textproduct: NWS Phoenix

UPDATE

06Z Aviation Discussion.

KEY MESSAGES

- A fairly typical Monsoon pattern will continue through the first half of the week, with early afternoon showers and thunderstorms forming over the Arizona high terrain daily followed by chances over the lower deserts focused later in the afternoon into the evening.

- A disturbance may approach the region from the east during the latter half of the week, bringing favorable conditions for more widespread showers and thunderstorms.

- Seasonably hot temperatures will persist through the middle of the week resulting in widespread Moderate Heat Risk and locally Major Heat Risk on Wednesday in Southeast California, followed by cooler temperatures late week.

SHORT TERM /TODAY THROUGH TUESDAY/

As of 1:13 AM MST this morning Phoenix Sky Harbor was able to measure with a total of 0.01", the first measurable rainfall since March 29th, 2026. Many surrounding areas in the Phoenix Metro were also able to measure between 0.01"-0.05" while areas in southern Maricopa County, Pinal County and the higher terrains received measurements between 0.25"-0.75" to locally higher amounts. This was due to a cluster of severe thunderstorms that developed in southern Maricopa County and Pinal County yesterday evening. While measurable rainfall is always exciting, especially here in the lower deserts, that was not the highlight of yesterdays activity as those areas, and even into the West Valley, received their first Dust Storm Warning since September 26th, 2025. The storms that developed were able to produce southeasterly gusts up to 45-50 mph at times, picking up a large amount of dust and reducing visibilities to under 1/4 of a mile to near zero in some areas last night.

Today GOES mid-level WV imagery shows the high pressure over the Northern Plains associated with a large area of dry air. The position of this high pressure is what has shifted flow aloft over the Desert SW out of the southeast, and allowing for good moisture advection. This increase in moisture has lead to PWATs between 1.5"- 1.8" across a vast majority of the CWA with locally higher, closer to 2", near the Gulf of California. This moisture is expected to linger throughout the week with 1000mb-700mb mixing ratios staying generally between 10-12 g/kg across the region. With yesterday's activity the atmosphere is slightly worked over resulting in chances today for activity to be lower, however not zero, with PoPs between 15-25% in the Metro, and between 30-50% in the Foothills. The latest HRRR run does show another round of storms developing today in much of the same areas as yesterday (eastern high terrain and South central AZ), however winds are expected to be lower this afternoon with the HREF guidance showing only a 50-70% chance (compared to Sunday's 70-90%) of winds above 35 mph focused along a corridor from Phoenix south/southeastward, and not near as widespread comparatively. Additionally with yesterdays rainfall dust may not be as easily lofted, hindering chances for widespread blowing dust tonight. Any activity that does form in our region tonight will continue to be highly conditional on upstream activity and if outflows from Central AZ high terrain storms can trigger additional cells. By Tuesday, thermodynamics may be slightly more favorable for strong storms, however, flow aloft weakens further and directions become complex as weak anticyclonic and cyclonic circulations begin to impinge on the region, creating a deformation area. The threat for lower desert storms will be even more conditional on lifting mechanisms from earlier storms or subtle lift from the deformation zones draped across the region.

Otherwise, temperatures this afternoon will be in the low to mid 100s across the lower deserts, with the Phoenix Metro slight higher between 105F-107F. Tuesday's afternoon highs will be slightly warmer, with temperatures ranging between 105F-111F. Despite the story weather these temperatures are still a few degrees above normal keeping widespread Moderate HeatRisk in place. With that said, be sure to keep heat safety in mind if spending time outdoors.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

There is still excellent agreement within the EPS and GEFS members regarding the placement of the upper high over the northern Plains and Upper Midwest through midweek before retrograding over the central Rockies by the latter half of the week. The overall position of the 500 mb high will maintain deep easterly flow across the Desert Southwest, helping enhance moisture transport. Latest EPS and GEFS continue to show PWATs hovering around 1.5"-1.8" through the entire week with low-level mixing ratios remaining between 10-12 g/kg. Therefore, conditions will continue to remain conducive for daily thunderstorm activity with variations in the overall coverage. Both the mean of the EPS and GEFS show an uptick in QPF across the region by the end of this week due to an easterly wave/inverted trough approaching the area by Thursday-Friday. If this occurs, this troughing feature will likely enhance convective activity potentially introduce a risk for heavy rainfall across portions of AZ. This will have to be monitored closely in the coming days.

Temperatures are expected to peak Wednesday mostly between 105F-110F across the Arizona lower deserts, but some areas of Major HeatRisk enter the picture for portions of Southeast CA and along the Lower Colorado River Valley, where latest NBM forecast shows highs as high as 113F and lows in the middle to upper 80s thanks to the inefficient overnight radiative cooling from higher humidity and likely some mid-high cloud cover. The NBM continues to indicate temperatures cooling to well below normal by the end of the week with highs falling into the 90s to around 100 degrees across the lower deserts by Friday. This is likely due to the increased signal for thicker cloud cover and the potential for more widespread rainfall.

AVIATION

Updated at 0515Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: After widespread strong gusty winds and thunderstorm activity earlier this evening, conditions are improving across the area. Conditions through Tuesday afternoon should remain tranquil with the overall wind pattern following the typical diurnal tendencies with easterly winds overnight through early Tuesday morning shifting out of the west late Tuesday morning/early afternoon with some occasional afternoon gusts in the mid to upper teens. At this time, there is a much lower chance of thunderstorm activity Tuesday evening with a better potential of an easterly outflow from distant activity. Outflow magnitude will be all dependent on the overall coverage and intensity of distant storm activity. SCT to occasional BKN mid to high clouds will prevail through the overnight hours before coverage decreases to FEW by Tuesday morning.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation concerns are expected throughout the TAF period under FEW to SCT mid to high clouds. At KIPL, light and variable winds currently will shift out of the southeast by early Tuesday morning and remain out of the southeast through the afternoon hours with another temporary shift out of the west during the early evening hours. At KBLH, winds will generally fluctuate between the south-southeast to southwest with a period of light variability Tuesday morning. Overall wind speeds are expected to remain aob 10 kts.

FIRE WEATHER

Seasonably hot temperatures will prevail through the next several days as readings will be near to slightly above normal. Daily thunderstorm activity will be possible through this week with the potential for more widespread wetting rainfall increasing across the eastern districts throughout this week, with higher chances by Thursday and Friday. Due to increasing boundary layer moisture, afternoon humidity levels will remain in a 20-30% range which will keep any fire weather concerns at a minimum. Overnight recoveries will be fair to good, or between 40-70%. Outside of any thunderstorm driven outflow, winds should favor diurnal trends with the typical afternoon breeziness around 20-25 mph.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...None. CA...None.