747 
FXUS65 KPSR 101039
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
339 AM MST Sun Aug 10 2025

.KEY MESSAGES...

- Above normal highs and warm overnight lows will continue to
  yield widespread Moderate to localized Major HeatRisk through 
  early this week.

- Major HeatRisk will be concentrated particularly over the
  central AZ lower deserts, the Lower Colorado River Valley, and 
  Imperial Valley where Extreme Heat Warnings remain in effect 
  through Tuesday evening. 

- Chances for showers and thunderstorms will continue to remain quite
  limited through the first half of this week, generally favoring
  the eastern Arizona high terrain. 

- Increasing moisture by late week will result in better coverage
  of thunderstorm activity across much of the region including 
  the lower deserts 

&&

.SHORT TERM /Today through Tuesday/...
Latest IR WV satellite imagery and 500 mb streamline analysis 
reveals an elongated ridge of high pressure stretching from 
southeast CA into west TX while a trough of low pressure is 
present over the Intermountain West. A large complex of 
thunderstorms over northern MX has sent an outflow boundary into 
our region, resulting in overnight convection and areas of blowing
dust. Shower activity with a few embedded lightning strikes will 
continue to track through southcentral AZ overnight but this 
activity is expected to diminish around sunrise.

Heading through the rest of today, the aforementioned high 
pressure center is projected to reposition over the CA/NV border 
resulting in upper level winds shifting from westerly to northerly
across our forecast area. Hghts aloft will still remain around 
593-594 dam allowing highs to again reach the 105F-112F range 
across the lower deserts this afternoon. Another round of 
convection is expected to fire up over the higher terrain areas, 
mainly across the Mogollon Rim and White Mountains, as well as 
across portions of southeast AZ this afternoon. The convection 
that fires up around the vicinity of the Mogollon Rim will move 
southward into portions of southern Gila County as well as into 
northeast Maricopa County but will likely not survive into the 
lower deserts due to greater inhibition in place. Thus rain 
chances for the Phoenix Metro will remain below 15% through this 
evening. Despite the low rain chances, there is still a moderate 
chance (30-50%) for gusty outflow winds up to 35 mph to reach E 
Maricopa and N Pinal Counties.

On Monday and Tuesday, dry N-NE flow aloft will prevail over the 
state as ridging continues to strengthen over the Great Basin 
region. In response shower and thunderstorm activity will remain 
isolated and confined to the AZ high terrain of eastern and 
southeastern AZ. Due to a slight increase in hghts aloft and 
warming of 850 mb temperatures, we will see sfc temperatures 
climb by a degree or two with highs reaching 108F-113F on Monday 
and 108F-114F on Tuesday across the lower deserts. The Extreme 
Heat Warning has remain unchanged and will continue through 
Tuesday evening. 

&&

.LONG TERM /Wednesday through Saturday/... 
Starting Wednesday, ensemble guidance continues to indicate a 
trough entering the Pacific Northwest while the ridge over the 
Great Basin begins to weaken and shift eastward toward the Four 
Corners area. This will allow a more favorable E-SE flow to set up
over the forecast region. Despite some model uncertainty between 
the EPS and GEFS regarding timing of the better moisture return, 
the overall trends during the latter half of next week favor 
increasing moisture (PWATs reaching 1.4"-1.6") followed by a 
return of monsoon rain chances by the Thursday through Saturday 
timeframe. NBM PoPs continue to trend upward by the latter part of
this week, peaking around 20-40% across the lower deserts on 
Thursday and Friday. Due to the increasing moisture, a cooling 
trend is expected to transpire from Wednesday-Saturday, with highs
falling back into the normal range by next weekend.

&&

.AVIATION...Updated at 0455Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: 
Bit of an unconventional TAF period is expected, with the main
concerns being gusty outflow winds early tonight. Guidance
continues to point toward a transient boundary approaching from
the SE, with the timing adjusted back about an hour (07-09Z). This
outflow will bring gusts around 25 kts and perhaps some reduced
visibilities due to blowing dust (especially at KIWA), but mention
of lower VIS has been excluded from the TAFs at this time because
of too much uncertainty. Once winds relax they will eventually 
turn more to the E/NE late tonight before switch out of the W/NW 
much earlier than usual (14-15Z). However, if this outflow never 
materializes, or fails to make through the metro, a continuation 
of more of a diurnal pattern should be anticipated, with E and W 
shifts occurring closer to their usual time windows. Generally 
clear skies early tonight will give way to FEW-SCT mid and high 
level clouds through the remainder of the period. 

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are expected over the next 24 hours
under generally clear skies. Winds at KIPL will generally remain
out of the SE through Sunday afternoon, while KBLH will continue
to see more S'rly winds with some occasional afternoon gusts
around 20 kts. 

&&

.FIRE WEATHER...
Above normal temperatures will continue through the middle of this 
week. There will continue to daily thunderstorm activity over the 
high terrain through the first half of the week followed by a better 
potential for scattered shower and thunderstorms across much of the 
region late in the week. Chances of wetting rainfall will remain 
below 10% over the next few days, resulting in potential for dry 
lightning and new fire starts. Minimum afternoon humidity levels 
will mostly range between 15-20% with fair to good overnight 
recoveries. Winds will retain an afternoon upslope component with 
gusts to 15-20 mph common.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Tuesday for AZZ530-532-534-
     537>544-546-548>551-553>555-559.

CA...Extreme Heat Warning until 8 PM PDT Tuesday for CAZ562-563-566-
     567-569-570.

&&

$$

SHORT TERM...Salerno
LONG TERM...Salerno
AVIATION...RW 
FIRE WEATHER...Salerno