Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 181129
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
529 AM MDT Thu Apr 18 2019

.SHORT TERM...(Today through Saturday)
Issued at 218 AM MDT Thu Apr 18 2019

Today...Rather strong north flow aloft prevails and with adequate
low and mid level gradients, it will be windy along and east of
Interstate 25. Fairly dry low and mid levels suggests a dry day.
Seasonably mild temperatures again based on projected 700 mb
temperatures.

Tonight...A quiet night with surface lee troughing developing.

Friday...Ridging aloft moves overhead as the flow aloft becomes west
northwest, inducing strengthening surface lee troughing and
producing a warmer day with 700 mb temperatures near 6 Celsius
yielding maximum temperatures from the upper 60s to middle 70s.

Friday night...Even more mild overnight with decent low level mixing
and a warmer than normal airmass in place.

Saturday...West flow aloft prevails with a surface cold front
dipping southward into our northern counties in the afternoon,
producing slightly cooler temperatures there. Looks like enough low
and mid level moisture for isolated afternoon showers and
thunderstorms primarily over and near the mountains.

.LONG TERM...(Saturday night through Wednesday)
Issued at 218 AM MDT Thu Apr 18 2019

A rapid transition to a cooler & more unsettled weather pattern is
likely early in the extended forecast period. The GFS & ECM are in
good agreement with H7 temperatures plunging from approximately +5
to +10 deg C on Saturday afternoon to only -2 to -5 deg C 24 hours
later around mid-day Sunday. The rapidly cooling profiles, coupled
with more extensive cloud cover suggests highs Sunday may be up to
20-25 degrees cooler than Saturday, possibly struggling to get out
of the 40s in some areas. It does appear a fairly significant mid-
level short wave will impact the area during the Saturday night to
early Monday time frame. Jet energy will be lackluster, but larger
scale forcing along w/ near-surface upslope flow will help support
widespread rain & snow. There is potential for minor accumulations
of snowfall at elevations above 6000 feet on Sun/Sun night, but do
not expect much for impacts at this time. Yet another trend toward
warmer/drier conditions through Wednesday with upper-level ridging
building in.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 520 AM MDT Thu Apr 18 2019

VFR prevails. Isolated to widely scattered rain/snow showers could
affect southeast Wyoming and western Nebraska terminals during the
morning hours, w/ activity gradually diminishing by afternoon over
much of the area. Heavier showers may be accompanied by brief MVFR
ceilings & visibilities, but low confidence precludes mention with
this TAF package. Otherwise, strong and gusty northwest winds will
occur from late this AM through this afternoon across a large part
of the region. Widespread wind gusts in excess of 30-40 knots will
be likely. Winds should decrease after about 0 to 3z this evening.

&&

.FIRE WEATHER...
Issued at 218 AM MDT Thu Apr 18 2019

Minimal concerns based on expected winds and humidities.

&&

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

$$

SHORT TERM...RUBIN
LONG TERM...CLH
AVIATION...CLH
FIRE WEATHER...RUBIN


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