Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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498 FXUS65 KGJT 110548 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1148 PM MDT Fri May 10 2024 .KEY MESSAGES... - Scattered to numerous showers and some thunderstorms continue into the early evening hours with a brief downturn in coverage tonight. - Widespread showers and scattered storms develop by early Saturday morning as a system lifts over the Four Corners. Snow levels will generally be above 9500 ft though storms could drive levels down to the higher valleys. Little travel impacts are expected during the day. - Unsettled conditions will persist through the weekend along with a slow warming trend...however temperatures will remain below normal. Above normal temperatures return next week. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 329 PM MDT Fri May 10 2024 A quick glance at the radar this afternoon would make you believe it was summertime as scattered to numerous showers and some storms persist across the Western Slope. The stubborn area of low pressure retrograded back towards southern Nevada early this morning and has since stalled over the southern Utah / northern Arizona border this afternoon. This has allowed ample moisture to wrap around the low into the Four Corners region with this morning`s 12Z sounding recording a PWAT of 0.43 inches, or one that is just slightly above the norm for almost mid May. As moisture continues to advect into the region in the south / southwest flow PWAT will increase to 130 to 150 percent of normal by early evening before the better moisture begins to shift east over the San Juan Mountains. This will be due to the gradual lifting of the low to the northeast on Saturday. During this transition the more widespread showers will taper off in coverage tonight, though activity will persist across the San Juans and adjacent foothills into Saturday morning. For Saturday itself the vort max associated with the low will swing through and, with moisture once again trending to above normal levels, ample forcing and diurnal support will fuel another round of widespread showers and storms. Under a well saturated profile periods of moderate precipitation and even some small hail can be expected. And, though snow levels will on average be above 9500ft, these convective showers could drive those snow levels down. Snow totals remain relatively unchanged with an additional 2 to 4 inches of snow likely in the southern and central Colorado mountains, though locally higher amounts of 6 or so inches will be possible. Either way, travel impacts will be limited with this late spring system and roads will remain wet for most areas. Elsewhere much of the region stands a good chance to see a soaking shower or storm sometime on Saturday, or at least plenty of clouds to keep temperatures unseasonably cool. Subsidence settles in for Saturday night in the wake of the departing low which will lead to a decrease in shower and thunderstorm activity. Showers will be slow to end along the Divide but elsewhere partly cloudy skies will close out the short term. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 329 PM MDT Fri May 10 2024 The current weather pattern and the one developing through next week has been one of the most maddening exercises in prognostication for a while. It really will be a roll of the dice looking at most probable ensemble cluster solutions for a first guess. The northern stream will be the main player...or so it appears now...but there will be a SoCal upper low being absorbed into the flow that may have to be dealt with. All said the models are in somewhat fair agreement Sunday into Tuesday as the next upstream high latitude wave drops into the PacNW and helps kick this upper low off into the central CONUS. There will be brief transitory ridging moving through on Monday between these systems but residual moisture and instability will keep a threat of mountain showers in place. Tuesday the trough swings across the region and we can again expect an increase in shower activity across all but the far Southwest portion of the CWA. Ensemble cluster-wise the monopole signature appears over the PacNW and only strengthens through Thursday as models struggle to agree on either a strong EPac ridge moving onshore or the arctic folding southward into the same region. The former pattern is reflected as more probable in the clusters through Thursday before flattening as a compromise by late week. For now higher confidence in showers being limited to the higher terrain Sunday into Monday with warming temperatures. Showers expand across the CWA Tuesday into Wednesday with the trough passage and temperatures drop back slightly as a result. No comment beyond this. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1148 PM MDT Fri May 10 2024 Isolated showers will continue over southwest Colorado overnight with showers increasing across southeast Utah after 12Z Saturday and spreading eastward across much of western Colorado by Saturday afternoon and evening. Expect scattered to widespread shower coverage with isolated thunderstorms also possible. Winds will be breezy near showers with gusts to 30 mph possible. Overall, VFR conditions should prevail with MVFR in any shower activity. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MMS LONG TERM...15 AVIATION...MDA