textproduct: NWS Phoenix

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/

A much quieter weather pattern is taking shape across much of the Western U.S. as an unseasonably strong high pressure ridge near the West Coast moves inland through Friday. The center of the ridge is forecast to set up over the Desert Southwest by Saturday and likely stay there well into next week. In the short term, some of the 'cooler' air remains over Arizona, but with abundant sunshine and increasing heights aloft daytime highs will be back in the lower 90s across the Phoenix area to as warm as the upper 90s across southeast California. Once the center of the ridge moves into our region on Friday, additional warming can be expected bringing lower desert highs up to around 95 degrees in the Phoenix area to around 100 degrees across southeast California and the Lower CO River Valley. Despite the drier air aloft, surface moisture will stay a bit elevated as breezy easterly winds are expected to set up beginning Friday morning. This easterly fetch, with morning gusts easily reaching 20-25 mph across southern Arizona will supply the area with some weak moisture advection in the low levels. This moisture will not be nearly enough to bring any rain chances, 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 0455Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Uncertainty in wind directions and timing of wind shifts will be the main weather issues through Thursday night under clear skies. Confidence is excellent that east winds will prevail into at least Thursday afternoon before significant uncertainty arises. Winds may attempt to become W/NW late afternoon, however may only be able to achieve a variable direction before reverting back to easterly mid evening.

Southeast California/Southwest Arizona including KIPL and KBLH: No weather issues will exist through Thursday night under clear skies. While light S/SE winds will more common through the period, light and variable winds will prevail for prolonged stretches.

FIRE WEATHER

Gradual drying as high pressure takes hold over the region will lead to somewhat lower humidities and mostly clear skies through the rest of the week. 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.