965
FXUS65 KPSR 191131
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
431 AM MST Thu Jun 19 2025

.UPDATE...Updated Aviation Discussion...

&&

.KEY MESSAGES...

- Extreme Heat Warnings remain in effect across south-central
Arizona through tomorrow as lower desert high temperatures range
from 108 to 116 degrees.

- Very dry and increasing breezy conditions will lead to elevated to
locally critical fire weather conditions across higher terrain areas
of south-central Arizona on Friday and Saturday.

- A cooling trend over the weekend will result in near normal
temperatures Saturday and slightly below normal temperatures
starting Sunday and lasting through the first half of next week.

&&

.DISCUSSION...
Current water vapor satellite imagery and objective analysis show
high pressure just east of our area with an abundance of dry air
overhead. High pressure will continue to build over our region
today, with the center of the high pressure straddling the AZ-NM
state line. The high pressure will max out this afternoon, around
592-594 dm, before weakening tomorrow. With the high pressure at
its max this afternoon, today will be the hottest day of the week.
The NBM gives Phoenix a 20-30% chance of at least tying the daily
record high temperature of 118 degrees set in 2016 and 2017. With
the high pressure weakening tomorrow, temperatures are forecasted
to be 3-6 degrees cooler than today, which is still several
degrees above normal. For today, widespread Major HeatRisk exits
across south- central AZ with widespread Moderate HeatRisk across
the western portion of the CWA. With cooling temperatures
tomorrow, the HeatRisk will decrease to widespread Moderate across
the entire CWA, with some pockets of Minor HeatRisk. Although
HeatRisk will decrease tomorrow along with afternoon high
temperatures, morning lows will still be on the warmer side with
lows ranging from the mid-70s to mid-80s. Therefore, the Extreme
Heat Warning remains in place across south-central Arizona through
tomorrow. Much of the population will be susceptible to the
extreme temperatures, especially this afternoon, so make sure to
limit your time outdoors (especially between 10am and 6pm) and
make sure to drink plenty of water.

The pattern will begin to shift tomorrow as the high pressure starts
to weaken, as mentioned above. This weekend the high pressure will
continue to weaken and negative height anomalies move into the
region from the NW, associated with a strong, anomalous Pacific
trough amplifying over western CONUS. Very dry conditions (minRH`s
of 5-10% on Friday and 10-15% on Saturday) in combination with
elevated afternoon winds (with gusts up to 30 mph) will lead to
elevated to locally critical fire weather conditions on Friday and
Saturday for the higher terrain areas to the north and east of
Phoenix. Elevated wind gusts (25-30 mph) will continue on Sunday
afternoon for the higher terrain areas to the north and east of
Phoenix. However, a slight increase in moisture (minRHs of 15-20%)
and further cooling of temperatures (~5-8 degrees cooler than
Friday) will lower fire weather concerns.

The aforementioned Pacific trough will bring much welcomed cooler
temperatures to the region this weekend and continuing into the
first half of next week. Temperatures will cool to near normal on
Saturday and fall slightly below normal Sunday. These slightly below
normal temperatures will continue into next week. High temperatures
during this timeframe will fall into the lower 100s across the lower
deserts and into the 90s across the higher terrain. During this
timeframe high pressure will build across eastern CONUS and will
keep troughing over western CONUS through the middle of next week.
The main discrepancy between the global ensemble models continues
to be how quickly the trough will dissipate and move eastward.

Global ensemble members continue to show a battle between dry air
and more moist monsoon moisture over our CWA early next week.
Models have shifted this slightly to be more of a Tuesday-
Wednesday timeframe rather than Monday-Tuesday. The aforementioned
Pacific trough will work to keep dry air and southwesterly flow in
place, at least over SE CA and western AZ. But, some deep
moisture over northern Mexico looks to make its way into SE AZ.
This moisture, in combination with upper-level support, could lead
to some isolated to scattered thunderstorms. This supports some
low end chances for showers and storms as far north as the White
Mountains and into Gila County.

&&

.AVIATION...Updated at 1130Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major aviation concerns are expected during the TAF period
under clear skies. East southeast winds through mid morning will
drift more out of the south late morning before shifting out of
the west southwest early afternoon. Area terminals are likely to
see gusts up to around 20 kts at times this afternoon/early
evening. After winds diminish later this evening, expect winds to
eventually turn back to the east between 07-10Z.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns are expected over the next 24 hours
under clear skies. For KIPL, southeast winds through early
afternoon will turn out of the southwest and become gusty up to 25
kts during the late afternoon and early evening. Southerly winds
will prevail at KBLH with afternoon gusts to around 20 kts.

&&

.FIRE WEATHER...
Hot and dry conditions will continue today with winds following
their typical diurnal patterns with some occasional afternoon
breeziness with gusts into the upper teens to low 20s.
Temperatures will remain above normal tomorrow with highs around
105-110 degrees across the lower deserts. Continued dry
conditions, with winds increasing even more tomorrow and into this
weekend. This will lead to elevated to locally critical fire
weather conditions across the eastern district higher terrain
tomorrow and Saturday. On Friday, very dry conditions will persist
(min RH`s 5-10%), with afternoon winds gusting 20-25 mph. On
Saturday, wind gusts will increase to 25-30 mph but min RH`s will
rise to around 10-15% as temperatures cool. Elevated fire weather
concerns will subside going into early next week as winds weaken
and temperatures continue to cool to around or just below normal
while also increasing MinRHs into the teens.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Friday for AZZ534-537>544-
     546>556-559>562.

CA...None.
&&

$$

DISCUSSION...Berislavich
AVIATION...Kuhlman
FIRE WEATHER...Berislavich/Young