Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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528 FXUS65 KRIW 021149 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 549 AM MDT Sun Jun 2 2024 .KEY MESSAGES... - Isolated thunderstorms are possible today with strong wind gusts the main threat. - A good chance of showers tomorrow, especially in Western Wyoming. Increasing wind Monday and Tuesday. - Mainly dry Tuesday through most of Friday with warming temperatures. Elevated fire weather and rising river levels are expected at this time. && .DISCUSSION... Issued at 306 AM MDT Sun Jun 2 2024 It looks like we have at least a chance of our usual charcuterie board of late spring / early summer weather across the area over the next week or so. They are, in rough order, convection, very warm temperatures, elevated fire weather and rising rivers and possible flooding from high elevation snowmelt. Convection will be the first concern of the period. We still have some light showers in the south and west as the second in a series of three shortwaves approaches the Cowboy State. The second wave is similar to the wave yesterday in that it has little moisture to work with so chances of showers would be 1 out of 3 at the best with most lower elevation locations having a 1 in 5 chance at best. We still have dry low levels though, especially East of the Divide. And with the large dew point depressions and model soundings showing more inverted Vs, any thunderstorm or even shower could have a strong wind gust past 45 mph. Most areas will be dry most of the day and many areas will see nothing. Temperatures will be similar to a degree or two cooler with somewhat more clouds than yesterday. And showers should end fairly quickly this evening with a balance of the night mainly dry. The last wave will approach on Monday and Monday night. This one will be the most potent. For one, precipitable water values will be higher, approaching 150 percent of normal Monday afternoon. In addition, there will be more upper level forcing courtesy of an 120 knot jet moving into the area. Strong thunderstorms look unlikely though. Surface CAPE is rather limited and with more cloud cover, instability will not be that high. There could be some decent rain across the west though, with a greater than 1 in 2 chance of a half an inch of rain across the western mountains. This should fall over an 18 hour period though, with an emphasis on the afternoon hours for the heaviest. The risk of flooding is low though. There have been several days of dry weather. The main threat would be rain falling on high elevation snowpack though. So, the threat is low but not zero. Models have trended drier East of the Divide though, We kept some POPs in but again, the chance is limited, generally less than 1 out of 3. The main concern will be gusty wind. The 700 millibar wind does not look sufficient for high wind, but gusty to strong wind is a possibility. This will be in the usual favored areas, like Casper ahead of the trough, and places like Buffalo post frontal. A few showers will linger into Tuesday morning before ending. Ridging will then begin building in Tuesday and begin to bring an increase in temperatures. Now, we have to start looking at possible fire weather concerns. Fuels are still in green up, so warnings are not expected. Nevertheless, elevated fire weather will be possible Tuesday and Wednesday as ridging will remain flat and gusty wind will continue across the area with relative humidity falling in the teens. The ridge should then become more amplified on Thursday over the area, decreasing the wind. Temperatures will rise through the week, with the warmest weather of the year expected Friday and Saturday. Some of our warmer spots, like Worland Greybull, could see the first 90 degree highs of the year. Things should remain dry through at least Thursday. The chance of convection may return Friday or Saturday as some moisture moves in from the southwest but coverage of storms looks sparse right now. And finally, we have rising rivers to worry about. A good rule of thumb for higher elevation snowpack to melt is three consecutive days in the 80s, and we should have that by Friday. So, we will have to keep a close eye for rising rivers and possible flooding. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 543 AM MDT Sun Jun 2 2024 VFR conditions will prevail through the period. Winds will begin to increase across the area from 16Z to 20Z, with gusts of 20 to 25 kt occurring through the afternoon for most terminals. Showers and thunderstorms will once again be possible across the forecast area, becoming more widespread around 20Z. However, chances remain too low to mention at any site. If a shower or thunderstorm does move over a terminal, it will be fast moving and not last more than 20 min or so. This convection will end or exit the area by 02Z. 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...Hattings AVIATION...LaVoie/Myers