600
FXUS65 KCYS 272100
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
300 PM MDT Mon May 27 2024

.KEY MESSAGES...

- Potential for some dry thunderstorms capable of producing strong,
  and sudden wind gusts possible across the I-80 corridor tomorrow
  afternoon.


- Chances for an active weather pattern with organized strong to
  potentially severe afternoon thunderstorms possible Wednesday
  afternoon/evening and possibly again on Thursday.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 208 PM MDT Mon May 27 2024

Not much to write about in the short term forecast period as the
weather conditions will be quiet and dry today and again tomorrow.
Much of the region today is under a modest NW flow aloft with
surface temperatures climbing into the 70s across much of the
region. Visible satellite just shows some fair weather cumulus
clouds beginning to develop across the region this afternoon.
Temperatures will warm a few more degrees through the afternoon
hours under mostly sunny skies.

Another warm day is on tap for tomorrow as an upper level ridge
builds into the region allowing for warmer 700mb temperatures to
advect into the region. Could be a weak disturbance embedded in the
mean flow coming through Tuesday afternoon underneath the main ridge
axis and this feature could be strong enough to help initiate some
isolated thunderstorms across the I-80 in SE Wyoming by the late
afternoon hours. Atmospheric parameters show minimal CAPE and shear
available, but storms that do develop will be high based with a
decently dry sub cloud layer yielding some 1000 J/kg of DCAPE which
poses an increasing microburst type wind threat with storms that
manage to develop.

Additionally these storms may be the dry thunderstorm variety which
may pose a locally fire weather concern. Outside of that much of the
region should see warming temperatures and a continuation of dry and
quiet weather.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 208 PM MDT Mon May 27 2024

Wednesday afternoon appears to be one of our most active weather
days this week in response to a shortwave moving through the
northern Rockies. This should allow for a good moisture feed
mainly east of the Laramie range where dewpoints could pool in
the 50s which may yield surface based cape values into the
2000-2500j/kg Wednesday afternoon/evening. The National Blend
of Models is showing lower probabilistic values since it leaning
towards the drier Global solutions. For now, we are favoring the
mesoscale NAMNEST which shows more support towards the higher
dewpoints. The main question will be the lifting mechanism.
Deterministic models are showing some signs of potential
vorticity moving through the area with upper level diffluence.
However, not seeing as much influence from the upper level jet.
Therefore, most of these storms could end up being more induced
along the sudo dry line or orographics. Either way, if we do see
a few storms develop along the Laramie Range, they stand a
pretty good shot of becoming strong to severe east of the I-25
corridor, due to the combination of high thetae air and 30 to
40kts of effective shear.

The models are projecting the frontal boundary and another
stronger shortwave moving through the forecast are on Thursday.
The main question is whether there will be enough moisture recovery
from the previous night`s convection. For now, the latest
GFS/ECMWF are showing the bulk of the convection developing east
of the Nebraska panhandle. Another concern is the potential for
gusty winds developing behind the front Thursday over areas
west of the Laramie Range. This could set the stage for
potential wind headlines near Arlington Thursday, but it should
be rather shortlived especially if the subsidence is rather
minimal. Otherwise, cannot rule out a few isolated showers and
thunderstorms unless the moisture does not scour out from the
previous day.

Friday-Monday:
The WPC clusters are showing the upper level flow transitioning
to a more flatter regime as we head into the weekend. Meanwhile,
the GFS is still the outlier in showing a deep upper level trof
developing over the area. If the GFS pans out we could end up
with much cooler temperatures with continued chance of showers
and thunderstorms. At this point, we are leaning towards the
ensembles which is favoring mild temperatures with scattered
showers and thunderstorms mainly in the Nebraska panhandle on
Friday and isolated showers and thunderstorms this weekend into
early next week.


&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 515 AM MDT Mon May 27 2024

A quiet TAF period is expected as a ridge of high pressure builds
over the region. Mostly sunny skies and diurnal wind gusts up to 25
kts are expected this afternoon. Winds will ease this evening with
mostly clear skies continuing overnight.

&&

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

&&

$$

SHORT TERM...AW
LONG TERM...REC
AVIATION...SF