Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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316 FXUS65 KRIW 181827 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1227 PM MDT Wed Sep 18 2024 .KEY MESSAGES... - Windy this afternoon, with lighter winds returning for Thursday. - Light rain and mountain snow continues this afternoon, decreasing this evening and overnight. - Thursday is dry, with slightly warmer temperatures. - The next weather system comes this weekend. Most of its impacts remain outside the area, but cooler temperatures and isolated rain is possible. && .DISCUSSION... Issued at 1226 PM MDT Wed Sep 18 2024 Current satellite shows an occluding low pressure system, centered over eastern Montana. Its influence today keeps cool temperatures and gusty winds. The main impacts from it decrease starting mid- afternoon through the overnight hours. A tight pressure gradient keeps strong west to southwest winds this afternoon. Gusts ranging from 20 to 70 mph continue across the area. Recent model trends show that these winds should begin to decrease after 3pm MDT this afternoon. Winds should be less than 20 mph by midnight, with the exception of the higher elevations, which continue to gust through Thursday morning. Wrap around moisture keeps precipitation falling across northwest and northern Wyoming as well. This should remain light. Snow levels are mostly above 10000 feet, but some areas are as low as 9000 feet. Precipitation decreases through the afternoon, with some lingering showers lasting until Thursday morning. All precipitation should be done by sunrise Thursday. High temperatures remain on the cool side today, with 50s to 60s west of the Divide, and 60s to low 70s east. As the low exits the area, Thursday is much calmer with the winds. Most areas are 10 mph or less. The Wind Corridor gets afternoon gusts to around 20 mph. Otherwise, no precipitation is expected, with high temperatures peaking a little warmer than today. Friday, temperatures are a little higher. Some moisture could bring very isolated (20%) showers to northwest and north Wyoming. An upper-level low tracks into the Four Corner area Saturday. Most of its influence should remain south and southeast of the area through the weekend. That being said, temperatures decrease, with highs returning to below seasonal values. No widespread precipitation is expected given the current model tracks, but some isolated (15% to 30%) showers could occur. These would be favored for southeastern locations of the area. Past this weekend, ensemble models are bringing in a ridge by the middle of next week. This would favor warmer and drier conditions to end the month. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1126 AM MDT Wed Sep 18 2024 Cloud cover and areas of light rain have been wrapping into northwest and northern Wyoming Wednesday morning within counter- clockwise flow around an upper-level low over Montana. Also, gusty southwest surface wind 30G50kts has plagued KCPR and similar speeds are likely to prevail there through about 22Z/Wednesday before slowly decreasing by 02Z/Thursday. The counter-clockwise flow leads to gusty westerly surface wind 15-30kts until around 01Z/Thursday at most other terminals, with 10-20kt winds lingering longest at KRIW in favored west-northwest flow. As for precipitation, KJAC will continue to flirt with MVFR/VFR threshold of 030AGL through mid-afternoon, with VFR likely to prevail after 21Z/Wednesday. All other terminals to be VFR. Scattered light rain showers remain favored at KJAC in west- northwest flow until 03Z/Thursday. KWRL has a less than 30 percent chance of seeing a brief light rain shower from 21Z- 24Z/Wednesday. Other terminals to remain dry. Cloud cover gradually dissipates and ceilings rise from south to north tonight. Any lingering light showers decrease between 06Z-12Z/Thursday. Mountain tops frequently obscured above 10K feet MSL until 06Z/Thursday across the northwest quadrant of Wyoming. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 4 PM MDT this afternoon for WYZ003-019- 020. && $$ DISCUSSION...Wittmann AVIATION...CNJ