Mesa, Arizona Weather Forecast Discussion

657
FXUS65 KPSR 111750
AFDPSR
Area Forecast Discussion
National Weather Service Phoenix AZ
1050 AM MST Thu Sep 11 2025
.UPDATE...Updated Aviation Discussion.
&&
.KEY MESSAGES...
- Temperatures gradually cool, with near to below-normal readings
  expected through the weekend.
- Breezy conditions will develop once again this afternoon for
  parts of the region with peak gusts around 25 mph.
- Outside of some isolated rain chances for eastern Arizona
  through the end of the workweek, the majority of out forecast
  area should remain dry over the next several days.
&&
.SHORT TERM /TODAY THROUGH FRIDAY/...
Morning 500mb analysis reveal fairly active pattern draped across
the western CONUS, with a decent area of low pressure spinning
over northern California and Nevada. This prominent feature has
shoved the sub-tropical high further to our south and east with
the center of the anticyclone now over Texas. Much of our forecast
area will find itself caught right in the middle of these
interacting regimes, resulting in a slight dichotomy in regional
conditions. Hi-res models are picking up on some isolated to
scattered shower and thunderstorm activity around the high terrain
areas of Gila County as the overall flow is still favorable for
sufficient moisture advection over this area to spark at least
some convective activity. The main impact with potential rainfall
activity will be locally gusty winds upwards of 35 mph. Elsewhere
across the lower deserts, dry southwesterly flow will largely
inhibit any rain chances. However, lingering moisture over
Maricopa County will set up an axis of instability that will be
mostly uncapped by this afternoon. It would not be completely out
of the question to see a quick shower pop up around prominent
terrain features such as the Estrella or White Tank Mtns around
the Phoenix metro, but chances remain around 10%. Otherwise,
thanks to large-scale enhancement of the regional pressure
gradient, some breezy conditions can be expected this afternoon,
mainly east of the Colorado River, with peak gusts hovering around
25 mph.
By Friday, the Pacific low will nudge slightly further to the east,
placing the Desert Southwest under greater influence of this system.
With better and more widespread ascent aloft thanks to the
introduction of mid-level and upper-level vorticity, along with
lingering moisture, parts of our CWA experience a favorable setup
for perhaps some more convective development Friday afternoon. The
axis of best moisture will heavily favor eastern Arizona so the most
likely areas to see rain will once again be the high terrain of Gila
County, while the rest of the region remains dry. What will be
experienced region-wide will be decreasing day-to-day
temperatures as cooler air and associated negative height
anomalies spread eastward. Lower desert highs through the end of
the workweek will hover near to slightly below normal, with lower
desert readings in the mid 90s to around 100 degrees.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Heading into the weekend, models have the Pacific trough continuing
its eastward progression, clearing Arizona by late Saturday/early
Sunday. As it migrates towards the Great Plains, unseasonably dry
air will cut off any further rain chances for our area as PWATs
fall to only 50% of normal for this time of year. The good news
is, even as we fully dry out, temperatures will not rebound as
quickly as we have seen this summer as flow aloft becomes more
zonal rather than rapidly shifting back to increasing high
pressure. Temperatures this weekend will continue their end-of-
week trend, with highs hovering near to slightly below normal.
The overall picture becomes a little less clear as we approach next
week. A lot of this uncertainty stems from what could become the
next Tropical Cyclone over the Eastern Pacific. As of now, models
generally favor the track of this system remaining off the western
coast of the Baja Peninsula before eventually falling apart.
However, it appears that some models want to bring some remnant
tropical moisture toward our forecast area, which could result in
considerable cloud cover and even rain chances. Subtle shifts in the
forecast could yield a vastly different foreast solutions for
this timeframe, so how this potential system evolves will be
something to monitor in the coming days. As of now, global models
favor the return of broad ridging by next week, which would
translate to increasing temperatures back to above-normal levels,
but there is a noticeable spread in the interquartile temp
forecast potentially reflecting model uncertainty relating to the
aforementioned tropical system.
&&
.AVIATION...Updated at 1748Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
S to SE winds this morning will continue to veer toward the W/SW
by early this afternoon with gusts increasing to upwards of 20-25
kts. Gusty winds will subside early this evening, however,
uncertainty then increases in regards to the timing and magnitude
of an easterly shift. Guidance show showers and thunderstorms
developing across the higher terrain east of Phoenix this
afternoon before sending an outflow toward the west into the
Valley this evening. This outflow may lead to an abrupt easterly
wind shift in the 02Z-06Z time range as well as a 5-10% chance for
a brief VCSH/VCTS. Otherwise, FEW-SCT cumulus decks around 8 kft
are expected through the afternoon into the early evening.
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns under clear skies are expected through the
forecast period. Westerly winds will prevail at KIPL, while KBLH
sees mostly S-SW, with a period of light northerly winds during
the morning hours Friday. Sustained wind speeds will mostly
remain aob 10 kts at both terminals, aside from a period of
westerly sundowner winds at KIPL, with gusts to around 20 kts.
&&
.FIRE WEATHER...
Near to slightly below normal temperatures will be common across
the region through this weekend thanks to an area of low pressure.
Outside of some breezy conditions this afternoon with peak gusts
around 25 mph, winds over the next several days will favor
familiar diurnal trends. Most of out forecast area will remain
dry, but some slight chances of wetting rains do exist for the
high terrain of Gila County both this afternoon and Friday.
MinRHs over the next few days are likely to range from 10-15%
across the western districts to 15-25% across the eastern
districts. By Friday and into the weekend, even drier conditions
are expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
SHORT TERM...RW
LONG TERM...RW
AVIATION...Smith/Benedict
FIRE WEATHER...Kuhlman/RW

NWS PSR Office Area Forecast Discussion