934 FXUS65 KPSR 262109 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 209 PM MST Sat Jul 26 2025 .KEY MESSAGES... - Near normal temperatures will warm to slightly above normal by the beginning of next week, resulting in widespread Moderate HeatRisk. - Very dry conditions will greatly inhibit any rain chances through the weekend. - Monsoonal activity should increase again across portions of Arizona region by the middle of next week. && .SHORT TERM /Today through Sunday/... Broad upper level troughing remains situated over the northeastern Pacific and extending into the Western US, with an embedded shortwave evident in mid-level wv imagery early this afternoon over Central CA and moving into Western NV. Meanwhile, a subtropical high is currently parked over the Southeast US, too far east to influence the flow aloft over AZ. This unusual late July setup has resulted in persistent, dry, southwesterly flow over the region, scouring out available moisture and eliminating rain chances across the entire state today. In fact, NAEFS/EPS mean PWATS today into the first half of Sunday are generally below 0.5" across AZ, representing values below the 10th percentile and in some places below the 2nd percentile of climatology for this time of year. Another consequence of the proximity of the trough to our northwest is a moderating of heights aloft, resulting in near normal temperatures (even slightly below normal further west this afternoon.) By Sunday, ensembles show heights aloft gradually building from the east as the subtropical high begins to shift westward. As this occurs, anticyclonic flow will begin to impinge on the eastern/southeastern portion of the state, reintroducing enough moisture for perhaps a few isolated showers/weak storms to develop. However, the forecast area will remain completely dry, with near zero PoPs through the remainder of the weekend. The primary sensible weather impact of this gradual pattern evolution starting Sunday will be increasing temperatures. Daytime highs are expected to reach near the 110 degree mark in the Phoenix area to 105-108 degrees across the western lower deserts. && .LONG TERM /Monday through Friday/... The first part of next week will see the trough to our northwest gradually weaken and likely lift a bit more to the north. As we begin to somewhat lose the dry westerly flow influence from this trough, the subtropical ridge is forecast to continue to retrograde westward. Previous guidance was fairly confident in a meaningful inverted trough moving out of northern Mexico and reaching southeast Arizona later Monday into Tuesday. This is still somewhat the case in the latest model runs, but the inverted trough looks weaker and now is likely to get held up, not reaching past southeast Arizona. The slight shift in the flow pattern should still allow for a period of southeast semi-moist flow into much of Arizona starting Monday, but the recent model shift now mostly keeps the better quality moisture across eastern Arizona through Tuesday. Very limited shower and thunderstorm chances will be possible across the eastern Arizona high terrain on Monday with slightly better chances on Tuesday, but still mostly relegated to the higher terrain. The flow pattern is not likely to change much going through the middle of next week and this should provide for daily chances for higher terrain convection and eventually increasing moisture into the south-central Arizona lower deserts via outflows. Guidance does try to indicate just enough moisture working as far west as the Phoenix area to provide for some very limited (10-15%) chances by next Wednesday. These daily low end rain chances may very well continue through the rest of next week as ensemble output shows little change in the positioning of the subtropical high to our east and the broad troughing to our northwest. Temperatures next week look quite stable with H5 heights mostly hovering within the higher end of the normal range. This should keep daily highs right around or maybe 2-3 degrees above normal throughout the entire week. The increased moisture and clouds should also lead to higher overnight lows across south-central and eastern Arizona with readings within the Phoenix metro mostly between 83-88 degrees each night. Lower humidities and generally clear skies across the western deserts should provide for overnight lows mostly in the mid 70s to lower 80s. && .AVIATION...Updated at 1756Z. South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Winds will follow typical diurnal trends through the TAF period, with speeds mostly at or below 10 kts and some afternoon gusts up to 15-20 kts. High cloud decks will become SCT this evening through tomorrow. No slantwise visibility impacts expected. Southeast California/Southwest Arizona including KIPL and KBLH: Winds at KIPL will predominantly favor the west while at KBLH winds will generally be out of the south to southwest. Wind gusts upwards of 20-25 kts are expected at both terminals this afternoon and evening. There is around a 20% chance winds exceed 30 kts at KIPL this evening for a couple hours. && .FIRE WEATHER... Very dry conditions with zero rain chances and near to slightly above normal temperatures will continue through the weekend. Some lower desert location may reach 110 degrees starting Sunday before moisture increases gradually across the eastern districts next week. MinRHs through Monday will be in the 5-10% range across the lower deserts with poor overnight recoveries of only 15-35%. Winds will tend to follow their typical diurnal tendencies with some afternoon upslope gustiness. With the increase in moisture next week there will also be increasing shower and storm chances across the eastern districts, especially later in the week. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ SHORT TERM...Whittock LONG TERM...Kuhlman AVIATION...Benedict FIRE WEATHER...Kuhlman