Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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152 FXUS65 KRIW 251948 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 148 PM MDT Wed Sep 25 2024 .KEY MESSAGES... - Three or four clouds possible during the next 24 hours. - Red Flag conditions return Thursday, with very low humidity and gusty winds. - A cold front may bring a sharp 20 to 30 degree temperature decline between Sunday and Monday, but no precipitation is expected with this front. && .DISCUSSION... Issued at 118 PM MDT Wed Sep 25 2024 A strong late-season H5 ridge remains dominant across the Four Corners and eastern Rockies, and is keeping skies absolutely clear today. This is also bringing temperatures well above normal, reaching the upper 80s and lower 90s. Tomorrow will see much of the same, with nearly clear skies and very warm temperatures. The main difference tomorrow will be a weak "cold" front moving across Montana into far north-central WY in the afternoon. This will initially tighten the gradient across the state, bringing gusty Wyoming winds. The unusually warm, dry, and windy conditions have prompted a Red Flag Warning for portions of the state (see Fire WEather discussion below). The front will bring some brief north winds to Johnson County, but the front does not have much of a southward push this time, so overall effects will be minimal. Ridging continues over the weekend, with well above normal temps and some increasing high clouds. Models have become a bit more aggressive with the next Canadian system sweeping by, bringing a better cold front southward Sunday night. Models are still differing on where the trailing cold pool will dive southward, but it`s becoming more likely that Monday will be much colder than the weekend. Current ensemble forecast holds highs only in the 60s for most of the state Monday. Sadly, the front still has minimal moisture to work with, so no precipitation will accompany this front either... && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1047 AM MDT Wed Sep 25 2024 High pressure will keep skies clear and conditions VFR through the TAF period. A weak trough will slide through the region Thursday, but it will be a very dry system, with almost no moisture or cloud cover as it passes by. Wind will be breezy this afternoon, as well as Thursday afternoon as the trough approaches/moves through. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued at 118 PM MDT Wed Sep 25 2024 A Red Flag Warning has been issued for portions of the state Thursday. A front crossing Montana on Thursday will bring brisk southwest winds across the most prone areas of central and southern WY. Humidity level 10 to 15 percent and wind gusts 25 to 35 mph will be common from RKS to CPR and across Johnson County. Another concern is the front will push southward across parts of Johnson County late in the afternoon, bringing an abrupt wind shift from the north 20 to 25 mph late afternoon. All winds will be decreasing at sunset. Winds will be much lighter on Friday, and will remain below Warning Criteria. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from noon to 7 PM MDT Thursday for WYZ279>281- 289. && $$ DISCUSSION...Straub AVIATION...Rowe FIRE WEATHER...Straub