textproduct: NWS Phoenix

UPDATE

12Z Aviation Discussion.

KEY MESSAGES

- Strong high pressure across the region will persist through at least early next week leading to dry conditions and temperatures hovering around 5 to 8 degrees above normal.

- A slight cooling trend is anticipated during the latter half of next week with temperatures falling to within a few degrees of normal.

SHORT TERM /TODAY THROUGH MONDAY/

A Rex block remains in place across the Western U.S. with the center of the ridge now off the coast of Washington, but extending all the way through northern Mexico. A trough passing through the center of the country has led to some slightly lower heights over at least eastern portions of our region, but overall little change in temperatures. As the Rex block evolves more into an Omega block starting Sunday, we are likely to see even more influence from the trough to our east pushing our daytime highs more into a 73-76 degree range. We are also expecting an increase in higher level clouds starting on Sunday and lasting through early next week. At this point the NBM shows little impact on our temperatures from the increase in clouds, but it would not be surprising to fall short of forecast highs (likely on Monday) if the clouds are thick enough.

LONG TERM /TUESDAY THROUGH FRIDAY/

The weather pattern for the bulk of next week will essentially remain the same with a blocking ridge either over the Western U.S. or just off the West coast. The ridge is currently forecast to persist across our region through at least the middle of next week, while a cut-off low takes shape off the coast of California. Dry conditions will prevail across our region at least through next Thursday or Friday due to the high pressure ridge, while temperatures very slowly drift lower. Forecast highs are currently shown to lower into the lower 70s late next week and potentially a bit lower thereafter depending on what happens with the cut-off low. Ensemble guidance is still quite divided with the cut-off low, but it's not out of the question to eventually have some rain chances by next weekend.

AVIATION

Updated at 0950Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation weather concerns under generally clear skies can be expected throughout the TAF period. Winds will continue to follow diurnal tendencies with a 3-4 hr period of elevated easterly flow around 8-10 kts anticipated at KIWA and KPHX early this afternoon. Winds should relax and shift out of the W-NW at KPHX by 21Z-22Z and then return back to the E-NE after sunset.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns under mostly clear skies can be expected throughout the TAF period. Winds should remain westerly this morning before switching out of the north at both terminals around 17Z-18Z. After this wind shift occurs, speeds will increase to around 8-11 kts, with gusts approaching 20 kts at times, especially at KBLH.

FIRE WEATHER

Unseasonably strong high pressure will continue to bring above normal temperatures and dry conditions into early next week. Daily MinRH values will mainly fall between 15-20% with overnight recoveries of 30-50%. Expect winds to be light across the majority of the lower deserts with some occasional breeziness across the Lower CO River Valley and over the Arizona high terrain. High pressure should persist through the bulk of next week with temperatures slowly drop closer to normal and humidities rising slightly.

PSR WATCHES/WARNINGS/ADVISORIES

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