textproduct: NWS Phoenix

UPDATE...Updated 06z Aviation Discussion

KEY MESSAGES

- Dry conditions with zero rain chances will persist through at least the weekend and likely much of next week.

- As high pressure builds over the region, a gradual warming trend will bring temperatures at least into a normal range starting this weekend and eventually slightly above normal for next week.

SHORT TERM /TODAY THROUGH FRIDAY/

Much drier and quieter conditions are ahead as the low pressure system that brought the rainy conditions earlier in the week continues to move eastward and is now centered over Northern Texas and the Oklahoma Panhandle. Meanwhile to the region's west a large ridge is building and is expected to move over the Desert SW by late Friday. Until then, today's temperatures will begin to climb, with the western lower deserts already influenced by the ridge as afternoon highs are in the mid to upper 90s, or near normal. Temperatures in South-central AZ will range in the low to mid 90s or just slightly below normal. Starting Friday as the ridge begins to set up over the Desert SW, temperatures across the entire region will respond to near to 1-2 degrees above normal for early October. During the peak of the heights, late friday into the weekend, the NAEFS climatological percentile is in the 90th percentile, mostly in western deserts, and along the Colorado River Valley. Otherwise, the main weather impact for the remainder of the workweek will be easterly gusty winds. These easterly morning gusts, easily reaching 20-25 mph across southern Arizona, will supply the area with some weak moisture advection in the low levels. Although this moisture will not be nearly enough to bring any rain chances, as the upper atmosphere will still remain fairly dry, but it will keep surface dew points in the 50s.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Little will change over the weekend and likely even for the bulk of next week. The high pressure ridge is heavily favored to remain over or at least very close to our region well into next week keeping us under dry air aloft but with a persistent easterly low level semi-moist flow. Subsidence under the ridge and the dry air should keep a lid on any potential convective chances most days. There are some hints at maybe some convective potential early next week over the highest peaks in eastern Arizona, but as of now the highest PoPs barely breach 10% over the White Mountains.

Temperatures are forecast to rise a bit further during the first half of next week with the western deserts likely reaching 100-104 degrees, while the south-central Arizona lower deserts may get close to 100 degrees. These early October temperatures would range from 4-8 degrees above normal. Overnight lows will also be at least a few degrees above normal, but generally staying in the upper 60s to lower 70s. The most interesting part of the forecast will be the daily easterly breezy conditions due to the expected position of the high over or just to our north and a weak trough setting up to our south. The easterly winds should reach their peak over the weekend and during the mid to late morning hours with gusts in some places reaching 30-35 mph. As daytime heating increases and the mixed layer rises, the winds will be more dispersed and decrease during the afternoon hours. We should keep these daily easterly mostly morning breezes through at early next week and possibly longer.

AVIATION

Updated at 0415Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation weather concerns under clear skies can be expected throughout the TAF period. Overall wind directions throughout the period will be out of the east. Light speeds under 10 kts will prevail through early Friday morning before gusts upwards of 20 kts materialize by the mid/late morning through the afternoon hours, subsiding around sunset.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather issues under clear skies can be expected throughout the TAF period. Winds through early Friday morning will generally be light and variable with periods of calm conditions before a more easterly direction materializes by the mid/late morning hours with overall speeds aob 10 kts.

FIRE WEATHER

Drier conditions are expected to last through the weekend, with persistent clear skies as a high pressure system sets up over the region. Near normal temperatures are expected with the warmest temperatures consistently across the western districts. MinRHs will mostly range from 15-25% over the western districts to 25-35% for the eastern districts with good to excellent overnight recoveries. After light winds today, breezy east winds will set up tonight into Friday and persist for several days. Morning wind gusts of 20-30 mph will be common starting Friday.

PSR WATCHES/WARNINGS/ADVISORIES

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