Marine Weather and Tide Forecast for Phoenix, AZ

SYNOPSIS
Dry conditions will persist through this week as temperatures warm from near to above normal temperatures heading through the middle and latter portions of this week. A weather disturbance moving into region this weekend will bring another round of breezy to windy conditions and much cooler temperatures going into early next week.

DISCUSSION
Early afternoon RAP analysis and WV satellite imagery show an upper level low spinning over northern Arizona, producing showers and isolated thunderstorms across the northern high terrain.
Meanwhile across the lower deserts, mostly clear skies are giving way to increasing CU development around the area. Heading into this evening this low circulation will migrate southward toward central Arizona, which may lead to some weak showers/virga moving off the high terrain and into the Valley. Additionally, some gusty outflow winds will be possible with this activity with the latest HRRR supporting upwards of a 10-20% of a few outflow gusts in excess of 35 mph. The upper low is then set to depart the state to the east overnight.

Following the exit of the aforementioned low, transient shortwave ridging will build into the Southwest and will promote rising heights and warming temperatures through the latter half of the week. Afternoon highs Wednesday will climb near to slightly above normal as lower desert highs warm into the upper 80s to low 90s.
Thereafter, forecast highs remain steady in the lower 90s across the lower elevations. Going into Friday, a weak Rex Block will develop over the West as a weak troughing feature shifts over the Desert Southwest with ridging over the Pacific Northwest. Despite the weak low moving over the southwest CONUS, there will be very little change in upper heights with temperatures remaining steady.
A stronger weather system will pushing into the region this weekend.

PREVIOUS DISCUSSION
The evolution of this troughing pattern heading into this weekend is coming more into focus as ensembles are now honing in better on how deep and intense this troughing feature will become. All ensemble members now depict some version of a cutoff low developing by Sunday as this trough deepens into the Desert Southwest, with just minor positional and mid-level negative height anomaly differences through Sunday. Thus, the region can expect the sensible weather conditions to transition starting Saturday, where breezy to windy conditions filter in from west to east through Sunday. Should the conditions line up right, at least elevated fire weather conditions may become a concern on Saturday due to the lingering low relative humidities and stronger winds for higher terrain areas of south-central Arizona.

Due to the position of this cutoff low remaining west of the region on Saturday, above normal temperatures are expected to remain in place prior to a dramatic cooldown on Sunday, on the order 10-20 degrees, depending on how strong this low becomes.
Widespread windy conditions may become a factor on Sunday as a result, although precipitation chances continue to remain minimal to none. Despite the pessimism on precipitation chances, there are a couple of ensemble clusters (representing 10-15% of the membership) that paint some light accumulations across some lower desert locations on Sunday should the trough amplify enough to advect more sufficient moisture into south- central Arizona.
However, current NBM PoP's still reasonably remain at 10% or lower Sunday onward at this time. As mentioned, temperatures are expected to dip to below to well below normal levels (still a 5-10 degrees interquartile range) beginning on Sunday and extending into early next week.

AVIATION
Updated at 0000Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:

Rain-cooled outflow winds are expected to push through the Phoenix area from the north between 00-04Z this evening, with around a 10-20% chance for wind gusts >30 kts. There is also a slight chance for some spotty virga or a brief light shower during the same timeframe. The gustiness following the outflow is anticipated for at most 2 hrs and then once subsiding wind directions will favor easterly for the remainder of the evening and through Wednesday morning. Typical diurnal wind tendencies are expected for Wednesday with a westerly shift by 19-20Z. FEW to SCT clouds down to 10k ft AGL now should persist through midnight before becoming SKC through Wednesday morning. High clouds then move in Wednesday afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:

Gustiness at KBLH will subside over the next couple hours. Both KBLH and KIPL will then see light winds persist through tonight and Wednesday morning, with some periods of very light variability. Winds at KIPL will eventually shift southeasterly by noon Wednesday and KBLH will see gusts pick up to around 20 kts from the SW by the afternoon. Mostly clear skies are expected through Wednesday morning, followed by SCT to BKN high clouds for the afternoon.

FIRE WEATHER
Warming and drying conditions will persist through the rest of the week with small chance of a few weak showers/virga this evening, which could result in some gusty outflow winds. There is about a 10-20% chance of outflow gust in excess of 35 mph this evening.
Expect minimum RH's of 10-20% to dip to 7-15% by the middle of the week, with overnight recoveries worsening to around 25-40%. Winds will maintain seasonally typical upslope gustiness in the afternoon through the entire week with likely stronger gusts arriving this weekend. A cool weather system will then approach and move through the region this weekend. This will bring minimum RH values back above critical levels. However, this system will also bring increased gradient winds across the area and it looks as though there will be a period of at least elevated fire weather conditions for South- Central AZ Saturday afternoon. Predictive services still show ERCs are below the 75th percentile, which should help limit the large fire risk.

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