Forecast Discussion
130 FXUS65 KTWC 272038 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 138 PM MST Mon Jan 27 2025 .SYNOPSIS...Seasonable temperatures today then below normal temperatures Tuesday through Thursday. A storm system will approach and move through the area through much of this week bringing breezy conditions today, and chances for valley rain and mountain snow with the best precipitation chances Wednesday. Temperatures then rebound to above normal this weekend. && .DISCUSSION...Water vapor shows an upper level low centered just south of Las Vegas. This is leading to scattered showers over north central Arizona and a cumulus field from Tucson westward and north. A light shower or two will be possible this afternoon and evening in western Pima County, but overall chances are low (15 percent) to see any measurable precip. Otherwise clouds will stick around over the western half of the CWA with high temperatures a few degrees below normal. Winds will also be breezy south and east of Tucson. The winds and dry conditions will lead to elevated fire weather conditions along the AZ/NM border. The upper level low will slowly move across Arizona over the next couple of days. Moisture ahead of the system will be fairly shallow and PWAT values will be right around normal to just above normal for this time of year. Tuesday, thanks to the orientation of the trough and area of synoptic scale lift the best precip chances will be to the north. HREF members do show a few very isolated showers across southeast Arizona, but little measurable rain is expected. Best chances will be from Tucson west and north. Wednesday rain chances become more widespread as the core of the trough passes just to the north of the area. Hi-res guidance, even though its at the tail end of their forecast, shows isolated to scattered shower activity. QPF will be on the lighter side, generally less than 0.15" with isolated higher amounts possible in Pinal, Graham, and Greenlee counties. Snow amounts in the mountains expected to be 1"-4" with mountains north of I-10 on the higher end of that range and those south of I-10 on the lower end. Snow levels drop to 3500-4000 feet Wednesday morning, so some flurries are possible for valley floors east of Tucson but no accumulation is expected. Lingering snow showers will be possible Thursday in the White Mountains. Temperatures will drop to 9-13 degrees below normal Tuesday into Thursday with Tucson possibly seeing another freeze Thursday morning. However cloud cover could keep overnight temperatures above freezing. By Thursday the low will be moving into the southern Great Plains and ridging will be building in behind it. With heights increasing temperatures will also be on the increase. Friday expect highs to be around normal then increasing to above normal by this weekend. Tucson could see high temperatures in the low 80s again by early next week. && .AVIATION...Valid through 29/00Z. From Tucson-Nogales west, expect BKN clouds 4-8kft AGL for the entire period. East of Tucson skies will be SKC through tonight then FEW-SCT cumulus 4k-8k developing Tuesday afternoon. Slight chance (20 percent) of -SHRA Tuesday afternoon mainly from Tucson northward. SFC winds SWLY winds 10-18 kts with gusts 25-30 kts through the early evening then becoming variable less than 8 kts. Strongest winds will be at KDUG terminal. Tuesday afternoon winds become southwesterly 10-15 kts with KDUG again on the higher end of that range. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Elevated fire weather conditions are expected mainly across Cochise County this afternoon, but not widespread enough for Red Flag issuance. As a weather system moves through this week it will bring a chance for mountain rain and valley snow with the most widespread precipitation chances on Wednesday. Min RH values will be 15-30 percent in the valleys and 30-45 percent in the mountains through Friday. This weekend min RH drops to below 15 percent. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Hardin Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
NWS TWC Office Area Forecast Discussion