textproduct: NWS Phoenix

KEY MESSAGES

- Drying conditions over the next several days will end rain chances altogether by Monday. - Temperatures will briefly warm back into the normal range starting today and last through around Tuesday before dropping off again during the latter half of the week.

- Localized Moderate Heat Risk is expected mainly across the south-central Arizona lower deserts during the first half of this week with highs as warm as 105 degrees.

SHORT TERM /Today through Tuesday/

The drying trend over the past day or so is now very noticeable as satellite imagery shows clear skies over nearly all of southern California and Arizona. Upper level ridging has also started to build over our region in response to the deepening of the Pacific low off the West Coast and heights over our area are forecast to peak later today into early Monday. The strong drying aloft will finally start to mix down to the surface this afternoon, but dew points are likely to stay above 60 degrees for one more day. The drying aloft has mostly ended the rain threat with only a few widely isolated showers or weak storms possible over the Kofas and over the far eastern Arizona high terrain this afternoon. The increased heights and sunny skies today will help to push highs across the lower deserts to between 99-102 degrees this afternoon.

Starting Monday, much drier air will finally work its way down into the boundary layer, completely ending any rain chances and lowering surface dew points into the 50s Monday afternoon and into 30s and 40s across the western deserts Tuesday afternoon. The warming trend will also continue with highs likely peaking on Monday between 100-104 degrees. By Tuesday, the southeastern fringes of the Pacific trough will begin to shift into northwest parts of our region. This will help to bring temperatures down a few degrees across southeast California and likely also result in some increased breezy conditions.

LONG TERM /Wednesday through Saturday/

The Pacific trough will become the main driver of our weather starting Wednesday as the low center moves into northern California and the base of the trough moves over central and southern California. This should push daytime highs well into the 90s across southeast California, but highs across south-central Arizona are still likely to top 100 degrees on Wednesday. Breezy conditions areawide are also expected Wednesday (and possibly Thursday) with afternoon gusts to around 25 mph. Guidance is also indicating some very modest moisture across eastern Arizona for Wednesday and Thursday, but it is expected to be quite shallow and should at most bring 10-20% PoP chances across the high terrain.

Ensembles are now in better agreement showing the Pacific trough stalling out over the Western U.S. as it continues to weaken before finally lifting the northeast next weekend. The lower heights from the trough should keep highs in the 90s across most of the lower deserts late this week to as high as around 100 degrees in the Phoenix area. Overnight lows should also continue to improve later this week with lows dipping into the 60s across the western deserts to the low to mid 70s in the Phoenix area. Eventually by late next weekend and into the following week, heights are favored to trend upward again after we lose influence from the trough. This should lead to some slight warming and highs back to just over 100 degrees.

AVIATION

Updated at 0530Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: An outflow boundary from distant storms is currently pushing nwd into Maricopa County and is progged to arrive at KIWA by this TAF issuance and KPHX at approx 07Z. This boundary will cause a brief southerly shift at both terminals with gusts up to 18-20 kts. Winds will return to the normal diurnal patterns later tonight, however there will likely not be an easterly shift at KPHX tonight and instead winds will go calm and vrb for a few hrs around sunrise. Winds will shift back out of the WSW at all terminals by 16Z-17Z Sunday. Expect clear skies overnight with another round of CU developing on Sunday afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns will exist over the next 24 hrs. Winds will generally favor SE at KIPL and S at KBLH, with sustained speeds 5-11 kts through Sunday afternoon. Expect skies to remain clear overnight with another round of CU developing early Sunday morning.

FIRE WEATHER

Drying conditions are expected over the next several days as high pressure influences our region. Rain chances have essentially ended and temperatures will briefly return into the normal range early this week. MinRHs today will stay elevated at 25-35% before gradually lowering to between 15-25% by Tuesday. Winds will continue to be light and favor diurnal patterns through Monday before a uptick in winds is likely during the middle part of the week. By Wednesday into Thursday, an incoming low pressure system mainly to our northwest may allow for some isolated shower and thunderstorm chances largely over the eastern Arizona high terrain. Temperatures will also cool back to slightly below normal later this week with humidities staying stable through Thursday before drying out even more Friday into next weekend.

PSR WATCHES/WARNINGS/ADVISORIES

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