086
FXUS65 KPSR 141222
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
522 AM MST Mon Jul 14 2025

.UPDATE...Updated 12Z Aviation Discussion.

&&

.KEY MESSAGES...

- Near to slightly above normal temperatures will last into
  Tuesday before dropping to slightly below normal later in the
  week.

- Rain chances will gradually improve over the next couple of
  days, initially confined to higher terrain areas today before
  descending into the lower deserts as early as Tuesday evening.

- Active monsoon weather is expected for Wednesday and Thursday
  across southern and central Arizona with strong winds and
  localized heavy rainfall and minor flooding all possible.

&&

.SHORT TERM /Today and Tonight/...
The current regional analysis shows the subtropical ridge still
centered to our west but extending into the Great Basin and
northern portions of our region. A weak trough is also seen
stretching from southern New Mexico into northern Baja. Storm
activity yesterday was fairly extensive across New Mexico and
Sonora Mexico and this has pushed a good amount of mid and upper
level moisture westward into Arizona. The subtropical ridge will
still largely be in control across the bulk of the area today, but
with moisture improving across southeast and eastern Arizona we
are likely to see a bit better coverage of shower and thunderstorm
activity to the east and southeast of Phoenix. Modest
northeasterly mid level flow today should allow for more
progressive cell movement with at least a 10-20% potential for a
few showers and/or thunderstorms reaching into central Pinal Co.
to as far west as eastern portions of Phoenix. Temperatures today
are expected to be nearly identical to yesterday with highs around
110 degrees across the western deserts to just under 110 within
the Phoenix metro. Tonight should bring a decent Gulf moisture
surge, likely setting the stage for a more active monsoon day on
Tuesday.

&&

.LONG TERM /Tuesday through Sunday/...
The weather pattern will become more favorable for monsoon
conditions starting Tuesday as the subtropical high splits with a
new (fairly weak) center forming over northern Arizona.
Additionally, the weak trough to our south will start to become
more organized with a closed low forming in the upper levels
somewhere just off the coast of central Baja. The recentering of
the high will allow for the flow in the low and mid levels to turn
more out of the south and southeast, advecting better quality
moisture northward into Arizona.

PWATs later on Tuesday are forecast to rise to between 1.3-1.5"
into south-central Arizona, but low level mixing ratios are still
likely to be a bit on the lower side at around 9 g/kg. The latest
HREF and the 06Z HRRR do show isolated to scattered thunderstorm
activity across southeast Arizona northward into southern portions
of the Mogollon Rim Tuesday afternoon. The better moisture should
result in MUCAPE of upwards of 500-1000 J/kg, while we also may
begin to see some weak difluence aloft from the developing upper
low to our southwest. NBM PoPs seem reasonable calling for 50%
chances across the higher terrain with 20-40% chances extending
into the south-central Arizona lower deserts. However, the lower
deserts are still likely to have to contend with some CIN, so an
organized outflow or a collision of outflows is likely to be
needed for development over the lower deserts. The main threats
with any stronger storms Tuesday should be strong wind gusts of
35-45 mph, while blowing dust may also end up being an issue if
any organized strong outflows form.

Wednesday into Wednesday night may represent our best chances for
more widespread showers and thunderstorms as guidance shows the
best difluence aloft setting up over Arizona. Moisture levels
should also increase further during this time with PWATs reaching
anywhere from 1.4-1.7" and low level mixing ratios closer to 11
g/kg. Despite the better moisture, instability may be an issue as
forecast MUCAPEs may struggle to break 1000 J/kg due to increased
cloud cover and decreasing lapse rates. This may limit the threat
for stronger thunderstorms, but the improving forced ascent from
the upper level low`s influence should increase the overall
coverage of showers and thunderstorms starting Wednesday afternoon
and lasting into early Thursday. NBM PoPs increase to 40-60% over
the Phoenix area with 20-30% PoPs extending as far west as La Paz
and Yuma Counties. Even higher PoPs of 60-80% are seen over the
eastern Arizona higher terrain. Given the better moisture, the
potential for heavy rainfall is expected to increase starting
Wednesday afternoon with WPC highlighting all of south-central and
eastern Arizona in a Marginal Risk of excessive rainfall.
However, forecast QPF still seems to be on the low side with
averages of 0.1-0.3" over the lower deserts to 0.3-0.5" in higher
terrain areas. Localized higher amounts are sure to occur with
some areas likely seeing over an inch.

