. Once again, strong north
winds develop in the GFS and ECM models Thursday, increasing to 25
to 30 mph.

Otherwise, a thermal ridge develops Wednesday, ahead of the arctic
front. This pushes h850mb temperatures to 15C to 20C and highs
should rise into the 70s. The 7-day QPF forecast from WPC is for
zero measureable rainfall. The forecast includes mostly isolated
rain or snow shower chances associated with the passage of the
arctic front Thursday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1225 PM CDT Sat Oct 21 2017

A line of showers will continue to lift northeast and dissipate
this afternoon. The latest high resolution data suggests east of
the KVTN terminal by 18z with the activity reaching KONL by 20z.
Visibility under remains at 6sm or higher will little reduction in
ceilings. Dry air behind the band will allow for a deck of high
clouds but not much more. Thus VFR remains through the 18z
forecast cycle. Pre-frontal winds have been breezy early this
afternoon, but the latest guidance suggests these winds weakening
as the sun sets this evening.


Issued at 309 PM CDT Sat Oct 21 2017

Strong northwest winds, 25 to 30 mph with higher gusts are likely
Monday with speeds decreasing to 15 to 25 mph Tuesday. Uncertainty
regarding RH values (too moist) suggest critical fire danger
thresholds will be not be eclipsed however later forecasts could
feature lower RH values which would necessitate a fire weather




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