Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 252337
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
530 PM MDT Wed Apr 25 2018

.SHORT TERM...(This evening through Friday night)
Issued at 215 PM MDT Wed Apr 25 2018

Tonight...Progressive and positively tilted shortwave trough aloft
moves into northern Wyoming around midnight, then to southern
Wyoming around dawn while its associated cold front enters our
northern counties this evening and exits our southern counties by
sunrise. Looking at low and mid level moisture, as well as the 500-
300 mb and 700-500 mb quasigeostrophic forcing, we expect to see
isolated to scattered showers spread southward, especially after
midnight, roughly north of a Rawlins, to Laramie to Scottsbluff
line. The combination of brisk winds in the post cold frontal
airmass and cloud cover will keep most minimum temperatures above
freezing.

Thursday...Quickly clearing skies anticipated as the fast moving
shortwave trough aloft moves off to the southeast of our counties
with surface high pressure building southward across eastern Wyoming
and western Nebraska. Cooler temperatures behind the cold front,
although still not too cool.

Thursday night...Quiet night as the flow aloft turns north northwest
with clear skies and light winds.

Friday...Decent warming trend expected as ridging aloft moves over
western Wyoming with plenty of sunshine and 700 mb temperatures near
5 Celsius, yielding maximum temperatures from the mid 60s to lower
70s at lower elevations.

Friday night...Definitely not as cold as the ridge aloft moves
overhead and the atmosphere continues to moderate, leading to
minimum temperatures above freezing at lower elevations.

.LONG TERM...(Saturday through Wednesday)
Issued at 215 PM MDT Wed Apr 25 2018

Quite mild across the CWA saturday through Sunday as an upper
ridge slips east of the area leaving southwesterly flow in its
wake. Could see some showers/tstms around the mtns by late
afternoon Saturday as some instability develops and a weak
impulse approaches the area. Somewhat drier Sunday as a surface
trough moves east over the plains leaving warm downslope flow
over much of the CWA. Cooler and unsettled conditions look to set
in for the Monday-Weds time period as upper troughing over the
western CONUS moves towards the area. Should see at least sctd
showers and a few tstms each day as shortwaves move across the
region ahead of the main upper trough with the most widespread
coverage looking to be on Tuesday.

&&

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

VFR conditions will prevail through tonight with light winds ahead
of a cold front.  The cold front will move across the area beginning
late this evening, and across the I-80 corridor around midnight with
increasing clouds and gusty northerly winds behind it. CIGS may
lower to near MVFR over the area late tonight and into Thursday
morning. Any shower activity is expected to be light with only minor
changes in VIS.

&&

.FIRE WEATHER...
Issued at 215 PM MDT Wed Apr 25 2018

Minimal concerns, although humidities will be less than 15
percent Friday afternoon over Carbon County, though fortunately
winds will be light during that period.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&

$$

SHORT TERM...RUBIN
LONG TERM...RE
AVIATION...TJT
FIRE WEATHER...RUBIN



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