Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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508 FXUS65 KCYS 011510 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 910 AM MDT Mon Jul 1 2024 .KEY MESSAGES... - Strong to severe thunderstorms possible this afternoon and evening...mainly across the northern Nebraska Panhandle into Converse and Niobrara Counties in east central Wyoming. - Much drier air and warmer temperatures expected Tuesday into Wednesday when we could see critical fire weather conditions for some areas along and west of the Laramie Range. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 245 AM MDT Mon Jul 1 2024 One more good day for severe storms for southeast Wyoming and Nebraska Panhandle. Currently...a 1006mb surface low in extreme southeast Montana. Cold front extends south southwest near Gillette to Jeffrey City to northern Utah. Another stationary boundary from this low extends south to Lusk...to just east of Cheyenne into northeast Colorado. Seeing dewpoints in the mid 60s across the Panhandle...westward to this stationary front. Cheyenne Reporting a dewpoint of 57...Wheatland 63 and Douglas 56. So we have a juicy atmosphere in place. Cold front/dry line expected to continue moving east through the morning. Forecast to be near Lusk to just east of Cheyenne by 18Z and then through the Panhandle by 00Z or so. Could be an early start today for severe storms as HRRR/RAP simulated radar showing storms beginning to form along this cold front around 19Z today across the southeast Wyoming plains and then into the Panhandle 20Z-00Z. NAM MUCAPE up near 1700 J/KG at 18Z in the Panhandle...peaking out around 2200 J/KG over the northern Panhandle at 21Z. Large hail and damaging downburst winds will be the primary hazards this afternoon as a few supercells develop and move east into the Panhandle. Need to be on the lookout for flash flooding as well as PWATS well above 1.25 inches for a time this afternoon. Finally...the cold front/dry line pushes into the Panhandle with storms coming to an end fairly quickly. HRRR showing a few residual storms across Cheyenne County in the southern Panhandle around 02Z. Any areas that received rainfall could see stratus and fog tonight as winds do shift northeasterly for a time behind the front. Focus for showers Tuesday will be up into northeastern Wyoming/southwestern South Dakota as upper shortwave tracks across that area. Did go higher on PoPs over Converse and Niobrara Counties into northern Sioux County in the Panhandle as this shortwave tracks into northern Nebraska. Wednesday looks to be hot and dry for the most part. Afternoon humidity for most of southeast Wyoming forecast to be in the low to mid teens. 700mb winds across southeast Wyoming 30-40kts...so fire weather concerns will be on the increase. May need some fire headlines for Wednesday in the next 12-24 hours for Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Issued at 245 AM MDT Mon Jul 1 2024 An upper-level trough is progged to dip down into the central CONUS Wednesday night into the day Thursday. Cooler 700mb temperatures will sink into the Rocky Mountain Region, leading to 700mb temperatures in the single digits, compared to the 14-16C mark on Wednesday. With northwesterly flow developing aloft as the trough pushes easterly, several 500mb vorticity lobes will traverse overhead, leading to increased chances for precipitation. Additionally, an attendant cold front will sweep across Wyoming strengthening the winds and turning them northwesterly. A breezy day is expected for Thursday with surface high temperatures in the mid- 70s to low-80s area wide. Did decrease PoPs across the CWA as the primary threat for precipitation will be Wednesday, with decreasing odds for Thursday. Overall, Independence day looks mostly dry with cooler temperatures making for an pleasant day across the region. Upper-level northwesterly flow remain overhead for Friday, resulting in similar temperatures as Thursday across the region. A few 500mb vorticity lobes will traverse overhead through the northwest flow and increase precipitation chances. Surface moisture looks to be lacking on Friday, so shower and thunderstorm chances are very low. Kept PoPs around 15% for much of the area as showers cannot be ruled out, but look unlikely at this time. Northwesterly flow looks to remain through the weekend as well, as an upper-level ridge builds just off the coast of California. Along with a messier upper-level flow regime and a building ridge, temperature will increase the weekend, back into the 80s and 90s for much of the area. The warmer 700mb temperatures will stick around through the weekend into early next week, favoring very warm temperatures. Surface moisture will once again be lacking due to the dry northwesterly flow. While it will be quite warm across the area, precipitation is not expected at this time. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 504 AM MDT Mon Jul 1 2024 Forecast concerns with the 12Z TAFs will be low stratus in the Panhandle and here at KCYS this morning...followed by thunderstorms this afternoon. IFR this morning at most Nebraska Panhandle airports and here at Cheyenne will break up after sunrise. HRRR showing IFR/LIFR breaking 13Z to 14Z at all airports. An early show for thunderstorms...starting late morning and peaking around 00Z in the Panhandle. HRRR continues to show KCDR and KSNY getting hit pretty good with strong to possibly severe thunderstorms this afternoon. Went ahead with TEMPO groups for these two airports. Hopefully...we get better timing on other airports for the 18Z TAFs. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...GCC LONG TERM...AM AVIATION...GCC