Severe Thunderstorm Warning 11, NWS Cheyenne, WY

Area Forecast Discussion
National Weather Service Cheyenne WY
Issued by National Weather Service Riverton WY
332 PM MDT Wed May 14 2025

.KEY MESSAGES...

- Scattered thunderstorms this afternoon and evening with the
  potential for severe thunderstorms in the Nebraska Panhandle.

- Very windy conditions expected for most of southeast Wyoming
  and portions of western Nebraska on Thursday. Gusts over 50
  mph possible.

- Active weather pattern creates daily precipitation chances in
  the afternoon and evening into the beginning of next week.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 113 PM MDT Wed May 14 2025

An upper level trough will be passing through the Intermountain
West today to give us some chances for some widespread showers
and chances for scattered thunderstorms in the afternoon. HI-Res
guidance shows showers in the late morning to the early
afternoon for our mountainous regions west of I-25. Later in the
afternoon for areas east of I-25 thunderstorms look to develop
around 2pm and push eastward into the late evening. Temperatures
have cooled down compared to yesterday allowing for the lower
levels to saturate easier which any precipitation will be able
to hit the ground. However, this morning and currently satellite
shows low level clouds dissipating over the Nebraska Panhandle.
These clouds may inhibit some of the severe potential despite
SPC placing a marginal risk (level 1 out of 5) risk for severe
t-storms will hail and winds as the main threats. The 12z model
guidance places MUCAPE between 400 to 600 joules across the
eastern portion of the Nebraska Panhandle with a bulk shear
between 35 to 45kts of shear. This is a sufficient amount of
CAPE and shear to sustain thunderstorms and possibly produce
severe thunderstorms. The most favorable area for any severe
storms to develop is the eastern portion of the Panhandle due to
the increased moisture, temperature, and higher CAPE values
with favorable shear. If severe thunderstorms due develop then
Hail sized up to quarters and winds greater than 60 mph can be
expected underneath or near these storms. On a synoptic scale,
The surface low looks to pass through the Intermountain west as
well as jetstreak divergence aiding in the lift generation
needed to make the environment favorable for storm development.
However, some of the HI-res guidance shows a mix of cluster and
QLCS storm modes depending on which model is viewed. This
disagreement in storm modes could signal some messy development
to which the severe thunderstorms may conflict with each other
and end up hindering each storms potential and we end up with
some strong showers and small hail. Given its planting season
the latter scenario of heavy rain and small hail will be more
beneficial to the Nebraska farmers. There is also pretty good
agreement between models with timing being around 20-21z for
initiation east of I-25 and storms being finished or moved out
of the area by 23z. As this trough pushes into the
Central/Northern Plains, there is some chances for isolated to
scattered showers on Thursday. Most of the better forcing and
dynamics will be further east on the front side of this low
however some synoptic support is still there will weak
divergence aloft. So any severe potential is not expected and
the SPC day 2 outlook shows us in the general thunder category
which meets our expectations for any storms that do develop for
tomorrow.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 113 PM MDT Wed May 14 2025

Friday...West northwest flow aloft develops and with 700 mb
temperatures near 5 Celsius, maximum temperatures will be in the
60s. A bit less available moisture, so areal coverage of
showers and thunderstorms will be reduced.

Saturday...The flow aloft turns west southwest, and with a
slight increase in mid level temperatures, high temperatures
will show a warming trend. Still enough low and mid level
moisture for scattered afternoon and evening showers and
thunderstorms.

Sunday...Southwest flow aloft develops in advance of the
approaching shortwave trough. With increasing low and mid level
moisture, and lift generated by a passing shortwave trough
aloft, scattered to numerous showers and scattered thunderstorms
will develop, focused along a low level convergence axis and
surface trough along the Wyoming-Nebraska state line.

Monday...The trough aloft moves into Wyoming. Decent low level
upslope and a moist airmass will lead to scattered to numerous
showers and thunderstorms. Cooler temperatures due to increased
cloud cover and precipitation coverage.

Tuesday...As the trough aloft moves into the Northern Plains
states, northwest flow aloft will develop over our forecast
area, helping to decrease precipitation chances. Warmer
temperatures also expected with a rise in 700 mb temperatures.

Wednesday...Similar conditions to Tuesday with brisk northwest
flow aloft. It looks breezy to windy based on low and mid level
gradients. Temperatures should be a bit warmer than Tuesday
based on 700 mb temperature trends.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 332 PM MDT Wed May 14 2025

High-resolution forecast models remain on track for this
afternoon, with widespread precipitation developing in
southeastern Wyoming. This thunderstorm activity will move
eastward through the evening, bringing winds gusting into the
40 to 50 kt range in the immediate vicinity of storms. Storms
are expected to be strongest near KSNY where instability is the
most pronounced, and large hail is possible in the strongest
storm cells here. Outside of storms, winds will be breezy, with
northwesterly gusts in the 25 to 35 kt range. Expect storm
activity to linger well into the overnight over the Nebraska
panhandle, but after 15/0500z, lightning activity should
decrease markedly, with a few hours of showers afterward before
precipitation moves off to the east.

Shortly after sunrise Thursday, strong mid-atmosphere winds
will mix to the surface bringing widespread gusts in the 30 to
40 kt range. These winds continue through the daylight hours,
with brief isolated afternoon showers popping up in the
afternoon.

&&

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

&&

SHORT TERM...MM
LONG TERM...RUBIN
AVIATION...WFO-RIW

Hazardous Weather Outlook
National Weather Service Cheyenne WY
Issued by National Weather Service Riverton WY
431 AM MDT Wed May 14 2025

NEZ002-003-019>021-054-055-095-096-WYZ101>119-151045-
Dawes County-Box Butte County-Scotts Bluff County-Banner County-
Morrill County-Kimball County-Cheyenne County-
Northern Sioux County-Southern Sioux County-
Converse County Lower Elevations-Niobrara County-
North Laramie Range-Ferris/Seminoe/Shirley Mountains-
Shirley Basin-Central Laramie Range and Southwest Platte County-
East Platte County-Goshen County-Central Carbon County-
North Snowy Range Foothills-Southwest Carbon County-
Sierra Madre Range-Upper North Platte River Basin-Snowy Range-
Laramie Valley-South Laramie Range-South Laramie Range Foothills-
Central Laramie County-East Laramie County-
431 AM MDT Wed May 14 2025

This hazardous weather outlook is for portions of panhandle
Nebraska...east central Wyoming...south central Wyoming and
southeast Wyoming.

.DAY ONE...TODAY AND TONIGHT

Much cooler temperatures are expected behind the cold front
today. Showers and thunderstorms will increase in coverage
this afternoon through this evening. Severe weather is not
expected.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

Very windy conditions are forecast for most of southeast
Wyoming and the higher ridges of the western Nebraska
Panhandle on Thursday. West to northwest winds between 25 to
40 mph are expected with gusts as high as 55 mph at times.
Stronger winds are possible along portions of Interstate 25
and the Interstate 80 Summit.

Slight chance of thunderstorms this weekend. Thunderstorms
will increase in coverage late in the weekend and early
next week.

.Spotter information statement...

Spotter activation will not be needed.

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