Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
703 FXUS65 KTWC 181700 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 1000 AM MST Sun Aug 18 2024 .SYNOPSIS...There will be a daily chance of mainly afternoon and evening showers and thunderstorms through the week across southeast Arizona. The thunderstorms will be accompanied by the typical monsoon threats of strong wind gusts, localized heavy rainfall and flash flooding, and blowing dust. High temperatures will be several degrees above normal into at least the middle of the week. && .UPDATE...Decent moisture still in place, but large areas from near Tucson westward have been worked over in the past 12 hours. Remnant MCV drifting north of the area with another drifting up from Sonora. We`ll have some storms around but likely less than yesterday. Eastern areas should be favored, but it`s a little drier over there too. Current forecast reflects this well with lower chances out west and easy mountain initiation and slightly less favorable valley support. No updates. Please see the previous discussion below for additional details. && .PREV DISCUSSION... /issued 224 AM MST Sun Aug 18 2024/ An MCS across Sonora extended into Arizona and resulted in the development of late night convection that continues into the early morning hours to the north and west of Tucson. This activity will generally diminish over the next few hours with debris clouds through the early morning hours for most locales. The combination of the MCS which likely at least partially worked over the atmosphere and the expectation of being on the backside of an MCV later today will tend to result in considerably less convective activity. The HREF/CAMs are rather tepid with storm intensity and for those scattered storms that do form, it will mainly be from Sells eastward. Some drier air is moving into far eastern areas where PWAT values will drop down to near 1 inch. High pressure aloft will remain centered over New Mexico on Monday with our flow becoming a bit more easterly. Monday should see a bit of an uptick in storm coverage compared to today. Again, eastern areas are on the dry side so most of the storms should be west of a line from Safford to Bisbee. Ensembles are showing an inverted trough across Sonora on Tuesday. Confidence is low on just how much that will impact us on our side of the border but nonetheless a continuation in scattered showers and thunderstorms with the best chances south of Tucson. For the mid to late week period, troughiness will move into the west coast with the mid/upper level high to our east gradually shifting into Texas. This will result in a more southerly flow for our area and still a decent moisture plume between these systems. Therefore, a continuation of daily chances for showers and thunderstorms is expected through the end of the week. Temperatures will be about 3 to 6 degrees above normal through Tuesday then gradually lower to just a few degrees above normal through the end of the week. && .AVIATION...Valid through 19/12Z. BKN-OVC clouds AOA 15K ft AGL will diminish aft 18/12Z. SCT SHRA/TSRA W/NW of KTUS will also taper off through the early morning hours. Otherwise, SCT-BKN clouds at 6k-9k ft AGL redevelop aft 18/18Z along with ISOLD-SCT SHRA/TSRA thru 19/03Z before tapering off tonight. Expect MVFR conditions near TSRA, with VSBY restrictions, wind gusts to 45+ kts, heavy rain and mountain obscurations. Outside of thunderstorm wind gusts, wind speeds will be 12 kts or less, favoring a SWLY through NWLY direction during the afternoon/early evening hours and variable in direction at other times. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...There will be a daily chance of mainly afternoon and evening showers and thunderstorms across southeast Arizona through this week. High temperatures will be 3 to 7 degrees above normal through the Tuesday, then lowering to a few degrees above normal. Min RH values will be in the 20-30 percent range in most valleys locations (lowering to near 15 percent in eastern Cochise and the upper Gila River valley) through the middle of this week. Outside of any thunderstorm outflow winds, 20-foot winds will generally be 15 mph or less, with afternoon/early evening gusts to 20-25 mph and light winds overnight. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson