831
FXUS65 KPSR 181748
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1048 AM MST Thu Jun 18 2026

.UPDATE...Updated 06z Aviation Discussion...

&&

.KEY MESSAGES...

- Temperatures will continue to cool closer to normal the remainder
of the week allowing moderate HeatRisk to be reduced towards a minor
category.

- An approaching east Pacific weather disturbance will dry out the
region, while bringing increasingly breezy conditions through the
weekend.

- Strong high pressure should build back into the region by the
middle of next week with increased odds of major HeatRisk impacting
the area.

&&

.SHORT TERM /Today through Friday/...
Early morning objective analysis suggests a consolidating mid/upper
level low situated over central Arizona with a retrograding, pinched
ridge over western Nevada. The westerly flow behind this low
pressure system has eroded moisture through SE California, however a
pool of 8-11 g/kg boundary layer mixing ratios still hovers over
southern Arizona. DCape values in excess of 1500 J/kg promoted
numerous outflow boundaries last evening, and just enough to locally
breach notable inhibition. Further scouring of moisture over Arizona
will take place today with mixing ratios falling closer to 7-9 g/kg
while the mid/upper level pattern becomes more anti-cyclonic and
subsident. Deep, moist convection should become relegated to higher
terrain areas of eastern Arizona, potentially clipping far eastern
Gila County. Otherwise, H5 heights will actually change very little
over the next 48 hours, however modest cooling in the H8-H7 layer
and wider diurnal spreads due to markedly drier air surging into the
region will result in temperatures retreating very near the daily
normals. With mixing ratios tumbling closer to 3-4 g/kg Friday, even
mountain cumulus development will be completely eliminated.

&&

.LONG TERM /Saturday through Wednesday/...
Ensemble member agreement remains very good through early next week
advertising East Pacific troughing migrating inland and deamplifying
over the Rockies. This evolution will create a dry zonal flow
pattern with mixing ratios falling very close to 2-3 g/kg and total
column PWATs as low as 0.25" though Monday. Forecast confidence is
very good that temperatures will hover near normal through the
weekend before beginning a warming trend next week as subtropical
ridging builds back north. Modest height falls combined with
seasonably deep mixing depths will promote repeated chances of gusty
afternoon winds, and combined with the incoming dry airmass and
receptive, dessicated fuels, fire danger will become quite elevated.

There is growing confidence among operational and NAEFS members that
subtropical ridging will continue strengthening towards the SW Conus
during the middle of next week as mean longwave troughing is
established over the eastern US. H5 heights should easily rebound
over 594dm with the anti-cyclone center becoming positioned either
directly over Arizona or towards the international border. GEFS
membership generally keeps H5 heights under 595dm while some of the
more extreme CMC and EPS members are highlighting H5 heights 597-
600dm during the midweek period. Regardless, numerical guidance
means strongly suggest lower elevation high temperatures by the
middle of next week flirting with 115F, and it would not be
unexpected for reading to breach this level. As a result, widespread
major HeatRisk and extreme heat appears increasingly likely during
at least the Wed-Fri time frame next week.

&&

.AVIATION...Updated at 1748Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation concerns are expected through the TAF period.
Current southerly winds will shift westerly for the afternoon
where another round of gusty conditions are expected between
22-03Z with speeds between 15-20 kts. Mostly clear skies today
with the FEW higher clouds expected to clear up by the afternoon.


Southeast California/Southwest Arizona including KIPL and KBLH:
Main aviation concern today will be gusty conditions, especially
at KIPL, with speeds expected between 20-25kts. At KIPL, generally
westerly winds will prevail while at KBLH, winds will generally
fluctuate between the south to southwest. Winds at KIPL may be
enough to reduced visibilities near 6SM but confidence is too low
at this time to include in this TAF package. Otherwise clear
skies are expected through the period.

&&

.FIRE WEATHER...
A pronounced drying trend will continue across the region the
remainder of the week with terrain induced showers/storms exiting
into far eastern Arizona and New Mexico. Temperatures will cool
closer to normal the rest of the week, however the much drier
airmass will allow minimum humidity levels primarily in a 10-20%
range to deteriorate into widespread single digits over the weekend
and early next week. Correspondingly, overnight recovery will fall
into a poor to fair 15-40% range. Winds will frequently become gusty
the remainder of the week yielding a widespread elevated fire
danger, however at this time, speeds appear to remain below critical
thresholds. By the middle of next week, temperatures will warm
markedly with minimum humidity levels hovering around 10-15% and
continued gusty winds yielding dangerous conditions for any ongoing
wildfires.

&&

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

$$

SHORT TERM...18
LONG TERM...18
AVIATION...Ryan
FIRE WEATHER...18

NWS Phoenix (PSR) Office