Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
363 FXUS65 KTWC 230926 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 226 AM MST Sun Feb 23 2025 .SYNOPSIS... Dry conditions and well above normal high temperatures expected for southeastern Arizona through this coming week. && .DISCUSSION... In the upper levels this morning, an exiting shortwave was moving into and through the southern plains, while a shortwave ridge was located over southern California. This ridge is expected to move over southern Arizona by Monday morning, with associated height rises and warmer low-mid level temperatures arriving with it. Into mid-week, this ridge will flatten with flow aloft becoming generally zonal. Under these positive height anomalies, temperatures are expected to become well above normal with highs in the 80s through at least mid-week across lower elevations of southeastern Arizona. Wednesday-Thursday, an amplified ridge is expected to develop over the western CONUS, with southern Arizona sitting at the base between the strongest height anomalies to the north and the flatter heights to the south. There is some modest uncertainty in high temperatures during this period thanks to shifting of the ridge axis and amplitude in guidance as well as the handling of a shortwave crossing southward through the eastern periphery of the ridge. Recent model trends have seen highs Wednesday and Thursday come down a bit thanks to this shortwave, however even the cooler solutions keep highs at least 10 degrees above normal. The combination of this ridge axis and shortwave passage may also tighten a surface pressure gradient on Thursday, increasing easterly winds. Though the aforementioned synoptic uncertainty applies here, a range of 10-20 mph sustained winds looks reasonable at the moment, with stronger winds in areas exposed to easterly flow. A shortwave should break off an eastern Pacific trough by late this week, potentially moving into the region by this weekend. There remains some fairly major differences in model guidance regarding timing and amplitude. Quicker solutions (about 20 percent of them) have the shortwave crossing southern Arizona on Friday while most of the others slow the crossing down until Saturday. This uncertainty will also impact any precipitation chances as a quicker and more progressive wave likely keeps precipitation into central to northern Arizona, while a closed and slower shortwave should bring precipitation further south. At this time forecast precipitation chances still remain very low given the range of possibilities and the weak moisture draw associated with this pattern. Temperatures and wind potential will also be impacted by how the wave emerges, though it looks likely that temperatures remain above normal this weekend. && .AVIATION...Valid through 24/12Z. Light winds and mostly SKC through the forecast period. Winds will transition from variable and terrain driven to north- northwesterly 5-10 kts this afternoon. Aviation discussion not updated with TAF amendments. && .FIRE WEATHER... Dry conditions with minimum relative humidity values in the 5-10 percent range through the week. Temperatures are expected to be warm with highs 10-16 degrees above normal. Winds generally light and terrain driven through Wednesday with occasional afternoon gustiness. Breezy easterly winds possible Thursday, which will need monitoring for potentially elevated fire weather conditions. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Public...Edwards Aviation...Edwards Fire Weather....Edwards Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson