056
FXUS65 KPSR 122320
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
420 PM MST Thu Jun 12 2025

.UPDATE...Updated 00z Aviation Discussion.

&&

.KEY MESSAGES...

- Dry conditions with temperatures remaining 3 to 5 degrees above
  average across the region through Friday.

- A ridge of high pressure will strengthen over the Desert
  Southwest this weekend, resulting in very hot temperatures with
  highs topping out near record levels.

- An Extreme Heat Warning is now in effect from Saturday morning
  through Monday evening for high temperatures ranging from 106
  to 114 degrees across the lower deserts.

&&

.DISCUSSION...
Latest mid-lvl wv imagery and 500 mb streamline analysis depicts a
ridge of high pressure centered just off the western coast of the
Baja California. 500 mb hghts over our forecast area continue to
remain around 588-590 dam which is slightly above seasonal norms.
These positive hght anomalies will promote above normal temperatures
again this afternoon with highs topping out between 104-109 degrees
across the lower deserts. Very similar conditions are anticipated on
Friday as the ridge of high pressure migrates ewd into N MX. 500 mb
hghts will not change much on Friday with 850 mb temps nearly
identical to today which will result in highs again topping out
around 3 to 5 degrees above average.

The aforementioned ridge of high pressure will become the
predominant feature over the Desert Southwest by this weekend
resulting in the hottest temperatures of the year thus far. On
Saturday, we will see a 594 dam high begin to take shape over the
AZ/NM border, resulting in increasing hghts/thicknesses over the
region. 850 mb temperatures will increase further to around 30C
across southcentral AZ on Saturday afternoon which would equate to
highs around 110F. The average first 110 degree day at Sky Harbor
is June 11th so we will not be far off from the normal date if we
hit this mark by Saturday. Ridging aloft will continue to strengthen
and amplify on Sunday, boosting temperatures to near record levels
across our region. The latest NBM has trended up again with high
temperatures on Sunday ranging from 110-114F across the lower
deserts. This will result in areas of Major HeatRisk extending
from southeast CA through southcentral AZ. The record high at
Phoenix Sky Harbor on Sunday is 115F and there is currently a 45%
chance that the record will be tied. There are signs in the
ensembles that the ridge will begin to weaken slightly on Monday,
however there is still a good probability (50-70%) that we will
continue to see highs topping out over 110F with pockets of Major
HeatRisk across our major population centers. Due to the near
record heat couple with it being Father`s Day weekend, we have
decided to upgrade the Extreme Heat Watch to a Warning which is
in effect beginning Saturday morning and ending on Monday evening.

.PREVIOUS DISCUSSION...
Models are still mostly in agreement showing a modest cool down
by Tuesday as a majority of clusters show a dry trough moving into
our region from the west. Despite the increasing forecast
confidence in this trough, there is still some uncertainty with
its strength and how much it may drop our temperatures. NBM highs
are showing a slight drop in temperatures to around 105-109
degrees Tuesday afternoon before already starting to trend back
up Wednesday into Thursday. This cool down will likely just be a
brief dip in temperatures as guidance favors the ridge to quickly
build back into our region late next week with 110 degree
temperatures likely returning for at least some locations. The
weather pattern over at least the next 7 days will continue to
promote dry conditions, but there looks to be some potential for
increasing moisture returning as early as next weekend.

&&

.AVIATION...Updated at 2320Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT;
Southeast California/Southwest Arizona including KIPL and KBLH:

No major aviation weather concerns will exist through the TAF
period. Winds will continue to follow their typical diurnal
tendencies with afternoon gusts continuing into this evening.
Winds speeds will relax by 04Z in the Metro before the E`rly shift
around 08-10Z with speeds aob 10kts for the overnight period. At
KPHX before the W`rly afternoon shift tomorrow there looks to be
a period of S`rly winds. Out west, at KIPL mostly SE winds with a
short W`rly component, aob 10kts. At KBLH gusty conditions
(~20kts) will continue into late tonight but will return tomorrow
afternoon. FEW-SCT high highs will persist at all terminals.

&&

.FIRE WEATHER...
Little to no change in the weather pattern through Friday will
keep temperatures 3-5 degrees above normal and humidities
seasonably low. Winds will follow typical diurnal tendencies
(upslope and downvalley) with periods of modest afternoon upslope
breeziness (gusts to around 20 mph at times). Minimum afternoon
humidity will bottom out between 8-12% Friday and 5-10% beginning
Saturday, with poor to fair overnight recovery mainly between
20-35% region-wide. Temperatures are forecast to reach near record
levels through the upcoming weekend with afternoon highs of 110
degrees or hotter as early as Saturday. By early next week, the
arrival of a dry weather system may result in an uptick in winds
across much of the area. These gusty winds combined with dry fuels
and very low humidity could result in elevated fire weather
concerns.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning from 10 AM Saturday to 8 PM MST Monday for
     AZZ530>544-546>556-559>562.

CA...Extreme Heat Warning from 10 AM Saturday to 8 PM PDT Monday for
     CAZ562>567-569-570.

&&

$$

DISCUSSION...Salerno
PREVIOUS DISCUSSION...Kuhlman
AVIATION...Ryan
FIRE WEATHER...Salerno/Kuhlman