000
FXUS65 KPSR 232026
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
126 PM MST Thu May 23 2019

.SYNOPSIS...
Well below average temperatures will persist today under mostly
clear skies. Warmer, but still below normal temperatures will be
seen Saturday before another mostly dry weather system affects the
region Sunday into Monday. This system will usher in another cool
air mass with high temperatures as low as the lower 80s on
Memorial Day. Gradual warming next week will eventually bring
temperatures closer to normal readings.

&&

.DISCUSSION...
The strong upper-level low which brought showers to the region
yesterday and this morning has moved north out of the state with
drier air advecting into the region from the southwest. This will
allow cloud cover to gradually diminish throughout the day today,
with mostly clear skies expected by tomorrow morning. Temperatures
today will once again fall about 20 degrees below average, with
highs across the lower deserts approaching the upper 70s/low 80s.

Weak troughing will continue through the weekend before another
Pacific low moves south along the western CONUS on Sunday.
Regardless of weak troughing tomorrow and Saturday, heights will
still be on a slight increase resulting in a slight warm-up
through Saturday. High temperatures tomorrow will reach the mid
to upper 80s, with temperatures on Saturday a few degrees warmer
(still below average). In addition, the pressure gradient will
start to increase on Saturday ahead of the aforementioned Pacific
low, resulting in breezy conditions during the afternoon (mainly
along the high terrain and across southwest Arizona).

The low bottoms out over central California Sunday morning before
beginning the process of rapidly filling and taking an easterly
track across the Desert Southwest through Monday. This next trough
will be a bit farther north then the current one and will be even
more moisture starved. Any rain chances with this Memorial Day
weather system should remain over the high terrain, but it will
bring another round of breezy to windy conditions and drop highs
back into the 80s.

A less active weather pattern should then take over through the
rest of next week, but considerable differences remain between the
GFS and European. The GFS points toward a much warmer solution by
late next week with 500mb heights rising to 580-584dm. The Euro
hints at another weak trough moving through our region later next
week. Either solution will bring warming conditions, but if the
GFS is correct, highs will likely top 100 degrees late next week
while the Euro would keep highs mostly in the lower 90s. The
current forecast is a blend between the two showing highs in the
lower 90s by next Wednesday and middle to upper 90s for late next
week.

&&

.AVIATION...Updated at 1810 UTC.

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

Relatively moist conditions in the lower levels persist in the
wake of the showers that moved through last night. Areas of low
stratocu (with bases generally around 6k ft) have consequently
developed, but will rise and gradually dissipate through the
afternoon. Otherwise, westerly winds will prevail this afternoon,
followed by a somewhat later than normal onset of the downslope
flow at KPHX overnight.

Southeast California/Southwest Arizona including KIPL and
KBLH:

Breezy conditions are expected this afternoon in the wake of a low
pressure system. Gusts up to 20 kt are possible, before subsiding
this evening and into Friday morning.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Sunday through Thursday:
Another weather disturbance will approach the Desert Southwest on
Sunday and move across the districts during the first half of
next week providing another period of cooler, unsettled weather.
Wetting rains are very unlikely with this next system, though a
scattered passing light shower is possible. On Sunday, locally
windy conditions will develop across the region with gusts mainly
up to 30 mph. Afternoon humidity levels will increase towards a
15-25% level Sunday and Monday with fair to good overnight
recoveries. Thereafter, minimum humidities will be on a downtrend,
with values dropping into the low teens by Thursday.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard operating procedures.

&&

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

$$

DISCUSSION...Hernandez/Kuhlman
AVIATION...Hirsch
FIRE WEATHER...Hernandez

NWS PSR Office Area Forecast Discussion