687
FXUS65 KPSR 072012
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
112 PM MST Mon Apr 7 2025

.SYNOPSIS...
Above normal temperatures will be prevalent throughout this week
and into the weekend with high pressure aloft building over the
region. The high pressure will be at its peak Thursday and Friday
with temperatures in the high 90s to low 100s across most of the
lower deserts. This high pressure will also continue to bring
mostly clear skies and dry conditions.

&&

.DISCUSSION...
Upper-level water vapor imagery early this morning shows a ridge
building over western CONUS and a longwave trough stretching from
the upper Midwest down into northern Mexico. The aforementioned
ridge will continue to build over western CONUS throughout the week.
This ridge will cause temperatures to increase along with
Moderate HeatRisk developing across portions of the lower deserts
by the end of the week. That being said, hot temperatures and
increasing HeatRisk will be the main forecast concern this week.

With the ridge really starting to move into our region today,
afternoon high temperatures are forecasted to be around 6-8 degrees
warmer than they were yesterday. With highs ranging from the mid 80s
to low 90s across the lower deserts and in the upper 70s to low 80s
in the higher terrain areas. As the ridge strengthens, lower desert
afternoon high temperatures are forecasted to rise to the low-to-mid
90s on Tuesday and mid-to-upper 90s on Wednesday. The center of the
ridge will be over the Desert Southwest and at its peak (H5 heights
around 588dm) by the later half of the week. Currently Friday is
forecasted to be the hottest day of the week with a forecasted
high of 102 degrees in Phoenix, AZ, Yuma, AZ, Blythe, CA, and
Imperial, CA. Current NBM forecast has a greater than 90% chance
that a lot of lower desert communities will reach the century
mark for the first time this year by the end of the week. With
temperatures around 15-18 degrees above normal they will also be
nearing new record high temperature marks as well (see CLIMATE
section below). There will be areas of Moderate HeatRisk
developing across the lower deserts starting Thursday, which will
have impacts on those who are sensitive to the heat, and/or those
who have prolonged exposure to the heat without adequate
hydration. So be sure to practice smart heat safety this week and
try to limit your time outdoors, especially during the peak heat
of the day, and make sure to drink plenty of water. There will be
adequate cooling at night with overnight lows dipping into the low
to mid 60s outside of urban core areas and in the upper 60s to
near 70 degrees in the urban core areas.

Global ensemble guidance continues to be in pretty good agreement
that by late next weekend and into next week a large scale trough
will move into our region. The ensemble members are in disagreement
with the exact strength and depth of the trough, but it is expected
to at least weaken the ridge leading to at least a brief cooling
trend for our region. Currently afternoon high temperatures are
forecasted to fall back into the upper 80s to low 90s across the
lower deserts by early next week. It is unlikely that this trough
would bring enough moisture to our region to support any rain
chances. However, it`s more likely that this trough would lead to
breezy to locally windy conditions for our region, which could
lead to some elevated fire weather concerns.

&&

.AVIATION...Updated at 1720Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT;
Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns will exist through Tuesday under
mostly clear skies. Winds are expected to follow typical diurnal
tendencies with speeds generally AOB 8 kts. Extended periods of
variable to nearly calm winds are anticipated at the SE California
terminals through early afternoon and again late tonight.

&&

.FIRE WEATHER...
High pressure will build over the region this week leading to
increasing temperatures, dry conditions, overall light winds, and
mostly clear skies. Temperatures are forecasted to be around 5
degrees above normal today, but rise to around 15-18 degrees above
normal (and near the century mark across much of the lower
deserts) by the end of the week. MinRHs will be less than 10%
through the week with poor overnight recovery, with maxRH around
15-30%. Winds will overall be light and tend to follow their
typical diurnal tendencies.

&&

.CLIMATE...

Record high temperatures this week:

Date       Phoenix        Yuma        El Centro
----       -------        ----        ---------

Apr  9   102 in 1989   102 in 1989   104 in 1989
Apr 10   100 in 2018   100 in 1960    98 in 2018
Apr 11    99 in 2023   101 in 1936   100 in 2018
Apr 12    99 in 1936   102 in 1962   103 in 1940

&&

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

$$

DISCUSSION...Berislavich/Ryan
AVIATION...Kuhlman/Benedict
FIRE WEATHER...Berislavich/Ryan
CLIMATE...Kuhlman