Forecast Discussion
380 FXUS65 KTWC 160825 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 125 AM MST Mon Mar 16 2026 .SYNOPSIS...High pressure along the West Coast will result in warm afternoon temperatures the next few days. More significant heat is on tap for the second half of the week into the weekend as high pressure strengthens across the Desert Southwest. High temperatures will become 20 to 25 degrees above normal during this period, especially Friday and Saturday. && .DISCUSSION...The upper pattern this morning is defined by a high amplitude ridge of high pressure along the West Coast, with a high center positioned off the central California coast near 36N/127W. The amplitude of the mean upper ridge will push a surface high south along the Rockies into ERN NM/WRN TX today, resulting in a weak back-door front nudging into the extreme SE corner of Arizona. This front will really struggle to get west of the continental divide in SW NM, but should be enough to cool afternoon temperatures down a few degrees east of Tucson. So, instead of it being 10 to 15 degrees above normal Sunday, it will be 10-15 degrees above normal from Tucson west, and 5 to 10 degrees above normal east of Tucson to the AZ/NM border. Otherwise, the mean ridge axis will slowly track east the next few days, with the high center moving through southern California Wednesday, and into southwest Arizona Thursday and Friday. The 16/00Z ECMWF (596 dam) and GEFS (595 dam) ensemble means peak around 20/06Z Thursday evening over south central Arizona, weakening Sunday as the ridge flattens into Sonora and Chihuahua Mexico. The hottest temperatures will be on Friday and Saturday, with readings 100 to 108 degrees from Tucson west into the lower deserts, and 95 to 100 degrees in the eastern valleys. These reading are 20 to 25 degrees above normal, and will result in a moderate to major HeatRisk across the lower elevations of Southeast Arizona. We still have an Extreme Heat Watch in effect from Thursday into Sunday, and confidence is high that these temperatures will pan out. This is supported by the 16/05Z NBM probability of 100+ degrees at the Tucson International Airport (KTUS) of 50-60% Thursday, 80-90% Friday and Saturday, and 50-60% again Sunday. The good news is that there is an end in sight for the heat. Numerical models want to flatten out the ridge with an impulse moving east into the Great basin late Sunday into Monday. Until then, all the attention will be on the heat slated to impact Southeast Arizona the second half of the week. && .AVIATION...valid through 17/12Z. SCT-BKN cirrus clouds at or around 20k ft AGL through the forecast period. Surface winds generally terrain driven and less than 10 kts through 16/17Z. SFC winds east of Tucson will then be southeasterly 10-15 kts with gusts to 20 kts this afternoon with the strongest winds in KSAD. From Tucson west, northwesterly surface winds around 10 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...High pressure along the West Coast will result in warm afternoon temperatures the next few days. More significant heat is on tap for the second half of the week into the weekend as high pressure strengthens across the Desert Southwest. High temperatures will become 20 to 25 degrees above normal during this period, especially Friday and Saturday. A surface high pressure moving south across eastern new mexico will result in easterly 20-foot winds 5 to 15 mph with gusts to 10-25 mph along the Arizona/New Mexico border today. Otherwise, 20-foot winds will be westerly under 5 to 10 mph with a few afternoon gusts to 20 mph through Saturday. Minimum RHs 8-18 percent areawide through the middle of the week, then lowering into the single digits late this week into this weekend. && .TWC WATCHES/WARNINGS/ADVISORIES... Extreme Heat Watch from Thursday morning through Sunday evening for AZZ501>509. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
NWS TWC Office Area Forecast Discussion