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642
FXUS65 KPSR 252025
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
125 PM MST Tue Jun 25 2024

.SYNOPSIS...
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Enhanced monsoonal moisture across the region will continue to
allow thunderstorm chances to persist into the weekend, overall
coverage will decrease and be confined mostly to the higher
elevations. Temperatures will continue to run several degrees
above normal, so hot and humid conditions will persist as well
during this period.
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&&

.DISCUSSION...
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The early afternoon radar and satellite imagery showing the usual
midday showers and thunderstorms forming over the high country
north and east of Phoenix with the exception of an isolated storm
across far southern Maricopa County. Visible satellite imagery
has been showing a remnant MCV from overnight convection drifting
northwest across the SC AZ through the morning. This has resulted
in overall increased cloud cover for most areas and keeping
conditions more stable. The latest SPC Meso analysis subsequently
showing convective inhibition persisting across the Phoenix valley,
unlike yesterday when we had full sunshine and eroded the cap.

For the rest of today, the latest HRRR convective trends seem
reasonable given the aformentioned instability trends. Most of the
convection should remain over the high country with a steering
flow to the north and away from the Pheonix area. An exception is
likely into western Maricopa County into La Paz County ahead of
MCV where more insolation has occurred and cap has eroded.
Forecasting some convection to develop in these areas into early
tis evening.

Shower and storm potential does try to trend downward as upper
level ridge retrogrades into AZ/NM region this week, which should
tend to inhibit convection, especially for the lower deserts.
HRRR hints at this trend on Wednesday. Also, by Thursday and
Friday, watching a stronger trough dig across the northern
Rockies, which will break down the ridge over AZ and also shunt
deeper moisture to the south with the development of a drier
west/southwest flow. This should further inhibit storm potential
and confine it to mainly far SE and Eastern AZ into first half of
the weekend.

After this trough passes to the northeast, ridge builds again
across the SE U.S. which will bring back the southerly flow and
moisture that is poised to move back north into the region as
early as Sunday. This will increase storm chances again into next
week. CPC outlooks for 8-14 days (the first week of July) favors higher
percentages for above normal precipitation.

As for temperatures, readings will remain above normal by several
degrees, but nothing on the record/extreme level. This will
maintain a consistent moderate HeatRisk across the region through
the period.
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&&

.AVIATION...Updated at 1825Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

VFR conditions are anticipated through the TAF period under SCT-
BKN mid and high level clouds. Some light showers/virga are
passing through the metro area at this hour but are not expected
to impact any of the terminals. Winds have begun to establish out
of the SW/W, and a westerly component is expected to prevail
through the remainder of the TAF period (aside from some very
light speeds below 5 kt and variability early tomorrow morning).
The greatest forecast uncertainty is the direction/timing of any
outflow boundaries making their way into the Greater Phoenix Area.
This will likely depend on where the strongest convection occurs
today, but the current best timing for outflows would be as early
as 00Z. Thunderstorms are expected to stay to the north of the
terminals over the high terrain, which would lead to a gusty
outflow boundary from the north, though some guidance indicates
the potential for storms making their way into western Maricopa
and eastern La Paz Counties this evening, which could send an
outflow from the NW/W. A 10-20% chance of VCSH/VCTS remains for
all the terminals this afternoon and this evening.

Southeast California/Southwest Arizona including KIPL and KBLH:

VFR conditions are expected at the SE California terminals through
the period. Winds will continue to be southeasterly at KIPL and
southerly at KBLH through most of the day. Expect some breeziness
this afternoon with gusts up to 20-25 kts at KBLH. SCT mid to high
lvl clouds will progress over the region, otherwise skies should
remain mostly clear.

&&

.FIRE WEATHER...
Monsoonal moisture will continue to result in daily chances for
shower and thunderstorm activity. The higher terrain areas will
see the greatest potential with some locally heavy rainfall with
any storms that develop. Best chances for storms are today, with a
gradual decrease in chances/coverage through Friday, where chances
drop around 15% or lower. Chances for wetting rains will
generally remain around 10-20% for the higher terrain areas and
5-10% for the lower deserts of south-central Arizona today, before
dropping below 10% across the region starting Thursday. With the
elevated moisture in place, MinRH values through the middle of
this week will range between 30-40% across the far eastern
districts to between 15-25% across the western districts before
slowly drying during the latter half of this week. Winds will
follow their typical daily tendencies, with gusty outflows from
any thunderstorm activity anticipated over the next several days.
Temperatures average several degrees above normal through the
forecast period.

&&

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

$$

DISCUSSION...Frieders
AVIATION...Whittock/Salerno
FIRE WEATHER...Young/Frieders