Forecast Discussion

FXUS65 KPSR 241956

Area Forecast Discussion
National Weather Service Phoenix AZ
1256 PM MST Mon Jun 24 2024

Daily thunderstorm chances will persist through most of this week
due to enhanced moisture levels lingering across the region. The
greatest chance will be through Wednesday, before decreasing some
late this week and into the upcoming weekend. Conditions will
remain hot and humid, with temperatures remaining several degrees
above normal.


The early afternoon radar and satellite imagery showing the usual
midday showers and thunderstorms forming over the high country
north and east of Phoenix. The Phoenix valley into southwest AZ
remaining more stable at the moment after early morning clouds
dissipated. The latest SPC analysis showing lingering convective
inhibition in these areas, but experiencing full insolation early
this afternoon. Plenty of moisture ready to be acted on with
Precipitable Waters close to 2 inches across the region.

Our early Monsoon enhanced moisture levels will result in more
shower and thunderstorm into this evening. The latest HRRR hinting
on a bit more widespread northeast outflow driven convection
spreading into the phoenix valley into this evening, even pushing
further southwest toward Yuma County after midnight. This seems
reasonable given more instablility and daytime heating across SC
AZ this afternoon with any outlfows able to break through any
lingering capping. Although, not a given, as many other high
resolution models not as robust with this solution. Have included
a 20 to 30 percent chance into the forecast. Strong outflow wind
probabilities continue to run low as HREF probabilities of 35+ mph
wind gusts remain around 10-30% across the higher terrain and
lower elevations of southcentral Arizona, so appears mainly a
heavy rainfall threat for storms that develop.

Shower and storm potential does try to trend downward as upper
level ridge retrogrades into AZ/NM region this week, which could
tend to inhibit convection, especially for the lower deserts.
However, given abundant moisture in place, the high country should
still see additional storm formation. By Thursday and Friday,
watching a stronger trough dig across the northern Rockies, which
will break down the ridge over AZ, but also shunt deeper moisture
to the south. This should further inhibit storm potential and
confine it to mainly far SE and Eastern AZ into first half of the

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.

With all the moisture and associated clouds and precipitation,
daytime high temperatures overall staying several degrees above
normal through the period, but at least not near record levels.
However, overnight lows will remain well above normal. This will
all spell a consistent moderate HeatRisk across the region through
the period for hot and humid conditions persisting. However, not
to the levels of excessive heat at this time.


.AVIATION...Updated at 1730Z.

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

VFR conditions will prevail over the next 24 hours. Winds will
follow light and diurnal tendencies, with periods of variability
during directional changes. Thunderstorms will once again fire
over the AZ high terrain, but the potential for convective
activity over metro terminals is low (10-15%). Distant
thunderstorms may send an outflow toward terminal sites this
evening, but potential is too low (10-30%) to warrant inclusion in
the TAFs at this time. FEW-SCT mid and high level clouds will
persist through the period, with skies occasionally becoming BKN
this evening/tonight.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation concerns are expected during the TAF period. Winds
will follow diurnal trends at both terminals, with occasional
afternoon and evening gusts near 20 kts. FEW-SCT high clouds will
continue to filter in through tomorrow morning.


Monsoonal moisture will continue to result in daily chances for
shower and thunderstorm activity, especially into midweek. The
higher terrain areas will see the greatest potential with some
locally heavy rainfall with any storms that develop. 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 through the first half of the week. Shower and
thunderstorm chances will gradually diminish throughout the week,
as high pressure builds into the region. With the elevated
moisture in place, MinRH values through early this week will range
between 30-40% across the far eastern districts to between 15-25%
across the western districts before slowly drying into the middle
to latter half of next 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.