281
FXUS65 KPSR 091956
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1256 PM MST Mon Mar 9 2026


.KEY MESSAGES...

- A low pressure system moving through the region will result in scattered
  showers and thunderstorms later this afternoon through tonight
  along with cooler temperatures.

- Any thunderstorms will be capable of producing small hail, strong
  gusty winds, and brief heavy rainfall.

- High pressure will build into the region by midweek, leading to dry
  weather and rapid warming with record warmth possible starting
  by the end of the week.

&&

.SHORT TERM /Today through Wednesday/...
Latest satellite imagery shows a potent cut-off low situated just
off the west coast of the northern Baja Peninsula and will be the
main weather maker later today. As the low gradually moves east
northeastward, good moisture advection with PWATs rising to 0.8-0.9"
(200-250% of normal) and increasing ascent in the form of upper-
level divergence will lead to the development of scattered showers
and storms. Latest HREF membership is in very good agreement in
showing areas of widely scattered showers and storms first affecting
portions of southwest AZ during the mid to late afternoon hours,
mainly across Yuma County, before the focus of the activity shifts
eastward into south-central AZ heading into the evening hours.
While 0-6 km shear values are expected to be strong, in excess of
40 kts, which would suggest that some of these thunderstorms that
do materialize could obtain some organized structure to them, the
main limiting for a more organized severe threat is the
instability as forecast soundings show CAPE values only peaking at
200-500 J/KG. Nevertheless, strong gusty winds in excess of 35
mph as well as small hail will be possible with any robust storms.
Rainfall amounts for the most part will be limited given the
overall widely scattered coverage and fast storm motion. However,
some areas could still receive over 0.25" with any heavier
thunderstorm. Scattered showers will remain a threat into the
first part of Tuesday, especially across the higher terrain east
of Phoenix, before ending sometime during the afternoon hours as
the low shifts eastward into southern New Mexico/western Texas.

Under the influence of the low, temperatures through Tuesday will be
noticeably cooler. Afternoon high temperatures today across the
western deserts under the influence of more persistent cloud cover
will only reach the middle 70s, whereas across the lower deserts of
south-central AZ, afternoon highs will still manage to reach 80
degrees as more abundant sunshine is expected into the afternoon
hours. Under the influence of lingering cloud cover and cool air
advection on the back side of the departing low, afternoon high
temperatures across the south-central AZ lower deserts are only
expected to top out in the mid to upper 70s. More sunshine will
allow afternoon highs across the western deserts to warm to around
80 degrees.

As the low fully exits the SW CONUS early Wednesday, strong upper-
level ridging will move in from the eastern Pacific with rapid
height rises expected as 500 mb heights rise above 580dam. As a
result, temperatures will be on rise with afternoon highs rising
into the mid 80s across most of the lower desert communities and
will be the transition of what is expected to be a prolonged stretch
of record warmth during the subsequent days.

&&

.LONG TERM /Thursday through Sunday/...
Forecast confidence for the latter half of the week is excellent
given remarkable ensemble agreement showing a low amplitude northern
stream jet constricting poleward towards a Hudson Bay vortex
allowing strong subtropical ridging to expand into the SW Conus. H5
heights will settle into a 585-588dm range through the majority of
the period with only a marginal chance of heights/thermal fields
dampening over the weekend due to shortwave energy digging into the
Upper Midwest/Great Lakes. Ensemble guidance spread is extremely
narrow and reflects climatologically anomalous tropospheric
height/thermal measures. Surface temperatures 15F-20F above normal
will become common by the end of the week resulting in widespread
minor HeatRisk while also setting daily records (see Climate
section). It would also not be out of the question for some the
warmer, lower desert communities to achieve the first 100F of the
season as the NBM 75th percentile easily covers this threshold. Just
beyond this forecast period, essentially all ensemble members
indicate even warmer weather as East Pacific blocking edges into the
SW Conus and subsident ridging builds stronger. The ensemble
guidance envelop is solidly above the 100F threshold for all lower
desert communities portending a prolonged period of record setting
warmth.

&&

.AVIATION...Updated at 1842Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The main aviation hazard for the forecast period will be the
possibility of VCTS/TS and brief lower CIG and VIS this evening
through tonight where the main TS impacts will be strong gusty
winds and small hail. Before this evening`s activity no
significant aviation concerns are expected with VFR conditions.
Wind directions are expected to favor a S/SW component through
this afternoon with speeds generally aob 10 kts. SCT-BKN mid-lvl
clouds, with bases around 7-10 kft, will develop rapidly by mid to
late afternoon. Cloud bases are forecast to stay above 5-6 kft
through the TAF period, but there is a 10-20% chance of briefly
dipping to 3-4 kft in TS. Most of the SHRA/TS activity will shift
east of the terminals by mid-morning Tuesday.

Southeast California/Southwest Arizona including KIPL and KBLH:
The main potential aviation weather impact will be the development
of SHRA/TS this afternoon and evening. Most of the activity will
stay east of the CO river, with 10-30% chances at the terminals.
Given the low chances, there is no VCSH/SHRA mention at KBLH in
the TAFs. Winds will favor a E-SE component at KIPL and will
predominantly favor S-SW at KBLH. Wind speeds at both terminals
should generally be around 6-11 kt, before becoming light and VRB
tonight through Tuesday morning. SCT-BKN mid-high clouds with
lowest bases around 5-7 kft will persist through the evening
hours.

&&

.FIRE WEATHER...
A weather system moving through the region today through early
Tuesday will bring cooler temperatures, increased humidity levels,
and chances for wetting rainfall. Dry weather with unusually warm
temperatures and low humidities will return during the latter half
of the week. Minimum humidity levels will only fall into a 25-40%
range this afternoon with good to excellent overnight recovery.
Better than a 50% chance of wetting rain with embedded thunderstorms
will exist in eastern districts through Tuesday afternoon before a
drying trend enters the region. Conditions will trend markedly drier
through the week with minimum afternoon humidities falling into a 5-
15% range by the end of the week while poor to fair overnight
recovery of 15-30% materialize. Outside of thunderstorm wind gusts
today, winds will be fairly light with only modest afternoon upslope
gustiness limiting a greater fire weather danger.

&&

CLIMATE...

Daily record highs later this week/early next week:

Date      Phoenix         Yuma         El Centro
----      -------         ----         ---------
3/12     94 in 1900    100 in 1916     95 in 2017
3/13     92 in 2017     95 in 2017     95 in 2017
3/14     95 in 2013     96 in 2017     97 in 2017
3/15     92 in 2013     98 in 1934    100 in 1934
3/16     99 in 2007     99 in 2007    100 in 2007
3/17     99 in 2007    101 in 2007    101 in 2007
3/18     95 in 2017     96 in 2017     95 in 2007

&&

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

$$

SHORT TERM...Lojero
LONG TERM...18
AVIATION...Benedict/Salerno
FIRE WEATHER...18
CLIMATE...18

NWS Phoenix (PSR) Office