textproduct: NWS Phoenix

UPDATE

Updated Aviation

KEY MESSAGES

- Dry weather is expected over the next couple of days with temperatures warming, albeit remaining near to slightly below normal. - Locally windy conditions will impact the western deserts today before spreading across the rest of southe-central Arizona Friday and Saturday.

- Wind advisories have been posted for portions of south-central Arizona through the Lower Colorado River Valley on Friday with wind gusts in excess of 40 miles per hour.

SHORT TERM /TODAY THROUGH FRIDAY/

The low pressure system that brought multiple rounds of showers and below normal temperatures earlier this week is now currently centered over Colorado, and continues to move northeastwards. Meanwhile, to the west, high pressure is beginning to build, bringing clear skies and H5 heights forecasted to reach between 582- 585 dam today. This will swing afternoon high temperatures up to 10 degrees higher than yesterday, expect highs in the mid to upper 80s across the lower deserts, with a low chance (10-20%) of Phoenix reaching 90 degrees. These temperatures, while higher than earlier this week, are still right around normal for mid October. Low temperatures on the other hand will lag behind with today's low expected to remain below normal in the mid to upper 50s. By Friday morning the lows will respond to the building high pressure, with forecasted lows in the upper 60 to low 70s, or near 5 degrees above normal.

The main weather concern will be increasing winds starting today and lasting into the weekend as a pressure gradient strengthens as the high pressure builds to the to the region's north. In addition to the building high, a cut off low will begin to form late tonight to the region's SW over the Norther Baja peninsula. The strongest breezes during the day will be between 25-35 mph and focused across northern AZ and across portions of southeast CA, including the lower Colorado River Valley. By late tonight winds across theses areas will begin to increase to between 35-45 mph, in response a Wind Advisory will begin and last through late Friday morning. By early Friday morning the gradient winds will become stronger and the orientation will shift more E-W, therefore expanding the Wind Advisory to include, southeast Arizona into southern Gila County and through Pinal, southern Maricopa, and Yuma Counties. These areas will also be the best corridor for strong winds, where gusts near 40 mph winds can be expected with the peak winds late Friday morning potentially reaching near 50-55 mph. During peak gusts these same areas will be prone to blowing dust, especially in Pinal County.Additionally, while not included in the Wind Advisories, areas just north of the advised areas can still expect winds between 25-35 mph Friday and into Saturday morning.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Winds will continue to be the main weather concern throughout Saturday morning with gusts between 30-35 in southern and central Arizona, but should remain below advisory level winds. However, another round of advisory level winds are expect in Yuma County and southern La Paz County Saturday morning, but currently allowing the earlier advisory to expire before reissuing to avoid confusion.

Aside from the wind concern, guidance is suggesting some lower end shower potential over the weekend. The placement of the cut-off low to our southwest starting Friday is expected to advect a decent mid and upper level moisture into the area. Some high-based light showers may become possible across southern Arizona as early as Friday evening with best chances Saturday afternoon as the cut-off low weakens and migrates over the region. Unfortunately, little if any measurable rainfall is expected, as most locations will struggle to get anything more than a trace to a few hundredths of an inch. The good news though will be around a 5F-6F decrease in afternoon highs on Saturday, so expect highs in the low 80s across the lower deserts. By early next week, weak upper level riding will effect the region, resuming near normal temperatures. Looking out even further, ensemble guidance is hinting at another deep Pacific trough moving into the Western U.S. early next week and potentially reaching our region during the middle part of next week. This next weather system could bring more rain chances and another cool down during the latter half of next week.

AVIATION

Updated at 1655Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Increasingly gusty winds and lofted dust will be the main weather impacts through Friday afternoon under clear skies. Confidence is good that winds will obtain a NE trajectory through the afternoon with gusts near 20kt. Confidence is lower with respect to gustiness after sunset as some areas will partially decouple and lose gusts, while other aerodromes maintain some measure of gustiness through the overnight. As a result, LLWS criteria may only become localized and brief in nature. Confidence is very good that increased gusts will materialize Friday mid morning with the strongest 30-35kt gusts likely in a 16-20Z time frame. Given uncertainties in recent land use, sfc BLDU may become a local issue with some potential for a period of MVFR visibilities. Regardless, lofted dust should become a more significant impact throughout the entire daylight period Friday.

Southeast California/Southwest Arizona including KIPL and KBLH: Gusty winds will be the primary weather impact through Friday afternoon under mostly clear skies. North winds with gusts 20-30kt will be common through the overnight with some potential for partial decoupling and temporary loss of gustiness after sunset. Confidence is good that winds will back to an E/NE direction late Friday morning with gusts maintaining 20-30kt.

FIRE WEATHER

Drier air will persist over the region over the next couple of days with mostly clear skies and lowering humidities. MinRHs will be between 15-25% across the western districts and 20-35% for the eastern districts. Northerly breezy winds will affect southeast CA and southwest AZ today before increasing to around advisory level late tonight and into Friday. The eastern districts will keep overall light winds for most of today before windy conditions settle in early Friday morning. Easterly wind gusts as high as 40-50 mph are expected Friday. Some moisture return Friday into Saturday may bring low- end rain chances, but wetting rains chances should remain below 10%. MinRH's are expected to then increase to between 25-35% areawide by Sunday.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...Wind Advisory from 5 AM Friday to 11 AM MST Saturday for AZZ552- 553-555-558-560>562.

Wind Advisory from 8 PM this evening to 2 PM MST Friday for AZZ530.

Wind Advisory from 5 AM to 3 PM MST Friday for AZZ531-532-536- 538-539-554-559.

CA...Wind Advisory from 8 PM this evening to 2 PM PDT Friday for CAZ564-565-569-570.