342 FXUS65 KRIW 130504 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1004 PM MST Sun Nov 12 2017 .SHORT TERM...(This evening through Wednesday) Issued at 137 PM MST Sun Nov 12 2017 Dry high pressure will be over the western and central Wyoming tonight and Monday. High and mid clouds will increase in southwest flow aloft on Monday and Monday evening. Downslope winds will increase along and near the east slopes of the mountains and through the wind corridor across Sweetwater, southern Fremont and Natrona counties. Monday night winds may reach high wind category across the Cody foothills and across southern Fremont and Natrona counties with the threat of high winds continuing through Tuesday. Some light snow showers will develop late Monday night increasing across the western mountains on Tuesday as southwest winds become quite strong over the higher ridges and passes of the west as well. The snow will end rapidly Tuesday evening with clearing through Wednesday. .LONG TERM...(Wednesday night through Sunday) Issued at 137 PM MST Sun Nov 12 2017 Beginning of fcst, a shortwave ridge passes through and to the east of WY while the upper levels begin transition to southwesterly Wednesday night with an advancing broad trof on the way toward/into the region. A brief strong wind pattern will become possible by Wednesday night over the nrn Mountains and Foothills as mid/upper level flow across this region (mountains) will be favorable to the formation of good amplitude mountain waves, combining with 50 - 60 kt winds at ridgetop and lee side troffing. The Wind Corridor is also expected to react to the approach of this system with increased winds...along with another brief period of marginal High Wind possible ahead of a cold front due to arrive across the FA later Thursday. As the large/broad upper level trof continues to approach WY, much of wrn,swrn/srn WY will be under increasingly favorable upper level dynamics from the jet (110-140kt), combining with increasing EPAC moisture and giving growing areas of clouds and also increasing precip chances across wrn/swrn/srn WY overnight Wednesday night, through Thursday morning and into/through Friday morning. As the trof axis passes through WY later Thursday/Thursday night, an associated front will get pushed through the FA with some lower chances for precip arriving east of the Divide. Highlights likely west of the Divide beginning sometime Thursday. The significant/persistent GFS/EC temporal differences (GFS overall quicker/EC slower) are still present although the gap continues to slowly close. The GFS solution is "slowing slightly slightly faster" than the EC's continued slow down. Spatial differences, however, seem to be at a minimum. This slow down trend within a quite progressive upper level pattern has continued over the past several days with both models well out of phase from a timing standpoint by Friday. Pushing higher POPs through Friday morning and into the afternoon is how this problem will currently be handled with respect to both models. Of course, there are split expectations at this point that in another 24 hrs either both models will finally be within 3 to 6 hrs of each other, ending Friday afternoon...or the slowing trend continues and significant POP chances will continue into Friday night. Betting on the trend? && .AVIATION...(For the 06Z TAFS through 06Z Tuesday) Issued at 1000 PM MST Sun Nov 12 2017 VFR conditions will prevail through the forecast period at all terminal sites. VCFG KWRL 11Z-15Z this morning. A gusty wind will return to KCPR airport Monday morning, decreasing around 00Z Tue. Strong gusty wind will develop Monday evening along the east slopes of the Absaroka and Wind River mountains. The wind at KCOD airport will become gusty after 01Z Tue. Areas of LLWS will be likely along the east slopes Monday night. && .FIRE WEATHER... Issued AT 137 PM MST Sun Nov 12 2017 Dry high pressure will be over the western and central Wyoming tonight and Monday. High and mid clouds will increase in southwest flow aloft on Monday and Monday evening. Downslope winds will increase along and near the east slopes of the mountains and through the wind corridor across Sweetwater, southern Fremont and Natrona counties. Monday night winds may reach high wind category across the Cody foothills and across southern Fremont and Natrona counties with the threat of high winds continuing through Tuesday. Some light snow showers will develop late Monday night increasing across the western mountains on Tuesday as southwest winds become quite strong over the higher ridges and passes of the west as well. The snow will end rapidly Tuesday evening with clearing through Wednesday. && .RIW WATCHES/WARNINGS/ADVISORIES... High Wind Watch from 5 PM Monday through 5 AM Tuesday for WYZ002-003. && $$ SHORT TERM...Baker LONG TERM...Braun AVIATION...AR FIRE WEATHER...Baker