National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS65 KPSR 192328
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
428 PM MST Fri Apr 19 2024

.UPDATE...Updated 00z Aviation Discussion.

&&

.SYNOPSIS...
Hot, above normal, temperatures and mostly sunny skies will
persist through early next week. Daily high temperatures in the
90s are expected across the lower deserts, with the hottest days
on Sunday and Monday, will lead to widespread minor heat-related
health risks. A weak passing disturbance this evening will lead to
breezy to locally windy conditions in southern California.
Otherwise, winds will be light through this weekend. A weather
system later next week is forecast to regionally cool temperatures
back down and increase breezes.

&&

.DISCUSSION...
Above normal temperatures, leading to widespread Minor HeatRisk,
will continue daily through early next week, with lower desert high
temperatures reaching into the 90s most days. There is a weak, low-
amplitude, shortwave trough seen in WV satellite this afternoon,
pushing eastward into SoCal. Given the low amplitude, little if any
change to the temperatures are expected. High temperatures today
will be very similar to yesterday, with most areas reaching the
upper-80s to lower-90s, as there has been very little change in the
lower tropospheric thermal profile over the past 24 hours. Saturday
will also be similar, despite the passage of the shortwave.
Following the shortwave, heading into late this weekend and early
next week, stronger positive height anomalies will build over the
Southwest with a transient ridge of high pressure passing through
the region. This will allow temperatures to warm another few
degrees, with lower desert highs pushing into the middle to upper
90s Sunday and Monday. The NBM spread continues to support a
~10-30% probability for 100+ F highs in many of the lower desert
valley locations Sunday-Monday, including Phoenix, with very
localized higher probabilities in some of the typical hottest
spots, like Phoenix Sky Harbor and on the west side of Salton Sea.

The one sensible weather impact the weak shortwave moving in today
will bring is an increase in winds in Southern CA, primarily late
this afternoon through at least early tonight. Sundowner winds
into the Imperial Valley could briefly peak up to 30-35 mph, with
a 10% probability of exceeding 35 mph. Winds will be highest in
the southwest corner of Imperial County, along I-8, where wind
gusts are expected to exceed 40 mph (100% HREF probability) and
could briefly exceed 50 mph. As a result, a Wind Advisory has been
issued for that southwest corner.

Model ensemble guidance is supporting a Pacific trough,
digging south in the eastern Pacific early next week before
slowly transitioning inland into the Western CONUS during the
latter half of next week. There is still a decent amount of
uncertainty with this next weather system, especially with the
depth of the trough, but it should at least lead to a gradual
cool down next week. The latest NBM suggests highs will fall back
into the 80s by the end of next week. The negative height
anomalies across the West may then persist for several days with
reinforcing shortwaves. Any potential for rain still looks very
low at this time, less than 10% across the southern lower deserts.
The Desert Southwest is heading into the dry season and fire
weather season. Climatologically it becomes difficult to see much
rainfall, even if the NBM may be suggesting chances in the
forecast. As with any spring weather system, breezy conditions can
typically be counted on.

&&

.AVIATION...Updated at 1750Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Winds will follow their typical diurnal patterns. Wind speeds
will generally be aob 10 kt through the period. Skies will remain
mostly clear through the period.

Southeast California/Southwest Arizona including KIPL and KBLH:

Winds will be westerly at KIPL, with wind speeds picking up this
evening. Winds will gust 25-30 kt during the evening hours and
around 15 kt for the overnight hours. Wind speeds will further
calm to aob 6 kt by the early morning hours and through the
remainder of the period. At KBLH, current light and variable winds
will become S/SW`rly this evening with occasional gusts of 15-20
kt possible. Winds will then become light and variable again late
this evening for the remainder of the period. Skies will remain
most clear.

&&

.FIRE WEATHER...
Dry conditions and above normal temperatures will persist through
the coming weekend as lower desert highs top out each day mostly
in the low to mid 90s. Winds today will pick up during the
afternoon with gusts to around 20 mph in most locations. Winds
Saturday will continue to follow diurnal daily trends with any
afternoon breeziness in the mid teens. Min RHs will continue to
fall into the 5-15% range each day, while overnight Max RHs
mostly stay in a 25-45% range for most places. A cooling trend
is forecast by the latter half of next week eventually bringing
temperatures back down to normal or below normal late next week.
Breezy to locally windy conditions are also expected for much of
next week with daily afternoon gusts commonly reaching to between
20-30 mph. Humidities are likely to stay quite low next week with
daily MinRHs of 10-15% through the middle of the week before some
improvement is forecast to around 20-25% late week as temperatures
cool down.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 5 AM PDT Saturday for CAZ562.

&&

$$

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