Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 160045

Area Forecast Discussion
National Weather Service Cheyenne WY
545 PM MST Wed Feb 15 2017

Issued at 542 PM MST Wed Feb 15 2017

Will allow the High Wind Warning for Bordeaux to expire this
evening. Winds peaked at 57 MPH a few hours ago and have started
to ease a bit early this evening. However...llvl gradients remain
high through the night so it will remain pretty windy with
sustained winds around 35 to 40 MPH at times.


.SHORT TERM...(Tonight - Friday Night)
Issued at 228 PM MST Wed Feb 15 2017

A High Wind Warning remains in effect for the BRX area through 01z
this evening. WYDOT observations have shown sustained winds AOA 40
MPH for much of the day, due to a strong surface pressure gradient
along the spine of the Laramie Range. The ARL-BRX MSLP gradient is
currently around 4 mb and is progged to remain at these levels for
another 24 to 36 hours with the H85 CAG-CPR gradient hovering near
50 meters. Although winds aloft are only around 40 knots, there is
potential for high sustained winds to continue tonight so the next
shift will want to consider extending the warning or possibly even
issue a High Wind Watch for Thu/Thu night. The mesoscale setup for
Thursday will be similar to what is currently in place. There will
be a better chance for strong wind gusts on Thursday night as wind
aloft increases markedly to near 50 kts at H75-H8 in response to a
strong potent disturbance moving across northern Wyoming on Thu PM
and Fri AM. This may also impact parts of the S. Laramie Range. It
will be very warm on Thursday with the models in good agreement w/
H7 temperatures of +6 to +8 deg C, and plenty of sunshine w/strong
subsidence beneath a large upper-level ridge. Many areas will most
likely see highs at least in the upper 60s, if not 70s along and E
of I25. This will certainly result in very low RH values, and some
fire weather concerns although fuels are not critical. There could
be some light mountain snow late in the period on Fri/Fri night w/
the return of active southwesterly flow aloft.

.LONG TERM...(Saturday - Wednesday)
Issued at 228 PM MST Wed Feb 15 2017

The models continue to show the weather over the weekend being very
nice with generally light south to southwesterly sfc winds and highs
around 15 degrees above normal.  A shortwave is progged to move over
WY on Sunday night into Monday.  With good Pacific moisture
streaming into the area and weak orographics, there will likely be a
brief period of light snow across the Sierra Madre and Snowy Ranges.
Breezy to windy conditions and slightly cooler temps will occur on
Monday, however gradients do not look strong enough to support high
winds at this time.  High temps will be back up into the mid 50s to
60s on Tuesday under strong zonal flow aloft.


.AVIATION...(For the 00Z TAFS through Thursday afternoon)

VFR conditions will continue tonight with some high clouds at times.
West winds will gust to 20-25 kts through the evening...mainly
across the southeast Wyoming terminals.  These winds may linger
through midnight at KRWL and KCYS.


Issued at 236 AM MST Wed Feb 15 2017
Edited at 228 PM MST Wed Feb 15 2017

Elevated fire weather conditions continue this afternoon with many
areas across the high plains of southeast Wyoming seeing RH values
as low as 10 percent, along with gusty winds. Warmer temperatures
Thursday with more widespread low humidities. Wind gusts of 25 to
35 MPH will create another elevated fire weather day. Grass fires,
if started will spread rapidly under these conditions. Cool down
begins Friday with afternoon humidities back above critical.





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