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368
FXUS65 KPSR 032138
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
238 PM MST Thu Jul 3 2025

.KEY MESSAGES...

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- After limited chances for isolated showers and thunderstorms
through this evening, the entire 4th of July weekend should remain
dry.

- Near to slightly below normal temperatures are forecast through
Saturday with above normal temperatures returning by Sunday.

- Daily highs for the lower deserts are expected to warm to around
or just over 110 degrees starting Sunday resulting in widespread
Moderate HeatRisk.
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&&

.NEAR TERM/THROUGH TONIGHT/...
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Water vapor satellite imagery this afternoon shows a low pressure
system in southern Nevada that is continuing to bring dry air into
the region. There remains enough residual moisture in combination
with the vorticity from this low and 1000-2000 J/kg of MUCAPE to
generate some showers and storms across northern AZ. Some vorticity
associated with the low stretches into southwest AZ, which could act
as a lifting mechanism to help storms form SW of the Phoenix
Metro. This can be seen in visible satellite where an area of
aggravated cumulus have formed. Models continue to show showers
and storms developing in this area, with some isolated activity
surviving and moving into the greater Phoenix Metro later this
afternoon/early this evening. Any activity in the Phoenix Metro
should be isolated (~20%). Subsidence is moving in quickly behind
the low, so any activity that does manage to form this evening
will struggle. We will have to watch for gusty outflows moving
into the Phoenix Metro from any activity that does form to the SW,
the HREF shows a 30-50% chance of winds greater than 35 mph in
the Phoenix Metro.

.SHORT TERM/FRIDAY AND SATURDAY/...
Once the trough lifts to the northeast of the area beginning
tomorrow, heights aloft will begin to rebuild allowing for a
gradual warming trend into the weekend. By Saturday, daytime highs
are expected to be back into the normal range in Arizona to a
couple degrees above normal across southeast California. Dry air
will also continue to push into the area this weekend, with PWATs
decrease to around 0.7-1.1" across the area. With this decrease in
moisture we will also see decreasing shower/storm chances. With
around a 15% or less chance for showers/storms over the higher
terrain east of Phoenix, with most/any activity this weekend
mainly confined to southeast AZ.
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&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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Considerable forecast uncertainty is seen by next week, mainly
involving any monsoon moisture. There seems to be a disconnect
between the GEFS and the EPS with the GEFS showing a modest moisture
return starting early next week, whereas the EPS shows continued dry
conditions. At this point, there is no clear evidence supporting
either model`s solution, so we will likely have to wait at least a
couple more days to have a better sense on what`s going to happen.

Both models do show the sub-tropical ridge building back over the
region this weekend and then lasting through much if not all of next
week. H5 heights are expected to rise to around 592-594dm this
weekend allowing for a fairly quick warm up with highs likely
topping out around 110 degrees by Sunday. Models also agree the
ridge will continue to strengthen through the first part of next
week with H5 heights likely reaching 595-597dm, or into the 90th
percentile of climatology. One of the main issues is exactly where
the high center will be with the GEFS suggesting it will be more
over northern Arizona, where the EPS favors more over central and
southern Arizona. If the GEFS is correct on its position, then we
are likely to see some sort of moisture return early next week and
likely a return of at least higher terrain storm chances. If the EPS
is correct, then we are likely to stay dry with nearly no storm
chances and even hotter temperatures. For now, the NBM seems to be
favoring more of the GEFS solution, likely due to the Canadian
agreeing with the GEFS position. However, we are doubtful of the
NBM`s PoPs as even if the high center is to our north, it will
likely be too strong to allow for much if any convection into the
lower deserts. We have lowered NBM PoPs by around 10-15% during the
first half of next week, but even that may not be enough.

The other forecast concern is if the EPS is correct and we stay dry,
we are likely to see another heat episode with areas Major HeatRisk.
The latest NBM forecast highs mostly keeps readings between 109-113
degrees, but this is assuming higher levels of moisture and at least
some daily convection. It would not be surprising to see forecast
temperatures for next week to creep several degrees higher once
models resolve the position of the high.
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&&

.AVIATION...Updated at 1815Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major aviation concerns are expected during the TAF period.
Winds will resume following familiar diurnal tendencies, with
periods of variability during the remainder of the morning. There
are hints of outflows moving through during the late afternoon and
evening hours, along with some isolated SH/TS popping up in the
airspace, but probabilities surrounding those impacts are too low
include in the TAFs at this time. FEW to occasionally SCT cloud
decks will prevail, with the lowest bases around 8-10k ft.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are expected over the next 24 hours
under mostly clear skies. Winds will follow typical diurnal
trends, with occasional afternoon gusts, especially at KBLH, and
windows of morning variability.

&&

.FIRE WEATHER...
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Lingering moisture today may bring a few isolated thunderstorms
across south-central and eastern Arizona, but CWR will be below
10%. Below normal temperatures and the moisture will help to keep
MinRHs between 20-30% for the eastern districts to 15-20% for the
western districts. Outflow boundaries are possible from any storm
activity with a 30-50% chance of wind gusts of 35 mph in the
Phoenix Metro this evening. The drying trend will continue
tomorrow with MinRHs of 20-25% across the SW and south- central AZ
and 10-15% across SE CA. Winds return to a more typical diurnal
trend today with any afternoon breeziness generally less than 20
mph. Highest wind gusts will be along the lower CO river valley
with afternoon breeziness of 20-25 mph today and tomorrow. High
pressure is then expected to rebuild across the region this
weekend into next week with temperatures warming to above normal
by Sunday. Limited moisture should also return early next week
providing at least daily chances for isolated showers and
thunderstorms for the eastern Arizona higher terrain.
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&&

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

$$

NEAR TERM...Berislavich
SHORT TERM...Berislavich/Kuhlman
LONG TERM...Kuhlman
AVIATION...Young/RW
FIRE WEATHER...Berislavich/Kuhlman