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000
FXUS65 KCYS 112324
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
524 PM MDT Thu Apr 11 2024

.KEY MESSAGES...

- Above normal temperatures expected across much of the region
  Friday and through the weekend. Afternoon highs in the 70s can
  be expected east of the Laramie Range and into the Nebraska
  Panhandle.

- Elevated to locally critical fire weather conditions possible
  both Friday and Saturday afternoon across the CWA.

- Potential for a storm system to impact the region next week,
  but confidence on any expected impacts are low at this time.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 122 PM MDT Thu Apr 11 2024

Very nice conditions outside this afternoon with 1PM
temperatures in the low to mid 50s. Satellite imagery showing
clear to mostly clear skies with radar PPINE at this time. Area
under the influence of surface high pressure with an upper ridge
building across Utah...Idaho and western Montana. Current 700mb
temperatures range from 0C across Carbon County to -6C over the
northern Nebraska Panhandle.

Upper ridge continues to build and move slowly eastward Friday.
Ridge axis looks to be over western Wyoming Friday morning.
700mb temperatures climb to +2C Friday morning and +4 to +6C
Friday afternoon. As a result...afternoon highs are expected to
be quite warm with upper 70s across the Panhandle to low to mid
70s east of the Laramie Range and upper 60s west.

Concerns for Friday look to be very low afternoon humidity with
these warmer temperatures. Fortunately...winds are expected to
be light from the Laramie Range east into the Panhandle. Area of
concern would be for our western fire weather
zones...especially near Rawlins...which could briefly hit Red
Flag conditions. Held off on any fire headlines as Red Flag
conditions (RH less than 15 percent and 25 mph gusts)...looks to
be short lived and only maybe 2 hours in length. Will let the
evening and mid crew take another look before issuing any fire
weather headlines.

Another warm day Saturday with 700mb temperatures still around
+4 to +6C. Similar high temperatures expected as what we see on
Friday. More widespread critical afternoon humidity expected
Saturday afternoon. May need fire weather headlines for Saturday
afternoon as 800/850mb wins out of the northwest 20-25mph across
the Panhandle.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 335 AM MDT Thu Apr 11 2024

After a warm weekend, the weather pattern next week will
gradually trend cooler and more unsettled.

A vigorous closed low will dive towards the California coast this
weekend and start to inch eastward on Sunday. Downstream
amplification of the ridge over the central Plains in advance of
this system is expected to lead to further warm air advection on
Sunday. Ensemble mean 700-mb temperatures jump to around +8C near
Cheyenne by Sunday late afternoon, supporting another day of highs
some 10-20F warmer than average. Many locations in the Nebraska
panhandle will get another shot at 80F, if this wasn`t already hit
on Friday or Saturday, but this should be the warmest day of this
warm spell. Breezy conditions Sunday may also lead to increased fire
weather concerns with low afternoon RH expected. The closed low then
ejects east of the Rockies late on Monday or early Tuesday, and
brings the warm spell to an end. Monday`s highs will depend on the
timing of the front, but most guidance has trended slower, which
would give us one more day of above normal temperatures Monday, but
still about 10F cooler than Sunday. Over the last 24 hours, models
have trended towards a solution that keeps the initial shortwave
more progressive and open, which inhibits effective wrap-around
precipitation Monday night into Tuesday. While scattered rain and
snow showers driven by frontogenesis still look like a good bet, the
widespread stratiform precipitation scenario shown by the ECMWF
ensemble yesterday at this time is looking less likely. Despite the
more progressive nature, models are still showing a potent surface
low winding up over the High Plains and quickly ejecting to the
northeast. This leads to a period of gusty northwest winds Monday
night into Tuesday across the area. This doesn`t look nearly as
strong as last weekend`s wind event, but there is certainly
potential for another round of High Wind Warnings. Ensemble median
700-mb wind speeds are around 40 to 45 knots over Cheyenne, but
there are a few outliers showing a more potent event. Regardless,
looks cooler and breezy Tuesday with a few rain/snow showers around.

This first system will move off to the east quickly, but another
trough will sink into the northern Rockies on Tuesday into
Wednesday. This northern branch disturbance will be considerably
colder than the first, but the dynamics and precipitation potential
remain fairly uncertain. Ensembles are split between showing a more
progressive trough vs. stalling the trough and associated frontal
boundary over the area for a few days. The cluster showing the most
progressive solution still leads to fairly widespread QPF on
Wednesday but dries the area out quickly by Thursday. The more
stalled scenarios keep precipitation chances around for Thursday and
even longer. There is better confidence in temperatures returning to
below normal values for Wednesday and Thursday. While there is still
quite a bit of model spread, ensemble median 700-mb temperatures
plummet to -10C by Thursday, which is around the climatological 10th
percentile.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 521 PM MDT Thu Apr 11 2024

A ridge aloft will build across the terminals overnight and on
Friday, with the flow aloft turning from northwest to west.

Clear skies will prevail. Winds will gust from 22 to 28 knots
until 02Z at Rawlins, Laramie, Cheyenne and Alliance, then from
20 to 27 knots at the Wyoming terminals after 15Z Friday.

&&

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

&&

$$

SHORT TERM...GCC
LONG TERM...MN
AVIATION...RUBIN