Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
179 FXUS65 KTWC 151857 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 1157 AM MST Wed Oct 15 2025 .SYNOPSIS... Dry conditions and below normal temperatures prevail this week. Expect a warming trend this weekend to near normal temperatures Sunday into early next week. && .DISCUSSION... Mostly clear skies were observed this morning across southeastern Arizona, with pockets of cumulus as surface dew points into the lower 50s indicate modest low level moisture remains. A deep upper level trough is centered over the Great Basin today, with dry southwest flow in the mid-levels over southeastern Arizona. The upper trough is expected to track east through the work week, putting the desert southwest through a period of low height anomalies. Unseasonably cool temperatures will be the feature this week while the troughing pattern continues, with temperatures about 6-12 degrees below normal over the next several days. Coldest lows across desert locations will include the Sulphur Springs Valley with lows into the lower 40s (potentially isolated upper 30s). By this weekend the main upper trough is expected to be well east of the region, while a shortwave should break off and become closed over the eastern Pacific west of the Baja peninsula. The loss of the main trough should allow temperatures to moderate closer to normal Sunday into early next week, however this is where details become a bit murkier. There remains differences in guidance in how to handle the eventual eastward transition of the Pacific closed low, the depth of a Pacific Northwest trough next week that may impact this transition, and the potential for a leading impulse crossing the region this weekend. Certainly a mess of moving parts there with subsequent uncertainty in the temperature trend and possible moisture return. The current thinking is that most guidance doesn`t bring a big warm up, so temperature probabilities top out at around normal for this time of year early next week...with a healthy chance of below normal temperatures returning...which is what the current forecast advertises next Tuesday and Wednesday. The forecast remains dry but a non-zero chance of modest moisture return can`t be ruled out. && .AVIATION...Valid through 17/00Z. Mostly SKC with a few cumulus at 4k-7k feet through 16/02Z. Surface winds west to southwest 8-12 kts through 16/03Z with occasional gusts to 20 kts. Thereafter, surface winds light and terrain driven. Surface winds remain light and under 12 kts on Thursday. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Minimum RH values will be 30-40 percent in the valley`s today, with higher values in the mountains, then will lower into the 20-30 percent range in the valleys Thursday into the weekend. 20-foot winds mainly 15 mph or less this week, with occasional gusts to 20- 25 mph. High temperatures will be below normal into this weekend, warming to near normal levels Sunday and Monday. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Public...Edwards Aviation...Edwards Fire Weather....Edwards Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson