574 
FXUS65 KPSR 310505
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1005 PM MST SAT JUL 30 2016

.UPDATE...Updated aviation discussion.

&&

.SYNOPSIS...
A humid airmass will remain in place over the Desert Southwest
through at least the middle of next week. The moisture availability,
as well as some weather disturbances, will make for an active period
of weather over the region, with locally heavy rain and gusty winds
possible.  A reduction in convective activity is possible towards
the end of next week as drier air attempts to move into the region
from the west.

&&

.DISCUSSION...

Latest radar imagery looks quite a bit different than it was this
time yesterday. However, scattered convection continues to develop
across southern Gila County and is tracking steadily westward. This
is likely due to the mid-tropospheric high migrating slightly to the
north and east, which has temporarily increased the easterly steering
flow.

Further to the south near Tucson, a complex of storms persists and a
northwestward propagating outflow boundary is likely to develop
within the next hour. This will increase the low-level moisture
convergence across eastern Maricopa and Pinal counties and the
latest runs of the HRRR along with the University of Arizona WRF(NAM)
confirm that this will trigger at least isolated convection in these
areas.

Evening Phoenix sounding showed a strong subsidence inversion
associated with the boundary layer cooling in the wake of yesterday's
storms. CIN remains plentiful and it is unlikely that organized
convection will develop across the lower deserts near Phoenix this
evening. However, there invariably are pockets that haven't been as
worked over and will support isolated showers and storms the next few
hours.

&&

.PREVIOUS DISCUSSION...

Tonight through Sunday...

As far as tonight and Sunday is concerned, a weak disturbance moving
into the region from the south later tonight/early Sunday is expected
to moisture and increase the winds through the mid-levels of the
atmosphere, which could help to trigger some isolated- scattered
showers/storms across the region, especially over south- central AZ.
Any storms that do develop will be slow-moving, and capable of
producing heavy rains. The activity could continue into Sunday
afternoon/evening, if it does not get too widespread during the
earlier part of the day. Temperatures will likely remain below normal
will considerable cloudiness reducing the amount of solar radiation
reaching the ground.

Monday through Friday... Deep moisture remains over the region
through at least Wednesday night. Models continue to depict easterly
waves/inverted troughs passing by or through, especially on
Tuesday night/early Wednesday when an inverted trough/upper low
tracks right through Arizona. Thus, keeping elevated storm chances
through the period, especially on Tuesday night/Wednesday. The GFS
continues to show a noticeable decline in available moisture starting
on Thursday and continuing into next weekend, as the flow aloft
becomes westerly over the region, while the EURO still hangs on to
some moisture. Temps to remain below normal through Wednesday before
climbing some late in the week. 

&&

.AVIATION... 
South-Central Arizona Including KPHX, KIWA, and KSDL:

Low-level flow will likely become east or southeasterly overnight as
converging outflow boundaries descend on the Phoenix area. However,
latest guidance suggests winds will not be very strong as the
boundaries move through. Some isolated showers and thunderstorms are
also possible overnight, though significant impacts at the terminals
are unlikely. More of the same expected for Sunday, with the best
chance for showers and thunderstorms across the higher terrain north
and east of Phoenix with the possibility of an outflow boundary
reaching the valley during the evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather impacts anticipated. Winds will generally retain
a southerly component through Sunday at both KIPL and KBLH,
occasionally reaching as high as 15 kt.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Tuesday through Saturday... Moisture values will remain quite
elevated through the entire week yielding good to excellent chances
for at least some wetting rains. Thunderstorm coverage will be more
extensive during the first half of the week with occasional gusty
winds and heavy rainfall. More regular thicker cloud cover will also
keep temperatures near to below normal during the week; and
scattered rainfall will force humidity levels above normal. Minimum
humidities in the 25-50 percent range early in the week will drop to
around 15-30 percent by the end of the week. Overnight recovery will
be good to excellent. Outside of thunderstorm wind gusts, wind
speeds will be typically light throughout the day.

&&

.SPOTTER INFORMATION STATEMENT... 
Spotter activation could be possible later today.

&&

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

$$

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DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Percha/AJ 
AVIATION...Hirsch
FIRE WEATHER...Percha