textproduct: NWS Phoenix

UPDATE

Updated Aviation

KEY MESSAGES

- Temperatures will cool further today and remain stable at around five to seven degrees above normal through Saturday. Temperatures should then dip into the normal range by early next week.

- Breezy conditions will develop along the Lower Colorado River Valley and Arizona high terrain this afternoon, then return to the area over the weekend.

SHORT TERM /Today through Thursday/

The strong high pressure ridge that brought near record temperatures early this week is getting pushed to the east of the region while a weak shortwave trough tracks northward across southern California. The exiting of the ridge today will continue to depress heights across the Desert Southwest leading to noticeably cooler daytime highs. Afternoon highs are forecast to top out right around 100 degrees across the lower deserts with some lingering clouds mainly across the eastern half of Arizona. An enhanced pressure gradient today will again lead to some breezy conditions focused mainly across southeast California and over the Arizona high terrain. Weak troughing is then expected to mostly stay over the Desert Southwest for Thursday, but little additional cooling is expected. Lower desert highs Thursday are forecast to reach into the upper 90s under sunny skies.

LONG TERM /Friday through Tuesday/

The weather pattern going into the weekend is shaping up to drive a deep Pacific trough through the Northwestern U.S. with at least one piece of energy reaching the Desert Southwest on Saturday and/or Sunday. West northwesterly dry flow is expected to dominate across our region through at least early next week keeping skies clear to mostly clear and humidities seasonably low. The main forecast concern will be the increased winds associated any passing disturbances bringing elevated to critical fire weather conditions. Differences in model timing and the track of the disturbances still remain, but based on pattern recognition it is likely to result in at least a day or two of elevated fire weather conditions. The current timing of the stronger winds favors southeast California and southwest Arizona Saturday, the Arizona higher terrain Sunday, and potentially the Lower CO River Valley on Monday.

Temperatures are expected to dip further starting around Sunday, but model spread is fairly high at this point. A deeper system could drop lower desert highs closer to 90 degrees, whereas one that somewhat bypasses to the north may only bring mid 90s for a day or two early next week. Beyond early next week, guidance mostly show a ridge building back into the region bringing gradually warmer temperatures. The latest NBM/WPC guidance shows readings potentially reaching 100 degrees again by next Wednesday.

AVIATION

Updated at 1700Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Winds will be the main weather issue through Thursday afternoon as mid/high cloud decks slowly clear through the period. Confidence is good that several hours of a southerly cross runway component will impact terminals through early/mid afternoon before completing the switch to W/SW. A few gusts around 20kt will be common before decoupling around sunset. The nocturnal switch to easterly will again occur somewhat later than usual, but earlier and more defined than this morning.

Southeast California/Southwest Arizona including KIPL and KBLH: Periods of gusty winds will be the primary weather issue through Thursday afternoon under a few passing high cloud decks. S-SW wind directions will be preferred at KBLH while a westerly component will be more common at KIPL. Confidence is good that gusts 20-30kts will extend from mid/late afternoon though the evening before decoupling and weakening overnight.

FIRE WEATHER

Hot, dry, and locally breezy to windy conditions will result in elevated fire weather potential this afternoon across the Lower CO River Valley. Wind gusts of 20-30 mph along with RHs 7-10% are expected across the Lower CO River Valley. Elsewhere today, winds will be lighter but with afternoon gusts of 15-20 mph possible. Wednesday will bring another round of breezy winds over southeast California and the Arizona high terrain with elevated fire weather conditions again a possibility. Temperatures today will be 10-15 degrees above normal dropping to 5-8 degrees above normal starting Wednesday. Winds will diminish starting Thursday, but very dry conditions will continue to prevail.

PSR WATCHES/WARNINGS/ADVISORIES

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