Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 200513

Area Forecast Discussion
National Weather Service Cheyenne WY
1112 PM MDT FRI AUG 19 2016

Issued at 802 PM MDT Fri Aug 19 2016

The main concern tonight will be how cold temperatures will be.

Latest satellite loop was showing the stratus and precipitation beginning
to clear out across eastern Wyoming due to strong subsidence.
Simulated IR imagery was advertising this as well through the
night. As a result, this should allow temperatures to tumble.
However, wind speeds may continue to stay up for a while this
evening before the surface ridge to the northwest begins to slide
east. This may cause the flow across extreme southeast Wyoming to
turn west which may limit a big cool down overnight. VWP is also
showing the flow around 9000ft turning to the northwest. With all
that said, Frost Advisory still looks valid overnight especially
in many areas west of the Laramie Range especially the valleys
where they may drop to near 30.


.SHORT TERM...(This evening through Sunday night)
Issued at 217 PM MDT Fri Aug 19 2016

Forecast challenges deal with PoPs today, near freezing
temperatures tonight, followed by increasingly critical fire
weather conditions Sunday.

Currently...Cold front just went through Cheyenne about a half
hour ago. Temperature here at the office peaked at 72.5 degrees
and is now down to 62.6 at 130PM. We have been seeing these
drastic temperature drops from upstream reporting stations as
well. Getting some convection going across southern Albany County
ahead of the front as well as out in the Panhandle. Areas behind
the front from Shirley Basin to Wheatland to Agate are reporting
rain showers. Thinking extreme southeast Wyoming is being shadowed
some from the Laramie Range with the northwest winds. Will hold
off lowering PoPs here at Cheyenne and across the southern
panhandle until the last possible minute before sending out

Precip ends quickly early this evening as the front continues to
plow to the southeast. Skies are going to clear out pretty quickly
after sunset, setting us up for a fairly cold night. MOS guidance
continues to show lows at Laramie down near freezing on both the
MAV and NAM with clearing skies and light winds. Will continue the
Frost Advisory for areas west of the Laramie Range tonight.

Quick rebound on temperatures Saturday as 700mb temperatures climb
from +2 to +4C this afternoon +8 to +10C Saturday afternoon. Low
to mid 70s look to be the norm for highs.

Critical fire weather conditions return Sunday as 700mb winds
begin picking up and afternoon highs climb to the 80s at most
locations. GFS soundings for Sunday showing 20kts at 700mbs Sunday
afternoon. Afternoon humidities across Converse and Carbon
Counties 12-15 percent. Think we may just be below conditions on
winds, but we will need to continue monitoring these winds. If
they pick up another few knots, we will probably need fire
weather headlines for Sunday.

.LONG TERM...(Monday through Friday)
Issued at 217 PM MDT Fri Aug 19 2016

Weak upper level ridging to our west going into early next week
will likely result in dry and warm conditions Monday. It could be
rather breezy again on Monday afternoon as a surface low is
progged to deepen over Montana ahead of the next upper level
system thus raising fire weather concerns (see fire weather
section of this discussion). By Tuesday we start to see some
return moisture in the southerly flow across the Sierra Madre,
Snowy and southern Laramie Range, and continued previous forecast
trend of chance PoPs in higher elevations Tuesday through midweek.


.AVIATION...(For the 06Z TAFS through 06Z Saturday evening)
Issued at 1112 PM MDT Fri Aug 19 2016

VFR expected overall for all terminals this period.  There is the
possibility for some fog and low clouds mainly over the Laramie
Valley early in the morning with associated IFR conditions.


Issued at 217 PM MDT Fri Aug 19 2016

Strong cold front making its way into southern Wyoming and the
southern Nebraska Panhandle this afternoon. Winds shifting to the
north and northeast behind the front with gusts to 35-40MPH. Some
wetting rains being observed behind the front and do expect most
locations to see scattered showers through the afternoon. Minimal
fire weather concerns through Saturday with the colder air.
Elevated fire weather conditions return Sunday as front moves off
to the southeast and dry westerly wins return. Could see critical
fire weather conditions Monday and possibly Tuesday as winds
increase. Monday looks to be the worst day at this time with gusts
to 35 MPH and afternoon humidities well below 15 percent.


.CYS Watches/Warnings/Advisories...
WY...Frost Advisory from midnight tonight to 9 AM MDT Saturday for



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