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
960 FXUS65 KGJT 141730 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1130 AM MDT Sat Sep 14 2024 .KEY MESSAGES... - Expect dry and warm temperatures again today before unsettled conditions return Sunday. - Above normal temperatures persist through Monday before a cold front moving through the region on Tuesday brings cooler than normal readings for the latter part of the week. - Aside from Wednesday, off and on showers can be expected across eastern Utah and western Colorado next week. && .SHORT TERM /THROUGH SUNDAY/... Issued at 251 AM MDT Sat Sep 14 2024 Another sunny and hence dry day is in store with temperatures warming back to a few degrees above normal in most areas today. Things are happening already to change this pleasant weather and bring back shower and thunderstorm chances by tomorrow. There is a weakening tropical storm down in the southern Baja region this morning. Isentropic surfaces suggest moisture from this system will be pulled northward by digging trough over the Pacific Coast...arriving to the 4 Corners region as early as sunrise tomorrow. The question is will this mainly be in the form of ACCAS with some virga or will there be a trigger strong enough for this elevated moisture and instability get showers to the ground or even pop an isolated thunderstorms during the morning hours over our SW CWA. There is an ill defined wave moving toward the Bay Area of California this morning which PVU fields show arriving just about the time the moisture arrives tomorrow morning over SE Utah. This wave will definitely help enhance lift over the eastern CWA during the heating of the day along with the usual ascent aided by the topography. Pulled some small pcpn chances farther West early tomorrow with this forecast with the best chances over the central and southern Colorado mountains tomorrow afternoon. Moisture will be on the increase but gusty outflow winds will still be more probable than excess runoff from storms...this may change by Monday. Temperatures Sunday may end up a degree or two cooler thanks to the added cloud cover and precipitation. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 251 AM MDT Sat Sep 14 2024 By Sunday night, a deep low pressure trough will be diving southward over the west coast, increasing the southerly flow across the area. Some sub-tropical moisture will advect northward allowing for increasing clouds and showers, although precipitation may initially have a tough time reaching the ground with more virga and gusty outflow winds initially before top down saturation occurs. The deep western low will park itself over the heart of the Great Basin on Monday before lifting northward across the Intermountain West Tuesday, helping drive a cold front and the negatively trough axis across the region Tuesday afternoon and evening. Monday and Tuesday appear to be the more active days in terms of more widespread showers and storms with plenty of diffluence as the region maintains a southwest flow ahead of this trough. Temperatures will start off near seasonal Monday before dropping to 5 to 10 degrees below normal on Tuesday in the valleys and 10 to 15 degrees below normal in the mountains following the trough and cold front passage. It looks to be breezy to windy as well during this time with a 100 kt jet streak rounding the base of this trough, H5 winds in the 50 to 60 kt range and H7 winds around 30 kts. Some of the highest peaks could end up with a dusting of snow by Tuesday. Wednesday and Thursday will still maintain a southwest flow but a much drier air mass looks to move in by then, affording us a break in the unsettled showery weather for a couple days. Another trough is projected to track through the Great Basin Thursday and move through our area Friday as an open wave, but this one looks weaker than the early week system and doesn`t appear to have as much moisture. This is different from previous model solutions so the jury is out beyond Wednesday. It does appear that the weather will turn cooler for mid to late week though and feel more like autumn which is right around the corner as the Autumnal Equinox occurs next weekend. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1030 PM MDT Fri Sep 13 2024 Expect mostly clear skies over the next 24 hours with terrain driven winds, becoming breezy at times during the afternoon. VFR conditions will prevail. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1130 AM MDT Sat Sep 14 2024 VFR conditions and light terrain driven winds are expected across eastern Utah and western Colorado during the next 24 hours. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...15 LONG TERM...MDA AVIATION...NL