Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 221723
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1223 PM CDT Sun Oct 22 2017

.SHORT TERM...(Today through Tuesday)
Issued at 246 AM CDT Sun Oct 22 2017

An elongated ridge of high pressure has settled into the forecast
area in the wake of the cold front that is moving into the
Mississippi Valley region this morning. Flattening of the surface
ridge will cause winds to become west to southwesterly by
afternoon, and allow for downslope warming that will counter
weak H8 cold air advection that will occur earlier in the day.
Temperatures will be slightly cooler than those seen on Saturday
by about a category as a result.

The main sensible weather concern in the short term will the the
potential for strong winds both Monday and Tuesday. A short wave
will move through the broader long wave trough that will extend
across the central Canadian provinces later today and will drive
a frontal boundary through the area tonight. The Candadian short
wave will merge U.S. southern stream short wave feature to carve
a deep meridional trough over the eastern U.S. and result in
deepening cyclogenesis over the Great Lakes. In turn, this will lead
to a sharp pressure gradient across the north central plains on
Monday into early Tuesday. Sustained winds and gusts will flirt
with wind advisory criteria, especially on Monday across northern
portions of the forecast area. For now, will highlight in the
hazardous weather outlook. Winds also will result in a fire
weather hazard in cured farmer/rancher fields; however, non-
agricultural areas still rather green so fire threat lesser.

Temperature-wise, cold air advection in the wake of the frontal
passage on Monday, will lead into a slight dip in temperatures
Monday afternoon. Steady surface/H8 cold air advection and
northerly trajectory of winds, will result in temperatures mainly
in the 50s on Tuesday. Overnight temperatures will stay above
freezing.

.LONG TERM...(Tuesday night through Saturday)
Issued at 246 AM CDT Sun Oct 22 2017

Weak H5 ridging will cause temperatures to rebound on Wednesday
back into the 60s and 70s.  The warm-up will be short-lived, as
a long wave trough begins carving into the intermountain West on
Thursday, driving a frontal boundary through the area. The
progresive wave marches across the central plains, but present
indications are that forecast area will see little if any
precipitation from this system. Medium range deterministic and
GEFS keep precipitation shield associated with dynamic forcing
generally to the north of the forecast area. The operational GFS
develops western warm conveyor belt precipitation moreso than
EC/Canadian and several GEFS members, and appears to the outlier
at time. As such, trended more toward EC/Canadian/GEFS mean
solution, that will give northern and eastern part of the forecast
area a slight chance of precipitation. Wet- bulb profile will be
at or below freezing Thursday night into early Friday, thus
introduced rain/snow mix. Time will tell how the system evolves.

Temperatures will be much colder late in the week, and there is
the potential for hard freeze on Friday night in those area that
have not sub freezing temperatures so far this fall. Strong cold
advection both Friday and Saturday, and brisk north winds will
make for a couple raw days, with high temperatures only in the
40s.  Wind chills on Friday look to be in the 30s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1221 PM CDT Sun Oct 22 2017

VFR conditiosn are expected through the TAF cycle, with clear
skies and unrestricted visibility. Winds may get a bit gusty this
afternoon but should relax to around 5-10kt tonight. As strong
mid-level winds reach the area, all sites are at risk of low-level
wind shear later tonight into Monday morning. After some heating
in the morning, those stronger winds will mix down to the surface,
with wind speeds ramping up quickly into the 20-30kt range with
30-40kt gusts through late morning into early afternoon.

&&

.FIRE WEATHER...
Issued at 246 AM CDT Sun Oct 22 2017

A weak cold front will move through the area tonight, in the wake
of the frontal passage, the surface pressure gradient will
increase and will result in strong and gust northwest winds
peaking at 25-30 mph in the afternoon with gusts around 40 mph.
Afternoon relative humidities will drop into the upper 20s and
lower 30s.  Fire weather conditions will be enhanced, especially
in dried/cured farming and ranching fields. Non-agricultural areas
still remain somewhat green, so the fire risk is not as great in
these areas.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...Fortin
LONG TERM...Fortin
AVIATION...Mayes
FIRE WEATHER...Fortin



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