Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 232322

Area Forecast Discussion
National Weather Service Cheyenne WY
522 PM MDT Mon Oct 23 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 235 PM MDT Mon Oct 23 2017

Gusty northwest winds were prevalent over much of the area this
afternoon, due to a fairly tight pressure gradient in between the
upper level ridge along the west coast and a fast moving upper
level trof moving through the northern Plains. This upper level
ridge is expected to build over the region during the next couple
of days and result in milder conditions. The wind speeds should
also be a bit lighter tomorrow compared to today along with more
downslope flow. Wednesday is expected to turn much warmer with
afternoon highs climbing to the 60s and 70s. The Scottsbluff and
Torrington areas may even reach 80. Although, wind speeds will be
on the increase especially over the gap areas of Bordeaux and
Arlington where they may see gusts over 50 mph. These areas may
need wind highlights on Wednesday since this appears to be like a
good setup with the height/pressure gradients tightening.

.LONG TERM...(Wednesday night through Monday)
Issued at 235 PM MDT Mon Oct 23 2017

A powerful Canadian front is expected to dive south through the
area Wednesday night into Thursday morning. This front will most
likely not have a lot of moisture with it. However, we are
concerned about the potential for banded snowfall right behind the
frontal boundary due to the potential of steep low level lapse
rates, plenty of low level moisture and strong low level
frontogenesis. We are not expecting much in the way of
significant accumulations, but we are bit concerned about low
visibility and high snowfall rates for a 1 to 3 hour period which
may result in slick roads over the I-80 summit...Laramie and
Arlington. Much colder air will also occur which will allow for
temperatures to tumble during the course of the morning. A slow
warm-up is expected to commence as we head into the weekend, but
we may see an artic front surge through the area again early next


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 520 PM MDT Mon Oct 23 2017

VFR with mostly clear skies. Gusty N-NW winds 25-35 kt will diminish
early this evening, but remain breezy at KSNY and KAIA tonight.
Elsewhere, wind speeds will decrease to 8-15 kt. NW winds will
increase once again mid-late Tuesday morning with gusts to around 30
kt east of the Laramie Range, and 20-25 kt to the west.


Issued at 235 PM MDT Mon Oct 23 2017

A weak upper level ridge is expected to build over the area during
the next couple of days. This will result in diminishing wind
speeds tonight, but deep mixing will prevail on Tuesday and
result in more gusty northwest winds. Although, the wind speeds on
Tuesday should be lighter than this afternoon. Wind speeds are
expected to increase again on Tuesday night into Wednesday as a
upper level disturbance moves into the northern Rockies. Afternoon
relative humidity values are also expected to drop off to 10 to 15
percent on Wednesday ahead of that strong disturbance, and will
most likely result in elevated-critical fire weather conditions.




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