Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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726 FXUS65 KCYS 060443 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1043 PM MDT Sun May 5 2024 .KEY MESSAGES... - Warmer today with strong southerly winds and the chance (~30%) for showers and thunderstorms to develop near the NE/WY border late this afternoon. - Accumulating snowfall expected starting late tonight in the Sierra Madre and Snowy Ranges, specifically at elevations over 8000 feet. - Strong winds return to southeast Wyoming and western Nebraska Monday with a prolonged period of elevated winds continuing through midweek. Wind gusts of 70-80 mph are possible for wind-prone locations. && .SHORT TERM /THROUGH TUESDAY/... Issued at 327 PM MDT Sun May 5 2024 Active weather next 24 to 48 hours as a strong cold front approaches from the west and moves through early Monday. Front currently located across western Wyoming near the Idaho state line. Temperatures in the low to mid 70s ahead of the front with mid 40s west of the front. Closer to us...winds have been fairly strong in the Panhandle. Have seen reports in the Panhandle of gusts in the low 50 mph range at Alliance and Chadron. The Kings Canyon RAWS site has been up and down on gusts above 58 mph through the morning and early afternoon. GFS 800/850mb winds in the Panhandle develop a strong low level jet this evening up to 50-55kts that persists through 12Z. Given the wind performance today with much lesser 800/850mb winds...decided to go with a High Wind Warning for the Panhandle zones through 12Z Monday. Cold front moves through southeast Wyoming Monday morning after 12Z with winds west of the front shifting westerly and increasing significantly. Craig to Casper 850/700mb height gradients rapidly ramp up to 119/93mtrs after 12Z as 700mb winds increase to 70-75kts behind the front. By Monday afternoon...GFS advertising 80kts at 700/750mbs...so a widespread strong wind event is looking very likely. Went ahead and upgraded watches to warnings for much of the CWA in southeast Wyoming. May take some time for winds to make it out into the Panhandle. Do think we will need wind headlines out there maybe Monday night into Tuesday. We have some time for the second round of wind headlines out there...so decided to hold off on anything else for the Panhandle until this first wind headline expires tomorrow morning. Finally...12Z guidance came in rather bullish on QPF with this system for the mountains. Now getting close to 20 inches in the Sierra Madre Range and close to a foot for the Snowy Range. Decided to upgrade the existing Winter Weather Advisory to a warning for the Sierra Madre Range and add the Snowy Range into a Winter Weather Advisory. Strong Craig to Casper 850/700mb height gradients continue through Tuesday with 700mb winds remaining at 50-60kts. Looks like wind prone areas may continue into Tuesday with possibility of adjacent lower zones seeing strong winds as well. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Issued at 327 PM MDT Sun May 5 2024 Unsettled long term pattern expected to remain for much of southeast Wyoming and western Nebraska. A broad, upper-level low will churn just north of the region through the day Wednesday before being pinched off into an elongated east to west trough. A second closed low will form within the base of the trough and spin around across the western CONUS through Friday before being ingested into the subtropical jet and ejecting off to the east. Behind this departing upper-level system, a high amplitude ridge will develop across the western CONUS. Northerly to northwesterly flow will develop as the ridge stalls and flattens to the west. This will once again open the door for precipitation chances to start the week. Closer to the surface, 700mb winds will begin to decrease late Tuesday night into Wednesday morning, leading to surface winds decreasing below high wind criteria. The 700mb low finally ejects off to the east by early Thursday morning, paving the way for unsettled winds at this level. The long range models hint at a second, broader 700mb low forming over California resulting in northeasterly to easterly winds at 700mb. Easterly winds develop at the surface under the influence of the 700mb low, leading to upslope flow at the surface for Thursday evening and Friday morning. With this broad upslope flow, showers and expected to develop across much of the CWA. Once the upper-level ridge impacts the region on Saturday, precipitation chances fall off rapidly. Saturday and Sunday are expected to be nice days with little to minimal precipitation chances and warm temperatures in the 60s and 70s. However, next week remains unsettled as northwest flow remains across the region, leaving the door open for quick hitting systems. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 1024 PM MDT Sun May 5 2024 Winds will be the primary concern at all aviation sites over the next 24 hours. Expect wind shear at all terminals overnight tonight with extremely strong southwest flow aloft switching to westerly on Monday. MVFR cigs are likely at SNY AIA and CDR however they should not drop to IFR given dry near surface layers. Expect mainly dry weather except for a few showers at RWL which should not lower VIS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Watch from 8 AM MDT Monday through Tuesday afternoon for WYZ101-102. High Wind Warning from 8 AM Monday to 9 PM MDT Tuesday for WYZ103>105-107>109-115-117>119. High Wind Warning from 4 AM Monday to 6 PM MDT Wednesday for WYZ106-110-116. Winter Storm Warning until 6 PM MDT Monday for WYZ112. Winter Weather Advisory until 6 PM MDT Monday for WYZ114. NE...High Wind Warning until 6 AM MDT Monday for NEZ002-003-019>021- 054-055-095-096. && $$ SHORT TERM...GCC LONG TERM...AM AVIATION...MAC