


Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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638 FXUS65 KPSR 082149 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 249 PM MST Tue Jul 8 2025 .UPDATE...Updated Short Term Discussion. && .KEY MESSAGES... - Strong high pressure over the region will result in well above normal temperatures through midweek with afternoon highs forecast to reach and exceed 115 degrees across most of the lower desert communities Wednesday - The heat will result in widespread Major HeatRisk with Extreme Warnings in effect for much of the region today through Thursday - Temperatures lower a few degrees by the end of the week through this weekend, but remain above normal - Thunderstorm activity will continue to be limited to the Arizona high terrain and southeast Arizona during the next several days && .SHORT TERM /TODAY THROUGH WEDNESDAY/... High pressure has spread across all of the Southwest and strengthened considerably since yesterday. Latest mesoanalysis is showing 597-598dam H5 heights over AZ and SoCal, which is right around record heights for this time of year. These near record mid level heights has not fully translated to max PBL heating quite yet, as indicated by a minimal increase in 850mb temperatures (+1-2C) on Phoenix aircraft soundings and mesoanalysis over the last 24 hours. Highs this afternoon are forecast to be 2-4F warmer than yesterday, with lower deserts topping out around 108-113F. An Extreme Heat Warning is now in effect for the South-Central AZ lower deserts and the San Carlos area, as today`s temperatures push the HeatRisk level up to Major, meanings everyone is susceptible to heat health impacts without adequate relief. The full impact of this strong high pressure over the region will be felt tomorrow as PBL heat peaks and surface temperatures warm another ~5 degrees over today`s highs. The Extreme Heat Warning will expand to nearly all of Southern AZ and SoCal tomorrow, with widespread Major HeatRisk as afternoon high temperatures are forecast to reach 114-118F across the lower deserts. A high of 118F is now forecast for Phoenix, from the latest NBM deterministic, which if it pans out would break the daily record of 116F set last year and in 1958. Daily records will also be reachable in Yuma and El Centro tomorrow. Morning lows the next few days will also be pushing daily record warm lows. The H5 height magnitude and 850mb temps with the current strong high is comparable to the heights and temperatures with the strong highs that produced 118H highs in Phoenix in 2024 and 2023. Aside from the heat, there was a low level moisture flux last night that pushed surface dew points into the 50s to around 60F. Despite this, strong subsidence and capping over the lower deserts will inhibit any convection potential and afternoon storms will remain focused over the higher terrain north and east of Phoenix and in Southeast AZ. A weak northerly steering flow over the Rim this afternoon will be capable of bringing a few showers and maybe an isolated storm down into parts of southern Gila County and far eastern Maricopa County. Any storm will be capable producing strong gusty outflow winds, given high DCAPE (1700-1800 J/kg), with around 30% HREF neighborhood probabilities for >35 mph outflow winds. There is also potential for some gusty outflows to descend toward the lower deserts this evening. Little to no rainfall accumulation is expected. HREF shows afternoon convection tomorrow will be even more isolated and less intense north and east of Phoenix tomorrow. && .LONG TERM /THURSDAY THROUGH MONDAY/... The subtropical high is expected to weaken slightly heading into Thursday as the energy leftover from the cutoff low migrates eastward into the Great Basin and Intermountain West Regions. This will result in a slight decrease in the heights aloft and thus afternoon high temperatures will be slightly cooler but still hot enough for areas of Major HeatRisk to remain in place with Extreme Heat Warnings remaining in effect for all of the lower desert communities. Heading towards the end of the week through next weekend, the high will continue to very gradually migrate westward towards the southern CA coastline and as a result heights aloft will continue to decrease slightly more. This will translate to slightly cooler temperatures, but still remain a few degrees above normal as afternoon highs across the lower deserts will average around 110 degrees, resulting in widespread Moderate HeatRisk. With the subtropical high migrating westward into southern CA towards the end of the week and weekend, the upper-level flow pattern will remain quite unfavorable for any deep moisture influx. Thus conditions are expected to remain mostly dry across much of the region, with any thunderstorm activity limited across the White Mountains through the southeastern third of AZ. As the high migrates into the southern CA coastline during the weekend, the upper-level flow is expected to turn out of the north, which will bring in even drier air with the latest EPS and GEFS showing PWATs dropping below one inch. Thus, thunderstorm activity will likely be more limited, even across the higher terrain areas. This overall dry pattern will continue into early next week before the high potentially repositions near the Four Corners by the middle to latter half of next week, which if it materializes, would be a more favorable flow pattern to advect deeper moisture into the region and reintroduce higher thunderstorm chances. && .AVIATION...Updated at 1755Z. South Central Arizona including KPHX, KIWA, KSDL, KDVT: No major aviation weather concerns will exist through the TAF period under FEW mid and high clouds. Winds will predominantly favor the W/NW through this evening. Followed by winds going light and variable during the overnight hours at KSDL and KDVT, KPHX going light and variable around sunrise, and KIWA going light southeasterly during the overnight hours. Expect gusts to around 20 kts this afternoon into the early evening. Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns are expected through the next 24 hours under periods of FEW to at times SCT mid and high clouds. Winds will continue to vary between S/SE and SW, with extended periods of light and variable winds, particularly at KIPL. Wind speeds will generally remain AOB 10 kts, though some gusts to around 15-20 kts are possible, particularly after the switch to a SW`rly direction this evening. && .FIRE WEATHER... Regionally dry conditions and above normal temperatures will persist through the next week as lower deserts highs reach and exceed 110 degrees nearly every day. MinRH values will range from 10-20% each day, while MaxRH values will be the lowest tonight and Wednesday night at 20-40% before increasing up to 30-50% the rest of the week for most of the area. One exception will be across Imperial and southern Yuma Counties where periodic gulf surges will result in MaxRH values in excess of 50%. The overall wind pattern will follow the familiar diurnal trends, with some afternoon/early evening breeziness (15-25 mph peak gusts). An uptick in the winds is expected Thursday and Friday afternoons (25-35 mph peak gusts). This may lead to locally elevated fire weather conditions, primarily on Thursday due to drier conditions. Very minimal rain chances will exist during the next several days, focused north and east of Phoenix and in Southeast AZ, with CWR <10% through at least next weekend. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Extreme Heat Warning from 10 AM Wednesday to 8 PM MST Thursday for AZZ530>533-535-536. Extreme Heat Warning until 8 PM MST Thursday for AZZ534-537>540- 542>544-546-548-550-551-553>555-559-560. Heat Advisory from 10 AM to 8 PM MST Wednesday for AZZ557-558- 563. Extreme Heat Warning from 10 AM to 8 PM MST Wednesday for AZZ541- 545-547-549-552-556-561-562. CA...Extreme Heat Warning from 10 AM Wednesday to 8 PM PDT Thursday for CAZ560>570. && $$ SHORT TERM...Benedict LONG TERM...Lojero AVIATION...Berislavich/Whittock FIRE WEATHER...Benedict/Lojero