Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 200444
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1144 PM CDT Thu Oct 19 2017

.SYNOPSIS...
Issued at 302 PM CDT Thu Oct 19 2017

Central United States dominated by an expansive upper ridge though
being undercut by a negatively tilted trough from NV into TX. Upper
PV anomaly moving across southern AZ currently and developing mid
and high clouds from the southern Plains into the central Rockies.
In addition a large trough is moving into the PacNW with a
significant PV anomaly moving onto the BC coast. Mainly clear skies
currently across western and north central NE with temps warming
well into the 70s and into low to mid 80s or 15-20 degrees above
average for this time of year.

&&

.SHORT TERM...(This evening through Friday)
Issued at 302 PM CDT Thu Oct 19 2017

The previously mentioned upper PV anomaly located over southern AZ
will move east into west TX in the next 24 hrs but the only sensible
weather expected in this area would be from mid and high level
clouds spreading northward as the larger scale trough also moves
east, displacing the upper ridge to the eastern half of the country.
The resulting southwest flow aloft would transport high level
moisture into the area overnight. This synoptic pattern would
support development of southerly winds across the Plains in the warm
sector ahead of the upper features. In addition, much drier air
located across the southern CO Plateau will cool quicker after
sunset tonight than the more moist air on the adjacent Plains which
is a typical setup for the Plains LLJ, so in this case it will
contribute in addition to the synoptic scale features. This is
mainly an aviation concern and this is covered in the aviation
section below. Otherwise the cloud cover and some wind overnight,
especially on hills above valleys, will keep temps well above
average for this time of year tonight.

Sunshine returns Friday but as mixing deepens through the day,
strong winds will be transported to the surface as upper height
falls continue to spread across the northern Plains with the PacNW
upper trough moving into the northern Rockies. Southerly winds will
therefore increase through the day east of where the surface trough
is expected to setup, which is across the eastern Panhandle. Temps
will respond as well to above average again, though maybe just a few
degrees cooler than today since the southerly winds will also bring
in slightly better low level moisture. This will also lessen
concerns for critical fire weather conditions with the better low
level RH but will have to watch areas of Sheridan county in Fire
zone 204 as this area will be close to the trough and lower RH
values. However as such, winds near the trough axis will be lighter
as well.

.LONG TERM...(Friday night through Thursday)
Issued at 302 PM CDT Thu Oct 19 2017

The extended period will oscillate between warmups and cool downs
as successive cold fronts cross the region through Thursday of
next week.

An upper trough will begin to emerge onto the central and northern
High Plains Friday night. This will push a cold front through the
forecast area after midnight, with northwest winds 15 to 30 mph.
Strong pressure rises as much as 7mb could cause gusts to reach 40
mph briefly toward daybreak. Then on Saturday, northwest winds
will continue to gust to 30 mph. There remains at least a slight
chance for showers after midnight Friday night into Saturday
morning, mainly north central. With the lower levels fairly dry,
mainly just a trace to a few hundredths of an inch possible.
Highs cool on Saturday to the upper 50s northwest and lower 60s
central and southeast. This is very close to normal for highs.

On Sunday, upper height rises and a downsloping westerly wind as
the trough axis moves across the Mississippi Valley. Highs warm
back up to the upper 60s to around 70.

Another cold front moves into western Nebraska Monday, although
highs still reach the upper 60s to near 70, as the cooler air
remains across the Dakotas and Montana. This cooler air will
arrive Monday night into Tuesday as a reinforcing cold front
move through and the upper trough amplifies across the Great
Lakes an Mississippi Valley. The GFS and European models are
similar, with 850mb temps of only 3C-7C. Therefore forecast highs
Tuesday lowered to the mid and upper 50s.

For Wednesday, another warmup expected, as the next cold front
exits the southern Canadian Prairies, and begins to move into
Montana and North Dakota. Highs Wednesday in the mid 60s. The cold
front forecast to arrive Wednesday night looks to be the coldest
of the season. By 12z Thursday 850mb temps cool to near 0C in
northern Nebraska. Some mid level frontogenesis indicated late
Wednesday night and Thursday morning behind the front, which will
be supportive of rain showers, and even snow showers possible.
This would be more favorable to occur across Sheridan and western
Cherry county. Given similar agreement between the GFS, Euro, and
Canadian Models, this will need to be watched closely with
upcoming model runs. Forecast highs in the upper 50s may be too
warm.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1144 PM CDT Thu Oct 19 2017

High clouds will continue to filter into western Nebraska over the
next 24 hours with skies scattered to broken in coverage. There
will be a threat for low level wind shear overnight with southerly
winds up to 45 KTS 2000 FT AGL. Corresponding surface winds will
be around 10 KTS at the KLBF terminal and 15 KTS at the KVTN
terminal. Winds will increase Friday morning and will gust in the
20 to 30 KT range on Friday. Winds will diminish slightly Friday
evening to around 15 KTS.

&&

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

$$

SYNOPSIS...Stoppkotte
SHORT TERM...Stoppkotte
LONG TERM...Roberg
AVIATION...Buttler


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