textproduct: Cheyenne

KEY MESSAGES

- Unsettled weather returns to the area today, with chances for showers and thunderstorms this evening through at least Tuesday.

- A cooling trend begins Monday with near or slightly below average temperatures expected mid-week. Another warming trend will resume for the end of the week.

SHORT TERM /THROUGH TUESDAY/

Issued at 220 PM MDT Sun Sep 27 2026

Most of our area is enjoying a pleasant day so far with temperatures surging above seasonal averages for most of the area. A backdoor surface front slowly moving into our High Plains zones from the northeast has resulted in a stubborn low cloud deck pushing into the northern Nebraska panhandle, and thus holding temperatures down in the 60s. This airmass has plenty of moisture associated with it, while the surface remains quite a bit drier southwest of the boundary, which is parked somewhere around the North Platte River. Meanwhile, GOES water vapor imagery shows a sprawling upper level low moving into the Pacific coast, with southwest flow ahead pushing abundant tropical moisture northward into our area. The approaching trough will split in the coming days, with the northern shortwave passing quickly to our north, while the southern shortwave closes off and slowly migrates eastward. These features will keep unsettled weather over the area for the next several days.

For this afternoon and evening, we can expect widely scattered showers and isolated thunderstorms to kick up shortly, but coverage looks fairly limited due to weak forcing. We have some minimal instability west of the surface boundary, while those to the east have a robust cap in place. Still, we can expect shower activity to continue well into the evening and possibly into Monday morning. Due to the influx of moisture, this activity will have the potential to produce brief heavy downpours. In addition, the low-level jet will kick up over the High Plains tonight with widespread gusty southerly winds expected into Monday morning. This may be able to support greater wind shear and thus an isolated strong to severe thunderstorm overnight.

A cool front will very slowly move across the area Monday. Partial sunshine in the morning will give way to a mostly cloudy afternoon. As a result, expect temperatures to be cooler than today, but still a touch above seasonal averages. Widely scattered shower activity will be present even in the morning hours, but expect coverage to increase after midday. A more potent surge of tropical moisture will push in along with more organized forcing in the form of potent positive mid-level theta-e advection ahead of the closed low in the desert southwest. PoPs remain in the 30-60% range Monday and Monday night, with scattered to possibly numerous showers and isolated thunderstorms expected. If we can get enough sunshine Monday morning to destabilize, there may be potential for a storm or two to become strong to severe, but confidence is low. Shower activity will once again continue all through the night as the surface front moves through. Tuesday will be cooler, with thick cloud cover in the southern part of the area, while sunshine works in north of Rawlins to Chadron. While global models remain unimpressive with any precipitation potential into Tuesday, a few Hi-res models (particularly the HRRR) continue to show fairly widespread shower activity continuing into Tuesday. This appears to be driven by northeast upslope / isentropic ascent winds below 600-mb, but this signal appears highly disorganized, and thus low confidence.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

Issued at 220 PM MDT Sun Sep 27 2026

Tuesday night through the end of the work week could see a few areas of showers trying to lift up into the region, but this remains largely uncertain and low confidence as models remain split on the evolution of low pressure to our south and how far north moisture can make it. While some ensembles have begun to push the low and moisture associated with what will be the remnants of Hurricane Polo further northwards compared to the last few runs, overall this system still looks to be too far south to bring any further appreciable moisture to our area beyond Tuesday outside of maybe our farthest southeast zones, primarily Cheyenne County in the Nebraska Panhandle. The NBM continues to keep us high dry as well, with the above scenario remaining in the grids as of this writing. Still through Thursday POP chances aren't completely zero, but outside of the I-80 corridor and southward it's not looking favorable for any meaningful moisture in the long term. Otherwise we'll see a very slight warming trend on Wednesday, with temperatures warming a few degrees with widespread 60's and a few 70's expected, but a second cold airmass should drop us right back down into the widespread 60's on Thursday. Friday and Saturday high pressure over the southwestern US will allow for a warming and drying trend, returning us to several degrees above normal with highs in the 70's across the region. Sunday flow turns more northwesterly and a glancing upper level trough will help push a weak cold front into the region, bringing temperatures back down to near normal, but a lack of notable moisture will keep our precipitation chances almost nil and provide little more than a brief cool down to end the long term forecast.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1143 AM MDT Sun Sep 27 2026

A mix of flight categories expected over the next 24 hours. Low clouds remain near KCDR this morning, and should lift over the next hour or two but expect MVFR conditions at least through the afternoon. Tonight showers and storms lift up across the region with a chance of precipitation for all sites. Any storms could bring locally lowered VIS. Overall CIGs will be generally mid level as precipitation moves in, but will lower tonight into tomorrow morning as an influx of moisture overspreads into the region. Winds pickup this afternoon and through the overnight hours, remaining strongest at Nebraska sites. Overall gusts will be around 20-30 knots, with winds turning to out of the south.

CYS WATCHES/WARNINGS/ADVISORIES

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