textproduct: NWS Phoenix

KEY MESSAGES

- Above normal temperatures with afternoon highs in the nineties will be common through the middle of next week as high pressure prevails over the region.

- There is a chance of scattered showers and isolated storms, especially on Monday, across the Arizona high terrain.

- Another weather system is likely to affect the region late next week and weekend, leading to increased winds and cooling temperatures.

SHORT TERM /Today through Monday/

Latest objective analysis shows a ridge of high pressure across the western third of CONUS with a very dry air mass currently overhead, with dewpoints in the single digits and teens. As a result, a tranquil weather day under mostly sunny skies can be expected. Temperatures this afternoon will warm into the upper 80s to low 90s across much of the lower deserts. As the upper-level ridge axis shifts further inland across the western CONUS Sunday, low-level thermal profiles will warm even further and thus afternoon temperatures will warm into the middle 90s across much of the lower deserts.

As surface high pressure builds across the Plains and pushes a backdoor front into southern AZ, a surge of easterly winds can be expected across much south-central and southeast AZ later tonight into Sunday morning, with the potential for wind gusts to peak between 25-35 mph across the higher terrain areas east of Phoenix and 15-25 mph across the lower elevations Sunday morning before weakening heading into the afternoon hours. Another surge of easterly winds is expected once again late Sunday night into Monday morning with similar speed magnitudes. This easterly wind surge will also cause a modest increase in moisture, leading to the potential development of a few showers and isolated storms starting Sunday afternoon across mainly the Mogollon Rim and White Mountains. Heading into Monday, a weak shortwave riding the subtropical branch of the jet stream will traverse the region likely increase the overall convective coverage, focused across the higher terrain of northern and far eastern AZ. Across the lower deserts, there will be too much dry air in the low levels, prohibiting convective activity from developing. Under the influence of considerable mid to upper-level clouds accompanying the passing shortwave, afternoon high temperatures on Monday will cool into the upper 80s to low 90s across the south-central AZ lower deserts while slighter warmer readings in the low to mid 90s can be expected across the western deserts.

LONG TERM /Tuesday through Friday/

Upper-level ridging will continue to prevail across the region through the middle of the week and thus afternoon highs will continue to run approximately 10 degrees above normal, with readings topping out in the middle 90s. Heading towards the end of next week and weekend, model guidance is indicating a more vigorous upper- level low moving in from the eastern Pacific into our region. However, considerable differences exist in terms of the timing and degree of amplification of this feature as it approaches. Cooler temperatures with readings retreating to near normal levels and increased winds appear more probable. However, if this feature becomes highly amplified as some of the guidance is suggesting, then there is a potential that enough moisture may be drawn in to give increased rain chances across portions of the region, particularly across the AZ high terrain heading into next weekend.

AVIATION

Updated at 1750Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Occasionally gusty east winds and lower than usual confidence on a full westerly shift late this afternoon into the evening will be the primary aviation concerns during the TAF period. E/NE winds around 10 kts with occasional higher gusts late this morning will relax heading into this afternoon. A period of variability is then likely as winds attempt to switch out of the NW late this afternoon/early this evening. This will be a briefer than usual westerly wind shift, as E/SE winds establish across the terminals between 04-07Z this evening and remain elevated (around 6-10 kts) overnight. Another period of gusty E/SE winds is expected beginning shortly after sunrise Sunday morning, with gusts to 15-25 kts for several hours before relaxing during the afternoon. Due to strong east winds over portions of the deserts and higher terrain east of the Phoenix airspace, slantwise visibility reductions may occur Sunday morning from lofted dust/haze. FEW-SCT and at times BKN high cloud decks will prevail.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns are expected through the next 24 hours under FEW-SCT high clouds. North northeasterly winds between 8-12 kts will relax heading through the afternoon and back out of the northwest (AOB 6 kts) this evening at both terminals.

FIRE WEATHER

Generally dry weather and above normal temperatures will persist during the next several days. Afternoon MinRHs will fall to near 10% today before increasing slightly on Sunday and Monday as moisture increases. The increase in moisture will result in some shower and thunderstorm chances, mainly confined to northern and far eastern AZ, particularly on Monday. Lighter winds are expected today before easterly winds increase Sunday and Monday mornings, particularly across the higher terrain areas of south-central AZ where peak gusts upwards of 25-35 mph are possible. Lighter winds briefly return Tuesday and Wednesday before increasing once again towards the latter portion of next week with the approach of another weather system.

PSR WATCHES/WARNINGS/ADVISORIES

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