180 FXUS65 KPSR 092315 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 415 PM MST Mon Jun 9 2025 .UPDATE...Updated 00z Aviation Discussion. && .KEY MESSAGES... - Dry conditions through the period with above normal temperatures through the week, peaking upwards of 7-10 degrees over the weekend - Fairly widespread Moderate HeatRisk through the entire week with increasing Major HeatRisk expected to increase by Sunday && .DISCUSSION... Satellite WV imagery and objective analysis this afternoon shows dry westerly flow aloft and clear skies dominating over the region as a subtropical ridge of high pressure remains centered off the coast of the Baja Peninsula. This is acting to keep temperatures several degrees above normal with highs expected to top out around 105-110 degrees this afternoon. In Phoenix, the high temperature this afternoon is expected to flirt with 110 degrees. If Phoenix does reach 110 degrees, it will be the first occurrence of the year. The average (1991-2020) first occurrence of 110 degrees in Phoenix is June 11th, so this would be pretty close to normal. Meanwhile, a shortwave trough is seen propagating through southern California into Arizona along the northern periphery of the ridge. Support from this weak trough combined with positive PWAT anomalies, daytime heating and orographic lift across northern portions of Arizona will promote the development of isolated to scattered showers and thunderstorms along the Mogollon Rim through the afternoon. Across our CWA, dry and hot conditions will continue with no rain expected. Following the passage of the weak shortwave Tuesday, zonal flow will prevail with the subtropical ridge pushing 500 mb heights to around 590 dm by Wednesday. Afternoon temperatures through the entire workweek will remain rather consistent with little day-to-day variability as daytime highs top out around 105-110 degrees each day. As a result, fairly widespread Moderate HeatRisk will be in place for the entire week, so everyone and those particularly sensitive to the heat should be sure to stay cool and limit time outdoors as well as drink plenty of water. By the end of the workweek, the stagnant pattern will begin to change as longwave troughing develops over the Pacific Northwest. Ensemble clusters show excellent agreement that this trough will amplify off the West Coast with the subtropical ridge shifting eastward and amplifying into the Desert Southwest. By this weekend, ensemble guidance show the subtropical ridge becoming centered near the AZ/NM border with 500 mb heights across the area rising to around 592-595 dm or above the 90th climatological percentile. As a result, the hottest temperatures of the year so far are expected this weekend into the beginning of next week with probabilities of reaching 110 degrees Sunday and Monday climbing in excess of 80-90% for Phoenix, Yuma, and El Centro. Latest NBM deterministic now has highs across the lower deserts climbing upwards of 110-115 degrees during this time. If these trends hold, the first Extreme Heat products of the year will likely be needed. && .AVIATION...Updated at 2315Z. South Central Arizona including KPHX, KIWA, KSDL, KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH: No major weather issues will exist through Tuesday afternoon under clear skies. Trends in wind speeds and directional shifts will be nearly identical to the past 24 hours. This will include periodic late afternoon/early evening gusts 15-20kt with minimal operational impacts. && .FIRE WEATHER... Dry conditions will continue through the week with above normal temperatures. Min RHs will be around 10-15% through much of the week, while Max RHs range between 20-50% (poorest in the eastern districts). Winds will tend to follow their typical diurnal tendencies with periods of modest afternoon upslope gustiness. Temperatures are forecast to further heat up this upcoming weekend with afternoon highs in excess of 110 degrees likely by Sunday across the lower deserts. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Smith AVIATION...Whittock/18 FIRE WEATHER...Smith/Young