textproduct: Cheyenne

KEY MESSAGES

- Red Flag Warning in effect for Converse and Niobrara Counties.

- Warming and drying trend expected through the end of the week.

- Precipitation chances return for the beginning of next week.

SHORT TERM /THROUGH FRIDAY/

Issued at 139 PM MDT Thu Sep 3 2026

TonightDry southwest flow aloft prevails with a quiet night on tap and cool overnight minimal to produce good sleeping conditions for opening up windows.

FridayThe main weather story will be the heat, with southwest winds aloft and surface low pressure and a thermal ridge axis over our counties. With 700 mb temperatures near 15 Celsius and downslope winds and little if any cloud cover, maximum temperatures will soar into the mid 80s to near 90 degrees west of I-25, with blistering heat further east of I-25, with maximum temperatures in the 90s, to near 100 degrees over the Nebraska panhandle. Record high temperatures, year and forecast high temperatures for September 4

Rawlins 95/199883 Laramie 89/202284 Cheyenne 94/202290 Chadron 104/1978101 Alliance 101/199896 Scottsbluff 102/199899 Sidney100/199899

Friday nightA weak shortwave trough aloft moves to our southern counties by dawn, spawning isolated to scattered showers near a Cheyenne to Torrington line, otherwise dry and cool.

LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/

Issued at 145 PM MDT Thu Sep 3 2026

Weak southwesterly upper-level flow is anticipated for Saturday with lax pressure gradients between troughing over the Pacific northwest and a ridge to the southeast. The majority of area will be capped through the early afternoon. A weak upper level shortwave would promote a few morning showers and general cloudiness before moving through in the early afternoon. A few showers and thunderstorms may be possible in the mountains and along I-25 early on with a few storms developing in the NE panhandle areas later on. A storm or two may be marginally severe, though limited bulk shear (25-35 kt) and CAPE (1000-1500 J/kg) will keep most activity on the weaker side. Pwat values are slightly elevated compared to climate average due to some monsoonal flow, so, storms may be better able to produce beneficial rain were they occur. Outside of storms afternoon high temperatures are expected to make it into the 90s east of I-25 and 80s to the west. Minimum relative humidity values in the low 20s and upper teens could lend itself to elevated fire potential though overnight recoveries are good.

Sunday is much the same as Monday. The trough over the Pacific NW will inch closer to our area allowing for slightly better forcing and advection of monsoon. Therefore, the odds of storms increase. The forecasted PoPs are about 40-60% area wide, while model ensembles are a little more giving with 50-75% chances of rain. PW values of an inch to 1.5 over southeast Wyoming and the Nebraska Panhandle may lead to a sneaky flooding potential. Corfidi vectors are in the 15 to 20 knot range with Bunkers right motion being nearly stationary. These parameters are sensitive to details that are hard to resolve at this range, but the chance of slow moving and heavy rainfall producing storms is possible.

The trend of showers and thunderstorms continue through Monday and Tuesday as the stubborn trough to the northwest finally ejects into the central plains. While moisture will remain high, a lobe of drier air associated with a ridge to the east may be pulled in ahead of the trough which would reduce rain potential. However, since the trough is ejecting it is possible that cyclogenesis occurs nearby increasing the severe weather potential. Some machine learning models are highlighting an uptick in that potential for the Nebraska Panhandle area. The details of how this unfolds will be ironed out as we get closer.

The remainder of the long term is in a drying trend. The ridge noses in. This would not completely shut down storm activity.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 519 PM MDT Thu Sep 3 2026

Weak gradient flow under the influence of an inverted surface trough to our east has resulted in tranquil conditions east of the I-25 corridor as we remain on the western periphery of a longwave upper- level ridge. High confidence that VFR will prevail, with just the typical pattern of high-based fair weather cumulus dissipating shortly after sunset and redeveloping mid-morning on Friday. SW winds are expected to increase tomorrow morning for the Wyoming terminals, with 15-20 knot southwesterly winds and peak gusts up to 30 knots. This is largely in response to downward mixing of a 40-50 knot mid-level speed maximum.

CYS WATCHES/WARNINGS/ADVISORIES

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