Coolidge, Arizona Weather Forecast Discussion

567
FXUS65 KPSR 192017
AFDPSR
Area Forecast Discussion
National Weather Service Phoenix AZ
115 PM MST Fri Sep 19 2025
.KEY MESSAGES...
- A few showers and storms will be possible through this evening,
but mainly confined around terrain features.
- Temperature not far from the seasonal normals will be common
across the area through at least the middle of next week.
- Modest shower and thunderstorm chances return during the first
half of next week before drier weather returns to the region.
&&
.SHORT TERM /Today through Sunday/...
Early afternoon WV imagery depicts a series of smaller vorticity
centers rotating about a larger circulation lifting into the Great
Basin while favorable difluence aloft and forced ascent exits
towards the four corners. While a substantially drier
midtropospheric airmass is entering the CWA, ample boundary layer
moisture with mixing ratios 12 g/kg will linger across much of the
forecast area. Behind one final vorticty wing of ascent which aided
in showers/storms forming with moist flow over terrain escarpments
around the Phoenix metro this morning, midlevel height rises and
large scale subsidence will continue to gradually spread into the
region. Thus while forecast soundings indicate impressive
thermodynamic profiles with MLCape around 1000 J/kg and minimal
CinH, the overarching lack of forcing mechanisms may keep any deep
convective development relegated to the most favorable terrain
induced areas through the early evening before loss of insolation
precludes more than residual lingering showers.
High pressure ridging, warming aloft, and subsidence will further
build over the forecast area Saturday as the western Conus pattern
transitions to a more blocked flow. Deep negative height anomalies
developing off the California coast will allow H5 heights to
increase close to 588dm across the CWA bringing temperatures back to
a near normal level. Boundary layer flow should remain fairly light
ensuring the only drying mechanism will be from vertical mechanical
mixing, and forcing mixing ratios down closer to 10 g/kg. Given this
moisture content and minimal inhibition with daytime heating, cannot
completely discount an isolated storm blossoming over terrain
features, but the preponderance of model guidance suggests very
limited opportunities.
By Sunday, unusually deep negative height anomalies will have become
established west of the Los Angeles basin forcing an intense
subtropical jet inland across the SW Conus. Fairly good model
evidence exists showing the jet core tapping thick moisture in the
H7-H5 layer and transporting this layer inland. While initially in
the form of merely showers, some minor instability could be realized
throughout the day to support thunderstorms, though with the
introduction of this thicker midtropospheric moisture, lapse rates
may be compromised resulting in meager instability. Nevertheless,
POPS increase throughout the day portending scattered light rainfall
opportunities.
&&
.LONG TERM /Monday through Thursday/...
The weather pattern for early next week remains fairly complicated
as the upper level low that develops to our west is forecast to
become cut off from the main flow. Cut-off lows are typically very
difficult for models to forecast and this is no different. Models
over the past couple of days have trended to hold onto the cut-off
low bringing it into or at least close to our region Monday. The
past couple of model runs have at least shown better consensus
between the GEFS and the EPS with the low center nearing the
southern California coast by Monday before it likely slowly lifts
northward on Tuesday as it weakens.
Despite better model consensus with the positioning of the cut-off
low, there are still differences with the amount of moisture and
rain chances for our region. NBM PoPs have increased across the
majority of the area through Monday, but PoPs are mostly staying
between 20-30%. It will probably take another day or so to have a
better handle on these upcoming rain chances, but for now it is not
looking like there will be any big impacts.
Since models are trending toward having the cut-off low move near or
into southern California early next week, the upper level ridge
should also get pushed back to the east and south. As a result,
forecast temperatures have been dialed back a good amount. A couple
of days ago, the NBM was showing 105 and 108 degrees for Phoenix on
Monday and Tuesday, but now it has lowered to 97 and 103 degrees.
Eventually, the cut-off low is expected to shift more into the Great
Basin region by next Wednesday or Thursday allowing higher heights
to build back over our region. This should allow for temperatures to
warm up a bit further with NBM showing highs likely reaching 100
degrees again across the entirety of the lower deserts.
&&
.AVIATION...Updated at 1740Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The primary aviation concern remains the potential for isolated
thunderstorms developing this afternoon into the evening. For now,
VFR conditions prevail with winds generally following typical
diurnal patterns. The latest high-resolution guidance continues to
hint at isolated convection developing over the higher terrain.
However, overall confidence in coverage and intensity remains low,
so have kept the TAFs dry for this issuance. Should any storms
manage to develop and move into the vicinity, gusty and erratic
outflow winds would be the main impact. Otherwise, expect
southwesterly winds this afternoon aob 12 kts before weakening and
becoming variable overnight, shifting ESE early tomorrow morning.
Scattered cloud decks will persist aoa 10 kft, becoming FEW after
sunset.
Southeast California/Southwest Arizona including KIPL and KBLH:
No significant aviation weather concerns are expected through the
TAF period, with persistent VFR conditions. At KIPL, winds will
remain light and variable. For KBLH, southerly winds will continue
through the afternoon before becoming westerly this evening and then
light and variable. Wind speeds will remain at or below 10kts. Skies
will be mostly clear.
&&
.FIRE WEATHER...
Drying conditions will be seen into the weekend, but lingering
moisture today over the eastern districts will provide for continued
chances for showers and thunderstorms mainly focused over the
Arizona high terrain. Despite moisture levels overall decreasing,
humidities will stay elevated through the weekend with MinRHs mostly
staying above 25-30%. Winds will remain rather light and mostly
follow diurnal directional trends. Another round of rain chances may
enter the picture by early next week with a low pressure system
nearing the region from the west. This system should help to keep
temperatures closer to normal and humidities fairly elevated through
Monday. Drier conditions should then fully take over by the middle
of next week as high pressure is likely to become more dominant
across the region.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
SHORT TERM...18
LONG TERM...Kuhlman
AVIATION...95/Lojero
FIRE WEATHER...Kuhlman

NWS PSR Office Area Forecast Discussion