Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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852 FXUS65 KGJT 260442 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1042 PM MDT Sat May 25 2024 .KEY MESSAGES... - Showers and thunderstorms continue this afternoon and evening before dissipating overnight. Gusty winds and some hail is possible with these showers and storms. - Mountain snow is possible generally above 9 kft with minor impacts to the roads occurring tonight. Highest chances for upwards of several inches of snow will be in the northern and central mountains. - Temperatures running below normal through the weekend will warm to five to ten degrees above normal by mid week. Precipitation chances remain low through mid week. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 236 PM MDT Sat May 25 2024 Models seem to be tracking well with satellite imagery trough axis moving through central Utah and will push into eastern Utah late this afternoon. H700 GFS has indicated three thermal boundaries, two ahead of the trough (not really frontal boundaries) and the primary cold front aligned more with the trough. Each of these boundaries has showers and thunderstorms associated with it. The first of these passed across the northern areas along and north of the I-70 corridor late this morning and is now just pushing east of the Divide. It was mostly showers, but did produce a few thunderstorms and a strong outflow gust over 60 mph. These storms are not expected to be especially strong as there is little upper level support with the left entrance region of the jet aloft, but the cool air through the mid levels and max diurnal heating this afternoon is producing surface CAPE values well over 300 J/kg and MLCAPE around 160 J/kg through the afternoon and early evening. The next wave of convection is now moving through eastern Utah and will push through Western Colorado between now and about 7 PM before moving east of the Divide. Close on the heals of the second wave is the frontal boundary that will produce the stronger storms late this afternoon and this evening with showers and thunderstorms extending south to the northern face of the San Juan Mountains as it moves east to west through the region. With the dry airmass in the lower levels, expect strong outflow winds exceeding 55 mph. Also dime sized to penny size hail and frequent lightning is likely with these storms and can`t rule out an isolated stronger storm with one inch hail stones possible. If you will be out through this evening, stay tuned for weather alerts and, if thunder roars, go indoors. The front will push east of the Divide around midnight with lingering showers over the northern and central Colorado mountains overnight into Sunday morning, ending around noon. Sunny skies under the subsidence as a ridge starts building in from the west Sunday will feel warm, but temperatures will stay about five degrees below normal across the region under the northwesterly flow. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 236 PM MDT Sat May 25 2024 A ridge of high pressure will move in from the west and build across the Northern Rockies with dry conditions to start the week. A low pressure trough will move onto the Pacific Northwest coast, causing the flow to shift to southwesterly over the region by Tuesday. A shortwave looks to eject out ahead of this low and result in some isolated to scattered showers and storms mainly over the higher terrain along the Continental Divide. The better moisture and instability resides east of the Divide though over the Front Range and Plains. As this PacNW trough tracks east across the US-Canada border, several embedded shortwaves will move through the flow, resulting in daily isolated storms over the Divide during the afternoon as enough instability remains present with daytime heating for this to occur each afternoon. Drier conditions will still remain on the western slope as the better moisture resides over the Front Range and Plains. The flow shifts to more westerly on Friday due to the passage of this trough across the north which looks to drag a cold front through the area, affecting the north and possibly central areas. PWAT anomalies come up quite a bit on Friday, so better chances exist for showers and thunderstorms. The deterministic models seem to be latching onto this potential while the NBM has yet to catch on, leaning more towards a drier solution with continued isolated convection over the higher terrain along the Divide. To what extent this trough affects us on Friday remains to be seen though as confidence is low this far out. This drier southwest flow will allow temperatures to warm up to above normal levels through the week by about 5 to 10 degrees above normal. Most lower valleys look to rise into the 80s with near 90 in the Grand Valley and low to mid 90s possible in the lower desert valleys of east-central and southeast Utah. Northern higher valleys look to rise into the upper 70s to low 80s in this pattern. Temperatures look to cool off some Friday, closer to normal, as a result of the potential increase in moisture and cold front boundary moving through. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 1040 PM MDT Sat May 25 2024 Conditions should begin to improve in the next few hours for the sites experiencing rain showers. Although clouds may hang around to cause extended MVFR or ILS at some of the sites. By late morning VFR conditions should prevail. A few showers are possible in the mountains this afternoon. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...DB LONG TERM...MDA AVIATION...TGJT