FXUS65 KPSR 232000 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 100 PM MST Sun Aug 23 2026 .KEY MESSAGES... - Isolated to scattered thunderstorms, some strong to severe, are expected this evening across south-central Arizona. - Increasingly less favorable conditions for thunderstorms will develop starting Monday with virtually no chances for rain from Tuesday through the rest of the week. - High temperatures will reach or exceed 110 degrees nearly every day this week and will be near daily records, while morning lows remain unusually warm. - Extreme Heat Warnings are in effect through Saturday with daily Major to Extreme HeatRisk. && .SHORT TERM /TODAY THROUGH MONDAY/... Some upper level jet support and mid-level gravity waves helped spark off a line of high-based scattered showers and storms across southwest AZ this morning. This activity has since weakened and dissipated. Surface-based moisture has also increased across southwest AZ and areas south of I-8. Dew point temperatures at midday in Yuma County to western Pima County were up to 65-75 degrees. This moisture return in southern AZ will likely help fuel later afternoon and evening thunderstorms. Overall, model guidance still suggests this afternoon through this evening becoming a somewhat busy monsoon period. Outside of southern AZ, where the best moisture return was, boundary layer conditions remain similar to the past couple of days with sub-optimal moisture (mixing ratios around 8 g/kg) and limited instability (few hundred J/kg MLCAPE). Initially through much of, if not all of, this afternoon storms should favor higher terrain areas, including portions of La Paz County, and it may even look like it will not become active at all. However, hi-res guidance continues to show the best time period for activity across south-central AZ coming around and after sunset. Guidance shows storms being a bit slower to develop in Pima County, but when they do they do they will have the best potential to become strong to severe, tapping into the best moisture and instability. The storms to the south this evening will then be capable of pushing one or multiple strong and dusty outflows northward into south-central AZ, which may then trigger additional storms. Some hi-res model runs also suggest outflow collisions may occur, with outflows also from the north, but confidence in outflows coming down from northern AZ is low. Additionally, there are indications the storms to the south may develop into an MCV and track northward through Phoenix this evening. Strong to locally severe wind gusts will be the primary weather hazards, with very high DCAPE values up to 1800-2000 J/kg. Localized flash flooding may also become a threat with any slow-moving storms or training of storms, with the best potential southwest of Phoenix where moisture will be highest. Convective chances for Monday are even more uncertain as guidance generally shows at most a 10% chance despite moisture and instability being better than today. However, subsidence will be much stronger on Monday as the subtropical ridge begins to move westward back into our region. We will have to wait until tonight to have a better idea on the storm potential for Monday, but it does seem to be considerably lower than this afternoon/evening. Temperatures today will again be right near record highs with lower desert readings from 110-115 degrees. The increased boundary layer moisture expected for Monday should hold daytime highs down a bit with NBM forecast highs currently between 106-111 degrees, but heat indices will mostly match what are expected today. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Forecast attention turns away from monsoon storm potential and back toward the extreme heat conditions starting Tuesday. The subtropical high center will continue to shift westward into our region into the middle part of the week with the center likely settling somewhere over southern Arizona from Wednesday through at least Friday or Saturday. Forecast H5 heights are also shown to reach 594-597dm for the latter half of the week which places it just shy of climatological records for late August. NBM temperature guidance remains quite consistent showing highs rising into a 112-116 degree range for the latter half of this week as conditions dry out. Daily temperature records in Phoenix will continue to be in jeopardy through the entire week, but are likely to fall short in Yuma and El Centro. Once the high center moves overhead by Wednesday, rain chances will essentially go to 5% or less. As of now, conditions for any monsoon storm activity do not look good through next weekend. && .AVIATION...Updated at 1800Z. South Central Arizona including KPHX, KIWA, KSDL, and KDVT: The potential for multiple outflow boundaries resulting in sudden, gusty wind shifts this evening, as well as SHRA/TSRA developing in the Phoenix Airspace presents the greatest weather issue during this TAF period. Winds will favor E/SE late this morning followed likely by a period of VRB winds before shifting out of a prevailing westerly direction by 20-22Z this afternoon. TS over the northern and eastern AZ high terrain are likely to send a first outflow towards the lower elevations late this afternoon/early this evening, which would cause a sudden wind shift out of a N/NE'rly direction. A cluster of strong storms is then expected to develop over western Pima, southwestern Pinal, and/or southern Maricopa Counties this evening, which would likely send a second, stronger outflow across the terminals from the S/SW. This second outflow may cause temporary surface VIS restrictions due to blowing dust and more prolonged slantwise VIS issues if rain does not follow. Chances for SHRA/TSRA remain around 20-30% across the terminals this evening, and so have included this in PROB30 groups between 04-07Z. The wind forecast is very low confidence this evening into the overnight hours due to the possible influence of multiple outflows, and gusty, erratic winds are expected if SHRA/TSRA develop near the terminals. Cloud bases will remain mostly above 10 kft AGL through the period. Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation concerns are expected through the next 24 hours. Winds at KIPL will favor southeasterly directions. TS activity over the Baja spine may send an southwesterly outflow into KIPL by the late afternoon hours, with a less than 20% chance for direct TS impacts. KBLH will swing between south to SW'rly winds, with occasional gusts to around 20 kts. There is also a low chance (less than 10%) for SHRA/TSRA conditions at KBLH, particularly during the overnight period. FEW-SCT mid and high level cloud decks will be common through the period. && .FIRE WEATHER... Hot temperatures will prevail through the entire week with shower thunderstorm chances mainly today and possibly Monday. Strong gusty winds will be possible late this afternoon and evening with any thunderstorms, while chances for wetting rains will remain below 20%. Minimum RHs will improve through Monday with readings of 15-25% today and 20-30% Monday, before dropping back into the teens into the middle part of the week. Temperatures will be around 5-10 degrees above normal, with lower desert highs eclipsing 110 degrees nearly every afternoon. Outside of thunderstorm outflow winds, winds will follow the typical diurnal tendencies with some modest afternoon upslope gustiness. && .CLIMATE... Record highs: Date Phoenix Yuma El Centro ---- ------- ------------- Aug 23 114 in 2011 115 in 2011 116 in 1969 Aug 24 115 in 2020 119 in 1985 117 in 1985 Aug 25 113 in 2011 116 in 1962 117 in 1962 Aug 26 117 in 2011 115 in 2020 115 in 1981 Aug 27 114 in 2023 120 in 1981 117 in 1981 Aug 28 117 in 2023 118 in 2023 117 in 2009 Aug 29 116 in 2023 117 in 1954 117 in 2005 && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Extreme Heat Warning until 8 PM MST Saturday for AZZ530>555-559- 560. CA...Extreme Heat Warning until 8 PM PDT Saturday for CAZ562-565>567- 569-570. && $$ SHORT TERM...Benedict/Kuhlman LONG TERM...Kuhlman AVIATION...Whittock FIRE WEATHER...Kuhlman CLIMATE...18/Kuhlman