textproduct: NWS Phoenix

UPDATE...Updated 12z Aviation Discussion

KEY MESSAGES

- Near to slightly above normal temperatures will be common this weekend before readings approach 110 degrees by the end of the work week and into next weekend.

- Daily locally breezy conditions will continue across the region the rest of the weekend and into the front half of next week, particularly across the lower Colorado River Valley and higher terrain communities of Arizona.

- Dry conditions under a mix of clouds and sunny skies will prevail through at least the next seven days.

SHORT TERM /Today through Tuesday/

Current objective analysis reveals two areas of low pressure flanking the Desert Southwest, one over the Central Plains, the other centered along the border of British Columbia and Washington. Both these systems have combined to generate breezy conditions across our forecast area over the past few days, and even though the influence of the eastern most disturbance has wained, the other located over the Pacific Northwest will keep our regional pressure gradient relatively tight. This will promote daily breezy conditions during the near term, especially for areas around the Lower Colorado River Valley and high terrain areas of south- central Arizona. Daily afternoon gusts 20-30 mph will be common, with the upper end of that range favoring the locations listed above. Even though no fire weather products have been issued for our area, the combination of these winds, very fuels, and relative humidity values around 10%, elevated to near critical fire weather conditions will remain.

In terms of our temperatures during this timeframe, near to slightly above normal readings can be expected through the end of the weekend and into the start of next week, which translates to lower desert highs between 99-106 degrees. If it were not for the presence of the previously mentioned lows, especially the one off to the north, we would likely be talking about being closer to the 110F mark , not that we are complaining. The longer days and more direct insolation will counteract the erosion of the positive height anomalies, which is why, even with more typical atmospheric height levels, most areas will see readings either at, or just a few degrees above early June normals. However, forecast trends over the past several days has been keeping the northerly trough further and further north, which has allowed for temperature forecasts to see daily increases. If this trend continues through the start of the upcoming week, it would not be surprising to see forecasted highs tick up a a degree or two further.

LONG TERM /Wednesday through Saturday/

There appears to be very good agreement amongst the model clusters regarding pattern evolution through the middle to latter portion of next week, though if you are a fan of more normal highs, it is not an outlook you look forward to seeing. Any influence from the previous troughs will finally exit the western CONUS with eastern Pacific ridging spreading over the Desert Southwest. The rising heights will signal warming atmospheric profiles which in turn will lead to warming temperatures at the surface. 110F readings were mentioned briefly above, and well, we might be talking about those more during the end of the week as warming leads us closer and closer to this point. The latest NBM puts Phoenix and Yuma just shy of 110F by Friday, but there is still several days to go before we get there so things could certainly change. If Phoenix were to reach 110F on Friday (6/12), it actually would not be completely abnormal as the average first 110F day is 6/14. Nonetheless, it is the Desert Southwest in June, so expect hot and dry conditions to continue for at least the next seven days.

AVIATION

Updated at 1100Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation weather concerns under SCT high clouds can be expected throughout the TAF period. Winds will follow the typical diurnal tendencies with a period of southerly winds mid/late morning into the early afternoon hours before the westerly shift. Occasional gusts upwards of 20 kts likely during the afternoon and early evening hours.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns under SCT high clouds can be expected throughout the TAF period. At KIPL, light and variable winds currently will shift out of the southeast by the mid-morning hours before shifting out of the west by the early evening hours. At KBLH, winds will generally be out of the south throughout the period. Overall wind speeds will fluctuate between 8-15 kts with afternoon gusts upwards of 20-25 kts likely at KBLH.

FIRE WEATHER

Elevated fire weather conditions will persist through the front half of the upcoming week thanks to continued breezy conditions and low afternoon RH values. Peak gusts will range close between 20-30 mph, with the top end of that range focused over the high terrain of Arizona and areas in and around the Lower Colorado River Valley. Daily MinRH values will hover between 5-10% with overnight recovery offering very little in the way of relief as Max RHs peak between 15- 45%. Even though we will see continued fire weather danger, gusts will should be low enough to inhibit any critical conditions, so no further products are expected going forward. We begin to lose breezy conditions for during the back half of the week, further diminishing fire weather concerns. However, low RHs will continue to be observed, so even marginal breezes, which become more common during the summer thanks to terrain influences and greater mixing heights, can create localized elevated conditions.

PSR WATCHES/WARNINGS/ADVISORIES

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