Model guidance is still unsure on how to handle the ejection of
the upper level low and how quickly drier air will spread
northeastward into the region. Models have essentially flip-
flopped from last night with the GEFS now the drier and faster
progressing model, while the EPS is slower with the low ejection
and keeps better moisture over our area through all of Thursday.
Forecast confidence for rain chances for Thursday is fairly low as
it will likely be contingent on how much the atmosphere is worked
over from Wednesday`s activity and how quickly to low lifts
northward. The NBM is keeping fairly high PoPs of 30-60% on
Thursday and this may be fine if moisture sticks around, but with
lowering instability potential rainfall amounts are likely to be
decreasing. Diminishing rain chances are expected Friday into
Saturday with both models finally agreeing on drier air working
into the area.

As far as temperatures for the rest of the week, the increasing
moisture, cloud cover, and lower heights aloft will all help to
drop daily highs to around or even slightly below normal for
Wednesday and Thursday. In fact, highs on Thursday in the Phoenix
area may not even reach 100 degrees if we see rain in the morning
and considerable cloud cover through the rest of the afternoon.
Temperatures should begin to warm back up by the weekend with
highs back to around normal. The subtropical ridge is then likely
to rebuild over the Southern Plains by early next week which
should in turn raise temperatures a bit higher over our region.

&&

.AVIATION...Updated at 1221Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
A push of W to NW winds just moved through the Phoenix area early
this morning. Westerly winds will prevail through this evening and
likely through midnight at all terminals. Afternoon winds around
10 kts and gusts around 20 kts are expected. A brief lull in winds
is anticipated this evening, but a relatively strong gulf surge
will lead to a period with winds around 15 kts and gusts to 20-25
kts around 05-08Z. Winds then trend E`rly by 09-10Z. Thunderstorm
activity is expected to stay well east of Phoenix today, with
easterly outflow winds not expected to reach terminals. Mostly
clear skies are expected through this morning, followed by FEW to
SCT at or above 16K ft AGL this evening/tonight. Slantwise
visibility impacts are possible this morning and evening with
lofted wildfire smoke.

Southeast California/Southwest Arizona including KIPL and KBLH:
Periods of lofted smoke creating slantwise visibility issues will
continue to be the main aviation impact through Monday evening,
with those issues enhanced during the sunrise and sunset periods.
Some gusty winds out of the SE and S at KIPL and KBLH will develop
this afternoon through early tonight, gusting around 25 kts.
Otherwise, winds will still tend to follow familiar diurnal
trends through the period.

&&

.FIRE WEATHER...
Moisture will gradually increase across Arizona into the middle
part of the week providing increasing chances for showers and
thunderstorms, especially by Wednesday. Temperatures will drop off
from slightly above normal today and Tuesday to below normal by
Thursday. Afternoon MinRHs should bottom out around 15% today
with southwesterly gusts of 20-25 mph at times. RHs will improve
Tuesday into Wednesday with MinRHs between 20-25% as chances for
rain increase. Rain chances should mostly be confined to the
eastern Arizona high terrain through Tuesday before moving into
the lower deserts by Wednesday. Good chances for showers and
thunderstorms across south-central and eastern Arizona are likely
to last into Thursday before drying begins from the southwest.
Eventually, high pressure is likely to return to the region by the
weekend with RHs dropping back into the teens and rain chances
ending for all but the higher terrain.

&&

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

$$

SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...Benedict/RW
FIRE WEATHER...Kuhlman