Flash Flood Warning 307, NWS Phoenix, AZ

Area Forecast Discussion
National Weather Service Phoenix AZ
1102 AM MST Wed Sep 28 2022

.UPDATE...18Z Aviation Discussion...

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.SYNOPSIS...
Moisture will continue to linger across the area through the rest
of the week, with slight chances of showers and storms that will
favor the high terrain generally south and east of the Phoenix
area. The above average temperatures, but slight cooling of a
couple degrees will be the trend going into the weekend.

&&

.DISCUSSION...
Although temperatures are expected to remain above average, an
upper level trough entering the Pacific Northwest this morning
will aid in slightly cooling temperatures across the area over
the next several days as this trough advances east-southeastward.
These cooler temperatures are resulting in only a Moderate
HeatRisk for areas across western Imperial County, while
everywhere else is generally under Minor HeatRisk during this time
period.

The best moisture and instability continues to linger across
southwest AZ and southeast CA for today. There are more expansive
10-20% NBM PoPs for this afternoon through the early morning
hours Thursday across this general area, with isolated showers
and thunderstorms favoring higher terrain. Although the moisture
and instability are limited, the main storm threats for today will
be gusty winds and the potential for localized blowing dust.
Measurable rainfall will be very sparse, but a few localized areas
under any stronger cells could see a half an inch or more of
rain.

Model ensembles show the Pacific trough slowly tracking east
southeastward through the Northern Rockies and Great Basin by the
end of the week, with weak westerly flow aloft developing by
Saturday across southern Arizona. Lingering moisture across our
region should still result in limited chances for showers and
possibly isolated thunderstorms for the rest of this week, but
eventually enough dry air is expected to spread over our area that
rain chances mostly come to an end by early next week.

&&

.AVIATION...Updated 18Z.

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

Elevated easterly winds will continue this morning with some gusts
to around 20kts through mid-afternoon. Winds will shift a bit
more out of the southeast and possibly out of the south for a few
hours this afternoon as distant showers and storms south of
Phoenix may send weak outflows northward into the Phoenix area.
Can't completely rule out a shower or even a weak thunderstorm in
the Phoenix area this afternoon/early evening, but chances are at
most 10%. Winds are then expected to revert back to more typical
easterly drainage winds around/shortly before midnight.

Southeast California/Southwest Arizona including KIPL and KBLH:

No significant weather issues are expected through the TAF period
with occasional SCT midlevel decks. Winds at KBLH will eventually
turn southerly, while southeasterly winds are mostly likely at
KIPL. There may also be some isolated gusts in the teens at both
terminals this afternoon. There should also be some widely
isolated showers and thunderstorms across the area this
afternoon/early evening, but the chances are quite low (10-15%),
so not included in TAFs.

&&

.FIRE WEATHER...
Above normal temperatures will continue through the rest of the
week, although slight cooling will occur going into the weekend.
Modest moisture across the western districts will provide chances
for isolated showers and thunderstorms through at least Wednesday
over higher terrain areas across southeastern CA and southwestern
AZ. Drying conditions by early next week will mostly end rain
chances across the majority of the area as high pressure rebuilds
across the region. Afternoon MinRHs through the end of the week
will mostly be between 15-25% each day, although slight increases
in MinRHs are expected going through the weekend. Enhanced
easterly winds are likely to prevail across much of southern
Arizona through today with morning gusts up to 25 mph. Winds
later this week should shift back to a more typical diurnal
pattern with lighter winds speeds.

&&

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

DISCUSSION...Young
AVIATION...Feldkircher/Kuhlman
FIRE WEATHER...Young