Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
072 FXUS65 KTWC 122141 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 241 PM MST Wed Jun 12 2024 .SYNOPSIS... Excessive heat continues through Thursday as high pressure results in very hot temperatures. Slight cooling Friday but temperatures still a few degrees above normal. Temperatures then nudge upward again this weekend into early next week. Generally dry conditions through the forecast period with a slight chance of mainly dry thunderstorms late Thursday into Friday. && .DISCUSSION... Upper level analysis features a low off the southern California and Baja coast, while a downstream ridge sits over Arizona. While the upper low will eject over the next couple days, the placement of the ridge axis will remain over southern Arizona long enough to persist excessive heat through Thursday. The high temperature on Thursday should approach 110 in Tucson, with MOS guidance ranging from 108 to 110 and the NBM providing a 20% chance of meeting the threshold. As the upper low approaches Thursday, a southerly push of modest mid- level moisture should at least create some cloud build-ups during the day. Measurable precipitation looks very unlikely, though a few areas receiving a few sprinkles or even an isolated dry thunderstorm can`t be ruled out. The low will fully eject on Friday, which should create an uptick in winds with a tightened pressure gradient. That said, the somewhat early timing of the wave passage along it becoming more open in nature leads to some uncertainty on the extent of the increased winds, and subsequently the level of fire danger Friday afternoon. At this time MOS guidance has winds approaching to around critical levels, with the NBM just a bit lower. With dry conditions still expected to be in place, the Fire Weather Watch looks to be in good standing for now. While temperatures should nudge down a few degrees under the passing low on Friday, broad ridging is expected to redevelop again this weekend which will bring temperatures back up around 6-8 degrees above normal. Heat Risk will increase, but potentially not as much as before as climatological temperatures are rising as well. Going into next week, western CONUS troughing will lead to southwest flow over southern Arizona, and an initially dry forecast. There continue to be signs however of the upper high shifting into the area around the end of next week, which may open the door for some better mid-level moisture to arrive. && .AVIATION... Generally SKC then FEW-SCT clouds around 20k feet AGL after 02Z. Northwest breeze gusting to around 15 kts decreases to 5 to 10 kts after 03Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER... Hot temperatures this week, with high temperatures 7-10 degrees above normal through Thursday and then 3-6 degrees above normal Friday through the weekend. Limited mid-level moisture will result in a slight chance of mainly dry thunderstorms in the higher terrain northeast of Tucson late Thursday and Friday. These storms may produce gusty and erratic winds, along with occasional lightning. Expect min RH values of 3-9 percent in the lower elevations and 7-15 percent in the mountains through this weekend, along with poor overnight recoveries between 20-35 percent in most locations. Outside of any thunderstorm outflows, 20-foot winds will follow typical diurnal patterns, with afternoon/early evening gustiness due to strong surface heating. Sustained 20-foot wind speeds will generally be 15 mph or less today, increasing to around 15 mph Thursday. Winds may increase a bit on Friday, especially east of Tucson-Nogales and closer to the Arizona/New Mexico border. A Fire Weather Watch remains in effect Friday for Fire Weather Zone 152 where winds of 15 to 25 mph and gusts up to 35-40 mph are possible. && .TWC WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM MST Thursday for AZZ501>509. Fire Weather Watch from Friday morning through Friday evening for AZZ152. && $$ Public...Edwards Aviation...Edwards Fire Weather....Edwards Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson