Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 170023
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
623 PM MDT Mon Oct 16 2017

.UPDATE...
Issued at 622 PM MDT Mon Oct 16 2017

As critical fire conditions continue to diminish this evening,
have allowed the Red Flag Warning to expire at 6 PM. Another
critical fire weather day will again be possible on Tuesday.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 200 PM MDT Mon Oct 16 2017

Warm and very dry weather pattern to persist through Tuesday. Weak
ridging remains in place over the intermountain west and SE
Wyoming/W Nebraska will lie on the southern fringe of moderately
fast zonal flow aloft. A subtle shortwave will skirt across the
area from the west during the day Tuesday which may enhance the
flow aloft as well as push the surface trough a bit further east
than today. Forecast soundings continue to show very dry and well
mixed conditions developing across the entire area Tuesday
afternoon with 700 mb temps warming to around 8C. Should see high
temps top out in the 70s to near 80 east of the Laramie Range
especially with the stronger west to northwest winds and
downsloping adding to the warming. Looks like another critical
fire weather day Tuesday for a large part of the area as mentioned
below.

.LONG TERM...(Tuesday night through Monday)
Issued at 200 PM MDT Mon Oct 16 2017

Warm and breezy conditions continue Wednesday with another possible
Red Flag day. Afternoon humidities across the Laramie Range and
adjacent foothills down below 15 percent, only question will be
winds. GFS soundings pretty close with 25-30kts right off the
surface, so another critical fire weather day likely Wednesday.

In fact, we could be dealing with fire weather conditions well into
the week as warm/dry weather looks to continue at least through
Friday. Forecast humidity in the low to mid teens both days.

Next chance for precip will be Saturday across our western zones and
we could be in for a fairly strong wind event Saturday night into
Sunday as well. GFS 700mb winds well above 50kts Saturday evening
into Sunday. GFS 700mb Craig to Casper gradient increases to
60mtrs after 06Z Sunday and continues through the day. If this
forecast holds true, we will be looking at warning level winds in
the wind prone areas (Arlington, Bordeaux, South Laramie Range).

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 622 PM MDT Mon Oct 16 2017

VFR conditions will prevail through the period, with just some
high clouds streaming through from time to time. Winds will
continue to diminish this evening, with another round of
west/southwest winds for southeast Wyoming terminals after 16z
Tuesday.

&&

.FIRE WEATHER...
Issued at 622 PM MDT Mon Oct 16 2017

Critical fire conditions continue to diminish this evening,
therefore the Red Flag Warning has been allowed to expire on time
at 6P. Little change in air mass is expected for Tuesday and
possibly even into Wednesday, so will continue the Fire Weather
Watch looks good on Tuesday. Will evaluate the latest information
this evening, before possibly upgrading with a later evening
update.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Fire Weather Watch Tuesday afternoon for WYZ301-306-309-310.

NE...Fire Weather Watch Tuesday afternoon for NEZ312-313.

&&

$$

UPDATE...CAH
SHORT TERM...DEL
LONG TERM...GCC
AVIATION...CAH
FIRE WEATHER...CAH



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