Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 282309
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
409 PM MST Sun Feb 28 2021

.SHORT TERM...(This evening through Tuesday night)
Issued at 200 PM MST Sun Feb 28 2021

Upper trough axis extended from the Upper Midwest through the
Central Plains and Four Corners. A upper ridge was building
northward along the Pacific Coast. Skies were mostly sunny with
some passing mid level clouds. Low level mixing and a decent
surface pressure gradient across southeast WY were producing
strong winds along the I-80 corridor between Laramie and Rawlins.
Gusts up to 60 mph were observed at Arlington and 62 mph at County
Road 402. As a result, the start time of the High Wind Warning
was changed to 1 PM this afternoon. Temperatures early this
afternoon ranged from the mid 20s to lower 40s.

Forecast concern will be strong winds affecting the southeast WY
wind-prone areas during the next 24 to 36 hours.

Upper ridge slides east across the Intermountain West and Rockies
Monday. Winds will be subsiding along and west of the Laramie
Range later Monday morning. The next upper level wave to affect
winds will be fast moving Alberta Clipper Monday evening through
Tuesday morning. 40-45 kt flow at 750mb combined with CAG-CPR/CAG-
BRX 850mb gradients between 60 and 90 meters along and west of
the Laramie Range will induce higher wind speeds, especially from
Arlington to Bordeaux. The time period of strong winds will be
between 00Z and 15Z Tuesday, with the likelihood for high wind
headlines issued Monday.

A warming trend will ensue Monday with highs closer to seasonal
normals in the 30s and 40s. Areas east of I-25 can expect highs
in the 50s Tuesday, while west of I-25, afternoon temperatures
will reach the 30s and 40s. No precipitation is forecast through
the short term.

.LONG TERM...(Wednesday through Sunday)
Issued at 200 PM MST Sun Feb 28 2021

A ridge pattern will begin starting Wednesday afternoon with a dry
line forming on the border of southeastern Wyoming and the western
Nebraska Panhandle. Tight gradients, strong negative omega values,
and GFS total wind vectors give forecast confidence into a High
Wind event Tuesday into Wednesday evening. Breezy conditions and
low minimum RH values Wednesday allude to fire weather concerns
across the Nebraska Panhandle although wind gusts trend right below
criteria for now. Spring-like temperatures are possible starting
Wednesday afternoon with highs across the region reaching above 40
degrees.

For Thursday, the uncertainty of the last few GFS runs seem to lead
to an upper level low pushing across the High Plains but keeping any
forms of precipitation south of us. We will continue to monitor this
event of any changes. Overall in the extended, dry, above-average
temperatures, and mild conditions prevail until Monday with the
slight chance of mountain snow occurring in the morning.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday afternoon)
Issued at 409 PM MST Sun Feb 28 2021

VFR prevailing at all terminals through the period.  Some gusty
westerly winds into early this evening with gusts about 25-30 kts,
easing off as the evening progresses.

&&

.FIRE WEATHER...
Issued at 329 AM MST Sun Feb 28 2021

Despite periods of gusty winds, fire weather concerns remain quite
low given recent precipitation and cooler temperatures. Trends are
pointing toward warmer & drier conditions as we head into early to
mid next week, leading to lower afternoon RH values.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 11 AM MST Monday for WYZ106-110.

NE...None.
&&

$$

SHORT TERM...MAJ
LONG TERM...AW
AVIATION...RE
FIRE WEATHER...CLH



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