textproduct: NWS Phoenix

UPDATE

06Z Aviation Discussion.

KEY MESSAGES

- Dry conditions with temperatures hovering around 5 to 8 degrees above normal will prevail through this weekend.

- A slight cooling trend is anticipated by early next week with lower desert highs falling into the low to mid 70s

SHORT TERM /TODAY THROUGH SUNDAY/

The Rex block pattern will begin to degrade by tonight, but strong ridging will remain in place over the NW coast line, and continue to result in above normal temperatures over our region. Deep troughing is also affecting much of the central and eastern U.S. with a strong shortwave currently digging southward through the Central Plains. As the Rex block degrades, the center of the high will shift up into the Gulf of Alaska, in conjunction to this shift, the troughing feature to our east will also help lower H5 heights, slightly. H5 heights through the weekend will generally be between 575-580 resulting in steady high temperatures in the mid to upper 70s for the lower deserts, and in the mid to upper 60s in the higher terrain areas. Morning low temperatures throughout the weekend will mostly be in the mid to upper 40s, with some localized areas, like Yuma, can see lows just over 50 degrees.

LONG TERM /MONDAY THROUGH THURSDAY/

Little change is anticipated for the first half of next week as the Rex block evolves more into an Omega block with upper level ridging persisting across much of the Western U.S. The center of the ridge will remain north of our region, but it should still provide a good amount of influence. Forecast H5 heights are shown to lower a bit further early next week and this should eventually push daily highs more into the lower 70s by Tuesday or Wednesday. A closed low is also likely to become a bit more organized off the West Coast during the first half of next week before potentially approaching our region late next week. Models usually have a difficult time handling the timing of the cut-off low evolution, so it would not be surprising if the timing of this low gets pushed back a few days. A minority of the ensemble members currently show a fairly organized closed low moving near our region by next weekend bringing a return of rain chances, but it is way too early to speculate on any details. If this low does come to fruition, it should be a fairly warm system with higher snow levels and temperatures at most falling back into a normal range.

AVIATION

Updated at 0535Z.

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 period of elevated easterly flow around 8-11 kts anticipated at KIWA and KPHX by late Saturday morning. Winds should relax and shift out of the W-NW by the afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns under mostly clear skies can be expected throughout the TAF period. Winds generally remain westerly overnight before switching out of the north at both terminals late Saturday morning. After this wind shift occurs, speeds will increase, 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 through at least the weekend. Daily MinRH values will mainly fall between 15-20% with overnight recoveries of 30-50%. Winds have also settled down, but some breezy northerly winds will remain possible through Saturday across the Lower CO River Valley and over the Arizona high terrain.

PSR WATCHES/WARNINGS/ADVISORIES

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