Fountain Hills, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

672
FXUS65 KPSR 201800
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1100 AM MST Sun Jul 20 2025

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Cloudier skies and spotty showers across South Central Arizona
  today will result in temperatures several degrees below normal.

- Slightly better chances for isolated afternoon and evening
  thunderstorms over South Central Arizona Monday, mainly south of
  Phoenix and over high terrain to the east.

- Near to below normal temperatures through midweek, with lower
  desert highs generally ranging from the upper nineties to around
  106 degrees, resulting in Minor to Moderate HeatRisk.

- By the latter half of the work week, conditions will dry
  considerably, reducing rain chances across the forecast area to
  near zero except perhaps over far eastern Gila County.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...
The remnants of a fairly expansive convective complex are apparent
over Sonora in early morning satellite imagery. As our region
remains sandwiched between an upper level closed low centered over
SoCal and subtropical high approximately over TX, much of the
forecast area falls under southerly flow with a sharp west to east
moisture gradient. The prevailing southerly flow is expected to
steer the remnants of the Sonora convective complex over South-
Central AZ today, quickly moistening the midlevels and bringing
slight chances (10-20%) for spotty, elevated showers. The 00z
Phoenix sounding showed a PWAT of around 1.1" and mean near-surface
mixing ratio around 6.7 g/kg. By the same time tomorrow, GFS bufr
soundings indicate PWAT increasing to 1.4" and near-surface mixing
ratios increasing upwards of 8 g/kg by end of day. However, it is
important to note that since most of this moisture is coming from
the remnants of upstream convective activity, the profiles only
really moisten above 700 mb (nearly saturated/moist adiabatic at
times this afternoon.) Latest NBM guidance has finally honed in on
the impact of the expansive cloud cover today with forecast highs
just below the century mark for the South-Central AZ lower deserts,
over 5 degrees below normal (The Sky Harbor normal high for 20 July
is 106F.)

As a result of cloud cover today, latest HREF indicates weak, if any
instability developing across the forecast area. A few high terrain
showers to the east of Phoenix could feasibly produce some
lightning, but probabilities for any thunderstorm impacts (strong,
gusty winds or heavy rain) across the CWA are near zero.

A pattern shift occurs Monday where the closed low over SoCal begins
to eject northeastward and a midlevel trough moves over the Pacific
Northwest. As the closed low begins to shift northeastward, it
appears the PVA could produce enough lift to trigger some early
morning showers and weak storms; CAMs place most of this activity
over western Maricopa and northeastern La Paz Counties. Clearer
skies by Monday afternoon and better environmental moisture in place
over portions of the eastern CWA will present an opportunity for
destabilization and isolated thunderstorms to develop across South-
Central AZ. Latest HREF shows a gradient in mean MUCAPE with <250
J/kg over Phoenix and 500-750 J/kg over Pinal County. Conditional on
a few stronger thunderstorms forming (better chances south and east
of the Phoenix Area), HREF gives a 10-30% probability for gusty
outflow winds in excess of 35 mph.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Ensembles continue to advertise the Pacific Northwest trough
retrograding offshore and settling off the Central CA Coast midweek.
During this time, the proximity of this trough will act to suppress
heights aloft, keeping temperatures generally below normal into the
middle of the work week. The trough will also act to strengthen dry,
southwesterly flow across the region, eroding PWATs to well below
their normal values for this time of year. In fact, ensemble mean
PWATs fall below 0.5" across the entire forecast area by the end of
the work week. This would end rain chances everywhere by Wednesday
except perhaps over far eastern Gila County. Ensembles advertise the
center of negative height anomalies offshore weakening late week,
allowing the subtropical high to rebuild over the Desert Southwest.
With this evolution in mind, expect daily highs to trend above
normal by the end of the work week and may return to 110 degrees
next weekend.

&&

.AVIATION...Updated at 1800Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
Thick mid-level CIGs (12-15K ft AGL) and areas of virga/-SHRA are
moving across the Phoenix area and will continue to do so through
22-23Z before lifting north. Uncertainty in wind directions will
be a forecast challenge through this evening, as the showery
activity may result in several hours of variable wind directions,
and confidence is somewhat low whether directions will settle on a
westerly component later in the afternoon and evening. There are
indications of another round of spotty showers may develop Monday
morning around daybreak and persist for a few hours, but
confidence is too low to include VCSH/-SHRA mention in the TAF.

Confidence in the forecast Monday afternoon is low, but there will
be better potential for thunderstorms south of Phoenix. There are
better odds of an outflow(s) from the south, but it is uncertain
if storms will develop close enough to cause more direct impacts
to terminals.

Southeast California/Southwest Arizona including KIPL and KBLH:
No weather issues will exist through Monday under mostly clear
skies. Wind trends will be similar to the past 24 hours with a
predominant southerly component and occasional afternoon gusts
around 20kt.

&&

.FIRE WEATHER...
Thunderstorm chances will remain mostly confined to the South-
Central Arizona high terrain east of Phoenix this weekend, with
potential for spotty light showers midday into this afternoon and
perhaps a slight increase in storm chances (15-25%) for the lower
deserts Monday afternoon through Monday night. Afternoon MinRHs will
be around 15-25% for most areas through Monday. Overnight recoveries
will vary generally between 40-60% tonight and drop to 30-50% by
Monday night. Conditions dry considerably during the second half of
the week, with MinRHs dropping below 10% across all districts by
Friday. Winds should mostly follow diurnal patterns with breezes in
the afternoons and early evenings, with peak gusts mostly between 15-
25 mph. Temperatures will be near to a few degrees below normal
through midweek before warming back up into next weekend.

&&

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

$$

SHORT TERM...Whittock
LONG TERM...Whittock
AVIATION...Benedict/18
FIRE WEATHER...Whittock/Benedict