Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
993 FXUS65 KTWC 242129 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 229 PM MST Tue Sep 24 2024 .SYNOPSIS...Dry and warmer. High pressure will push temperatures back to well above normal levels this week and through the weekend with the hottest days expected to be Friday and Saturday. An Excessive Heat Warning is in effect both days from Tucson westward. && .DISCUSSION...An omega blocking pattern has set up over the western CONUS characterized by a closed low off the coast of California, ridge from the Pacific Northwest to the Southwest, and a trough over the Midwest. Unfortunately this general pattern will be in place for at least the next 7 days, which will lead to it feeling like summer again. Current temperatures are 2-4 degrees warmer than this time yesterday and will top out 6-8 degrees above normal. The warmup continues into the weekend with temperatures reaching their peak Friday and Saturday when highs will be 10-15 degrees above normal. Many locations will see record to above record highs over the next several days. The Tucson airport could see its latest occurrence of 105 degrees with the current record being Sep 22 (1989). Tomorrow chances of 105 or greater are around 20 percent at the airport and increase to 60 percent by Saturday. Probabilities are even higher in Marana and western Pima County. An easterly gradient will also set up through the weekend, which could also elevate overnight temperatures thanks to downslope warming. These temperatures are also supported by 850mb-700mb thicknesses. HeatRisk values are in the major category for the majority of the area from Tucson westward. Because of this and with temperatures being at or above record levels an Excessive Heat Warning has been issued for Friday and Saturday from Tucson westward. After Saturday temperatures decrease just enough to be out of the major category for most of the area, but with the ridge still in place temperatures will still be well above normal. && .AVIATION... Valid through 26/00Z. Generally SKC-FEW clouds 9k-12k feet through the forecast period. Surface winds east to southeasterly and under 12 kts through 25/15Z, then increasing to 12 to 17 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Dry conditions with a warming trend this week. Temperatures will be 6 to 12 degrees above normal through Thursday, peaking at 10 to 15 degrees above normal Friday and Saturday. 20-foot winds will generally be less than 15 mph with an easterly component through the weekend. Wednesday will see breezy southeast winds east of Tucson. Min relative humidities will be in the teens for the lower elevations and the middle 20s for the higher elevations. && .TWC WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning from 10 AM Friday to 7 PM MST Saturday for AZZ501-502-504-505. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson