449
FXUS65 KPSR 052316
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
415 PM MST Sat Apr 5 2025

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
Gradual warming and drying conditions will continue through the
weekend as the slow moving low pressure system exits the region.
For today, there will still be some lingering light shower chances
mainly east of Phoenix, before shower chances come to an end later
in the evening. High pressure will then spread into the region
Sunday into early next week allowing a quick warm up and
temperatures reaching to above normal readings starting Monday. The
high pressure system will strengthen further through the middle of
next week resulting in highs steadily climb well into the 90s to
around 100 degrees across the lower deserts, peaking on Thursday and
Friday.

&&

.DISCUSSION...
The slow moving upper level trough over our region is finally
shifting through the southeast of our CWA with the low centered over
Northern Mexico. This progress will continue through the day today,
but the western fringes of the trough will remain across Arizona
into tonight. As with the past couple of days, we can expect some
additional afternoon light shower development within the cold core
mainly lingering across far eastern Arizona, from Fountain Hills to
Globe/Miami areas. Impacts today will again be minimal with little
measurable rainfall over the higher terrain and likely only a few
sprinkles over northern portions of the Metro and eastern portions
of the Phoenix Metro. Gusty conditions are expected to relax by this
evening, especially out West, and continue to lighten considerably
throughout next week.

Once the trough fully exits the region on Sunday, a ridge will
quickly build in from the southwest raising H5 heights to between
577-580dm by Monday, or into the upper end of normal for this time
of year. As the ridge builds in and the atmosphere dries out, we can
expect generally clear skies starting Sunday with temperatures
briefly back into the normal range. The warming trend will be quite
steady through the first half of next week as the ridge continues to
strengthen over our region. This will lead to temperatures warming
on average by around 5 degrees per day through next Thursday as we
see highs breaking 90 degrees by Tuesday and then well into the 90s
during the latter half of the week. Guidance continues to favor H5
heights peaking at around 589dm across our region on Thursday, which
would be near records for the climatological period. The hottest
temperatures are still forecast to be on Thursday and Friday with
NBM forecast highs into the upper 90s to around 100 degrees with at
least a 30-60% probability for seeing record highs of above 100
degrees. This will likely introduce some localized Moderate HeatRisk
late next week before we eventually see some cooling next weekend.
Ensembles are still mostly showing potential for a Pacific trough
moving near or into the Western U.S. next weekend and if this
occurs, it would either flatten out the ridge over our region or
eject it to the east prompting the cooling trend.

&&

.AVIATION...Updated at 2315Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Low confidence in timing of wind shifts this evening remains the
primary forecast challenge through Sunday afternoon as scattered
decks quickly clear with sunset. SHRA north and east of terminals
are less expansive than previous days with more limited impact on
wind direction. Thus, there is low confidence whether abrupt wind
shifts will enter the Phoenix airspace, but rather resulting in an
earlier than usual switch to E/NE this evening. Otherwise, far more
tranquil conditions will exist Sunday with more typical wind
behavior.


Southeast California/Southwest Arizona including KIPL and KBLH:
Gusty winds this evening will be the only weather issue through
Sunday afternoon under clear skies. Stronger N/NW gusts should abate
quickly after sunset with a tendency for directions to back towards
a W/NW component overnight. Light and variable winds should become
more common Sunday afternoon.

&&

.FIRE WEATHER...
Isolated to widely scattered showers will again be possible mainly
across the high terrain of southcentral AZ this afternoon/early
evening, but wetting rain chances are near zero. Winds are expected
to increase out of the north across the western district today where
gusts could reach 30-35 mph at times. Much calmer and drier
conditions are anticipated starting on Sunday with Min RHs falling
to around 10-15% area-wide and trending below 10% on Tuesday through
Friday. Max RH values are expected to be below 40% and as low as 25%
each consecutive night. Temperatures will also quickly warm up over
the next several days with readings reaching into the normal range
by Sunday. High pressure will build over the region during the first
half of next week resulting in the return of above normal
temperatures and seasonably dry conditions.

&&

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

&&

$$

DISCUSSION...Kuhlman/Ryan
AVIATION...18
FIRE WEATHER...Kuhlman/Ryan