063 FXUS65 KPSR 022005 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 105 PM MST Mon Jun 2 2025 .DISCUSSION... Key Messages: - Slight chance (less than 20%) of light showers Tuesday night and Wednesday, then significant drying the remainder of the week - Temperatures quickly rebounding towards normal levels during the middle of the week, then above normal late week Early afternoon WV imagery clearly depicts a compact negative PV anomaly filling and lifting into NE Arizona while a separate circulation center has detached from the northern jet core off the central California coast. With the departure of the initial vorticity center, shortwave ridging and increasing weak subsidence will briefly move into the forecast area over the next 24-36 hours, however abundant lingering moisture may still support a few spotty showers over higher terrain areas. In fact, surface dewpoints in the lower/middle 60s are being sampled across the region while objective analysis suggests boundary mixing ratios 10-12 g/kg still encompassing the entire CWA. This anomalous low level moisture (more typical for mid July vs. early June) will slowly, but steadily be eroded away such that shower chances quickly begin to evaporate the next few days, and more typical June weather resumes. The greatest forecast uncertainty is the influence and impacts of the aforementioned California vorticity center as it eventually migrates inland and deteriorates substantially becoming re-absorbed into the northern stream flow downstream of the forecast area late Tuesday into Wednesday. Despite an impressive appearance in satellite imagery, there isn`t much optimism of better rainfall potential with notably dry air entrenched around the circulation and current in situ moisture availability likely falling closer to 7-8 g/kg by arrival time. Ensembles have narrowed down uncertainty in timing and magnitude of this system yielding better forecast confidence, yet this still only supports local POPs maximized around 20%. NBM POP forecasts are once again displaying a subjective high bias considering the vast majority of model and BUFR sounding output, and have made notable reductions to the automated forecast. General longwave troughing will continue to linger across the SW Conus through late week, however midlevel heights will gradually increase with the ejection of the second shortwave and subtropical ridging strengthening over south Texas. Ensemble membership is in very good agreement with this evolution as H5 heights rise into a 584-588dm range by the end of the week. This type of range is fairly typical for early June, and a narrow guidance spread yields good confidence of temperatures returning to a normal range during the latter half of the week. By early next week, ensemble spread grows slightly depending on the expanse of subtropical ridge retrogression with some of the more aggressive modeling suggesting H5 heights closer to 592dm which would be a decent proxy for temperatures flirting with 110F. Regardless, a return of widespread moderate HeatRisk to the region by this weekend seems inevitable, but fortunately not yet near major/extreme levels. && .AVIATION...Updated at 1735Z. South Central Arizona including KPHX, KIWA, KSDL, KDVT: No additional rainfall is expected over the next 24 hours and skies will feature FEW to SCT cumulus through this afternoon with bases rising from 4-5K ft AGL now up to 7-8K ft AGL this afternoon. Skies then clear tonight. Light variable winds now will establish out of the west by early afternoon with wind speeds mostly around 5-10 kts. Light easterly winds return tonight after midnight. Southeast California/Southwest Arizona including KIPL and KBLH: No aviation impacts are expected through the period with mostly clear skies. Expect southeasterly winds for much of the period at KIPL, with the exception of some southwesterly winds this evening, and southerly winds for the entire period at KBLH. && .FIRE WEATHER... An unusually moist environment will persist over the region the next couple days with even a few lingering showers are possible Tuesday and Wednesday. However, wetting rain chances remain very low (under 15%) with most districts likely remaining dry. This pattern will quickly transition back to more typical dry conditions and seasonable temperatures during the latter half of the week. Minimum afternoon humidity levels generally 20-30% through Wednesday should degrade near 15-25% later in the week, then near single digits over the weekend. Fair to good overnight recovery of 40-60% will correspondingly retreat into a poor to fair range of 20-40% late in the week. Winds should be fairly typical for late spring with the usual afternoon upslope gustiness. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...18/Young AVIATION...Benedict/Kuhlman FIRE WEATHER...Young/18