Surprise, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

399
FXUS65 KPSR 122336
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
436 PM MST Tue Aug 12 2025

.UPDATE...Updated 00z Aviation Discussion.

&&

.KEY MESSAGES...

- Areas of major HeatRisk with Extreme Heat Warnings in effect
through Wednesday for portions of the central AZ lower deserts, the
Lower Colorado River Valley, and Imperial Valley.

- Increasing moisture later this week will result in better coverage
of thunderstorm activity across much of the region including the
Arizona lower deserts.

- Temperatures will gradually lower later this week likely reaching
into the normal range by Friday.

&&

.SHORT TERM /Today through Wednesday/...
The latest Water Vapor Satellite Imagery as well as streamline
analysis show the upper ridge centered near the CA/NV border with
northerly flow entrenched across much of the region. This northerly
flow has brought in a slightly drier air mass with PWATs across
much of the region below 1.2". Thunderstorm activity, similar to
the last couple of days, will once again develop along the
vicinity of the Mogollon Rim and White Mountains as well as across
southeast AZ, but will have difficulty surviving into the lower
elevations as moisture levels remain meager leading to strong
convective inhibition. For the lower deserts, there is a low
chance (10-30%) of an outflow moving through later this evening.
Heading into Wednesday, the ridge is forecast to shift eastward
near the vicinity of the Four Corners. This shift will cause the
steering flow to switch more out the east to northeast. In
addition, model guidance is showing an increase in upper-level
divergence. Thus, thunderstorm activity Wednesday
afternoon/evening that develops over the higher terrain will
likely be greater in coverage. However, moisture values continue
to be meager as PWATs will remain below 1.3" with low-level
mixing ratios still very marginal at 7-9 g/kg. As a result, any
thunderstorm activity that attempts to descend into the lower
deserts will likely struggle to do it and weaken. There will be a
higher chance, however, for gusty outflow winds to impact the
lower deserts and this is reflected in the latest HREF, showing a
30-50% of wind gusts of 35+ mph Wednesday evening.

Aside from the thunderstorm perspectives, the other main story
during the next couple of days will continue to be the hot
conditions as areas of Major HeatRisk will continue to be
prevalent. Afternoon high temperatures through Wednesday will
range between 108-114 degrees with above normal lows, with
central Phoenix likely not dropping below 90 degrees. As a
result, areas of Major HeatRisk will continue to be concentrated
across the south-central AZ lower deserts as well as across the
Lower Colorado River Valley and the Imperial Valley with Extreme
Heat Warnings in effect through Wednesday evening.

&&

.LONG TERM /Thursday through Monday/...
The forecast for later this week is still fairly uncertain as the
subtropical ridge center shifts farther to the east into the
Southern Plains while a weak trough moves onshore into California.
The main uncertainty is with how much moisture will advect into
southern and central Arizona between Wednesday and Friday. Both the
GFS and Euro show a period of southerly moist flow into Arizona from
Wednesday night through Thursday night with PWATs rising to 1.3-1.6"
centered over south-central Arizona for Thursday night into Friday.
The positioning of the trough to the northwest should also provide
for a day or two of modest upper level support over the region. This
scenario does provide for the potential for an active monsoon day,
but some negatives are seen, such as a weak southwesterly steering
flow and lower desert convective inhibition.

Shower and thunderstorm chances are expected to increase on Thursday
before peaking on Friday as moisture levels reach their peak. NBM
PoPs still look too high for both days considering the set up, so we
have adjusted lower to 20-30% and 30-40% chances for south-central
Arizona for Thursday and Friday. Both days should present at least a
40-50% chance across the eastern Arizona high terrain. Some very
marginal moisture may seep into southeast California and southwest
Arizona leaving a 10-15% chance of some isolated showers or storms
focused more over any higher terrain features. Both days could
result in a storm or two that may end up being strong or marginally
severe, but overall guidance doesn`t indicate this will support any
organized strong to severe storms. Moisture levels should also be
too low to support a decent heavy rainfall or flood threat, but due
to the weak steering flow we may end up seeing a few storms getting
anchored to higher terrain features that could produce localized
heavy rainfall.

Eventually guidance shows the trough shifting more into our region
later Friday into Saturday pushing drier air in from the west
southwest. This should reduce the rain potential considerably by
Saturday and even more so on Sunday as PoPs lower to only a 10-20%
chance over the eastern Arizona high terrain.

Temperatures will also cool off across the region late this week,
partially due to the falling heights with the introduction of the
trough and also due to the increased moisture and convection. The
biggest drop should happen between Thursday and Friday as NBM
guidance shows highs dropping to between 102-107 degrees across the
lower deserts. Near normal temperatures should hold into Saturday
before beginning to warm again Sunday into early next week.

&&

.AVIATION...Updated at 2340Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Uncertainty regarding outflow winds and periods of reduced
slantwise visibilities will be the primary weather issues through
Wednesday afternoon under a few mid/high cloud decks. West winds
will continue through late afternoon/early evening with occasional
15-20 kt gusts. Lofted wildfire smoke may continue to affect
slantwise visibility towards sunset, though there should be no sfc
restrictions. While TS/SHRA will remain well northeast of
terminals, there is some model evidence that outflow winds will
attempt to sweep into terminals creating an earlier than usual
easterly wind shift. However, there is equal probabilities that
outflow winds decay when reaching the metro, so continued to
maintain a slightly earlier easterly shift.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather issues will exist through Wednesday afternoon
under mostly clear skies. Winds will follow a near persistence
forecast with directions varying between SE and SW and gusts
around 25kt common at KBLH.

&&

.FIRE WEATHER...
Above normal temperatures are expected over the next couple days
with moisture levels remaining fairly limited. Isolated afternoon
thunderstorms will remain possible mainly over the eastern Arizona
high terrain with dry lightning a possibility due to less than 10%
chances of wetting rainfall. As moisture increases by Thursday, rain
chances will increase and spread into the Arizona lower deserts.
Minimum afternoon humidity levels will mostly range between 15-20%
with fair to good overnight recoveries. Winds will continue to
follow diurnal trends with afternoon gusts up to 15-20 mph.

&&

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

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

&&

$$

SHORT TERM...Lojero
LONG TERM...Kuhlman
AVIATION...Young/18
FIRE WEATHER...Kuhlman