FXUS65 KPSR 161019 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 319 AM MST Thu Apr 16 2026 .KEY MESSAGES... - A weather system passing the region to the north will result in widespread breezy conditions by this afternoon followed by locally windy conditions and elevated fire weather concerns Friday along the Lower Colorado River Valley. - A Wind Advisory will be in effect from early Friday morning into the early afternoon for the Lower Colorado River Valley and portions of Southeast California. - After a brief stint of near and below normal temperatures over the next few days, readings will rebound with widespread afternoon highs in the 90s expected by the end of the weekend. && .SHORT TERM /TODAY THROUGH FRIDAY/... Midlevel water vapor imagery early this morning depicts a shortwave trough progressing over the Pacific Northwest with its base now rounding the Great Basin. Meanwhile, a much weaker upper level low off the Northern Baja has formed and begun to draw closer to the forecast area, sending abundant high clouds towards the region. The more potent shortwave over the Pacific Northwest will continue progressing over the intermountain west over the next 24-36 hours, becoming somewhat more amplified as its southern extent brushes Northern AZ. Regional pressure gradients will increase through tonight as a result, leading breezy conditions to materialize over much of the area later today. However, guidance has backed off slightly on the magnitude of gusts this afternoon, perhaps picking up on the influence of the high clouds streaming over the region, which will inhibit better momentum transfer towards the surface during the typical peak mixing timeframe. Thus, expect widespread gusts to between 15-25 mph later today, with locally higher gusts in the areas typically prone to gap winds and mountain rotor activity in Western Imperial County. The strongest winds from this initial shortwave will actually come Friday, particularly along the Lower Colorado River Valley and wind prone areas/prominent terrain features in Southeast CA. As the shortwave progresses E/SE'wrd, it will send a dry front down the Colorado River Valley. Pressure packing behind the front will be the impetus to form a nocturnal LLJ, with NAEFS mean 850 mb winds accelerating upwards of 30 kts over a relatively small area. This is above the 99th percentile of CFSR climatology. Expect windy conditions to materialize, particularly after sunrise, with northerly gusts to 30-45 mph becoming common and locally stronger gusts over ridgelines/terrain features. This will present difficult driving conditions, especially for high profile vehicles along the section of I-10 near and west of Blythe, CA, and some localized channels of blowing dust may be observed. A Wind Advisory has been issued for Friday, valid 3 AM through 1 PM MST/PDT for the affected areas. Temperatures today will be within a few degrees of normal, with afternoon highs reaching the upper 80s for the typically warmer lower desert locales. However, the abundant high clouds may cause highs to underachieve today. NBM highs Friday are slightly warmer than the past few runs but still 2F-6F cooler than today thanks to the lower heights aloft and passage of a poorly defined cold front. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Ensembles advertise the overall pattern stagnating somewhat for a few days late this weekend into early next week, with upper level ridging building over the West-Central CONUS and another relatively potent upper low diving southward from the Gulf of Alaska and settling off the West Coast. The influence of high pressure over the region will allow temperatures to rebound over the weekend, with lower desert highs once again reaching the 90s and in a decidedly above normal category by Sunday. Something that is becoming more clear in the global model guidance is that a strong surface high will shift from the Intermountain West to the Southern Plains by Sunday, allowing another E/SE'rly gradient wind event to take shape Sunday morning. This will mostly impact Southeastern AZ, but likely extend into South-Central AZ higher terrain east/southeast of Phoenix. Forecast uncertainty increases considerably heading into the middle of the upcoming workweek, when the upper low off the West Coast is expected to move inland over the Great Basin or even over the Desert Southwest. The uncertainty is reflected in the probabilistic NBM temperatures, as IQRs for the forecast highs/lows increase to 5F or greater Tuesday onward. Overall, temperatures should retreat closer to or even slightly below seasonal normals during the middle of next week. Another uncertainty is whether the forcing from the incoming upper low will combine with meager moisture (mostly in the mid levels) to produce light shower activity over portions of AZ. However, the vast majority of global guidance shows the area remaining dry, with PoPs below 10%. From experience, the track of this low is also not promising to produce anything more than light precip totals favoring upslope areas and higher terrain. && .AVIATION...Updated at 0510Z. South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH: No significant weather issues will exist through Thursday night under developing high cirrus cigs. Timing of directional wind shifts should be similar to the past 24 hours, although west winds will be maintained around the Phoenix metro longer into Thursday night than usual. Wind speeds from the mid afternoon through early evening will be stronger than the past several days with occasional gusts 15-20kt across the region. && .FIRE WEATHER... Dry and occasional breezy conditions will prevail through the next week. Temperatures will cool from near normal today to slightly below normal Friday, then warm above normal over the weekend. A weather system passing the region to the north will send a cold front down the Colorado River Valley and produce gusty winds Friday morning, with gusts to 30-45 mph for portions of Southeast CA and Southwest AZ. Winds will gradually relax heading into the afternoon as humidity drops into the single digits. Elevated and locally critical fire weather conditions are expected to materialize for portions of the western deserts Friday as a result, particularly along the Lower Colorado River Valley. Afternoon MinRHs below 15% and at times in the single digits will be common through the next 7 days, with minor day to day variations. Overnight recoveries between 30-50% tonight will drop into 15-30% range Friday and Saturday nights. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Wind Advisory from 3 AM to 1 PM MST Friday for AZZ530. CA...Wind Advisory from 3 AM to 1 PM PDT Friday for CAZ560-561-564- 565-568>570. && $$ SHORT TERM...Whittock LONG TERM...Whittock AVIATION...18 FIRE WEATHER...Whittock