863
FXUS65 KPSR 112210
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
310 PM MST Mon May 11 2026

.KEY MESSAGES...

- An Extreme Heat Warning remains in effect for portions of the
  western deserts today and for the Phoenix Metro area through
  Tuesday.

- Today will be the hottest day of the week with lower desert
  highs reaching 105-112 degrees, followed by a gradual cooling
  through the remainder of the week.

- Dry conditions will prevail this week with periods of passing
  high clouds. Breezy conditions are anticipated along the Lower
  Colorado River valley on Tuesday and the AZ high terrain on
  Wednesday.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...
A robust upper-lvl ridge has expanded over our forecast region this
afternoon with H5 heights now peaking between 588-590dm, or near the
99th percentile of climatology for mid-May. These positive hght
anomalies coupled with clear skies and very low relative humidity
will result in highs of 106-112 degrees this afternoon, or around 15
degrees above normal. The forecast high in Phoenix is still around
109 degrees today which is only one degree shy of the daily record.

On Tuesday, a weak upper level disturbance will move up the Baja
coastline into SE California. As this occurs, mid-lvl winds will
become more southerly and draw some moisture into our region.
Overall, PWATs will rise to around 0.6-0.8" and promote at least
scattered afternoon cloud cover and potentially isolated shower
activity across southeast Arizona to as far north as eastern Pinal
and southern Gila Counties. Even if some showers do manage to
develop, we are not anticipating any measurable rainfall in our
area. Instead, much of the precipitation will fall as virga and
could result in localized wind gusts up to 30 mph. An increased
pressure gradient associated with the passing shortwave will help
to drive a decent push of southerly winds across far southwest
Arizona and southeast California. Temperatures Tuesday will react
to the falling heights mainly across southeast California and
southwest Arizona where highs will fall back to between 102-106
degrees. The Phoenix area will only dip a couple of degrees from
today`s highs with readings topping out 104-107 degrees. Thus, the
Extreme Heat Warning will continue into Tuesday for only the
Phoenix Metro.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Wednesday will be a pattern transition day for the Desert Southwest
as upper level troughing from a much larger Pacific trough nudges
southeastward into the region while a sub-tropical upper level jet
comes on shore across northern Mexico into Arizona. The jet will
drive increased higher level clouds across at least the eastern half
of Arizona for much of Wednesday, while the lowering heights will
allow for cooling conditions. Forecast highs Wednesday range from
the upper 90s to around 100 degrees across the western deserts to
around 100 degrees in the Phoenix area.

The main Pacific shortwave is set to miss our region well to the
north on Thursday, but the broader upper level troughing is still
favored to move through Thursday into Friday. This will drive
heights even lower while dropping highs more into a 95-99 degree
range for both Thursday and Friday. The pattern for the upcoming
weekend is likely to support a weak ridge moving through giving a
slight boost in temperatures as readings may top 100 degrees again
for some of the lower deserts. The westerly dry flow late this week
and through next weekend should provide for mostly clear skies.

&&

.AVIATION...Updated at 1710Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Uncertainty in timing of wind shifts and directions will be the
primary weather issue through Tuesday afternoon under clear skies.
Confidence is good than an easterly component will prevail through
mid afternoon, then attempting to switch to a westerly component
late afternoon. However, extended periods of variability are
possible late afternoon/early evening with directions potentially
260v030 until settling on a W/NW trajectory beyond mid evening. A
west component may hold longer into the overnight before making the
typical nocturnal easterly switch prior to sunrise.

Southeast California/Southwest Arizona including KIPL and KBLH:
No weather issues will exist through Tuesday afternoon under clear
skies. Confidence is fair that wind directions will oscillate
between an early morning/daytime SE component and an evening SW
direction with speeds remaining under 12kt.

&&

.FIRE WEATHER...
Hot and dry conditions will prevail with lower desert highs topping
out 10 to 15 degrees above normal through Tuesday. Temperatures will
cool closer to average by the end of the week. Minimum humidity
levels will bottom out around 10% or lower each afternoon with
overnight recoveries remaining poor to fair, averaging 20-35%.
There will be increased breeziness, particularly across the
western districts Tuesday afternoon where gusts up to 25-30 mph
will be possible. These stronger winds coupled with very dry
conditions will result in elevated to near critical fire weather.
The breezy to locally windy conditions will shift over the AZ high
terrain on Wednesday. Winds will diminish later in the week, but
overall very dry conditions will prevail.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST this evening for AZZ530-532.

     Extreme Heat Warning until 8 PM MST Tuesday for AZZ537-540-
     542>544-546-548-550-551.

CA...Extreme Heat Warning until 8 PM PDT this evening for CAZ562-563-
     566-567-569-570.

&&

$$

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