FXUS65 KTWC 032149 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 249 PM MST Tue Dec 3 2024 .SYNOPSIS... Near to above normal temperatures through the weekend. Slight chances for light rain and high elevation snow arrive east of Tucson during the second half of the work week. Cooler temperatures are possible early next week. && .DISCUSSION... The upper level pattern remains defined by an amplified ridge centered over the west coast with a weak trough underneath. This trough and an associated jet streak were beginning to cross the southwest coastline this afternoon. Under modest upper level divergence associated with the approaching jet streak, a tightened surface pressure gradient has produced breezy southeast winds earlier today, which will turn southwest as the upper jet crosses through this evening. Observed wind gusts have ranged from 15 to 25 mph across much of southeastern Arizona today and while breezes will continue through the early evening, these gusts should gradually diminish in magnitude over the next few hours. The upper low will stall and become at least partially cutoff over the desert southwest over the next several days. This will bring temperatures down closer to normal, though still likely a few degrees above with a lack of a more significant cold push associated. Additionally, recent model trends bring in a bit more moisture into eastern portions of the area as the low wraps up. The depth of this moisture remains uncertain however as there are model differences in the strength of of the upper low and how far west its able to bring in moisture adequate for precipitation. At this point chances for light showers and high elevation snow are highest in the White Mountain area and near/east of Safford- Willcox-Douglas, with probabilities Thursday and Friday ranging from 20 to 30 percent and near 40 percent in the Whites (with slight chances there starting as early as tomorrow afternoon). Overall precipitation amounts should be light with no more than a few hundredths likely at any one location with just light snow at the mountain tops. An upper level pattern switch still looks reasonably likely early next week with a digging trough dropping south/southeast out of the Pacific northwest. At this lead time there remains notable differences in the wave amplitude (partially dictated by how soon the previous cutoff low exits), which will impact temperature probabilities. Ensembles generally agree on the occurrence of the pattern switch overall, with the warmer side of the ensemble spread still bringing highs down to normal levels (instead of the above normal temperatures southeastern Arizona has been seeing). A deeper solution would bring colder temperatures and potentially precipitation chances, however a more dry outcome with cooler temperatures looks more likely given the trajectory. && .AVIATION...Valid through 05/00Z. Southeasterly winds in the Upper Gila River Valley and southerly to southwesterly winds elsewhere will drop to 7 to 10 kts this evening, before becoming light and terrain driven after 04/03Z. Winds will then be light through Wednesday. Generally SKC through the period with a few cirrus clouds. Some low stratus can't be ruled out early Wednesday morning in eastern areas such as near KSAD- KDUG, however confidence is low in this outcome. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Near normal to above normal temperatures continue through the week. Minimum relative humidities will be on the gradual increase over the next several days. Values tomorrow range from 15 to 20 percent west of Tucson and south near the International Border, to 30 to near 40 percent in the Upper Gila River Valley. By Friday lowest values should exceed 25 percent across most of southeastern Arizona with minimum relative humidities above 35 percent east of Tucson. This moisture push will also bring slight chances for light showers and high elevation snow during the second half of the week, generally in eastern zones. Winds Wednesday through the weekend will be light and terrain driven. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Public...Edwards Aviation...Edwards Fire Weather....Edwards Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson