textproduct: NWS Phoenix

KEY MESSAGES

- Lingering breezy conditions coupled with low humidity and very dry fuels through today will result in elevated fire danger, primarily for the Arizona higher terrain.

- Below normal temperatures will prevail through much of the week.

- More tranquil conditions and a slow warming trend will arrive during the latter half of the work week.

SHORT TERM /TODAY THROUGH THURSDAY/

Mid level WV imagery and RAP40 500mb analysis shows the abnormally strong upper level low still positioned over the Western CONUS. The extent of this upper level low that is over our region today is between the 3rd and 10th percentiles of climatology for this time of year, with H5 heights today expected to be between 580-585 dam. In response to this unseasonably strong low, temperatures have followed suit, with Phoenix Sky Harbor recording a high temperature yesterday of 103F, or 4 degrees below normal. The last time Phoenix Sky Harbor recorded 103F or less on June 29th, was in 2020 at 101F. Ensembles are in good agreement that this upper level low will linger over the region through mid to late this week before being displaced to the north. That being said, afternoon highs will continue to be 2F-8F below normal, with much of the lower deserts staying in the upper 90s to low 100s. In addition to below normal highs, the overnight/morning low temperatures will also be well below normal. This is due to the system being very dry, bringing no additional moisture into the desert SW. PWATs will be near 0.2"-0.4" or near 30- 50% of normal. This has lead to clear skies across the region allowing for radiative cooling overnight. Low temperatures in south- central AZ will be in the mid to upper 70s (5F-7F below normal), while the western lower deserts will be in the upper 60s lower 70s (10F-12F below normal).

Afternoon breezy conditions will continue today as a shortwave moves through the base of the trough today. While gusts have relaxed compared what areas received this past weekend, gusts between 20-30 mph will be common in the Northern/Eastern AZ high terrain and in the southwestern corner of Imperial County. Elsewhere gusts between 10-15 mph will be common through the afternoon/evening periods. Between lingering gusts and very dry conditions, fire conditions today will remain elevated to near critical, primarily over Northern/Eastern AZ high terrain, before improving by Wednesday.

LONG TERM /THURSDAY THROUGH SUNDAY/

Ensembles model guidance remains in good agreement that the upper level low will be displaced to the region's north as a subtropical high begins to build. As the high builds, H5 heights aloft will start to increase leading to a gradual warming trend. The latest NBM remains confident that temperatures will return to near normal as early as Friday then gradually warming each day to above normal by Sunday. Highs By Sunday are expected to be in the 105F-110F range, with widespread Moderate Heatrisk returning as well. With the high pressure building, more tranquil weather conditions are expected with only some minor afternoon breezy conditions expected with the highest winds across the Lower CO River Valley and the higher terrain north and east of Phoenix. Very dry conditions will also remain in place and thus there will be no rainfall chances through this weekend.

AVIATION

Updated at 0500Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation weather concerns under clear skies can be expected throughout the TAF period. The overall wind pattern will follow the typical diurnal tendencies with a period of southerly winds during the late morning/early afternoon before the westerly shift. Some occasional gusts near 20 kts can be expected once again Tuesday afternoon/early evening.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns under clear skies can be expected throughout the TAF period. At KIPL, winds will generally be out of the west while at KBLH, winds will fluctuate between the south-southeast to southwest. Another round of afternoon/early evening gusts between 20-25 kts can be expected, strongest at KIPL.

FIRE WEATHER

Elevated fire danger, and locally near critical for the high terrain of the eastern district, will continue today due to low humidity, very warm temperatures, breezy southwest winds during the afternoons/early evenings, and very receptive dry fuels. Afternoon minimum humidities will be between 7-15% today then dropping into the 5-10% range for the eastern districts beginning Wednesday and areawide by Friday. Poor to fair overnight recoveries between 20-45% through Wednesday night will decrease into a 15-30% range Thursday night onwards. Winds will diminish more noticeably during the latter half of the work week, but afternoon/early evening upslope and upvalley gusts to 15-25 mph will continue. Temperatures will remain below normal through the majority of the week, with lower desert highs around 100F through midweek, then gradually warming into a near normal range this weekend.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...None. CA...Wind Advisory until 8 AM PDT this morning for CAZ562.