textproduct: NWS Phoenix

UPDATE

Updated Aviation

KEY MESSAGES

- Above normal temperatures with moderate HeatRisk will prevail through the remainder of the week before readings retreat closer to normal by the end of the weekend.

- Other than a slight chance of a shower or thunderstorm this afternoon over eastern Arizona, dry conditions under mostly sunny skies will prevail through at least the middle part of next week.

- Locally breezy conditions will develop for the end of the week and into the weekend, particularly across the lower Colorado River Valley and higher terrain communities.

SHORT TERM /Today through Saturday/

The Desert Southwest finds itself in the midst of a messy upper- level pattern with areas of low pressure to the north and south, and ridging to the east and west. In turn, conditions have been a bit atypical for June for parts of eastern Arizona and western New Mexico with convective activity spawning over high terrain areas yesterday afternoon thanks to the presence of some unseasonably enhanced low-level moisture levels. This moisture will stick around for one more day, creating a favorable setup for another round of convective activity. However, it will once again be limited in scope, being confined mostly to the White Mountains and around enhanced terrain features of Graham and Greenlee Counties. Much like yesterday, a very isolated cell cannot be ruled out over far southeastern Gila County. The main impacts from potential storms will be some occasional lightning and gusty winds in excess of 35 mph. Any locations that find themselves under any rainfall will only see minimal totals, generally 0.10" or less, but some localized higher totals are not completely out of the question.

Even with this messy upper-level pattern, the regional height field continues to run slightly above normal for early June. This, in turn, will help to keep our thermal profile warmer than normal during the back half of the week and into the weekend. Afternoon highs this afternoon for many locations with flirt with some of the highest readings we have seen so far this year as temperatures range between 105-109 degrees for lower desert communities. Phoenix and El Centro, CA forecasted highs are at the top of that range, so the first 110 degree readings of the year for these areas cannot be completely ruled out. On average, 110F is reached at these locations on 6/11 and 6/14 respectively, so it would not be completely out of left field if we do reach that mark this afternoon. The silver lining in this that the NBM is not confident that we will get there, giving only about at 10-15% chance for both Phoenix and El Centro. Temperatures beyond tomorrow will follow a slight downtrend, falling closer to normal for early June (which is around 100 degrees for our three main climate sites) by the end of the weekend.

Interactions between a lingering area of low pressure, currently over northern Mexico, and an eastern Pacific ridge will set the stage for a day-to-day uptrend in regional wind strength starting this afternoon. Breeziness will be marginal to start off and peak gusts will only reach upwards of 25 mph around the Lower Colorado River Valley. However, pushing closer to the weekend, another low diving south from the Gulf of Alaska will also begin to squeeze the pressure gradient, adding another layer to the interplay mentioned above. This will create stronger and more widespread breeziness for Friday and Saturday as gusts approach 25-30 mph for higher terrain areas and previously mentioned communities near the Colorado River. With afternoon humidity values only hovering around 5-10% the next several afternoons, any enhanced gusts will result in periods of elevated fire weather conditions.

LONG TERM /Sunday through Wednesday/

It appears that ensembles have come into better agreement in terms of the evolution of the previously mentioned Gulf of Alaska low. Some friction remains, but trends point towards a weaker solution that was being favored by the GEFS at this time yesterday. Both the GEFS and ECMWF Ens show this closed low becoming an open wave and extending from the British Columbia down the length of the Pacific Coast, so there will likely be at least some influence from this disturbance on the Desert Southwest. This influence will more than certainly come in the form of continued breezy to locally windy conditions through the end of the weekend and into the weekend. The associated negative height anomalies will promote some slight cooling, but the vast majority of lower desert highs will remain in triple digit regardless. This trough will not provide anything in terms of moisture flux, so with continued breeziness forecasted, daily elevated fire weather risk is expected to extend at least into next Monday for parts of the forecast area.

There appears to be better agreement, compared to 24 hours ago, regarding the pattern toward the middle of next week. Clusters have honed in on the continued presence of troughing across the Great Basin, but where they differ is how strong this feature might be. Some clusters even suggest cyclonic curvature collocated with positive height anomalies over the Desert Southwest, perhaps keeping breezy conditions in the forecast as well as triple digit temperatures. There is still some wiggle room so things are likely to change over the next few days. One thing that does appear certain is continued dry conditions through at least the middle of next week.

AVIATION

Updated at 1730Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; Southeast California/Southwest Arizona including KIPL and KBLH:

No major aviation concerns are expected through the TAF period. Winds in the Phoenix Metro will exhibit typical diurnal tendencies with periods of elevated speeds and gusts up to 20kts possible this afternoon and tomorrow afternoon. Out west, KIPL will maintain a SE'rly component throughout the period, with wind speeds mostly aob 10kts with the exception of this afternoon where sustained speeds can be 10-15kts before relaxing for the evening/overnight hours. KBLH will maintain a S/SSW component with speeds generally aoa 10kts throughout the period, with gusts between 20-25kts this afternoon possible. Skies will be clear for most of the period with FEW mid level clouds passing this morning and again tomorrow afternoon.

FIRE WEATHER

The threat for an isolated dry thunderstorm over southern Gila County this afternoon is the main fire weather hazard in the short term. Winds through this afternoon will follow typical diurnal tendencies with typical afternoon upslope breeziness. Gusts pick up Friday and into the weekend, mainly across the Lower Colorado River Valley and high terrain areas of the eastern districts with readings reach upwards of 25-30 mph. With daily MinRHs hovering close to 5- 10% for the majority of the region, even marginal breezes will result in periods of elevated fire weather conditions. Isolated instances of near critical to critical conditions can be expected with localized higher gusts. Overnight recovery will offer very little in terms of relief as MaxRHs run only between 15-45% for most locations. Breezy conditions are likely to continue into the weekend, perhaps even lingering into next week, potentially resulting in a prolonged period of daily occurrences of elevated to near critical fire weather conditions starting Friday.

PSR WATCHES/WARNINGS/ADVISORIES

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