Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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573 FXUS65 KGJT 122322 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 522 PM MDT Wed Jun 12 2024 .KEY MESSAGES... - Hot and dry conditions continue Thursday with temperatures 10 to 15 degrees above climatological averages and near record levels for some areas. - A storm approaches the region Thursday night leading to widespread showers and a few thunderstorms favoring the San Juan and central Colorado mountains Thursday afternoon/evening. - Expect a short-lived break in the heat Friday. && .SHORT TERM /THROUGH THURSDAY NIGHT/... Issued at 401 PM MDT Wed Jun 12 2024 Localized showers/virga and thunderstorms north of the I-70 corridor should diminish by, or shortly after sunset. Thereafter, expect clearing and cooling during the remainder of the night. Another hot day on tap Thursday as the upper level ridge axis shifts overhead. A low moves over the Desert Southwest during the day which will deliver a weak push of mid- level moisture. This may bring a few showers/thunderstorms to the Divide mountains, but most of the area, just much warmer than normal temperatures with moderate afternoon breeziness. Lift and moisture increases Thursday night as the low tracks eastward across northern Arizona. Models were consistent in suggesting that this will bring a chance of light showers and/or thunderstorms for the Four Corners area later Thursday night. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Issued at 322 PM MDT Wed Jun 12 2024 Friday looks to be the coolest and most unsettled day of the period as what was a closed low off the SoCal coast tracks inland and moves across the Great Basin as an open wave by Friday morning. This open wave trough will move across the CWA Friday afternoon and exit Friday evening. This low will pull in some deeper moisture from the southerly flow ahead of the system, with mixing ratios rising to around 5 to 6 g/kg and PWAT rising upwards of 0.75 to 0.9 inches by Friday afternoon. This moisture advection will be starting in the predawn hours, likely resulting in plenty of cloud cover and some light showers across the area by Friday morning. The timing of this moisture advection is key to whether we would see stronger convection and based on the earlier onset, would expect thunderstorm activity to be more isolated with embedded storms in the afternoon but generally light rainfall in the valleys with more moderate precipitation possible in the higher elevations. This is reflected pretty well in the QPF forecast as well as chance of wetting rain being higher in the mountains and low in the valleys where gusty outflow winds are still a concern. All this cloud cover and more widespread shower activity means high temperatures on Friday will take quite a hit as daytime heating will be limited, with high temperatures on Friday about 12 degrees cooler than the previous hot day on Thursday. We will end up closer to normal and maybe slightly cooler than normal for central and southern areas that look likely to see better shower activity on Friday, which will actually be a welcome reprieve from the unrelenting early Summer heat. The trough exits stage right Friday night and is quickly replaced by drier southwest flow as a high pressure sits over the Desert Southwest and keeps the PacNW trough at bay, leaving us in a dry southwest flow this coming weekend into early next week. Some moisture could linger over the Continental Divide in the far eastern peaks of our CWA for isolated afternoon convection, but overall, temperature should warm back up to 5 to 10 degrees above normal. The increasing southwest flow will result in breezy afternoon winds and lower relative humidity, especially Sunday and Monday as the jet associated with the PacNW trough dips into our CWA and tightens the gradient more. Some of our fuels are drying out and so those areas with dry fuels will need to be monitored closer as critical fire weather conditions may result in needing some Fire Weather products. No precipitation is expected beyond Friday`s unsettled weather as any shower activity with the PacNW trough later in the weekend into early next week looks to remain north of the Colorado-Wyoming border. So, conditions look to return to hot and dry shortly after our brief cool, cloudy and wet spell on Friday. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 519 PM MDT Wed Jun 12 2024 Showers and thunderstorms will continue across the north for the next 3-4 hours, until loss of daytime heating causes them to dissipate. Until then, terminals such as KHDN, KVEL, KEGE, and potentially KASE, can expect to see gusty and erratic winds as well as brief heavy rain and lightning. Remaining terminals will continue to see some gusty southwest winds and FEW to SCT skies. Clear skies will prevail tonight, with light and terrain driven winds. Drier conditions are expected tomorrow. VFR conditions will prevail for the next 24 hours. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...NL LONG TERM...MDA AVIATION...TGJT