876
FXUS65 KPSR 021155
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
455 AM MST Wed Jul 2 2025

.UPDATE...Updated Aviation Discussion

&&

.KEY MESSAGES...

- Today is expected to bring isolated to scattered thunderstorms
  across south-central and eastern Arizona with the potential for
  strong gusty winds, blowing dust, and localized heavy rainfall.

- After lingering chances for a few isolated thunderstorms on
  Thursday, drier conditions will end any rain chances starting
  Thursday night.

- Near normal temperatures are forecast for today through
  Saturday, before heating back up by early next week.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
The main forecast concern continues to be the potential impacts
from the anticipated thunderstorms for today. The current synoptic
set up shows an unseasonably strong Pacific low centered near Los
Angeles and the sub-tropical high slowly retreating to the
northeast into Colorado. Southeasterly flow since yesterday
continues to feed modestly moist air into Arizona to as far north
as southern Nevada with PWATs now up to between 1.0-1.2" over the
southern half of Arizona. This moist fetch is expected to last
into this afternoon with PWATs likely peaking between 1.2-1.4" and
low level mixing ratios mostly between 8-10 g/kg. This amount of
moisture would normally not be sufficient for a good amount of
monsoon storm activity, but with the help of the incoming
(weakening) Pacific low, the moisture should end up being
sufficient.

Through the rest of the morning hours, we can expect isolated
showers and thunderstorms across portions of the area, likely
focused west and south of the Phoenix area where there is better
forcing. Once the heating of the day kicks in and instability
continues to build, we are likely to first see convection firing
over higher terrain areas of central and eastern Arizona early in
the afternoon. Hi-res CAMs then suggest this would likely be
followed by additional development later in the afternoon over
the south-central Arizona lower deserts due to steeper than
normal lapse rates, MUCAPE upwards of 1000 J/kg, and little
inhibition. The CAMs show scattered showers and thunderstorms
anywhere east of a line from Wickenburg to Ajo during the late
afternoon into the evening hours. The biggest threats from any
storms today should be strong gusty winds and the potential for
blowing dust given expected DCAPEs of 1200-1400 J/kg. Moisture
levels may just be high enough when combining with fairly weak
steering flows to allow for some very localized heavy rainfall
amounts of greater than 1" and minor flooding of area washes and
low water crossings. The activity is likely to linger through the
rest of this evening, but with the coverage and intensity
weakening as the evening progresses. After midnight, guidance
mainly just shows some lingering shower activity possible across
the higher terrain east of Phoenix.

For Thursday, model guidance continues to show the weakening
Pacific trough tracking northeastward through northern Arizona
with dry air surging eastward across the state. For the most
part, guidance shows only 10-15% chances for any additional
showers or thunderstorms across the south-central Arizona lower
deserts Thursday morning and early afternoon to as high as 30-35%
over Gila Co. Given the drying, any activity will likely be on
the weaker side with potential rainfall amounts much less than
today. Temperatures for today and Thursday will be noticeably less
hot than the past few days with highs at or just below normal.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
As the weather pattern settles back into westerly dry flow over
the majority of the region, rain chances are expected to come to
an end by Thursday night. PWATs are forecast to drop down to
between 0.8-1.0" starting Friday and likely last there through
the rest of the 4th of July weekend. Near normal temperatures are
likely to continue into Saturday with overnight lows for rural
desert areas easily falling into the 70s as moisture decreases,
but lows within Phoenix area still likely to stay just above 80
degrees.

Model uncertainty increases considerably next week as the GEFS
shows an increase in moisture by around Tuesday, whereas the EPS
keeps the moisture well to the south. Both generally agree the
sub-tropical ridge will again set up over our region by early next
week, first centered just to our east before gradually shifting
westward through our region during the middle of next week.
Heights are also favored to rise during this time as the ridge
strengthens, pushing H5 heights from 590-592dm starting Sunday to
as high as 595-597dm by the middle of next week. The recent shift
for a stronger ridge setting up over our region has abruptly
turned conditions noticeably hotter for next week with NBM highs
now mostly between 110-113 degrees by Tuesday. If this new
scenario of a stronger ridge comes to fruition and moisture stays
out of our area, expect forecast temperatures to trend even hotter
than the latest forecast. If the GEFS is more correct showing
better moisture, than we may see at least a return of monsoon
activity for higher terrain areas. However, for now it does not
look very promising for any decent monsoon storms through at least
the first half of next week.

&&

.AVIATION...Updated at 1155Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major aviation concerns are expected through the afternoon as
winds follow familiar diurnal trends, with occasional gusts in the
mid-teens to around 20 kts. A very isolated shower late this
morning cannot be completely ruled out, but chances are only
around 10%, too low to include any mention of VCSH/SH in the TAFs.

Greatest aviation impacts will occur late this afternoon into
early this evening, with slight (30%) TS chances and erratic wind
shifts. The most favorable direction for an outflow to move
through still appears to be from the south, but multiple outflows
remain possible and could result in multiple wind shifts. Best
timing for convection currently looks like 02-05Z, but could start
as early as 00-01Z, and current probability for wind gusts >30kts
is 50-60%.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns are anticipated during the next 24
hours. Some light shower activity has been observed over parts of
SE CA early this morning, so a shower in the vicinity of a
terminal (mainly KBLH) cannot be ruled out over the next few
hours. Winds will follow typical diurnal trends, SE to W`rly a
KIPL, and S`rly at KBLH with occasional afternoon breeziness
around 20 kts. Outside of a FEW-SCT mid-level clouds this morning,
skies should be mostly clear through the period.

&&

.FIRE WEATHER...
Increased moisture along with an incoming weather system is
expected to bring an active day today across the eastern
districts. Shower and thunderstorm chances today across the
eastern districts are between 30-50% with gusty erratic winds
likely to occur with the thunderstorm activity. Humidities will
continue to improve today with MinRHs of 20-30% for the eastern
districts to 15-20% for the western districts. A drying trend
will begin Thursday with much more isolated chances for showers
and thunderstorms for the eastern districts. MinRHs Thursday will
mainly dip to between 15-20%. Even drier air will filter into the
region by the weekend with MinRHs falling to 10-15% by Sunday.
Temperatures will run near normal through Saturday before heating
up again into next week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Blowing Dust Advisory from 3 PM this afternoon to 7 PM MST this
     evening for AZZ553-554.

CA...None.
&&

$$

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