657 FXUS65 KTWC 160857 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 156 AM MST Thu May 16 2024 .SYNOPSIS...Locally breezy today, with showers and thunderstorms likely in the White Mountains and a slight chance of showers and thunderstorms to the east of Tucson. A slight chance of showers and thunderstorms persist in the White Mountains on Friday with dry conditions elsewhere. Dry conditions return areawide Saturday into next week. High temperatures will be right around normal today, with highs warming to several degrees above normal Friday into early next week. && .DISCUSSION...Partly to mostly cloudy skies were observed across most of the state early this morning. While some weak convection still persists across southeast Arizona at 0145, the trends over the last hour are downward and little if any precipitation is reaching the ground (maybe a few sprinkles). Dewpoints remain low across the forecast area, in the mid 20s to mid 30s, although mid level moisture has increased versus 24 hours ago. Satellite based total precipitable water values are generally between 0.50-0.65", with lower values around 0.35" along the International Border. A weak upper low lifting northeast across the forecast area today will interact with this moisture, resulting in precipitation chances across mainly the eastern half of the forecast area. The highest probabilities for measurable rainfall will be in the White Mountains, with likely pops this afternoon/early evening. Overall, there will be a slight chance of showers/thunderstorms east of an Oracle to Sierra Vista line. However, the thunderstorms further south will be mainly dry, with gusty/erratic winds and lightning potentially causing new fire starts, but little to no rainfall. Observed and model soundings across the south/southeast portion of the forecast area have the classic inverted V look with mid level moisture residing between 600-650 mb (and DCAPE values around 1500J/kg), which all translates into the potential for some stronger thunderstorm outflows. Outside of any thunderstorm outflows, this system will result in elevated wind speeds and near critical fire weather conditions to the east of Tucson today, with west-northwest winds of 15-20 mph and gusts to around 30 mph (although min RH values may be just above the critical thresholds of 15 percent). Shortwave ridging begins to build in across the desert southwest on Friday. This will lead to warmer temperatures and drier conditions, with just a slight chance of showers/thunderstorms persisting in the White Mountains. High temperatures will top out 3-5 degrees above normal on Friday. Dry conditions then return areawide Saturday and Sunday with even warmer temperatures. Highs will be 6-9 degrees above normal, with readings in the upper 90s in the lower deserts from Tucson westward. Tucson hitting the century mark either Saturday or Sunday is not out of the question. The ensembles/deterministic models show another weak system moving across the area at the start of next week. This will result in breezy to locally windy conditions on Monday and high temperatures lowering back to near or slightly above normal readings by Tuesday. && .AVIATION...Valid through 17/12Z. SCT-BKN clouds at 8k-11k ft AGL thru the forecast period. Numerous -SHRA/-TSRA to the northeast of KSAD in the White Mountains between 16/17Z and 17/05Z, with a slight chance of -SHRA/-TSRA east of a KE77 to KALK line between 16/19Z and 17/03Z. SFC wind less than 12 kts and variable in direction thru 16/17Z and again aft 17/04Z. SFC wind between 16/17Z and 17/04Z, WLY/NWLY at 12-20 kts and gusts to 22-30 kts, with the strongest SFC wind east of KTUS in the vicinity of KALK, KDUG and KSAD. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...High temperatures will be right around normal today. Highs then warm to 3-5 degrees above normal Friday and 6-9 degrees above normal Saturday and Sunday, before lowering back to within a couple of degrees of normal next Tuesday. Min RH values in the valleys will be in the 10-20 percent range today and then in the single digits to lower teens Saturday into the middle of next week, with values in the mountains between 20-35 percent today and 10-20 percent Saturday through the middle of next week. 20-foot winds will generally follow typical diurnal wind trends through early next week, with afternoon and early evening gustiness due to strong surface heating. The strongest 20-foot winds will be today and next Monday, especially to the east of Tucson, with wind speeds of 15-20 mph and gusts to around 30 mph. West-northwest winds are expected today, with southwest-west winds on Monday. Mid level moisture in place, combined with a weak upper low will result in showers and thunderstorms likely in the White Mountains today and a slight chance of showers and thunderstorms to the east of an Oracle to Sierra Vista line. While some wetting rainfall may occur in the White Mountains today, the majority of the thunderstorms will be dry, with gusty/erratic winds and lightning, but little to no measurable rainfall. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Zell Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson