Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 182330
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
530 PM MDT Wed Oct 18 2017

.SHORT TERM...(This evening through Thursday)
Issued at 200 PM MDT Wed Oct 18 2017

Fire weather concerns the main issue in the short term.

Currently...Surface analysis showing cold front remaining north
from near Chadron to Newcastle to Sheridan to south central
Montana this afternoon. Winds were pretty strong this morning with
widespread gusts to 30+ MPH across southeast Wyoming. Latest
observations though have shown a decrease in winds to a point now
that most areas are below Red Flag Warning criteria (25MPH). WIll
give it another 30 minutes to an hour and see if these winds come
back up before cancelling any fire headlines.

Attention turns to Thursday as another low pressure system tracks
into the northern Rockies. GFS 700mb winds increasing again to
over 30kts during the day across our western zones up into
Converse County. Going to keep dry air in place, so the only
question is how strong the winds are going to get. Forecast
soundings do show 20-25kts of wind mixing down over the Summit and
a little stronger out west.

May just cancel the current Red Flag Warning here shortly and re-
issue for Thursday if winds stay down here. Updates may be needed
shortly.

.LONG TERM...(Thursday night through Wednesday)
Issued at 200 PM MDT Wed Oct 18 2017

Thursday night...Relatively mild night with southwest flow aloft and
a mild atmosphere in place, along with decent low level mixing.

Friday...Quite a mild day with prefrontal warming ahead of the
approaching cold front. With downslope warming and progged 700 mb
temperatures near 7 Celsius, high temperatures will soar into the
70s and lower 80s east of I-25. Perhaps enough moisture for
scattered afternoon showers over the Snowy and Sierra Madre Ranges,
dry elsewhere.

Saturday...Strong cold front sweeps across our counties early in the
day with strong winds possible in our wind prone locations. With
limited low and mid level moisture, only chances for precipitation
will be over and near our Snowy and Sierra Madre Ranges. Much cooler
on Saturday in the wake of the cold front with 700 mb temperatures
near -6 Celsius, yielding high temperatures in the mid 40s to near
60 degrees at lower elevations.

Sunday...As the flow aloft backs to northwest and downslope winds
develop, the atmosphere will warm with high temperatures climbing
into the 60s at most lower elevations. Continued dry with lack of
low and mid level moisture. May see near high wind criteria at our
typically wind prone locations.

Monday...Continued dry with temperatures about the same as another
cold front moves by in the afternoon.

Tuesday...Slightly cooler in the wake of the cold frontal passage
and as the flow aloft becomes almost due northerly. Not enough low
and mid level moisture for any precipitation.

Wednesday...Warming trend develops as the large scale ridge aloft
moves closer from the Great Basin states.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 519 PM MDT Wed Oct 18 2017

VFR conditions will continue tonight and Thursday with breezy
conditions by late morning, mainly around KRWL and KLAR. West winds
may gust up to 30 knots at these locations in the afternoon.
Elsewhere, winds should be out of the south between 5 to 15
knots.

&&

.FIRE WEATHER...
Issued at 200 PM MDT Wed Oct 18 2017

Dry conditions and gusty winds are going to be common across southeast Wyoming
the next few days with critical to near critical fire weather conditions for
some areas. A series of dry low pressure systems track across Montana and
northern Wyoming that will keep fire weather conditions active. Elevated to
strong winds will continue through the weekend.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

WY...Red Flag Warning from 11 AM to 6 PM MDT Thursday for WYZ301-306-
     309.

NE...None.
&&

$$

SHORT TERM...GCC
LONG TERM...RUBIN
AVIATION...TJT
FIRE WEATHER...GCC


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