textproduct: NWS Phoenix

KEY MESSAGES

- The weather pattern for the rest of this week, and likely through most if not all of next week, will support continued dry weather with occasional periods of breezy to windy conditions.

- Near normal temperatures will be common into next week with most days presenting lower desert highs in the mid to upper eighties.

SHORT TERM /TODAY THROUGH FRIDAY/

A large upper level trough is currently situated over much of the Western U.S. with the bulk of the energy across the Northern Rockies. The base of the trough does stretch far enough south to bring some influence across our region, but overall dry quasi- zonal flow will be in place for today and Friday. This will lead to tranquil weather conditions both days with periods of high clouds and occasional breezes late morning through the afternoon hours. Temperatures today will stay within seasonal normals, but some slight warming will be realized on Friday as upper level heights rise a bit. Forecast highs in the upper 80s and lower 90s across the lower deserts Friday are the warmest through the end of the month.

LONG TERM /SATURDAY THROUGH NEXT WEEK/

By Saturday, the next weather system will be taking shape off the coast of southern California as a modest upper level jet strengthens to the west of northern Baja. The jet should support some strengthening of the weather system as it approaches our region later on Saturday, but it will be temporary as once the system moves onshore by Saturday night guidance shows it weakening quite quickly. Southern California is likely to get some shower activity on Saturday, but there is little chance any will survive making it past the interior mountains. Moisture cross-sections show a good deal of upper level moisture out ahead of the system early on Saturday, but that moisture gets pushed eastward out of our area as the system moves onshore later Saturday. Guidance does show an increase in mid-level moisture along and ahead of an advancing cold front Saturday evening and Saturday night, but it's marginal and contained only within a narrow 9-13K ft layer. As usual for this time of year with these fast moving weather systems, forecast soundings indicate a decent amount of dry air within the boundary layer. Once the energy from the mid-level shortwave moves through the northwestern 2/3rds of Arizona Saturday night it should be enough for some higher terrain light shower activity, but it remains quite doubtful it will impact the lower deserts. NBM PoPs do suggest 20-25% PoPs over Phoenix and 25-40% PoPs over the higher terrain to the north, but that has been dialed back to 10-15% and 15-30% in the latest forecast.

Saturday will also present more breezy to locally windy conditions, especially in the afternoon and evening hours. Advisory level winds will be possible for very localized areas across southeast California while gusts across the rest of the area should mostly stay below 30 mph. Temperatures will also begin to cool off on Saturday, partially because of the mostly cloudy skies, as highs are expected to reach the lower 80s across southeast California to the mid 80s across south-central Arizona. Once the weather system exits to the east by Sunday afternoon, the cooler air mass behind the front should limit highs to mostly the upper 70s.

The weather pattern is likely to repeat the same scenario next week as quasi-zonal flow takes over early next week before another weather system develops and eventually moves through our region at some point mid to late next week. After the below normal temperatures Sunday, readings should quickly climb back into the normal range by Tuesday and either stay stable or rise a bit further into the latter half of next week. Guidance is somewhat uncertain on the timing of the system later next week as it may get close to becoming partially cut off from the main flow. For now, guidance is leaning toward no cut-off system and pushing it through our region around next Wednesday or Thursday. If this occurs, we should get a slight dip in temperatures (slightly below normal) again before rising to above normal into next weekend. Models do show some potential light QPF amounts during the middle of next week with the passage of the weather system, but given the time of year we are not putting much faith in those chances.

AVIATION

Updated at 0500Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No significant weather concerns will exist through Thursday night under occasional high cirrus decks. Confidence remains very good that W/SW winds will persist longer into the overnight than usual before finally shifting to a light easterly. Directions should shift back to W/SW late Thursday morning with speeds somewhat weaker than the past few days.

Southeast California/Southwest Arizona including KIPL and KBLH: No major weather issues will exist through Thursday night under periods of high cirrus decks. Confidence remains very good that W/NW winds will persist at KIPL with speeds weaker and gusts more limited than the past couple days. Winds at KBLH should veer from SW to NW overnight though may incur some variability through the period.

FIRE WEATHER

Near to slightly above normal temperatures and seasonably dry conditions will prevail through Friday. Winds will be lighter than the past few days, but some afternoon upslope breeziness should result in occasional gusts to around 20 mph. Expect MinRHs both today and Friday to be between 10-15%, while overnight recoveries will only be poor to fair at 30-45% for most locations. A mostly dry weather system is then expected to bring another round of breezy to windy conditions Saturday potentially leading to elevated fire weather conditions for some areas. Humidities will improve over the weekend with MinRHs rising to 15-25%, but this will be short-lived as they are forecast to fall back to between 10-15% early next week. Seasonably breezy afternoon winds are forecast for early next week, but winds should fall short of creating widespread elevated fire weather concerns.

PSR WATCHES/WARNINGS/ADVISORIES

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