296
FXUS65 KPSR 121705
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1005 AM MST Tue May 12 2026

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- An Extreme Heat Warning remains in effect for the Phoenix Metro
area through early this evening.

- Breezy conditions will develop along the Lower Colorado River
valley today and Wednesday, then over Arizona high terrain on
Wednesday.

- A noticeable cooling trend will begin Wednesday and continue
through the weekend, albeit with temperature remaining slightly
above normal.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...
A strong upper level ridge with near climatological record H5
heights is positioned across the Desert Southwest. Additionally, a
weak shortwave trough is also located over central Baja.
Southeasterly flow in between the two systems did result in some
scattered convection across northern Mexico yesterday along with
some remnant moisture from the convection making its way
northwestward into southern Arizona. This moisture may result in
some morning mid level clouds, but overall today will again be sunny
to mostly sunny for most locations.

As the weak shortwave continues to move northward into southern
California later today, height falls across the western deserts will
bring some slight relief from yesterday`s near 110 degree highs as
readings mostly top out between 102-106 degrees. The ridge will
remain more dominant across Arizona resulting in highs of 105-107
degrees in the Phoenix area where an Extreme Heat Warning remains in
effect. The southeasterly flow continuing across the area through
the rest of today may allow for some widely isolated convective
showers across southeast Arizona and likely some clouds into the
south-central Arizona lower deserts by this evening. Southerly
breezy to locally windy conditions will also affect portions of
southeast California and southwest Arizona this afternoon with gusts
as high as 25-30 mph in some locations.

By Wednesday morning the weak shortwave is forecast to have moved
into central California and western Nevada as another stronger
Pacific wave moves eastward across the Pacific Northwest. Both
systems will combine into a larger trough with a trailing trough
axis eventually making its way into our region by Thursday. At the
same time, it will completely displace the ridge to the east of our
region allowing for modest height falls and cooling temperatures.
Forecast highs for Wednesday drop into the upper 90s to just over
100 degrees across the lower deserts.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
The weather pattern later this week is expected shift to a more
zonal westerly dry flow pattern, but with some influence from
passing troughs to our north. The drying flow will result in clear
to mostly clear skies for Thursday-Saturday with temperatures
remaining quite stable averaging 5-7 degrees above normal. Ensembles
are currently favoring a larger Pacific trough moving through the
Pacific Northwest this weekend bringing lower heights as far south
as the Southwestern U.S. NBM/WPC temperature guidance suggests
daytime highs falling back more into the upper 90s by around Sunday.

&&

.AVIATION...Updated at 1705Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds will be the primary weather issue through Wednesday afternoon
under periods of mid/high cloud decks. Confidence is good that a
westerly component will develop by early afternoon, then obtain
enhanced gustiness early/mid evening. There is some uncertainty in
the magnitude of wind gusts, and virga may create some erratic
directions and speeds for a few hours. Otherwise, the switch to the
nocturnal easterly component should be delayed again tonight. A
period of 8-12kt southerly cross runway winds are likely Wednesday
late morning/early afternoon.


Southeast California/Southwest Arizona including KIPL and KBLH:
Periods of gusty winds will be the main weather issue through
Wednesday afternoon under occasional mid/high cloud decks. A S/SE
component will be favored across the area through the afternoon with
directions at KIPL likely abruptly shifting to SW early evening.
Confidence is excellent that gusts 20-30kt will become common
through the afternoon and early evening before decoupling and
weakening overnight.

&&

.FIRE WEATHER...
Hot, dry, and locally breezy to windy conditions will result in
elevated fire weather potential this afternoon across the Lower CO
River Valley. Wind gusts of 20-30 mph along with RHs 7-10% are
expected across the Lower CO River Valley. Elsewhere today, winds
will be lighter but with afternoon gusts of 15-20 mph possible.
Wednesday will bring another round of breezy winds over southeast
California and the Arizona high terrain with elevated fire weather
conditions again a possibility. Temperatures today will be 10-15
degrees above normal dropping to 5-8 degrees above normal starting
Wednesday. Winds will diminish starting Thursday, but very dry
conditions will continue to prevail.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST this evening for AZZ537-540-
     542>544-546-548-550-551.

CA...None.
&&

$$

SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...18
FIRE WEATHER...Kuhlman