SYNOPSIS
Temperatures will continue to cool across the region and are forecasted to fall below normal by the beginning of next week.
Breezy to locally windy conditions will continue across southcentral Arizona through sunset this evening. Shower and thunderstorm chances increase across the region this weekend as we get a push of tropical moisture. Best chances for rain look to be late Saturday through Monday afternoon.

DISCUSSION
Broad troughing continues across western CONUS with the associated low pressure system centered over Idaho. This trough moving into our region today has caused the breezy to locally windy conditions across the region today. Wind gusts of 25-35 mph will continue into the afternoon and start to subside shortly after sunset. There is still some thin wildfire smoke overhead from the California wildfires. The smoke/haze is noticeably thinner than yesterday and will continue to thin and clear out through the evening.

Dry conditions will continue into the weekend with well below normal PWATS across the region. The aforementioned trough currently overhead will lift north and eastward throughout the day on Friday.
As this trough lifts moisture from Tropical Storm Ileana, which is currently south of the Baja California Peninsula in the Eastern Pacific Ocean, will start to make its way into our region. Models show an initial increase to near 1" PWATS late Friday. PWATs will continue to increase through the weekend maxing out in the 1.3-1.6" range on Sunday.

Ensemble and deterministic runs of the ECMWF and GFS depict a secondary trough digging across western CONUS on Sunday and into Monday. These models also depict a shortwave trough out ahead of this secondary trough moving through on Sunday. These troughs in conjunction with the increase in moisture will result in a favorable conditions for shower and thunderstorm activity, mainly across southcentral Arizona, Sunday into Monday. Sunday's shower and thunderstorm activity will depend on how the shortwave trough plays out. The ECMWF is more aggressive with the shortwave trough resulting in higher PoPs than the GFS across the region for the overnight hours Saturday night into Sunday afternoon. If the shortwave is not as robust as the ECMWF depicts, better shower and thunderstorm activity may hold off until Sunday night through Monday afternoon when the aforementioned secondary trough finally makes its way into the region. Current NBM PoPs peak Sunday morning (30-50%)
and then again during the overnight hours Sunday into Monday (40- 60%).

Since there is still uncertainty in the exact timing of the showers and storms this weekend there is still uncertainty in the exact rainfall amounts. Rainfall totals across the lower deserts look to range from 0.1-0.5", with the lower amounts expected out in western Maricopa County and the higher amounts expected in the foothills to the north and east of the Phoenix Metro. Rain amounts for the higher terrain look to be in the 0.75-1.0" range. Isolated higher amounts are possible across the region, especially in any thunderstorms, which could lead to areas of localized flash flooding. WPC still has southcentral and eastern Arizona under a marginal risk (<15% chance)
for flash flooding on Saturday, Sunday, and Monday. The Saturday threat would be for the overnight hours Saturday into Sunday morning (06-12Z Sunday). Rain and storm chances will quickly come to an end Monday afternoon/evening once the cold front, that is associated with the aforementioned secondary trough, moves through brining in colder and much drier air with it.

Temperatures will cool to near to slightly above normal for Friday and Saturday. On Sunday, near normal temperatures will continue in southeastern California and southwestern Arizona, but across southcentral Arizona there is a large spread in temperatures. The temperatures for southcentral Arizona on Sunday will be heavily dependent on rain and storm activity. If there is an abundance of cloud cover from shower and storm activity we will likely see temperatures in the 80s and 90s. But if we see less showers and storms and hence less cloud cover, temperatures will likely continue to be near normal and near the century mark.

Below normal temperatures are expected across the region by Monday, with the NBM giving the Phoenix Metro a 70-90% chance of seeing afternoon highs below the century mark. If we don't see temperatures below 100 on Sunday, Monday looks to be the first day Phoenix will have a high temperature in the 90s since way back on May 27 (which would break a potential 112 day streak). Global ensemble models are in pretty good agreement on the overall synoptic pattern through the majority of next week. Overall a broad troughing pattern is expected across the region through much of next week with a 3rd low pressure system expected to dig southward into our region towards the middle to latter portion of next week. While ensembles are in agreement with a 3rd trough next week, they differ on the exact strength of this trough which will determine just how cool temperatures get.
Either way below normal temperatures are expected through next week, with the lower deserts (higher terrain) seeing high temperatures in the 90s (80s) and morning lows in the mid 60s to low 70s (50s to low 60s).

AVIATION
Updated at 0528Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Southerly cross runway winds midday Friday and possibly some slantwise visibility impacts Friday morning will be the greatest weather issues through through next 24 hours under a thin elevated layer of smoke. A prolonged period of southerly cross runway winds are likely late morning through mid afternoon.
Though, speeds should be much lighter than Thursday, with a few midday gusts into the teens, before slowly veering to a SW component late afternoon. Easterly winds tonight will be capable of pushing smoke from nearby wildfires into the Valley tonight through early Friday morning, which may lead to slantwise visibility impacts.

Southeast California/Southwest Arizona including KIPL and KBLH: No weather issues will exist through Friday afternoon under a thin layer of elevated smoke. Light variability is favored through tonight, then an E/SE direction Friday afternoon.

FIRE WEATHER
Dry conditions will continue through most, if not all, of the day on Saturday. Temperatures will continue to cool to near normal through the weekend and fall below normal by the beginning of next week.
Breezy to locally windy conditions will continue across the eastern districts through sunset, with wind gusts between 25-35 mph possible. Humidities will remain low through the rest of the week, with MinRHs between 5-15% across the lower elevations to around 10- 20% over higher elevation areas. The combination of the low humidities and gusty winds during this afternoon will likely promote elevated fire weather conditions across the eastern districts today.
Conditions will gradually improve Friday into the weekend, with increasing moisture resulting in increasing RH's and shower/storm potential going through this weekend, where wetting rain chances top out around 30-60% across southcentral Arizona by Sunday.

PSR WATCHES/WARNINGS/ADVISORIES
AZ...None.
CA...None.