textproduct: NWS Phoenix

KEY MESSAGES

- Breezy to locally windy conditions will return for the back half of the work week with elevated Fire Weather conditions focused around the Lower Colorado River Valley.

- After a brief stint of near and below normal temperatures over the next few days, readings will rebound, with widespread afternoon highs in the 90s expected by the end of the weekend.

SHORT TERM /TODAY THROUGH THURSDAY/

Current objective analysis reveals a very active pattern for the central and western tier of the CONUS will multiple disturbance embedded in the broader flow. Meanwhile for the Desert Southwest, rather benign weather will exist through at least the next couple of days as low-amplitude ridge overspreads the region. After yesterday, when we saw our first day with an average temperature below normal since the beginning of March, and only the 11th such day this year, temperatures will bounce back upwards closer to normal thanks to the warmer atmospheric profile. Lower desert highs this afternoon will hover in the middle to upper 80s, while higher elevations locales can expect values in the 70s to lower 80s.

A potent Pacific trough, currently spinning over Southern British Columbia and Northern Washington, will work its way further to the south and east, traversing the the Intermountain West Thursday. At the same time, another weaker system will be developing west of the Baja Peninsula. Both of these features will have at least some minor influences on our weather on Thursday as the northern system begins to tighten our regional pressure gradient slightly, and the southern low throws some upper-level moisture toward the region. The expectation is that some marginal breeziness will develop for higher elevation spots and the Lower Colorado River Valley with peak gusts 20-25 mph, with some higher gusts for the typical windy spots of Southwestern Imperial County. The previously-mentioned moisture will yield only some high cloud cover, but that could have an impact on temperatures depending on how optically thick it becomes. Current NBM highs call for readings in the middle to upper 80s for the lower elevations, with perhaps a few spots reaching 90 degrees. However, it would not be surprising if temperatures underachieve due to the lower insolation.

LONG TERM /FRIDAY THROUGH TUESDAY/

Model guidance over the past couple of runs has shifted the track of the Pacific trough a bit farther to the north with the track of the main shortwave across Utah into Colorado. However, it should still be close enough to our area to bring a period of northerly windy conditions down the Lower CO River Valley during the first half of Friday while also resulting in a noticeable cooldown. Wind gusts Friday morning across southeast California and the Lower CO River Valley are likely to reach Advisory level in some spots before gradually weakening during the afternoon hours. Elsewhere Friday, afternoon wind gusts should be similar to Thursday with gusts mostly under 25 mph. The latest NBM forecast highs Friday have actually dropped a degree or two from previous runs with readings in the upper 70s to lower 80s across the western deserts to the lower 80s across south-central Arizona.

The weather pattern into the weekend and early next week supports another passing ridge with the expectation this ridge will last a bit longer and have more influence on temperatures. The weekend shows very low RHs with readings dipping into the single digits during the afternoon across the lower deserts, while temperatures warm back to near 90 degrees Saturday before topping out in the low to mid 90s on Sunday. Ensembles then favor a deep Pacific low dropping southward off of Oregon and northern California late Sunday and Monday before eventually moving inland somewhere across the Great Basin or even the Desert Southwest by next Tuesday and/or Wednesday. Assuming this occurs, the system would lower temperatures again going into the middle of next week, but it is unlikely to result in any meaningful precipitation chances.

AVIATION

Updated at 1732Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH:

No major aviation weather concerns will exist through the next 24 hours. Winds will continue to follow diurnal tendencies across the Phoenix terminals with speeds generally aob 8 kts. Across SE CA, winds will favor a S-SE component through this afternoon before switching around to the W/SW this evening; expect speeds to mostly remain under 10 kts with extended periods of variability. Breezy conditions will pick up heading into tomorrow afternoon. SKC conditions will persist today before high clouds increase later tonight into tomorrow.

FIRE WEATHER

Gradual drying conditions will prevail over the next couple of days as temperatures return into a normal range. Winds today will again be light while MinRHs fall to 10-15%. Thursday will bring an increase in winds by the afternoon with occasional gusts between 20-25 mph for much of the area. MinRHs Thursday will also fall into the upper single digits across the lower deserts. Locally windy conditions across the western districts on Friday are likely to bring elevated to possibly critical fire weather conditions late morning into the afternoon. Warmer temperatures, even drier conditions, but lighter winds are then expected for the coming weekend.

PSR WATCHES/WARNINGS/ADVISORIES

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