Sunrise 5:35 AM   Sunset 7:14 PM Moonrise 2:59 AM   Moonset 2:29 PM

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FXUS65 KPSR 031121 AFDPSR

Area Forecast Discussion National Weather Service Phoenix AZ 421 AM MST Fri May 3 2024

UPDATE
Updated Aviation Discussion...

SYNOPSIS
Slightly above normal temperatures are expected today and tomorrow, with afternoon highs peaking in the low to mid 90s across the lower deserts. A dry weather system will traverse the Intermountain West this weekend leading to widespread breezy to windy conditions Saturday evening and Sunday, as well as cooler temperatures on Sunday and Monday. Dry weather will persist through next week, and temperatures are expected to rebound into the low 90s by Tuesday.

DISCUSSION
Quasi-zonal flow currently exists over the Desert Southwest while the persistent troughing feature over the Intermountain West gradually begins to push east this morning. Though a weak upper ridge will traverse the Pacific Northwest later today and continue eastward, heights aloft will be relatively unchanged over the forecast area through tomorrow, and so afternoon high temperatures will be stable in the low to mid 90s across the lower deserts.

The trough evident in current mid-lvl wv imagery off the Pacific Northwest Coast is expected to dive south along the West Coast Saturday, move inland, and traverse the Great Basin Sunday. The tightening pressure gradient ahead of and along the southern periphery of this trough will bring widespread breezy to windy conditions Saturday afternoon/evening and Sunday. A dry cold front associated associated with this system will also sweep through the CWA Sunday, leading to high temperatures dropping between 5-10 degrees across the lower deserts (and potentially more in the western deserts) on Sunday compared to their forecast values on Saturday.

NBM guidance continues to show upwards of 80-90% probability for gusts to 40+ mph across Southwest Imperial County including the Imperial Valley Saturday afternoon/evening. As a result, Wind Advisories have been issued for portions of Imperial County late Saturday afternoon into the evening, with the Advisory over far southwestern Imperial County remaining in effect through Sunday afternoon. Global models depict 700 mb winds peaking around 40-50 kts early Sunday morning over Southeastern California, so the strongest winds aloft will not coincide with peak daytime heating that would allow higher momentum air to mix down to the surface.
Thus, the strongest winds will be confined to high terrain locations overnight. Strong winds spread east across Arizona Sunday with afternoon gusts to 30-40 mph likely (>70%) across portions of South-Central Arizona. Additional wind headlines may be needed for portions of Imperial County on Sunday, as well as the high terrain zones of South-Central AZ within and around Southern Gila County. Dust channels may develop across dust prone areas as a result of the strong winds this weekend, which can reduce visibilities and make travel hazardous.

Longwave troughing will continue to be reinforced over the Intermountain West through Monday which will also feature near to slightly below normal temperatures and continued daytime breeziness across the region. Heading into the middle of next week, temperatures look to slowly rebound to slightly above normal, however the overall longwave troughing pattern across the Western CONUS looks to persist.

AVIATION
Updated at 1120Z.

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

No aviation weather concerns under clear skies are expected through the TAF period. Wind pattern will continue to exhibit diurnal tendencies, with easterly winds this morning transitioning to a period of southerly winds through the early afternoon hours before a full transition out of the west. Wind speeds will generally remain aob 10 kts.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns under clear skies are expected through the TAF period. Winds will generally be southerly through the period at BLH aob 10 kts, while southeasterly winds at IPL are expected to become westerly during the evening hours.

FIRE WEATHER
Warm and dry weather will persist into this weekend, with light and diurnal winds expected today. Afternoon highs will be slightly above normal today and tomorrow in the low to mid 90s across the lower deserts. A dry weather system will pass to the north of the region this weekend, leading to gusty winds, as well as cooler temperatures on Sunday and Monday. Winds could gust in excess of 40 mph across parts of SE California Saturday afternoon and evening and again Sunday morning/afternoon, while gusts climb to 30-40 mph across southcentral AZ on Sunday. Afternoon min RHs will bottom out around 10-20% over the next few days, while overnight recoveries remain in the poor to fair category between 30-60% for most areas.

PSR WATCHES/WARNINGS/ADVISORIES
AZ...None.
CA...Wind Advisory from 3 PM Saturday to 5 PM PDT Sunday for CAZ562.

Wind Advisory from 3 PM to 11 PM PDT Saturday for CAZ563-566-567.

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