072 FXUS65 KPSR 032316 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 415 PM MST Thu Jul 3 2025 .KEY MESSAGES... - After limited chances for isolated showers and thunderstorms through this evening, the entire 4th of July weekend should remain dry. - Near to slightly below normal temperatures are forecast through Saturday with above normal temperatures returning by Sunday. - Daily highs for the lower deserts are expected to warm to around or just over 110 degrees starting Sunday resulting in widespread Moderate HeatRisk. && .NEAR TERM/THROUGH TONIGHT/... Water vapor satellite imagery this afternoon shows a low pressure system in southern Nevada that is continuing to bring dry air into the region. There remains enough residual moisture in combination with the vorticity from this low and 1000-2000 J/kg of MUCAPE to generate some showers and storms across northern AZ. Some vorticity associated with the low stretches into southwest AZ, which could act as a lifting mechanism to help storms form SW of the Phoenix Metro. This can be seen in visible satellite where an area of aggravated cumulus have formed. Models continue to show showers and storms developing in this area, with some isolated activity surviving and moving into the greater Phoenix Metro later this afternoon/early this evening. Any activity in the Phoenix Metro should be isolated (~20%). Subsidence is moving in quickly behind the low, so any activity that does manage to form this evening will struggle. We will have to watch for gusty outflows moving into the Phoenix Metro from any activity that does form to the SW, the HREF shows a 30-50% chance of winds greater than 35 mph in the Phoenix Metro. && .SHORT TERM/FRIDAY AND SATURDAY/... Once the trough lifts to the northeast of the area beginning tomorrow, heights aloft will begin to rebuild allowing for a gradual warming trend into the weekend. By Saturday, daytime highs are expected to be back into the normal range in Arizona to a couple degrees above normal across southeast California. Dry air will also continue to push into the area this weekend, with PWATs decrease to around 0.7-1.1" across the area. With this decrease in moisture we will also see decreasing shower/storm chances. With around a 15% or less chance for showers/storms over the higher terrain east of Phoenix, with most/any activity this weekend mainly confined to southeast AZ. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... Considerable forecast uncertainty is seen by next week, mainly involving any monsoon moisture. There seems to be a disconnect between the GEFS and the EPS with the GEFS showing a modest moisture return starting early next week, whereas the EPS shows continued dry conditions. At this point, there is no clear evidence supporting either model's solution, so we will likely have to wait at least a couple more days to have a better sense on what's going to happen. Both models do show the sub-tropical ridge building back over the region this weekend and then lasting through much if not all of next week. H5 heights are expected to rise to around 592-594dm this weekend allowing for a fairly quick warm up with highs likely topping out around 110 degrees by Sunday. Models also agree the ridge will continue to strengthen through the first part of next week with H5 heights likely reaching 595-597dm, or into the 90th percentile of climatology. One of the main issues is exactly where the high center will be with the GEFS suggesting it will be more over northern Arizona, where the EPS favors more over central and southern Arizona. If the GEFS is correct on its position, then we are likely to see some sort of moisture return early next week and likely a return of at least higher terrain storm chances. If the EPS is correct, then we are likely to stay dry with nearly no storm chances and even hotter temperatures. For now, the NBM seems to be favoring more of the GEFS solution, likely due to the Canadian agreeing with the GEFS position. However, we are doubtful of the NBM's PoPs as even if the high center is to our north, it will likely be too strong to allow for much if any convection into the lower deserts. We have lowered NBM PoPs by around 10-15% during the first half of next week, but even that may not be enough. The other forecast concern is if the EPS is correct and we stay dry, we are likely to see another heat episode with areas Major HeatRisk. The latest NBM forecast highs mostly keeps readings between 109-113 degrees, but this is assuming higher levels of moisture and at least some daily convection. It would not be surprising to see forecast temperatures for next week to creep several degrees higher once models resolve the position of the high. && .AVIATION...Updated at 2315Z. South Central Arizona including KPHX, KIWA, KSDL, KDVT: Some minor uncertainty regarding SHRA/TSRA chances early in the period with variability in wind direction are the main weather concerns through Friday afternoon. Under FEW-SCT 10-15K ft AGL decks through this evening, a few SHRA well SW of the terminal could progress into the western parts of the PHX airspace with erratic wind directions. However, probabilities are under 20% for any direct impact on operations with KPHX more likely than other aerodromes to experience weakening SHRA. Otherwise, clearing skies and a drier airmass will move into the region overnight with no weather impacts Friday. Southeast California/Southwest Arizona including KIPL and KBLH: No weather concerns will exist through Friday afternoon under mostly clear skies. Wind trends will be similar to the past 24 hours with directions generally varying between SE and SW. Some enhanced gusts 20-25kt will be possible at times. && .FIRE WEATHER... Lingering moisture today may bring a few isolated thunderstorms across south-central and eastern Arizona, but CWR will be below 10%. Below normal temperatures and the moisture will help to keep MinRHs between 20-30% for the eastern districts to 15-20% for the western districts. Outflow boundaries are possible from any storm activity with a 30-50% chance of wind gusts of 35 mph in the Phoenix Metro this evening. The drying trend will continue tomorrow with MinRHs of 20-25% across the SW and south- central AZ and 10-15% across SE CA. Winds return to a more typical diurnal trend today with any afternoon breeziness generally less than 20 mph. Highest wind gusts will be along the lower CO river valley with afternoon breeziness of 20-25 mph today and tomorrow. High pressure is then expected to rebuild across the region this weekend into next week with temperatures warming to above normal by Sunday. Limited moisture should also return early next week providing at least daily chances for isolated showers and thunderstorms for the eastern Arizona higher terrain. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ NEAR TERM...Berislavich SHORT TERM...Berislavich/Kuhlman LONG TERM...Kuhlman AVIATION...18 FIRE WEATHER...Berislavich/Kuhlman |