Area Forecast Discussion
Issued by NWS Tucson, AZ
Issued by NWS Tucson, AZ
242 FXUS65 KTWC 101627 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 927 AM MST Sat Aug 10 2024 .UPDATE... Going forecast is in good shape. Morning sounding came back with PWs at 1.55 inches, which is pretty decent. Storms that develop will have a tendency to be heavy rainers. && .PREV DISCUSSION... /issued 146 AM MST Sat Aug 10 2024/ .SYNOPSIS...Isolated to scattered mainly afternoon and evening showers and thunderstorms each day through the middle of next week. Storms will have the potential for heavy rainfall and strong wind gusts. High temperatures will be a couple of degrees above normal over the weekend, lowering to right around normal at the begining of next week and then rising to above normal levels again late next week. && .DISCUSSION...In the big picture, high pressure aloft will remain centered to our east/southeast between eastern New Mexico and central Texas into the middle of next week. This will keep southeast to south steering flow across southeast Arizona and the monsoonal moisture tap in place. Some drier air (PW values of 0.75-1.0") has pushed into Cochise, Graham and Greenlee counties from the east, which will limit convective activity in those areas today. Deeper moisture is then expected to move back into southern Arizona at the beginning of next week, as the upper high becomes centered over central Texas and a trough develops along the west coast, turning the flow across southeast Arizona more southerly. During the second half of next week, the models show the high pressure ridge splitting into two, with a center to our east over eastern Texas and another to our west over the eastern Pacific/southern California. The high pressure center to our west will shift eastward across northern Arizona late next week, with the upper ridge consolidating to our north/northeast over Utah and Colorado next weekend. This will lead to a drying trend late next week, with most shower/thunderstorm activity confined to southern most portions of the forecast area. For today, the CAM`s are showing isolated to scattered showers and thunderstorms primarily west of a Safford to Sierra Vista line. The HRRR and U of A WRF models indicate CAPE values are up today (versus Friday), with values generally between 700-1200J/kg and values peaking around 1500J/kg during the early evening hours from Nogales to Tucson and westward across central/western Pima County. This will be the focus area for thunderstorms late this afternoon through the evening hours tonight. The main threats will be localized heavy rainfall/flash flooding, strong gusty winds and blowing dust. Little change is expected on Sunday, with isolated to scattered mainly afternoon and evening showers and thunderstorms. Coverage however, will spread back east to the New Mexico border. The CAM`s are hinting at the possibility of an MCS developing just south of International Border, south of Nogales. The current forecast has the highest POPs Sunday in southern Cochise and Santa Cruz counties. Monday through Wednesday of next week, deeper moisture returns to southeast Arizona, with an areal increase in shower and thunderstorm coverage. Scattered to numerous afternoon and evening showers and thunderstorms are expected, with day to day variability due to the previous days activity and how late convection persists into the evening hours. At this time, the models are showing Monday to be the most active day. Thursday into the next weekend, drier air moves into western and northern portions of the state from the west/northwest. Isolated shower and thunderstorm chances will prevail from Tucson westward and to the north of Tucson, with scattered showers/thunderstorms to the south and southeast of Tucson. High temperatures will be a couple of degrees above normal (2-4 degrees) though Sunday, lowering to right around normal Monday through Wednesday of next week and then 1-3 degrees above normal Thursday through next weekend. && .AVIATION...Valid through 11/12Z. FEW clouds at 9k-12k ft AGL and BKN-OVC clouds AOA 15k ft AGL, becoming SCT-BKN clouds at 6k-9K ft AGL and BKN-OVC clouds at 10k- 14k ft AGL from 10/19Z thru the end of the forecast period. ISOLD- SCT SHRA/TSRA developing aft 10/19Z and persisting through 10/04Z before slowly diminishing. 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 less than 12 kts, favoring an SELY/SLY direction. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated to scattered mainly afternoon and evening showers and thunderstorms are expected through the weekend, with an increase in coverage early next week. Min RH values will be in the 20-30 percent range through the weekend, increasing early next week into the 25-40 percent range in the valleys (and higher in the mountains). Outside of 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. && $$ Public...Singer Aviation...Singer Fire Weather....Singer Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson