Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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730 FXUS65 KRIW 252313 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 513 PM MDT Sat May 25 2024 .KEY MESSAGES... - Scattered showers and thunderstorms will continue through the evening. - Showers will be more limited to northern Wyoming on Sunday. Gusty winds elsewhere. - Warmer and dry Memorial Day. - Unsettled conditions are favored to return by midweek. && .DISCUSSION... Issued at 231 PM MDT Sat May 25 2024 After a day of quieter weather, unsettled conditions have returned to Wyoming. This is due to increased Pacific moisture and a fast- moving shortwave currently visible on water vapor imagery. Showers and thunderstorms will become more widespread early this afternoon from west to east as this feature pushes farther in. The best coverage of convection will be across western and southern Wyoming which will generally see instability in the 400 to 600 J/kg range. All areas though will have a good chance of seeing a shower or storm in the vicinity at some point through this evening (at least 25 percent for most). On the flip side, cloud cover across western Wyoming could limit instability there later this afternoon. Otherwise, the system is not very cold; snow will be limited to the mountains, with only light accumulations on the highway passes. As for rain accumulations, western and southern areas will have the best chance of at least a quarter inch (~50 percent chance). East of the Divide, amounts will generally be less than a tenth of an inch. Showers will come to an end this evening save for some lingering activity across northern Wyoming into Sunday morning due to another quick shortwave clipping the area. Sunday continues to trend drier for most locations with Saturday`s wave moving off to the east. The exception will still be across northern Wyoming, and especially the Bighorns and the Powder River Basin. These areas will see another weak wave dipping down from Montana, as well as a better moisture pool for an additional round of showers in the afternoon. Again, though, these are looking more isolated as of late; we expect most of the area to be dry on Sunday. Otherwise, it will be a much breezier day for most, especially across southern Wyoming which will see gusts over 35 mph during the afternoon. Memorial Day will be dry all around as stronger ridging returns to the area. Temperatures will return to around or a few degrees above normal. The warming trend will continue on Tuesday as highs reach into the 80s east of the Divide and upper 70s west. There will be a chance of some afternoon convection, however, as the ridge begins to break down. By Wednesday guidance is showing a stronger trough pushing into the northwestern US. This will push east through Wednesday, though how far south it drops will have a large impact on the weather across Wyoming. For now, the forecast continues to show increased precipitation chances on Wednesday, with the best chances across the northern half of the area. Further out, guidance is hinting at a continued active pattern through the end of the week, though there is quite a bit of uncertainty at the moment. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 512 PM MDT Sat May 25 2024 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals. Ongoing lingering convection fades between 01Z-03Z/Sunday with the loss of solar heating. A few light showers may persist over far northwest Wyoming through the evening hours before shortwave energy clears the region after 08Z/Sunday. VFR conditions prevail with cloud heights rising during the early morning. Mid-level cloud deck of 060-090 prevails much of the night at KJAC. Gusty westerly wind increases to 15-25kts between 15-18Z/Sunday at the three southwest terminals in favorable west-northwest flow aloft. KJAC wind increases to 10-20kts between 16Z-18Z/Sunday. Other than a few orographic showers over Yellowstone, Sunday afternoon is dry and VFR regionwide. Mountain tops occasionally obscured through 06Z/Sunday. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals. VFR conditions prevail through the entire forecast period. Convection lingers over mainly central Wyoming through mid-evening, although coverage and intensity decrease with the loss of solar heating. Outflow wind gusts 25-35kts are the greatest hazard. Shortwave energy across the Northern Rockies keeps light showers over far northern Wyoming in the vicinity of KCOD into the early morning hours. Sunday finds only isolated showers along and north of a Cody-to-Casper line within drier west-northwest flow aloft. Westerly surface wind increases to 13-25kts between 17Z-20Z/Sunday at all terminals but KWRL. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Myers AVIATION...CNJ