Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
024 FXUS65 KTWC 080953 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 253 AM MST Mon Jul 8 2024 .SYNOPSIS... Excessive heat continues through mid-week with high temperatures expected to approach record levels in some locations. Substantially drier air moving in from the north has reduced thunderstorm chances today, but returning moisture should begin to increase chances again starting Tuesday. && .DISCUSSION... The heat spell across southeastern Arizona continues with forecast highs approaching or exceeding at times daily record highs over the next several days. Forecast highs today and tomorrow in Tucson (111 and 110 degrees) would tie records for each day. The strong ridge over the western CONUS responsible for these hot temperatures will remain generally stationary through Tuesday, then will begin to shift east before becoming centered over Utah/Colorado this weekend. With this pattern shift will come a turning of the mean winds from northerly to easterly, and in turn better flow for moisture return into the region. The ongoing Excessive Heat Warning was expanded into the Santa Cruz county area zone and extended into Wednesday. It`s possible excessive heat may continue into Thursday, however the influx of moisture at that point adds uncertainty to the mix. Mid-level warming and a dry atmospheric column remains in place today, which leaves little opportunity for convection to develop. A very slight chance of a thunderstorm is forecast near the southern and eastern edges of Cochise county. On Tuesday, 500mb temperatures will cool a couple degrees and allow for modestly better instability to develop. While precipitable water should remain unimpressive still, a few thunderstorms will be possible Tuesday afternoon and evening, generally near and east of Tucson- Nogales with best chances closer to the New Mexico border. With a deeply mixed boundary layer in place, strong outflow winds will be possible under any thunderstorm. Similar setups are likely Wednesday and Thursday before flow becomes more easterly by Friday, ushering in richer moisture for the weekend. Daily precipitation chances increase notably through this period across southeastern Arizona as precipitable water values should range from near 1 inch to 1.5 inches and the upper low will become favorably positioned to usher in a stream of easterly shortwaves. && .AVIATION... SKC across southeastern Arizona outside of areas near KDUG and the New Mexico border where FEW-SCT ceilings around 12k feet are possible after 08/18Z, with a slight chance of a thunderstorm through the evening. Winds today become west to northwesterly and increase to 10 to 15 kts with gusts to 20 to 25 kts after 08/17Z, decreasing after 09/02Z. && .FIRE WEATHER... Today should see the lowest minimum relative humidities of the week as moisture is expected to gradually push back into southeastern Arizona in the coming days. Relative humidity values should fall into the single digits in lower elevations today, while west to northwest winds of 12 to 16 mph, with wind gusts up to 25 mph, are expected. Tuesday through Thursday minimum relative humidities should remain in the 10 to 16 percent range in lower elevations and 15 to 30 percent in mountain areas. 20-foot winds will generally be 15 mph or less each afternoon with occasional gusts to 20 mph. Daily chances for thunderstorms begin to arrive Tuesday, with the possibility of strong outflow winds under any thunderstorm. && .CLIMATE... Near record to record high temperatures today, Tuesday, and Wednesday. DATE Jul 08 Jul 09 Jul 10 FCST RCD/YR FCST RCD/YR FCST RCD/YR Tucson Intl Airport 111 111/1994 110 110/1979 110 109/2021 Picacho Peak 114 114/2017 113 113/1994 112 111/1995 Safford Ag Station 112 107/2002 108 108/1956 108 110/2003 Sierra Vista FD 102 102/2023 100 103/2003 100 102/2003 && .TWC WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM MST Wednesday for AZZ501>506- 509. && $$ Public...Edwards Aviation...Edwards Fire Weather....Edwards Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson