textproduct: NWS Phoenix

KEY MESSAGES

- Rain chances will continue for the first part of today with a break tonight and much of Friday. Additional chances for light rain will mainly affect Arizona higher terrain areas Friday night and Saturday.

- Temperatures will cool to near normal readings over the weekend before returning to slightly above normal for the first half of next week.

SHORT TERM /TODAY THROUGH SATURDAY/

A large Pacific trough continues to impact much of the Western U.S., including the Desert Southwest. The low center is currently well to the west of northern California with two main shortwaves tracking eastward into California and another into Arizona. The shortwave pushing across western Arizona is helping to drive a band of light to moderate rainfall which has dropped anywhere from 0.10" to upwards of 0.50" in a few spots. Additional scattered light showers continue to move across portions of south-central Arizona with rainfall amounts generally under 0.05". Hi-res CAMs are still struggling to depict the scattered shower activity, but have picked up on the main rain band. This band is already starting to show signs of drying up as it moves into southwest Arizona and it's likely to continue as it mainly lifts to the northeast into the Arizona high country. The scattered shower activity may continue into mid to late morning focused more across the higher terrain north and northeast of Phoenix before tapering off completely during the afternoon hours as drier air filters in from the west. We should also see much more sunshine by this afternoon with highs likely topping out in the low to mid 70s.

The upper level low is forecast to quickly fill going into Friday with guidance now settling more on some remnant energy of the system moving through our region Friday night into Saturday. Given moisture levels will have dropped a decent amount by this time, we are not expecting much additional precipitation. The latest NBM PoPs are mostly 10% and below for the lower deserts to 15-30% across higher terrain areas. The passage of this trough will also usher in noticeably cooler air this weekend with lower desert highs mostly dropping into the upper 60s, or within a couple degrees of normal.

LONG TERM /SUNDAY THROUGH NEXT FRIDAY/

Model guidance has shifted away from any rain chances early next week as much drier air is likely to filter into the region from the north Sunday into Monday. We should also see some ridging over the region early next week, but guidance continues to change the positioning of a potential cut- off low off the coast of Baja. If the ridge fully takes over across our region, we are likely to see a boost in temperatures by around Tuesday with highs potentially pushing near 75 degrees by Wednesday. Although guidance continues to overall suggest the cut- off low will become a factor for our region again at some point later next, forecast confidence remains quite low. NBM PoPs seem too high for next Wednesday and Thursday given the uncertainty, so we have trimmed PoPs by 30% across the entire area. If the cut- off low does move back close to our region or even into our region later next week, it at least looks promising for some meaningful moisture return with PWATs again forecast to reach near 1", or around 250% of normal.

AVIATION

Updated at 0900Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: The main aviation impacts will be the lower CIGs this morning and the scattered shower activity. The lowest CIGs may briefly dip to between 4-6K feet around sunrise before improving by late morning and scattering out later in the afternoon. Winds through the TAF periods will predominantly favor the east with speeds mostly aob 10 kts and periods of variability. There may end up being a brief northerly or northwesterly shift late in the afternoon and early evening before settling back out of the east by mid to late evening.

Southeast California/Southwest Arizona including KIPL and KBLH:

Showers will quickly come to an end by sunrise with skies gradually scattering out by mid morning. Some patchy fog will be possible across the Imperial Valley this morning, but confidence is too low to include in the TAF. Winds will be somewhat variable this morning before settling out of the south at KBLH and out of the west southwest at KIPL by the afternoon.

FIRE WEATHER

An unsettled weather pattern will result in cooling temperatures and increased humidities through the weekend and chances for light to moderate rain showers mainly today. Additional chances for light rain may return over the AZ high terrain Friday evening into Saturday. MinRHs will range between 40-60% areawide through Saturday. Winds will mostly be out of the south today, with some breeziness across portions of Southwest AZ and Southeast CA. Winds will be light on Friday before becoming breezy at times again over the weekend.

PSR WATCHES/WARNINGS/ADVISORIES

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