Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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646 FXUS65 KRIW 041119 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 519 AM MDT Tue Jun 4 2024 .KEY MESSAGES... - Drier and warmer weather will arrive this afternoon and continue through at least Thursday. - Windy conditions are expected today and tomorrow, with elevated fire weather possible on Wednesday afternoon. - Warm temperatures will lead to high elevation snowmelt which could bring rising river levels and minor flooding late this week. && .DISCUSSION... Issued at 125 AM MDT Tue Jun 4 2024 Summer, at least weather wise, will be arriving, especially starting on Wednesday. As for now, we still have some showers across northern portions of the area in response to the Pacific trough moving across the area and the left front quadrant of an 120 knot jet providing some upper level divergence. These showers should continue to decrease through the overnight but a few may linger into the morning hours before everything ends by around 10 am or so. The main concern then shifts to wind as we shift from the left front to right front quadrant of the jet this afternoon, enhancing downward forcing. Reasoning remains the same as yesterday. The 700 millibar winds do not look sufficient for high winds, but gusty to strong winds are certainly possible. Some windier areas, like Rock Springs, have greater than a 1 in 2 chance of seeing wind gusts over 40 mph. Temperatures today will average close to slightly above normal. Humidity should remain high enough to prevent many fire weather issues. Wednesday also looks dry. This is where temperatures will begin to rise, with many locations likely seeing their warmest temperatures of the calendar year with lower elevations seeing highs well into the 80s. This a day when elevated fire weather may be a concern. The low that brought the rain will be held up by a blocking ridge over eastern Canada, with the low spinning over Manitoba. A tight height line gradient between the low and ridging building across the desert southwest. In addition, the jet will be close enough to keep breezy to windy conditions continuing. With relative humidity falling into the teens at times, fire weather statements may be needed for Wednesday. Thursday looks dry and warmer as well, and probably the first possibility to see high temperatures hit 90 in our warmer spots. Also, with the ridge building northward, wind will decrease. The heat really looks to peak on Friday, with the best chance of seeing high temperatures in the 90s. This is also the day some mid level moisture will be introduced to the area, bring a possibly, although a small one (generally less than 1 out of 4 chance) of some afternoon or evening convection. And, with the hot temperatures, rising rivers will likely become a concern. A general rule of thumb around here is three days with highs in the 80s is when high level snowpack really starts to melt. So, we will have to start watching for this, especially starting on Friday. More uncertainty creeps into the forecast stating on Saturday. The ridge looks to get suppressed just a bit with some shortwaves moving into the area, bring chances of convection, mainly of the diurnal variety. There are still differences in guidance in the timing of the waves, so details are still hard to come by though. It does look more active for the weekend and Monday as well. Nevertheless, I think we can safely say, welcome to summer in western and central Wyoming. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 515 AM MDT Tue Jun 4 2024 Any lingering showers will wane over the next couple of hours, leaving dry conditions at terminals through the period. Wind will be the main terminal impact today as westerly surface flow is reestablished in the wake of this morning`s cold front. Wind will increase through the morning hours, with gusts of 25 to 35 knots becoming fairly widespread through the afternoon. Gusts will begin to decrease after sunset. 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...Hattings AVIATION...Myers