


Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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319 FXUS65 KCYS 111733 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1133 AM MDT Fri Jul 11 2025 .KEY MESSAGES... - A strong cold front will move south across the area Friday morning, with potential for strong storms and heavy rain Friday afternoon and evening. - Temperatures will be warming Saturday through Monday, before a potent cold front brings another round of cooler temperatures for Tuesday and Wednesday. Shower and thunderstorm chances will be greatest for Tuesday and Wednesday. && .SHORT TERM /THROUGH SATURDAY/... Issued at 240 AM MDT Fri Jul 11 2025 Current IR Satellite this morning shows the Pacific shortwave disturbance, which brought the widely scattered thunderstorms yesterday, continues to quickly move southeast of the area into Kansas and Nebraska. Mid to upper level flow will continue to shift into the northwest today with veering winds aloft. This is area of the next relatively strong cold front for early-mid July digging south into the Front Range today. The leading edge of the cold front is still across northern Wyoming and is forecast to quickly move south this morning across the High Plains. A cluster of showers and embedded thunderstorms continue to push across east central Wyoming, but are likely not producing much rainfall. Frontal position will likely be through most of southeast Wyoming and in northern Colorado around noon today, and then the front is forecast to stall near the Colorado/Wyoming border. This should keep temperatures across the I-80 corridor and near the Colorado border in the upper 70s to mid 80s for a while today...so not much lower compared to yesterday. Further north, highs will struggle to reach the low to mid 70s. Another round of showers and thunderstorms expected mid to late afternoon, but this time most of the activity should be confined to the I-80 corridor near the front. Can`t rule out some isolated thunderstorms north of the north Platte River Valley, but coverage will be limited with the cooler airmass already through the area. Frontal boundary is expected to fluctuate into this evening before heading south tonight. Any warm air advection in the midlevels will aid in storm development with a good chance of at least strong thunderstorms along and south of a line from Elk Mountain eastward to Scottsbluff and Sidney Nebraska. Can`t rule out some severe thunderstorms in this pattern either with very heavy rainfall, hail, and gusty winds. Can`t rule out an isolated tornado or two as well. Current 00z and 06z NAM shows ample 0-3km CAPE over 2000 j/kg and EHI`s approaching 2 near the stalled frontal boundary and thunderstorm initiation area from Elk Mountain over towards Cheyenne, and a secondary area across the lower North Platte River valley later in afternoon. Northwest flow at the midlevels and east to southeast surface winds indicate decent lower level shear within the boundary layer. However, the lack of deep 0-6 km shear and not much CIN suggest short duration circulations and storms quickly becoming outflow dominant through the afternoon, so confidence is limited on this overall threat this afternoon but should be kept in mind for portion of far southeast Wyoming and the southern Nebraska Panhandle today. Thunderstorm activity should end around sunset with remnant showers near the cold front boundary mainly near the Colorado border. Kept Low stratus and the potential of fog, and extended the mention of patchy fog further east since we`re expecting decent rainfall amounts and a continuation of moist east to southeast winds tonight. Saturday is trending drier across the area so lowered POP below 10 percent for most locations but kept slight chance of showers and thunderstorms for the Laramie and Cheyenne areas, including the I-80 summit, with decent low level convergence. Most of the area will be fighting some much drier air aloft than previous forecasts indicated, which will likely cap most of the convection. Pleasant day with highs in the upper 70s to upper 80s...warmest north of the Interstate 80 corridor. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 147 AM MDT Fri Jul 11 2025 For later this weekend and Monday, a gradual warming trend will continue as the upper level high across the desert southwest slowly builds northward and intensifies. Thunderstorm activity is forecast to become more isolated through by late Saturday and Sunday as 700mb climb above 15c. Highs in the upper 80s to mid 90s will return for much of the forecast area by Sunday and next Monday. Tuesday...A progressive shortwave trough aloft moving across Montana and North Dakota will send a fairly strong cold front southward across our counties, dropping high temperatures into the mid 70s to mid 80s. With decent low level upslope winds and plenty of low and mid level moisture, we expect to see scattered afternoon and evening showers and thunderstorms. Models are not quite as aggressive with the amount of cold air behind the front compared to yesterday, but still show 700mb dropping between 5c to 10c across northern Wyoming. Wednesday...Another relatively cool day for mid July with low level upslope, plenty of cloud cover and high temperatures only in the mid 60s to mid 70s. Adequate moisture for scattered afternoon and evening showers and thunderstorms, most numerous near the Colorado state line where the moisture will be the deepest. Thursday...The atmosphere will slowly moderate with 700 mb temperatures returning to near 15 Celsius, yielding high temperatures in the upper 70s to mid 80s. Warm temperatures aloft will limit convection, though still should see isolated to scattered late day showers and thunderstorms. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1128 AM MDT Fri Jul 11 2025 Thunderstorms expected across the region starting this afternoon which could bring MVFR or lower conditions along with gusty, sometimes variable winds, primarily to KLAR/KCYS/KSNY. These storms could be strong to severe with hail and severe winds. Otherwise winds will be breezy most sites with gusts 20-30 knots from a north to northeasterly component. Winds should then calm overnight. Cloud bases will drop to mid levels this afternoon and evening thanks to the storm activity, and should mostly clear and risk overnight. The exception to this will be KCYS and possibly KSNY where low CIGs may develop and linger through the morning hours bringing further MVFR to IFR conditions. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...TJT LONG TERM...TJT/RUBIN AVIATION...CG