755 FXUS65 KPSR 271151 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 451 AM MST Sun Apr 27 2025 .UPDATE...Updated 12z Aviation Discussion. && .SYNOPSIS... Winds will subside today, but daily afternoon breeziness can be expected through most of this week. Temperatures will run below normal through the early parts of the week ahead of above normal temperatures through the end of this week with dry conditions. Attention will then turn to a pattern change that is anticipated to at least cool temperatures again this upcoming weekend. && .DISCUSSION... Amplified troughing across western CONUS, with the upper low circulation centered over the Great Basin, will bring the coolest temperatures of this feature to the region today. While the core of the upper level jet from this feature will slide east of the region today, breezy conditions will continue across the region, particularly the higher terrain peaks in Gila County this afternoon. While this main circulation will lift to the northeast over the central Rockies, the overall longwave trough will continue to amplify across the Southwest, keeping cooler temperatures and daily afternoon breeziness across the region through Tuesday. Negative height anomalies from this trough will linger into the middle of this week, but due to the trough weakening, temperatures will warm back to normal levels as early as Tuesday. As the trough begins to slide eastward into New Mexico by Wednesday, zonal flow will follow as ridging builds into the Intermountain West late this week. While positive height anomalies remain mostly to the north of the region, temperatures are expected to warm back above normal levels with dry conditions continuing through the latter portions of this week. As advertised over the last several forecast periods, uncertainty becomes much larger heading into this upcoming weekend, as ensemble model spread increases over the development of another Pacific trough moving into Western CONUS. While previous forecasts indicated uncertainty on whether this trough would remain progressive (remaining well north of the region) versus amplifying into the Desert Southwest, there is a much stronger signal towards this trough amplifying across the region this upcoming weekend (~75% of the ensemble suite). In a more amplified pattern scenario, cooling temperatures would be a certainty. Thus, the main uncertainty, which still remains pretty wide at this time, is in regards to how amplified this trough becomes, which will affect timing/onset and potential of enhancing the breezy to windy conditions across the region. While the most amplified solutions would result in increased moisture levels into the Desert Southwest, none of the cluster solutions for Saturday onward are advertising much in the way of precipitation chances aside from far northern Arizona at this time. Stay tuned for further updates in regards to the outlook for this upcoming weekend. && .AVIATION...Updated at 1150Z. South Central Arizona including KPHX, KIWA, KSDL, KDVT: The primary aviation concern during the TAF period will be gusty southwest winds this afternoon into the early evening, under FEW- SCT passing high clouds later this morning. Confidence is fairly high that winds will remain W/SW this morning at all the terminals except KIWA, which may see several hours of SE winds between now and 15-17Z, though a period with lighter speeds and variability may occur before SW winds pick up again late morning/early afternoon. This afternoon, expect gusts to around 20 kts before winds relax to AOB 10 kts around sunset. A more typical switch to light SE winds is likely late tonight or early Monday morning. Southeast California/Southwest Arizona including KIPL and KBLH: Winds will remain W`rly at KIPL and S`rly/SW`rly at KBLH through the period. Speeds will generally remain elevated at KIPL to AOA 10 kts through the period, whereas speeds will be light at KBLH this morning and during the overnight hours tonight. Afternoon and early evening gusts to 20 kts at KBLH and 25 kts at KIPL will be common. SCT high clouds early this morning will give way to mostly clear skies by mid morning. && .FIRE WEATHER... Temperatures cooling below normal will allow an increase in humidity levels early this week, however warming conditions during the latter half of the week will return conditions back to more typical for early May. Winds will maintain a seasonally typical upslope gustiness through the entire period with the strongest gusts occurring this afternoon. With dry weather prevailing, afternoon minRHs will generally fall into a 15-25% range during the first part of next week before returning to a 10-15% range by the middle of the week. Fair to good overnight recovery of 30-60% will retreat towards poor to fair (20-40%) levels. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Young AVIATION...Whittock FIRE WEATHER...Young/18