315
FXUS65 KPSR 211727
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1027 AM MST Sat Mar 21 2026

.UPDATE...18Z Aviation Discussion

&&

.KEY MESSAGES...

- Record breaking lower desert high temperatures near 100 degrees
  will be common through the upcoming work week, with the hottest
  of the next 7 days likely today.

- Extreme Heat Warnings will remain in effect across the lower
  deserts through Sunday.

- The unprecedented afternoon heat will be dangerous, especially
  with any strenuous or long-duration outdoor activities without
  proper hydration and taking breaks in the shade, or air
  conditioning.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...
An impressively strong and expansive midlevel anticyclone remains
in place centered over Central AZ at this hour, with analyzed H5
heights still up to 592-593 dam, though its strength will wane as
we head into the weekend. The waning strength is thanks in large
part to a more active storm track developing in the northern
stream, with guidance showing several shortwaves progressing over
Canada and skimming the northern tier states into early next week,
dampening heights aloft over much of the Western US. While H5
heights fall through Sunday-Monday and eventually bottom out in a
583-585 dam range, these values still sit at or above the 97th
percentile of climatology, so daily highs will not fall much, but
at least enough to end the widespread Moderate HeatRisk by Sunday
and especially by Monday.

In the near term, lower level temperatures still remain well
above climatological maximum values through this afternoon, with
NAEFS mean 850 mb temperatures around 24C-28C across the forecast
area. This will unfortunately support another day with record
smashing highs across the lower deserts, in a 101F-107F range
today, or still near 25F above daily normals and 3F-8F above daily
records. Forecast highs then drop into a 96F-102F range for the
lower deserts Sunday. Some high cloud cover may play a role in
keeping temperatures lower on Sunday in addition to the lower
heights aloft. Monday still looks to be the "coolest" of the next
7 days, with highs solidly in the 90s, 15F-20F above daily normals
and flirting with the century mark in some of the hottest spots.
The signal for a Gulf Surge is still present in the guidance,
which is very atypical for this time of year, but would
nonetheless act to increase moisture in a shallow near-surface
layer Sunday night and Monday night. This will help ensure that
Monday and even Tuesday do not see such widespread highs in the
triple digits, especially in the Yuma area and surrounding
valleys where dewpoint temperatures are forecast to reach a
45F-55F range.

Aside from the heat, the combination of this initial anticyclone
shifting southeast of the area this weekend and an approaching
weak disturbance from the west will induce a southwesterly MSLP
gradient, allowing for increased breeziness late this afternoon
into the early evening. This will be especially apparent for
portions of Southeast CA, like the southwestern corner of Imperial
County. Gusts to 20-25 mph will develop in some areas and locally
stronger gusts for the aforementioned wind prone parts of
Southeast CA. Lingering afternoon and early evening breezes around
20 mph will remain common across portions of the region into
early next week.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
During the middle of the upcoming workweek, ensembles remain in
excellent agreement that another significant yet more transient
ridging feature will build under an anticyclonically curved jet
streak. Though the ridging will be lower amplitude compared to the
current ridge, and anticyclonic subsidence will be shorter lived
(likely peaking in its influence sometime Tuesday-Wednesday), H5
heights are forecast to rise into a 587-590 dam range - once
again above CFSR climatological maximum values for this time of
year. This will allow temperatures to warm for the latter half of
the workweek, with highs hovering in the upper 90s to lower 100s
across the lower deserts. Latest probabilistic NBM output
advertises IQRs of 4F or less for the forecast temperatures during
this timeframe, yielding good confidence in this abnormal March
heatwave sticking around and daily highs staying in record
territory through at least the next 7 days.

&&

.AVIATION...Updated at 1730Z.

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

No aviation weather concerns are expected during the TAF period.
Winds will continue to follow familiar diurnal patterns at the
Phoenix Metro terminals with speeds remaining aob 8 kts. At the
SE California terminals, expect predominantly westerly winds at
KIPL and southwesterly winds at KBLH. Intermittent gusts up to
around 25 kts can be anticipated at KIPL this evening. Clear skies
will give way to increasing high cirrus decks later this evening.

&&

.FIRE WEATHER...
Record breaking heat and dry conditions will continue through
next week. Afternoon highs around 25 degrees above daily normals
will be common today, falling to around 15 to 20 degrees above
normal by Monday. Afternoon MinRHs between 5-10% will persist
through Sunday, increasing slightly into a 10-20% range for
portions of the Western Deserts early next week. Overnight
recoveries will be poor, around 15-35% areawide tonight. Overnight
recoveries improve to 40-60% Sunday through Tuesday night
primarily for valley locations in the western deserts like the
Yuma area, lower Colorado River Valley, Imperial Valley, and lower
Gila River Valley. Elsewhere, MaxRHs will range between 25-40%
into the middle of the work week. Late afternoon and early evening
breeziness will increase this weekend into early next week, with
gusts locally to 20-25 mph.

&&

.CLIMATE...

Daily record highs through the upcoming work week:

Date      Phoenix         Yuma         El Centro
----      -------         ----         ---------
3/21     97 in 2004    102 in 2004    100 in 2004
3/22     94 in 1990     98 in 2004     96 in 2004
3/23     93 in 1990     96 in 1990     93 in 1990
3/24     96 in 2025     97 in 2025     96 in 2025
3/25     99 in 2025     99 in 1896     99 in 2025
3/26    100 in 1988     99 in 1988     98 in 1988
3/27     98 in 1986    100 in 1986     99 in 1988

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Sunday for AZZ530>555-559-
     561.

CA...Extreme Heat Warning until 8 PM PDT Sunday for CAZ561>570.

&&

$$

SHORT TERM...Whittock
LONG TERM...Whittock
AVIATION...Salerno
FIRE WEATHER...Whittock/Ryan
CLIMATE...Whittock/18

NWS Phoenix (PSR) Office