809
FXUS65 KPSR 191056
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
356 AM MST Sun Jul 19 2026

.KEY MESSAGES...

- Daily chances for showers and thunderstorms will exist through
  this weekend, mainly over the AZ high terrain, with around
  20-30% chances for storms surviving into the lower deserts.

- Thunderstorm chances may be more favorable (30-40%) for the lower
  deserts on Tuesday through Thursday.

- Temperatures will gradually climb to near normal through the
  upcoming workweek with areas along and west of the Colorado
  River valley topping out above 110 degrees by mid-week,
  resulting in a locally major HeatRisk.

&&

.SHORT TERM /Today through Monday/...
Latest mid-lvl wv imagery and 500 mb streamline analysis reveals
an elongated area of high pressure encompassing the Intermountain
West and the Central Plains. Meanwhile, the Desert Southwest
remains to the south of the high pressure center allowing deep
easterly flow to prevail. Multiple vortmaxes embedded in this
flow are present on wv imagery with one currently located over N
AZ, left over from a decaying band of showers and thunderstorms.
This area of vorticity will slowly drift S-SW over the next
several hours allowing for additional shower development across
south-central and southwestern AZ through early this morning.
Coincidentally NBM PoPs are around 20-30% through 12Z, lowering to
around 10-15% by 18Z. Another round of showers and storms will
materialize late this afternoon, but are expected to again remain
relegated to the higher terrain of S Gila and Yavapai Counties
with only a 10-30% chance of a weak outflow making it down to the
lower deserts. Skies should gradually clear out by early this
afternoon allowing temperatures to warm into the upper 90s with
some lower desert locations including the Phoenix Metro area
warming back into the triple digits. These temperatures will still
by around 3 to 6 degrees below the daily normal. Across the
western deserts where less cloud cover will be present, highs
should top out closer to normal in the 105-109 degree range.

On Monday, the positing of the subtropical high will not change
much, remaining centered over the Intermountain West and Southern
Rockies. This will allow deep easterly flow to continue over AZ. The
most noticeable difference will be a slight shift wwd of an easterly
wave/inverted trough which has been sitting over W TX. This feature
will continue to slowly progress into far W TX and N MX by Monday
afternoon. Ahead of this feature, we could see a more robust vortmax
progressing wwd into N AZ which will promote another round of
convection across the Mogollon Rim and eastern AZ where the
highest instability will be present. CAPE values in the lower
deserts will still be moderate at best, upwards of 500 J/kg with a
capping inversion present so it may be difficult for storms to
survive off the higher terrain Monday evening. A longer lived
outflow boundary is more likely which could at least foster
isolated storms over far E Maricopa and Pinal Counties. Due to the
strengthening of the 500 mb high over the Intermountain West and
responding low-lvl thermal profiles, temperatures will tick up a
couple more degrees Monday afternoon with most lower desert
locations reaching the triple digits.

&&

.LONG TERM /Tuesday through Saturday/...
Deterministic guidance and ensemble members continue to indicate
that the subtropical high will shift southeast over the Southern
Plains beginning on Tuesday. This will cause steering flow over
the Desert Southwest to shift from easterly to more of a
southeasterly direction. The afomentioned inverted trough will
slowly progress through N MX and into S AZ Tuesday into Wednesday.
This feature will enhance large scale lift over the region and
promote additional moisture transport from N MX into AZ. In
response, shower and thunderstorm activity will likely increase in
coverage and intensity with much better chances for the lower
deserts to receive measurable rainfall. Currently NBM PoPs are
highest during the late evening on Tuesday through the overnight
period, peaking around 20-40% across the Phoenix Metro. If
convection is more robust on Tuesday, then Wednesday may be a
quieter day overall. Confidence decreases in timing and overall
coverage of thunderstorm activity later next week as ridging aloft
expands over the forecast area and drier air begins to intrude
into southeast portions of AZ.

Model consensus indicates an overall expansion and strengthening
of the subtropical high, allowing positive height anomalies to
build over the forecast area from Thursday into next weekend. The
GEFS and EPS indicate mean hghts approaching 594-596 dam which
around the 90th percentile of climatology for late July. Thus we
will likely see temperatures increasing back above normal starting
Thursday. Unfortunately this means the return of Major HeatRisk,
especially across SE California and SW Arizona on Thursday and
Friday. Temperatures will increase further across the lower
deserts by next weekend with good indications that highs will
reach 110+F in Phoenix beginning Saturday.

&&

.AVIATION...Updated at 1055Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Isolated showers should diminish across the Phoenix metro around
sunrise with another round of showers and storms this
afternoon/evening expected to stay over the higher terrain. Winds
this morning will be somewhat variable with an initial north
northwesterly component, but still a decent chance of switching to
the east for a few hours mid morning. Winds should then settle out
of the west southwest by noon and stay light. FEW to SCT clouds
will be common through the TAF period with lowest bases around
8-10K ft AGL.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns are expected throughout the TAF
period. At KBLH, winds will generally remain out of the south. At
KIPL, westerly winds will shift to the southeast mid morning and
then gusty west winds will develop again this evening with gusts
up to 20-25 kts. FEW to SCT clouds aoa 10 kft will be common
throughout the period. There is also a low chance (10%) for spotty
showers to develop near KBLH through the rest of this morning.

&&

.FIRE WEATHER...
Recent wetting rainfall has resulted in drastic improvements in
fuel moisture across south-central AZ where ERC values have fallen
below the 25th percentile. Additional rounds of beneficial wetting
rainfall will be possible each day through at least the middle of
this week, especially over the foothills and high terrain of the
eastern districts. Winds will remain light, mostly below 15 mph
and follow typical diurnal upslope and downvalley patterns, the
main exception being gusty and erratic winds in the vicinity of
thunderstorms. Elevated moisture levels will keep minimum
afternoon humidity above 20% across the western districts and
between 30-40% over the eastern districts. Overnight recovery will
range from fair to good across the western districts and very
good to excellent for the eastern districts.

&&

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

$$

SHORT TERM...Salerno
LONG TERM...Salerno
AVIATION...Kuhlman
FIRE WEATHER...Salerno