Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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809 FXUS65 KRIW 141127 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 527 AM MDT Fri Jun 14 2024 .KEY MESSAGES... - Some waterways continue to run high for at least the next 24 hours. - Hot and mainly dry Friday with some isolated thunderstorm activity east of the Divide. - Elevated fire weather risk Saturday with gusty winds and low humidity. - A cooler and more unsettled pattern for late Sunday through mid next week. && .DISCUSSION... Issued at 1238 AM MDT Fri Jun 14 2024 Current IR depicts a low to the southwest over southern California pushing ample mid to upper level moisture into the upper Rockies and the CWA. Some lingering rain showers east and southeast of the Winds that will push eastward through sunrise Friday morning. Some stronger storms are pushing into Yellowstone as well with some gusty outflow coming out of Idaho as indicated with some observations. These should diminish as well moving into a more stable environment less favorable to stay in tact as the night moves on. Otherwise, another warmer than average temperature afternoon for the entire CWA. A weak shortwave will spin off an upper level low nearing the Pacific northwest coast supporting a weak frontal boundary draped across the northern border with Montana. This will slowly pushed east and southeastward during the afternoon sparking some isolated thunderstorms with peak heating east of the Divide. The main concerns for stronger outflows will be across northern parts of the CWA and especially through the Bighorn Basin. This is where the greatest destabilization will occur with CAPE values over 600-700 J/kg. Sufficient enough shear will be present to allow for possible stronger storms to see wind gusts up to 50-60 mph. Confidence low at this point (only 10-20% severe possibility) as much of the much better ingredients being well eastward into the high plains. With this slow moving front, it will tighten the gradient for Saturday seeing 6-7 mb spreads through the CWA. By late morning and especially for peak heating of the afternoon and strongest mixing to the surface, wind gusts up to 40-50 mph are likely with the wind prone areas the strongest across the I-80 corridor and through the Rattlesnakes to the Casper area. Combined with low relative humidity values, elevated fire concerns are present, even with green-up across most of the area. Any storm activity will be constrained to higher elevations of the Bighorns and Winds to the northern Absarokas with no significant impacts expected at this time. The stronger cold front will push through Sunday with timing not solidified with ample discontinuity between a multitude of models. Thus, temperatures will fluctuate at this point in time dependent on FROPA with warmer highs further south and cooler behind it to the north. Precipitation chances and cooler temperatures will come with the front late Sunday and into the first half of next week. Accumulation amounts are uncertain at this point as well but looks to impacts the northern half of the CWA as models are more aligned to the northern path of the aforementioned upper level low to the northwest. The low looks to fill with its eastward progression with decreasing divergence aloft and thus, QPF amounts do not look to have a big impact. Models are even hinting at some higher terrain snow above 7-8kft with minor accumulation`s possible. Lower areas will remain liquid rain with chances through Wednesday. The low will elongate into an upper level trough as it becomes more progressive through the upper Rockies quickly pushing into the Great Plains by late Wednesday. Upper level ridging will build back in from the south for the rest of the work week and into the next weekend. Dry conditions and a warming trend will return heading into the later stages of the month of June. Hopefully, some decent rainfall and moisture will occur with this upcoming system Sunday night through Wednesday morning as precipitation chances outside of this time frame look to be minimal at best moving forward. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 521 AM MDT Fri Jun 14 2024 Conditions will remain VFR through the TAF period, unless a strong thunderstorm moves directly over a terminal Friday afternoon. If that occurs conditions may drop to MVFR briefly with reduced VIS. Wind will be light (5-10 knots) this morning and then will increase into the afternoon as a weak cold front moves through the area. Gusts will be 20-25 knots on average Friday afternoon. Scattered rain showers and thunderstorms continue across portions of the CWA this morning, and will linger through the afternoon as this front moves through. KJAC is seeing localized shower activity now, and there is a band heading toward KCPR as well. The best chance for thunderstorms later today in the vicinity of a terminal will be at KCOD as convection develops along the eastern slopes of the Absarokas and moves east with the general flow. So, have included VCTS at KCOD Friday afternoon. A lower chance for showers and storms at KWRL for Friday afternoon, so included a PROB30 group with -TSRA. Strong wind gusts around 40 knots will be possible (40-50%) with any thunderstorms that develop. 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... None. && $$ DISCUSSION...Lowe AVIATION...Rowe/Swanson