Area Forecast Discussion
Issued by NWS Cheyenne, WY

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835
FXUS65 KCYS 181629
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1029 AM MDT Wed Oct 18 2017

.UPDATE...
Issued at 1027 AM MDT Wed Oct 18 2017

Southern FWZ 310 hitting Red Flag Warning criteria at this time
and it is expected to continue through the afternoon. Went ahead
and issued a Red Flag Warning for Laramie County (southern FWZ
310) through 5PM this afternoon. Updates have been sent.

UPDATE Issued at 355 AM MDT Wed Oct 18 2017

Hitting Red Flag criteria over zone 309 early this morning with
westerly winds gusting to 40 mph and humidities between 10 and 15
percent. Red Flag Warning effective now through late this
afternoon.

&&

.SHORT TERM...(Today through Thursday night)
Issued at 300 AM MDT Wed Oct 18 2017

The unseasonably warm weather will continue across the CWA through
Thursday with westerly upper flow today becoming southwesterly
tonight and Thursday. Varying amounts of high clouds will move
across as batches of higher air moisture interact with the mtns
and create some high cloudiness. Winds should be less today as the
gradient relaxes but still a bit gusty in the afternoons today
and Thursday with good mixing. A weak impulse will lift northeast
over the CWA late Thursday but dry air will preclude any pcpn.

.LONG TERM...(Friday through Tuesday)
Issued at 300 AM MDT Wed Oct 18 2017

Forecast concerns will focus on timing of next cold frontal passage
and the potential for a couple high wind episodes Saturday through
Sunday night.

The 00Z medium range model/ensemble consensus depicts a progressive,
highly amplified large scale flow. A Pacific upper trough and cold
front will progress eastward across the Intermountain West, Rockies
and High Plains Friday through Saturday. The trough and front usher
in cooler temperatures and isolated to scattered rain/snow showers.
Snow levels will drop to 7500 feet over the Snowy/Sierra Madres
Friday night, with upwards of three inches possible. 700mb gradient
flow increases late Friday west of the Laramie Range, with 40-50 kt
winds Friday night/early Saturday morning. Craig-Casper 850mb
gradient peaks 50-55m midnight Friday night. may be looking at a
short-duration high wind event for our wind prone areas
(Arlington, Bordeaux and south Laramie Range). West-northwest flow
aloft and 850mb gradient peaks 60-70m Sunday/Sunday night. This
second high wind episode may affect the southeast WY plains. Will
continue to assess the high wind potential as we get closer to the
event.

After a cool, brisk Saturday, temperatures will moderate to above
seasonal normals Sunday through Tuesday as a upper ridge builds
over the western CONUS. It will remain breezy to windy Monday,
with lighter winds Tuesday under the influence of a surface ridge.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 230 AM MDT Wed Oct 18 2017

VFR with occasional high clouds this morning. Gusty westerly winds
of 20-30 kt will continue today along and west of I-25. A backdoor
cool front will shift winds to northerly across western NE and
eastern WY plains this morning, veering southeasterly this
afternoon. Winds will become southerly 5-10 kt this evening.


&&

.FIRE WEATHER...
Issued at 215 AM MDT Wed Oct 18 2017

A relatively short period of Red Flag conditions expected over
parts of Zone 309 this afternoon so upgraded the watch to a Red
Flag Warning as air is already quite dry and should see a period
of gusty winds into early this afternoon. Dry and warm weather
over the next few days before turning much cooler over the weekend.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 5 PM MDT this afternoon for WYZ309-310.

NE...None.
&&

$$

UPDATE...GCC
SHORT TERM...RE
LONG TERM...MAJ
AVIATION...MAJ
FIRE WEATHER...RE



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