Sunrise 5:34 AM   Sunset 7:15 PM Moonrise 3:29 AM   Moonset 3:39 PM

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FXUS65 KPSR 050024 AFDPSR

Area Forecast Discussion National Weather Service Phoenix AZ 524 PM MST Sat May 4 2024

UPDATE
Updated Aviation Discussion.

SYNOPSIS
Slightly above normal temperatures will continue today, before a dry weather system passing to our north ushers in cooler temperatures by Sunday. This weather system will lead to breezy to windy conditions today across southeast California and across the majority of the area on Sunday. Heading into next week, temperatures will slowly rebound while remaining seasonably dry.

DISCUSSION
Latest water vapor satellite imagery shows a very potent upper-level low pressure system just off the Oregon coast as of this morning.
This system during the next 24-30 hours will move through the Great Basin and Intermountain West. Out ahead, temperatures today will continue to run a few degrees above normal with highs across the lower deserts topping out in the low to locally mid 90s. As the low pressure system moves inland later today, a tightening pressure gradient will lead to strong gusty winds later this afternoon and evening across portions of southeast California. The strongest winds are expected across Imperial County, where gusts in excess 40 mph are likely and where a Wind Advisory is in effect. The strong gusty winds can lead to areas of blowing dust, resulting in temporary reductions in visibilities.

Heading into Sunday, as the low pressure system moves through the Great Basin and Intermountain West, the pressure gradient will tighten across the entire area leading to widespread breezy to windy conditions. Widespread afternoon and early evening gusts upwards of 30-35 mph are likely across the Arizona lower deserts while locally higher winds in excess of 40-45 mph are likely across portions of southeast California and the higher terrain to the north and east of Phoenix. Along with the gusty winds, cooler temperatures are expected with highs only topping out in the upper 70s to low 80s across the western deserts while the south-central Arizona lower deserts will see higher temperatures in the mid 80s.

The weather pattern through a good portion of next week will feature a general large trough extending from the Plains through the Pacific Northwest with the southern fringe setting up across the Desert Southwest. As a result, a mostly zonal flow will set up over the region with temperatures gradually rebounding into the low 90s across the lower deserts heading through the middle of next week. Heading into the end of next week through next weekend, as the troughing pattern dissipates, a ridging pattern is being hinted by the ensembles in building in from the west. This would result in temperatures rising a bit more, potentially into the mid to upper 90s across the lower deserts with a 20-30% chance of approaching 100 degrees.

AVIATION
Updated at 0024Z.

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

Southerly variable winds still persists at KPHX and will likely do so until ~01Z before W to SW prevails. The W to SW winds this evening will be capable of gusting to around 20 kts at all terminals. E to SE, 5-8 kt, winds will prevail between 10-15Z. By 15-16Z Sunday, S to SW winds increase with speeds initially around 8-12 kts. W to SW winds further increase by 20Z, with sustained speeds up to 15-20 kts and gusts to around 25-30 kts. Between ~22-02Z, occasional gusts may reach 30-35 kts. FEW to SCT high clouds around 20 kft will pass over the region throughout the period with lower bases to around 8 kft expected Sunday afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:

Winds will be the primary aviation weather concern through the TAF period. Strong westerly winds at KIPL and southwesterly winds at KBLH will prevail through this evening. Winds will be strongest at KIPL where gusts will climb upwards of 30-35 kts with occasional gusts exceeding 35 kts at times this evening. Meanwhile at KBLH, gusts between 25-30 kts will be more common. There will be a small reprieve from the winds tonight through early Sunday, more so at KBLH. Slightly stronger winds are then expected during the day at the terminals, with westerly gusts to 30-35 kts at KIPL and southwesterly gusts to around 30 kts at KBLH. The strong winds will be capable of generating blowing dust which will likely lead to slantwise visibility reductions at a minimum, but could also briefly reduce surface visibility as well. Expect to see fluctuating coverage of high clouds throughout the period.

FIRE WEATHER
A weather system moving just to the north this weekend will bring breezy to windy conditions focused more during the afternoon and evening hours along with cooler conditions starting Sunday. Wind gusts above 30 mph are likely later today across much of the western districts and then areawide on Sunday. The strong winds and dry conditions will lead to elevated fire weather conditions over much of the area this weekend. Min RHs through the weekend will be around 10-20%, while overnight Max RHs will be around 30-60% for most areas. For next week, weak high pressure will remain over the region allowing for temperatures returning to slightly above normal, while seasonably dry conditions persist with MinRHs dropping to around 10%. Lighter winds are expected into next week, but some afternoon breeziness can be expected each day.

PSR WATCHES/WARNINGS/ADVISORIES
AZ...None.
CA...Wind Advisory until 9 AM PDT Sunday for CAZ560.

Wind Advisory until 8 PM PDT Sunday for CAZ563>567.

Wind Advisory until 11 PM PDT Sunday for CAZ562.

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