Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 220837
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
237 AM MDT Sun Oct 22 2017

.SHORT TERM...(Today through Tuesday)
Issued at 230 AM MDT Sun Oct 22 2017

Clear to partly cloudy and windy conditions the story in the
immediate short term. Currently seeing gusts as high as 76 mph at
Arlington and winds should continue to increase in the other wind
prone areas such as Bordeaux and the South Laramie Range through
the remainder of the night. Kept wind headlines in place for the
adjacent plains for Sunday as well. Forecast soundings continue to
show mixing potential up to around 5 kft which should be enough
to tap into the 50 to 60kt flow around 700 to 750 mb during the
late morning into afternoon hours. Low level CAG-CPR gradients
peak around 74 meters by Sunday afternoon so would not be
surprised to see a gust or two as high as 80 mph near
Arlington/Bordeaux today.

Latest GFS/NAM keep the gradients over 60 meters until late
tonight and 700 mb winds remain near 65kt over the South Laramie
Range through midnight. Thought it prudent to extend the timing of
the warning through 4 AM Monday morning for at least the wind
prone areas.

Upper jet becomes more amplified on Monday as ridging begins to
build along the west coast. This will drive a surface cold front
southward through the plains on Monday morning, turning the winds
more northwesterly. While the winds along and west of I-25 will
decrease a bit on Monday with the weaker gradient and less
favorable direction, am a bit concerned about high wind potential
for the eastern Nebraska Panhandle. Forecast soundings are quite
impressive, showing deep mixing developing in the afternoon
underneath a strong mid/upper jet. Feel guidance may not be
handling the potential for stronger gusts over the Panhandle very
well and so increased winds here Monday afternoon. For now, kept
gusts just below high wind criteria but later shifts will need to
monitor the potential for wind headlines there Monday afternoon.
A few weak showers may accompany the front but most areas will
remain dry.

.LONG TERM...(Tuesday night through Saturday)
Issued at 230 AM MDT Sun Oct 22 2017

Winds and precip chances are the challenges in the long term.

Starting off Tuesday night, we will be in northwest flow which
will shift more westerly Wednesday. Initially fairly light, they
do begin increasing Wednesday afternoon. By 00Z Thursday, GFS
700mb winds over 50kts across Albany County, so winds at Arlington
could be approaching warning levels again. Did go higher than
guidance on winds for Arlington and the wind prone areas for
Wednesday afternoon and evening.

Front begins to move into our western and northern zones Thursday
morning with fairly widespread precip breaking out behind the
front. 700mb temperatures -5C behind the front Thursday morning
and continue decreasing to -11C by 00Z Friday. All precip should
fall as snow Thursday. Getting several inches of snow across
Carbon and Albany Counties Thursday, so a winter headline will
likely be needed for these areas. 700mb winds pretty strong out
there as well with GFS advertising 35-40kts. Good news is the
front moves through rather quickly, so heavy snow is probably not
likely.

Cold, raw day for Friday with 700mb temperatures -13 to -16C. Am
probably too warm on highs Friday and we will likely to lower
these temperatures more if the current solution holds true in
upcoming model runs.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1108 PM MDT Sat Oct 21 2017

Windy conditions for southeast Wyoming airports the next 24
hours. Mainly a west to southwest direction and could see gusts to
50kts at KLAR and KDGW. Will continue monitoring. VFR skies and
visibilities all southeast Wyoming and Nebraska Panhandle
airports.

&&

.FIRE WEATHER...
Issued at 140 AM MDT Sun Oct 22 2017

Afternoon RH values will remain around 20 percent over the plains
through Monday afternoon. Elevated fire weather conditions are
likely in the Wyoming/Nebraska plains on Monday afternoon, but
cooler temperatures should limit RH values from dropping to
critical levels. Continued dry conditions through at least
Wednesday but significant fire weather concerns not expected at
this time.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 4 AM MDT Monday morning for
     WYZ106-110-116- 117.

     High Wind Warning from 9 AM this morning to 6 PM MDT this
     evening for WYZ101-107-109-115-118.

NE...None.
&&

$$

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


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