Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 210344
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
944 PM CST Mon Nov 20 2017

.UPDATE...
Issued at 939 PM CST Mon Nov 20 2017

Have not seen anything in the 00Z NAM to warrant an alteration of
the wind advisory. The strongest cold air advection and pressure
rises, along with tightest pressure gradient come through late
tonight and Tuesday morning when mixing potential is somewhat
minimized. But would not be surprised to see a few sites occasionally
hit wind advisory criteria during this time frame, with the most
consistent wind advisory type winds in the headlined area.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 330 PM CST Mon Nov 20 2017

Mostly uneventful short term forecast. Upper trough will swing
through the MB/ON/MN border region this evening, focusing any
forcing strong enough to produce precipitation far to our north.
Only impact here will be the passage of the surface cold front and
the gusty northwest winds that will arrive in its wake. With
clearing skies and strong cold advection, expect lows to drop into
the 20s for most of the CWA with wind chills as low as 10.

The gusty northwesterly winds will continue through Tuesday.
Expecting some of the sustained winds and a potentially a couple
gusts to hit wind advisory criteria in southwest Minnesota so have
issued a Wind Advisory. Because of the strong cold advection,
despite the mostly clear skies, temperatures will struggle to get
above 30 through the day Tuesday.

.LONG TERM...(Tuesday night through Monday)
Issued at 330 PM CST Mon Nov 20 2017

Pressure gradient and with it the winds finally let up Tuesday night
as high pressure builds in overhead. Luckily, all the mixing from
the preceding gusty periods will leave us with reduced surface
moisture and scant fog potential even with winds close to calm.

Amplified upper pattern off the Pacific coast once again spurs broad
lee troughing across the western portion of the northern plains.
This will induce a return of gusty southerly winds and some mid
level clouds to the region Wednesday. The mid level clouds along
with a quasi-stationary boundary will help keep highs down across
southwest MN and northwest IA down while south central SD could mix
out into the mid 50s. Have boosted highs a bit in south central SD
in deference to the impressive warm layer aloft.

Quasi-stationary boundary hangs around for Thanksgiving. Another
little push of mid level clouds in the afternoon will once again
reinforce the gradient across the CWA. Have again boosted highs for
the same reason as Wednesday. With less of a pressure gradient
across the region, will stick with consensus winds. No foul weather
anticipated.

Pacific NW trough finally breaks down a bit and translates energy
across the northern Rockies early Friday. This will induce a rather
impressive surface cyclone in southern Canada. Luckily for people
traveling, the strongest forcing and deep moisture associated with
this system will focus well to our north. There is some suggestion
the Highway 14 corridor could be affected by precipitation
associated with the 700mb front Friday afternoon. Low level
temperatures will be plenty warm enough to ensure any precipitation
will fall as rain. Will once again need to boost winds Friday night
in the wake of the frontal passage.

General guidance agreement after Friday is for dry conditions as
longwave ridging aloft dominates the northern plains.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 524 PM CST Mon Nov 20 2017

A strong cold front will push through the region overnight, likely
starting in the pre-dawn hours bringing gusty northwesterly winds.
Sustained winds around 20 kt with gusts 30 to 35 kts will be
common. Skies look to remain clear for most areas with this dry
cold front, but sites in southwest MN could see short-lived MVFR
cloud deck around 2500 ft AGL on the leading edge of the front.
Winds continue through the day Tuesday, but quickly diminish after
sunset.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...Wind Advisory from 6 AM to 2 PM CST Tuesday for MNZ072-081-090.

IA...Wind Advisory from 6 AM to 2 PM CST Tuesday for IAZ003.

NE...None.
&&

$$

UPDATE...MJ
SHORT TERM...Ferguson
LONG TERM...Ferguson
AVIATION...VandenBoogart



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