Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 162020
AFDCYS

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

.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 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1127 AM MDT Mon Oct 16 2017

VFR conditions with gusty west to southwest winds continuing
through the afternoon hours this afternoon. Winds easing towards
sunset and are expected to once again pick up Tuesday.


&&

.FIRE WEATHER...
Issued at 200 PM MDT Mon Oct 16 2017

Critical fire weather will likely continue at least on Tuesday and
possibly into Wednesday. RH values this afternoon have plummeted
to as low as 7 to 10 percent across the entire area and forecast
soundings show a very similar airmass in place tomorrow. Winds
should gust to 30 mph over much of SE Wyoming and could see winds
near Red Flag criteria even into the central and southern
Panhandle, again similar to this afternoon. Added zones 312 and
313 to the Fire Weather Watch for Tuesday afternoon and some or
all of these areas will likely need to be upgraded by the evening
or overnight shift.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 6 PM MDT this evening for WYZ301-306-309-
     310.

     Fire Weather Watch Tuesday afternoon for WYZ301-306-309-310.

NE...Red Flag Warning until 6 PM MDT this evening for NEZ312-313.

     Fire Weather Watch Tuesday afternoon for NEZ312-313.

&&

$$

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



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