357
FXUS65 KPSR 171704
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1004 AM MST Thu Jul 17 2025

.UPDATE...Updated 18z Aviation Discussion.

&&

.KEY MESSAGES...

- Chances for scattered showers and isolated thunderstorms will
  continue mainly this morning across southwest Arizona.

- Drier conditions into the weekend will limit any rain chances
  to the eastern Arizona high terrain.

- Near to below normal temperatures are forecast to persist
  through at least the middle of next week with lower desert
  highs mostly between 101 and 106 degrees each day.

&&

.SHORT TERM /Today through Friday/...
The remnant MCV from yesterday morning is still the main driving
force of shower activity with a fairly large area of showers and a
few embedded thunderstorms encompassing much of southwest Arizona
into western Maricopa County. This activity should yield rainfall
amounts upwards of 0.50-0.75" in some locations through sunrise
this morning. The upper level low is finally making progress
northward with the center now just off the coast of central Baja.
Southerly flow on the eastern fringes of the low is also starting
to bring dry air northward through Sonora with this dry air slated
to push through much of southern and central Arizona by this
afternoon. Once we lose the support from the MCV and any remaining
instability over southwest Arizona, we are not expecting anything
other than a few isolated convective showers this afternoon. PoPs
have been curtailed considerably from the NBM baseline as Hi-Res
CAMs show little if any activity after sunrise today.

The extensive cloud shield will also get eroded from south to
north by mid to late morning with much more sunshine expected this
afternoon compared to yesterday. Temperatures will in turn
respond by warming to just above 100 degrees for the majority of
the lower deserts this afternoon.

Dry air is forecast to continue spreading into the region from the
south on Friday as the weakening upper level low likely shifts
into southern California by Friday afternoon/evening. There may be
enough lingering moisture for some isolated showers or maybe a
thunderstorm or two west of the Phoenix area and over the eastern
Arizona high terrain, but once again the convection should be very
limited. Temperatures Friday will continue to warm as we dry out
with highs likely topping out at around 105 degrees across the
lower deserts.

&&

.LONG TERM /Saturday through Wednesday/...
Guidance continues to show overall quiet and not so hot weather
conditions this weekend through the first half of next week.
Southwesterly dry flow is likely to persist at least into next
Monday with only meager amounts of moisture over eastern Arizona.
This should be enough to bring some daily chances (10-30%) for
isolated showers and thunderstorms over eastern Arizona, but
chances over the lower deserts are generally less than 10%.
Chances may improve slightly by Monday or Tuesday as guidance
shows some additional moisture drifting northward out of Mexico,
but overall moisture is not likely to be very plentiful and there
are no discernible features within the models to help bring
anything other than the typical afternoon mountain convection.
The synoptic pattern is rather stagnant over the weekend and
through the first half of next week with a large trough sitting
just to our northwest and the subtropical ridge mostly over the
Southern Plains. Model trends over the last couple of days have
actually showed the upper low having more of an influence on our
region keeping our temperatures from warming up any further. The
latest NBM forecast highs through the middle of next week keep
readings right at or even a couple degrees below normal. This
should keep the HeatRisk over our area anywhere from high-end
Minor to low-end Moderate.

&&

.AVIATION...Updated at 1705Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
Overall quiet weather expected this TAF period. Isolated showers
could form late this afternoon, but should remain anchored to
higher terrain and thus not expected to impact valley TAFs.
Otherwise, winds will remain light and variable with slight
diurnal direction tendencies. Expect FEW-SCT clouds AOA 8 kft.

Southeast California/Southwest Arizona including KIPL and KBLH:
Overall quiet weather expected this TAF period. Isolated
showers/storms could form late this afternoon but confidence and
coverage remains only at 5-10 percent, so not warranted in TAFs.
KIPL wind tendencies will be from the southeast with more of a
southerly component for KBLH.

&&

.FIRE WEATHER...
Below normal temperatures and increased humidities will continue
today before drying occurs Friday into the weekend. Expect
scattered showers and a few isolated thunderstorms today with very
limited chances on Friday. Afternoon MinRHs will stay between
25-30% today before dropping closer to 20% Friday and into the
teens this weekend. Winds over the next few days should mostly
follow diurnal patterns with only light periodic breezes in the
afternoon. High pressure will somewhat return to the region this
weekend with RHs dropping back into the teens, but temperatures
will at most return to normal. Any rain chances should be quite
limited and only over the eastern Arizona high terrain.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...Frieders
FIRE WEATHER...Kuhlman