Dense Fog Advisory 12, NWS North Platte, NE

Area Forecast Discussion
National Weather Service North Platte NE
641 AM CST Sat Dec 4 2021

.SHORT TERM...(Today through Sunday)
Issued at 313 AM CST Sat Dec 4 2021

The forecast focus in the short term will be the breezy to windy
conditions developing today into this evening.

A west northwest upper flow pattern will remain in place today.
Surface high pressure will move into the western Great Lakes as
surface low pressure deepens across WY into eastern CO. This will
bring a tightening surface pressure gradient to western NE.
Southerly winds will increase to 20 to 35 mph by this afternoon with
the stronger winds over the central and northern Sandhills. Highs
today will be warmest across the west in the 50s.

Tonight, a cold front will drop into north central NE late tonight.
Fairly mild air will be in place ahead of the front as winds turn to
the southwest and west. Portions of the northwest Sandhills and
northern NE will range in the 40s before the cold front arrives.

On Sunday, retained a slight chc for rain or snow over the Pine
Ridge during the morning. Colder air will spill southward with H85
winds from 40-50kts from the Dakotas south into NE. Northwest winds
will be strong, sustained at 25 to near 30 mph with gusts from 35 to
45 mph. Gusts to near 50 mph possible at VTN and ANW, as is
supported by the HRRR. Used the NBM 90th percentile for winds. Do
not feel a High Wind Watch is needed at this time, but will be
monitored during the next forecast package this afternoon. Highs
upper 30s to lower 40s across the northwest should fall by mid
afternoon while the southeast manages to reach the upper 40s and
lower 50s (mid 50s far southwest).

.LONG TERM...(Sunday night through Friday)
Issued at 313 AM CST Sat Dec 4 2021

The main forecast focus in the long term will be colder temperatures
Monday into Tuesday, followed by the potential for accumulating snow
Thursday night through Friday night.

Colder air will be in place Monday into Tuesday as an upper trough
crosses the region. Models are not in very good agreement in
placement of potential light snow, with slight chances possible
Monday night into Tuesday night mainly across the north and west.

A slight warmup into the 40s to low 50s Wed. and Thu. as a deep
upper trough digs into the Intermountain west. This upper trough
will move into the region Thursday night through Friday night. The
deterministic GFS continues to develop a potent storm system with a
closed upper low developing over western NE into eastern SD with
a surface low as deep as 981mb over eastern NE. A 300mb coupled
jet is indicated with strong baroclinicity and mid level
frontogenesis across the forecast area. While this scenario could
bring significant snowfall, the deterministic ECMWF and Canadian
models show a differing solution. The ECMWF shows a weaker surface
low near 991-996mb tracking from sern CO into OK. The Canadian
model surface low track is similar. The GFS ensemble and ECMWF
ensemble are also weaker with the system. So while this looks like
the best opportunity for some light snowfall not seen since Nov.
1st, confidence is low that a well developed winter system will
impact western NE.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 623 AM CST Sat Dec 4 2021

An area of low stratus clouds and patchy fog continues to spread
southwest across western and north central Nebraska early this
morning. IFR and MVFR is occurring within this area of cloud
cover and will persist through late this morning. As winds
increase from the south this afternoon the lower ceilings should
erode from south to north with VFR expected. South winds will be
gusty, over 25 kts at times this afternoon and tonight. As the
low-level jet increases tonight, wind shear will become a concern.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

SHORT TERM...Roberg
LONG TERM...Roberg
AVIATION...Taylor

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