textproduct: Cheyenne

KEY MESSAGES

- Scattered showers and thunderstorms through late Tuesday evening will bring the potential for strong, gusty, and erratic winds.

- A few more organized strong to severe storms are possible in the central and southern Nebraska panhandle through Tuesday night.

- Elevated fire weather conditions will continue for the week ahead with warm and dry weather expected and daily chances for PM thunderstorms or gusty showers.

- A warming trend will occur for Thursday and Friday, before somewhat cooler temperatures occur for our bisesquicentennial, the 250th anniversary of our country on Independence Day, then a slow warming trend develops again for Sunday through Tuesday.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 300 PM MDT Tue Jun 30 2026

Warm, dry, and breezy conditions continue today across the area, but fortunately, winds are much lighter than they were yesterday. Still, near critical fire weather conditions are ongoing as another, weaker, upper level shortwave approaches the area. This is apparent on GOES satellite imagery over northeast Utah. As the upper level feature lifts northward, a stalled convergence/frontal boundary over our area is slowly lifting northward as well. This is currently located roughly from Medicine Bow Peak up towards Wheatland and eventually the southwest corner of South Dakota. Low-level convergence along the boundary is supporting the development of some cumulus cloud activity and a few pulsey showers showing up on radar. Instability is minimal right now, so these are not lasting very long, but we should see longevity of this activity improve after about 4PM or so as synoptic lift ahead of the approaching shortwave and upper level moisture improve.

Meanwhile, the approaching upper level disturbance is supporting lee cyclogenesis over the Denver area this afternoon. As this moves off to the northeast and strengthens, potent frontogenesis will develop over northeast Colorado extending up into far southeast Wyoming and the central/southern Nebraska panhandle. Positive moisture advection in this same area will also build elevated instability. So, expect these two areas (the convergence boundary, and the frontogenesis) to be the primary zones of focus for shower and thunderstorm activity this evening but a few will probably filter through in between. At least initially, the dry surface environment will mean that the primary hazard will be dry microbursts. Expect the coverage of gusty and erratic winds to be significantly greater than the coverage of appreciable rainfall. While these won't technically be dry thunderstorms, there will be areas exposed to winds and lightning with little to no rainfall. Confidence is pretty high in gusty and erratic winds this evening, but lower in the more organized severe thunderstorm potential. The second area of forcing in the southern Nebraska panhandle will see increasing moisture and instability this evening. Therefore, additional rounds of showers and thunderstorms will be more likely to become strong to severe later in the evening. However, this remains a fairly conditional threat. RAP forecast soundings for Sidney show a fairly dry boundary layer until about 9PM, after which time, severe thunderstorm parameters climb rapidly. However, dry air aloft and weakening forcing will begin to move into the area as early as 12AM-1AM, so the window is fairly short. Isolated large hail and locally heavy rainfall will be possible if a storm manages to develop in this environment.

Wednesday will start off with clear skies as tonight's vort-max moves off to the northeast. The area will remain in southwest flow aloft, and highs tomorrow are expected to be fairly close to their values today. Synoptic wind is expected to be overall lighter tomorrow, but gusty westerlies are still expected mainly in the morning to early afternoon. Winds will die down later as humidity drops, so confidence in critical fire weather conditions is lower tomorrow. We will have another round of potential gusty showers or storms in the afternoon and evening, but coverage will be lower than today due to weaker forcing aloft.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 300 PM MDT Tue Jun 30 2026

Thursday...The Storm Prediction Center in Norman, Oklahoma at spc.noaa.gov, forecasts a marginal risk of severe thunderstorms in the afternoon and evening, for our northeast counties in our county warning area, north of a Sheridan to Scottsbluff line. Concur with their assessment as a shortwave trough aloft passes near the Wyoming and Colorado state line at peak heating, with a north to south oriented surface boundary or dryline stretching across southeast Wyoming. Although bulk shear values at 00Z will be limited, near 30 knots, CAPE progged to be some 2500 to 3600 J/kg across western Nebraska. Quite impressive 850/700 mb theta-e ridge axis will extend across western Nebraska at late afternoon with dewpoints in the mid to upper 50s. Thus isolated to widely scattered thunderstorms, some strong to severe, look increasingly likely in the aforementioned marginal risk area. A warming trend ensues with 700 mb temperatures near 18 Celsius.

Friday...Although another weak perturbation, or shortwave trough, will lie across western Nebraska in the late afternoon, with adequate low and mid level moisture, the 850/700 mb theta-e ridge axis will be a bit further east compared to Thursday, though we will need to watch for decent low level convergence across the eastern row of counties in the Nebraska Panhandle for isolated strong to possibly severe thunderstorms. With less cloud cover compared to Thursday, the warming trend will continue.

Independence Day...The flow aloft remains westerly, and with decent moisture in the 850-500 mb layer, and individual layers, combined with low level convergence east of I-25, we anticipate seeing isolated to widely scattered afternoon and evening thunderstorms east of I-25 in the afternoon, and over western Nebraska in the evening. All in all, the 250th anniversary of our country should see quite pleasant weather conditions across southeast Wyoming and western Nebraska, with minimal late day showers and thunderstorms, near perfect for outdoor activities. Somewhat cooler for the holiday due to more cloud cover and in a post cold frontal airmass, with maximum temperatures in the 80s, near perfect for the bisesquicentennial, 250th anniversary of our country's birth.

Sunday...With warm temperatures aloft, the CIN, convective inhibition, will increase markedly with 700 mb temperatures near 18 Celsius, limiting convective potential, and allowing for at best, isolated to widely scattered afternoon and evening thunderstorms along and east of I-25. Another warming trend begins based on 700 mb temperature trends.

Monday and Tuesday...Similar synoptic pattern to Sunday, with decent southerly low level moisture advecting northward into our counties, especially east of I-25, though warm temperature aloft will produce enough convective inhibition, CIN, to limit afternoon and evening thunderstorms to isolated to widely scattered. Temperatures will continue their warming trend based on 700 mb temperatures and the paucity, limited amount, of cloud cover.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1045 PM MDT Tue Jun 30 2026

Showers and thunderstorms are moving out of the CWA, VFR conditions will make a return and prevail across all terminals for the duration of this TAF period. Winds for the remainder of the night should remain generally less than 10 knots. For the southeast Wyoming terminals, winds will briefly pick back up by 18Z with westerly gusts to around 20 knots. This is short-lived as winds will wind back down to less than 10 knots after 00Z Thursday.

CYS WATCHES/WARNINGS/ADVISORIES

WY...None. NE...None.