Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
207 FXUS65 KGJT 121708 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1108 AM MDT Sun May 12 2024 .KEY MESSAGES... - Mountain snow and valley rain will continue through the morning hours for the central and southern areas with 2 to 4 inches of additional accumulation mainly above 11,000 feet. Steadier precipitation should come to an end by late morning as this low moves southeast of the area. - Daily showers and thunderstorms, favoring the mountains along the Divide, are expected this afternoon and continuing each day through the coming week. More widespread activity returns Tuesday into Wednesday. - A gradual warming trend will bring near normal temperatures today, and above normal temperatures from Monday onward. && .SHORT TERM /THROUGH MONDAY/... Issued at 315 AM MDT Sun May 12 2024 At this early morning hour, wraparound precipitation is occurring on the northern and western sides of the low pressure system that appears to be centered somewhere around Salida, southeast of the Leadville area. This is resulting in an easterly flow on the north side of the low with the Front Range easterly upslope areas seeing the best snowfall rates. It should be noted that easterly upslope flow does not particularly favor the western slope areas with significant snowfall and this is evident when looking at observations around the area. Webcams indicate primarily wet roads at this time with snow accumulating at elevations above 11,000 feet as snow levels still remain high. The ski resorts around Aspen and Snowmass seem to indicate about 6 inches of snow has accumulated thus far since yesterday and the rest of the area appears to have had 2 to 4 inches on average, which is about what we expected. Webcams indicate snow rates are lessening with light snow falling in the Elks with little additional accumulation at Aspen and Snowmass ski areas since midnight. This is due to the precipitation band shifting southward as the low continues to progress southeastward, projected to end up in southeast Colorado by late this morning. The wraparound precipitation will move out of here with the southeast movement of the low. Valleys are still too mild where rain is the likely precipitation type but limited impacts are being seen on our highways across the western slope and expect this to remain the case through the morning with the best accumulating snow above 11,000 feet in the realm of an additional 2 to 5 inches through noon, with the highest elevations of the West Elks and Sawatch Range seeing the locally higher amounts. The higher impacts appear to be further east over the easterly upslope areas and Front Range though with minimal impacts on the western side. Conditions improve by late morning as the low shifts southeast of the area and takes the better precipitation banding with it. Drier northerly flow moves in on the backside of this trough this afternoon but enough moisture will remain along the divide areas to combine with daytime diurnal heating to produce some isolated to scattered showers and thunderstorms this afternoon. Snow levels also rise as a result with maybe another 1 to 2 inches of snow at the higher elevations above 11,000 feet. Temperatures are projected to be milder with a decent increase of about 4 to 8 degrees higher than yesterday. Lower elevations across eastern Utah, northwest and west-central Colorado should be closer to normal with below normal readings elsewhere, about 5 degrees below normal. Showers and storms come to an end shortly after sunset with clearing skies for Sunday night. A shortwave ridge of high pressure moves in for Monday for drier and warmer conditions for much of the area, although lingering moisture along the western Colorado divide will spark some afternoon convection once again. Otherwise, much of the area will see a return to above normal temperatures by Monday with highs around 4 to 8 degrees above normal. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 315 AM MDT Sun May 12 2024 Monday night sees eastern Utah and western Colorado on the backside of a transient ridge, with the next trough dropping south through the Pacific Northwest. In addition, an area of low pressure will be located just off the southern California coast. Models are in decently good agreement that the cutoff low and the approaching trough will phase as they move east, creating a weak but extensive area of dynamic lift that will slowly move across the region. This lift will begin acting on above average moisture pooled across eastern Utah and western Colorado starting Tuesday, and is expected to be maximized Wednesday afternoon. This means scattered to widespread shower and thunderstorm activity each day, with the higher terrain most favored. Current QPF forecasts remain modest, with most spots seeing between 0.01" and 0.10" of liquid, while the mountains could see up to 0.20" each afternoon. This will likely change as higher resolution guidance begins to come in. Warm air ahead of this trough, and very modest cooling behind it, will keep snow levels high, with forecast accumulations of 2-3 inches expected only above 11000 feet, and therefore only limited impacts to travel for Tuesday and Wednesday. The trough axis shifts east of the Divide by Thursday morning. From Thursday onward, a ridge tries to nudge in and brings drier and warmer conditions. Mountains and adjacent high elevation valleys can still expect isolated to scattered showers most afternoons as daytime heating acts on residual moisture pooled across the region, but otherwise most of eastern Utah and western Colorado can expect mostly sunny skies. Overnight lows will remain fairly mild, with near to a few degrees above normal values expected. Daytime highs will start out near normal for Tuesday and Wednesday as showers and clouds keep things cooler, but a warming trend will kick in for Thursday onward under clear skies and warm air advection. Look for highs running around 5 degrees above normal by the end of the week, with desert valleys once again seeing low 80s, and higher valleys seeing 70s. Mountain towns can expect upper 50s to low 60s. So, if this forecast verifies, it looks as though we`ll finally see a bit of a break from this cool and unsettled pattern we`ve been stuck in. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1108 AM MDT Sun May 12 2024 VFR conditions will continue through much of the period. Occasional gusts to 20 kts can be expected this afternoon with isolated to scattered storms developing over the high terrain of western Colorado divide. Other than VCSH/VCTS at times for KASE, KEGE, KTEX and KGUC...TAF sites are not expected to be impacted this afternoon by passing showers. Activity diminishes tonight as weak ridging slides overhead with CIGS remaining above ILS breakpoints into Monday morning. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MDA LONG TERM...BGB AVIATION...TGJT