Quartzsite, Arizona Weather Forecast Discussion

365
FXUS65 KPSR 152007
AFDPSR
Area Forecast Discussion
National Weather Service Phoenix AZ
107 PM MST Mon Sep 15 2025
.KEY MESSAGES...
- Hotter conditions will be seen over the next few days with lower
desert high temperatures topping out between 101 and 105  degrees.
- Rain chances will enter the picture again by Wednesday with the
best chances focused across southeast California on Wednesday
and Thursday and across southern and central Arizona on Friday.
- Temperatures are likely to return to normal later this week into
next weekend.
&&
.SHORT TERM /TODAY THROUGH TUESDAY/...
Dry conditions continue across the CWA today as dry westerly flow
remains in place across the area. The broader synoptic pattern is a
little bit more messy as a weak closed low has formed in the eastern
Pacific, off the coast of southern CA. TC Mario is still just
southwest of the Baja with another tropical wave south of Mexico,
that the NHC is giving a 70% chance of forming within the next week.
These three features will play a role in our weather for the end of
the week as they push an abundance of moisture (up to 150-200% of
normal) back into the region. Broader large scale troughing remains
entrenched over much of the NW portion of CONUS along with a
subtropical ridge over TX and Mexico.
PWATs remain below an inch across our area this afternoon, which
will keep precipitation chances at 0%. Some moisture will start
to move back into the region tomorrow as TC Mario pushes
northwestward. PWATs will go back over an inch, with models
showing PWATs around 1.0-1.2" across south-central AZ and anywhere
from 1.3-1.6" PWATs across southeastern CA and southwest AZ.
However, the only forcing mechanism will be the terrain itself. So
a few isolated showers and storms along more prominent terrain
features (in southern Gila County, southeastern CA, and the Kofas)
are possible tomorrow afternoon and evening.
Temperatures will be near to a few degrees above normal over the
next couple of days as the aforementioned subtropical ridge
builds over the region. Afternoon high temperatures will be in the
100-105 degree range across the lower deserts and in the 90s
across the higher terrain. Models show the ridge maxing out over
our area tomorrow, making it the hottest day of the week. The
continued clear skies will make for maximum radiational cooling at
night keeping overnight and morning low temperatures on the more
pleasant side. However, with the building ridge, morning lows will
be warmer than they were this weekend. Tuesday morning low
temperatures are forecasted to be in the mid 70s to low 80s across
the lower deserts and in the low 70s across the higher terrain.
The combination of these warmer temperatures on Tuesday will
result in widespread Minor HeatRisk with areas of Moderate
HeatRisk across south-central AZ, including the Phoenix Metro, and
across western Imperial County.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Model uncertainty remains quite high for the latter half of the
week as guidance is having difficulty resolving the evolution of
TC Mario. As of now, the most likely scenario calls for Mario to
gradually dissipate as it slowly moves northwestward off the coast
of southern Baja. There is still a slight possibility of its
remnants reaching as far north as southern California, but of much
higher likelihood is its moisture will get absorbed into the
larger scale upper level low just to its north.
For our area, the main uncertainties are how much moisture will
reach southern California and Arizona and when exactly will be the
best rain chances. The latest NBM model run has backed off on the
rain chances for much of our area as the best area of moisture
and rain looks to have shifted to more along the coast of
southern California and northward. This shift is more seen within
the EPS as the GEFS is still holding onto better moisture and rain
chances farther to the east into our area. Have mostly maintained
the NBM PoPs, but have adjusted upwards slightly for Wednesday
and Thursday as they seemed too pessimistic. Moisture levels are
at least likely to rise to near 200% of normal across southeast
California and to around 150% of normal for southern and central
Arizona by Thursday.
Moisture is not likely going to be an issue during the latter half
of this week, but there should be an overall lack of forcing for
widespread precipitation. As of now, showers and the potential for
thunderstorms may end up being focused along a trough axis moving
from south to north later on Wednesday and then from overall
large scale upper level jet forcing for Thursday and Friday.
Chances later Wednesday and Thursday are likely to be focused
more across southeast California and far southwest Arizona before
shifting more across central Arizona on Friday. The higher levels
of uncertainty means PoPs are mostly between 20-40% as of now, but
chances may rise (at least for a small window) once uncertainty
decreases. QPF amounts have also been dialed back a good deal with
the moisture shift to the west with amounts mostly from 0.2-0.5"
across southeast California to as little as trace amounts from
Phoenix and areas to the east of Phoenix. As a reminder, there is
still a small minority of members that show much better rainfall
totals for southern and central Arizona, so big changes to the
forecast may still happen.
Going into the weekend, guidance mostly agrees the best moisture
will push to the north of our area as the subtropical ridge
centered just to our south begins to shift northward. We may have
some residual slight rain chances over the weekend, but overall
chances look to be at most 10-15%.
Temperatures for the latter half of the week will trend slightly
lower with the increased moisture and clouds, but highs are not
expected to fall much below 100 degrees. Assuming the subtropical
ridge does move more overhead for the upcoming weekend,
temperatures may begin to drift back above 100 degrees again.
&&
.AVIATION...Updated at 1730Z.
South Central Arizona and Southeast CA including KPHX, KIWA,
KSDL, KDVT, KBLH and KIPL:
No aviation weather concerns are expected through the forecast
period under mostly clear skies over the region. Winds will
follow typical diurnal patterns with speeds remaining aob 7 kts.
Periods of calm and vrb winds will also be likely, especially at
the SE California terminals and prior to diurnal wind shifts.
&&
.FIRE WEATHER...
Hotter temperatures and increasing moisture will continue through
the middle of the week. After another dry day today, rain chances
will also gradually increase by mid week, particularly across the
western districts. Tomorrow most will stay dry, with only isolated
showers and storms possible over prominent terrain features.
Minimum RH values should average 15% today, around 20% Tuesday and
25% for Wednesday, with improved overnight recoveries starting
tonight. Winds will remain light over the next few days with
directions mostly following diurnal trends. Daily rain chances of
20-40% are expected for later this week with humidities staying
elevated and temperatures returning into the normal range.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
SHORT TERM...Berislavich
LONG TERM...Kuhlman
AVIATION...Salerno
FIRE WEATHER...Kuhlman/Berislavich

NWS PSR Office Area Forecast Discussion