186
FXUS65 KPSR 232300
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
400 PM MST Tue Jun 23 2026

.UPDATE...00Z Aviation Discussion

&&

.KEY MESSAGES...

- Temperatures between 5 and 10 degrees above normal will result
  in widespread Moderate Heat Risk with localized Major Heat Risk
  through Thursday.

- Extreme Heat Warnings will remain in effect for portions of the
  area through Thursday.

- Marginally better moisture levels through the middle of the week
  could lead to isolated showers and virga, with better chances
  for showers and storms over Northern Arizona high terrain.

- Drying conditions and a regional increase in winds late this
  week will result in areas of critical fire weather, and so Fire
  Weather Watches have been issued for the Lower Colorado River
  Valley and Tonto National Forest on Friday and Saturday.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
Local conditions through Thursday will be heavily influenced by
the subtropical high currently centered near El Paso according to
early afternoon water vapor satellite imagery and 500 mb RAP
analysis. Heights aloft have increased over the forecast area as
this high amplifies/strengthens, with analyzed H5 heights up
around 595-597 dam, between the 97th-99th percentile of
climatology. Meanwhile, a period of southerly flow imposed by the
high has imported marginal levels of midlevel moisture into the
area. The 12Z KPSR sounding indicated PWATs around 0.95", up from
0.41" only 24 hours ago. In Yuma, a sounding taken at 12Z this
morning showed PWAT around 1" and increased to around 1.2" by 18Z
in a followup sounding. However, the bulk of this moisture is in a
relatively shallow layer above 600 mb, and low level mixing
ratios below 8 g/kg coupled with poor lapse rates/instability
measures preclude chances for deep moist convection over the
forecast area. A few disturbance may rotate through the area along
the periphery of the subtropical high, increasing midlevel
moisture and providing a transient lifting mechanism for isolated
showers/virga and maybe even releasing some elevated instability
at times, resulting in some localized rumbles of thunder. One of
these disturbances can be seen in the midlevel water vapor imagery
moving north northwestward over the Gulf of California and will
be overhead late this afternoon into the evening.

The levels of moisture forecast in the short term with this
period of southerly flow will be supportive of Northern Arizona
high terrain thunderstorms, especially by Wednesday. From
experience, storms will not form or survive over lower elevations,
away from prominent terrain features. The greatest coverage of
high terrain showers and thunderstorms will likely occur
Wednesday, coincident with the best available moisture, then flow
turns southwesterly aloft and increases as northern stream
cyclonic curvature enters the Northwest US. This will begin a
drying trend from west to east across the area through the latter
half of the week.

Temperatures will likely peak Wednesday, as lower level thermal
profiles will have had time to respond to the increased heights
aloft. However, some amount of cloud cover associated with the
increased midlevel moisture complicates the forecast, and lower
desert highs have trended down a degree or two in some places.
Regardless, much warmer overnight lows (80s across the typically
warmer spots) and afternoon highs near or in excess of 110F to as
much as 113F-114F will result in areas of Major HeatRisk,
particularly for urban areas like the Phoenix Metro. Drying
conditions and less cloud cover Thursday should result in
similarly hot conditions to that of Wednesday, but decreasing
heights aloft will preclude the possibility of temperatures
warming any further. Thus, Extreme Heat Warnings will be in effect
Wednesday and Thursday for portions of the area.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Global ensemble members remain in pretty good agreement on the
overall synoptic patter for the end of the week and into the
beginning of next week. The aforementioned upper level trough will
push further into our region by the end of the workweek and this
weekend. This trough will linger over our area into the beginning of
next week. This trough feature will lead to lower heights aloft and
as a result cooling temperatures. Temperatures will cool heading
into the weekend before leveling out by the end of the weekend and
beginning of next week. Temperatures on Friday and Saturday are
still forecast to be around 2-5 degrees above normal for this
time of year. Then by the end of the weekend and beginning of next
week temperatures are forecast to fall slightly (2-4 degrees)
below normal. Afternoon high temperatures are currently forecast
to be in upper 90s to around 105 degrees across the lower deserts
and in the 90s across the higher terrain areas for the end of the
weekend and beginning of next week. Morning low temperatures will
also be decreasing and are forecast to fall into the 70s to upper
60s across the lower deserts and in the 60s across the higher
terrain areas. As a result of these decreasing temperatures,
HeatRisk will also be decreasing across the region. In fact, with
temperatures forecast to fall below normal, HeatRisk will fall
into the Minor category across the entire region.

In addition to the cooler temperatures this trough will also bring
in much drier conditions along with increasing winds. These drier
conditions in combination with increasing winds will result in
increasing fire danger. Thus, a Fire Weather Watch has been
issued for the Lower Colorado River Valley and Tonto National
Forest Foothills/Southern Gila County on Friday and Saturday.

&&

.AVIATION...Updated at 2300Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation concerns are expected during the TAF period
under increasing mid-level cloud cover. Winds will continue to
favor diurnal trends with occasional gusts during the afternoon
and evening hours. Much like the previous night, confidence
regarding a full E`rly shift at KPHX is low, with a few hours of
VRB conditions looking more likely at this time. Regardless of
what comes to fruition, W`rly flow should become established a bit
earlier than normal on Wednesday. Some virga around the terminal
cannot be ruled out this evening, but chances of SHRA at the
terminals is too low to include in the TAFs.

Southeast California/Southwest Arizona including KIPL and KBLH:
The potential for some virga and erratic winds this evening and
tonight will be the main aviation concern. However, chances for
SHRA in the vicinity of the terminals is less than 10% so any
mention of rain has been excluded from the TAFs. Outside of any
erratic winds, typical diurnal trends will be favored at each
site, with flow fluctuating between SE and W at KIPL, and
generally S`rly flow at KBLH. Windows of VRB to calm conditions
can be expected during the overnight hours.

&&

.FIRE WEATHER...
Locally elevated fire weather conditions due to low humidity and
afternoon breeziness will continue through the middle of the
week. Afternoon minimum humidities will increase to around 15%
areawide Wednesday before drying out again through the rest of the
week and into the weekend. Poor to fair overnight recoveries
between 20-40% tonight and Wednesday night will also deteriorate
through the rest of the week and this weekend. Temperatures will
remain in an above normal category much of the week with lower
desert highs topping 110 degrees at least through Thursday, and
overnight lows will offer little relief, mostly in the 80s for
the lower deserts. Winds will remain generally terrain driven
through the middle of the week with upslope/upvalley gusts between
20-25 mph during the latter half of the afternoon into the early
evening. Areas of critical fire weather conditions look likely by
Friday and into this weekend as southwesterly winds increase
across the region. A Fire Weather Watch has been issued for the
Lower Colorado River Valley and Tonto NF/Southern Gila County
zones Friday-Saturday.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning from 10 AM Wednesday to 8 PM MST Thursday
     for AZZ530-532-533-537-540-542>544-546-548-550-551.

     Fire Weather Watch from Friday morning through Saturday evening
     for AZZ131-133.

     Extreme Heat Warning until 8 PM MST Wednesday for AZZ560.

CA...Extreme Heat Warning from 10 AM Wednesday to 8 PM PDT Thursday
     for CAZ562-566-567-569.

     Fire Weather Watch from Friday morning through Saturday evening
     for CAZ231.

&&

$$

SHORT TERM...Whittock
LONG TERM...Berislavich/Whittock
AVIATION...RW
FIRE WEATHER...Whittock/Berislavich

NWS Phoenix (PSR) Office