National Weather Service Raw Text Product

057 
FXUS65 KPSR 160908
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
208 AM MST Mon Jun 16 2025

.KEY MESSAGES...

- Hot and dry weather is forecast throughout the entire week with
  the hottest days expected to be today and Thursday.

- An Extreme Heat Warning is currently in effect through this
  evening for high temperatures ranging from 109 to 114 degrees 
  across the lower deserts.

- Widespread Moderate HeatRisk will be seen on Tuesday and
  Wednesday before areas of Major HeatRisk are likely for 
  Thursday.

&&
  
.DISCUSSION...
The extreme heat conditions will continue today with the sub-
tropical ridge still dominant over the Desert Southwest. H5
heights of 592-594dm are forecast to remain in place through this
afternoon with highs easily topping 110 degrees this afternoon for
most lower desert locations, to as high as 115 degrees in a few
spots. Fortunately, a weak shortwave trough is now nearing Oregon
and northern California with guidance tracking the system across 
the Great Basin and northern portions of the Desert Southwest 
tonight into early Tuesday. This system will somewhat push the 
sub-tropical ridge to the south of our region, but we are only 
looking at a short reprieve from the worst of the heat as H5 
heights only briefly drop to between 590-592dm. We are expecting
to see a few degree drop in daytime highs on Tuesday, but some 
locations may still see 110 degrees, or still around 5 degrees 
above normal. 

After the weak trough exits well to the east Tuesday night into
Wednesday, the ridge is forecast to begin rebuilding back over the
Southwestern U.S. with H5 heights back to between 592-594dm by
Thursday. NBM forecast temperature trends for the latter half of
the week are still inching upwards with most of the lower deserts
now likely to reach 110 degrees starting Wednesday and with some
potential for the hottest locations to see 115 degrees on
Thursday. The areal coverage of Major HeatRisk has also expanded,
mainly on Thursday, with more than 50% of south-central Arizona
covered. It seems likely additional Extreme Heat Watches/Warnings
will be needed later this week. However, this next potential 
period of extreme heat should not last long as guidance continues
to favor a large Pacific trough pushing into the Western U.S.
Friday into Saturday.

The timing and the depth of this trough will likely determine 
whether Friday's temperatures will be near Major HeatRisk 
thresholds, but by Saturday temperatures should be dropping below 
110 degrees. This trough should continue to keep lower heights 
over our region into early next week with temperatures eventually
dropping to around or even a few degrees below normals. Models 
have been trending toward a stronger trough as well as a slower 
progression, likely keeping dry air over most if not all of our 
region. Modest monsoon moisture over Mexico still tries to push 
northward into far southeast Arizona by early next week, but with 
the trough providing southwesterly dry flow this moisture will 
have a hard time gaining any foothold within our region. 

&&

.AVIATION...Updated at 0520Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No aviation weather concerns will exist through the TAF period
under clear skies. Winds will follow typical diurnal patterns,
with speeds remaining generally AOB 12 kts through tomorrow
afternoon and periods of variability during transition periods. An
earlier than usual switch to west winds is expected by late Monday
morning, with gusts to 15-20 kts becoming common during the
afternoon hours tomorrow afternoon, with gustiness subsiding
during the evening hours.

Southeast California/Southwest Arizona including KIPL and KBLH: 
No aviation weather concerns will exist through tomorrow afternoon
under clear skies. Winds will generally follow familiar patterns,
favoring S/SE this afternoon into the early evening before
shifting SW/W at both terminals. Speeds should remain mostly AOB
10 kts except during the late afternoon and early evening hours,
as a period of gusty SW/W winds 20-25 kts expected to develop at
both terminals before subsiding going into the overnight hours.

&&

.FIRE WEATHER...
Hot and dry conditions with some afternoon breeziness will
continue early this week. Temperatures will remain above normal 
with highs near or above 110 degrees each day across the lower 
deserts. Wind patterns will continue to follow diurnal trends 
(upslope and downvalley) with afternoon gusts up to around 20-25 
mph, particularly across the higher terrain east of Phoenix. 
Humidities will stay low with MinRHs between 5-10% and overnight 
MaxRHs only between 15-30%. Afternoon gusts combined with the dry 
conditions may lead to some elevated fire weather conditions, 
especially across the higher terrain east of Phoenix. High 
pressure will remain the dominant weather feature through the rest
of the week with temperatures remaining above normal through at 
least Friday and afternoon MinRHs likely staying between 5-10% 
each day.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST this evening for AZZ530>544-
     546>556-559>562.

CA...Extreme Heat Warning until 8 PM PDT this evening for CAZ562>567-
     569-570.

&&

$$

DISCUSSION...Kuhlman
AVIATION...Young/Whittock
FIRE WEATHER...Smith/Kuhlman