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000
FXUS65 KPSR 221721
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1020 AM MST Mon Apr 22 2024

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
Unseasonably warm temperatures under mostly sunny skies will
continue into midweek with the warmest readings occurring today as
highs top out in the upper nineties across a good portion of the
lower deserts. A cooling trend will begin Tuesday before the first
in a series of weather systems moves through the region Wednesday
and Thursday. By Thursday, temperatures are forecast to retreat back
to around or just below seasonal normal. Winds will also increase by
midweek resulting in gusty afternoon and evening winds each day
through the end of the week.

&&

.DISCUSSION...
Yesterday`s temperatures easily topped out in the mid to upper 90s
across the lower deserts with Phoenix Sky Harbor recording its first
100 degree day of the year. Current objective analysis shows
generally clear skies across the region under a weak ridge moving in
from the west. This ridge with H5 heights around 580dm will again
allow for another very warm day today with highs essentially
mirroring yesterday.

Starting tonight, a Pacific trough will develop west of California
and begin to dampen our heights aloft. This will start a slow
cooling trend, lowering highs on Tuesday into the lower 90s across
the western deserts to the mid 90s in the Phoenix area. This dry
trough is then expected to enter southern California later in the
day Wednesday before tracking through Arizona Thursday morning.
Winds will increase ahead of the trough starting Tuesday with
daytime wind gusts as high as 25 mph over the western deserts to
then areawide starting Wednesday. Behind the dry cold front on
Thursday, we expect to see daytime highs falling back into the 80s
with NBM guidance mostly calling for readings in the lower 80s to
around 85 degrees, or a few degrees below normal.

Ensemble guidance then shows the progressive weather pattern will
persist through the rest of the week with broad troughing continuing
across the Western U.S. This will continue to support breezy to
locally windy conditions each day through at least Saturday and
periods of high clouds. Guidance is still supportive of a stronger
shortwave trough tracking either directly through our region or
glancing across the northern portion of our region late Friday into
Saturday. Either track would keep our temperatures near normal
through the weekend with highs most likely in the mid 80s. This
system is also likely to contain a bit more moisture than the
midweek disturbance, but it should mostly only bring low end rain
chances for the Arizona high country.

&&

.AVIATION...Updated at 1720Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major weather issues will exist through Tuesday afternoon under
clear skies. Confidence is good that easterly winds will only
gradually shift to W/SW through the afternoon with a period of a
southerly cross runway component during the early afternoon (speeds
up to 10kt). Otherwise, any gustiness late afternoon/early evening
should be limited in magnitude and duration with a switch back to an
easterly component likely occurring slightly later tonight than in
previous days.


Southeast California/Southwest Arizona including KIPL and KBLH:
No weather issues will exist through Tuesday afternoon under clear
skies. Wind directions will generally vary between SE during
daylight hours and SW after sunset with a few gusts 15-20 mph common
during late afternoon/early evening.

&&

.FIRE WEATHER...
Dry conditions with above normal temperatures will persist early
this week with winds steadily becoming more breezy ahead of an
approaching weather system set to move through midweek. Afternoon
humidity levels will continue to fall to around 10% following poor
to fair overnight recovery of 20-40%. Cooler weather arriving during
the latter half of the week will allow an improvement to RH with
afternoon values only falling into a 15-25% range. As this weather
disturbance moves through the region later in the week, very breezy
conditions will also occasionally impact districts with afternoon
gusts commonly reaching 20-30 mph. Given this combination of winds
and humidity levels, a periodic elevated fire danger should be
planned for during the second half of the week.

&&

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

&&

$$

DISCUSSION...Kuhlman
AVIATION...18
FIRE WEATHER...18/Kuhlman