309
FXUS66 KSGX 261107
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
343 AM PDT Thu Sep 26 2024

.SYNOPSIS...
There will be slow warming through Saturday, slight cooling on
Sunday, then warming for Monday and Tuesday followed by gradual
cooling for the latter half of next week. Saturday is expected to
be the warmest day for the deserts with Tuesday of next week the
warmest day for the coast and valleys. Night and morning coastal
low clouds will continue to spread inland into portions of the
western valleys late each night. A cooling trend is expected for
the latter half of next week.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

.SHORT TERM (Today through Saturday)...
There will be a warming trend through Saturday with the greater
warming for the coast and valleys today and with the warming for
the mountains and deserts mostly on Friday and Saturday. With the
warming, high temperatures on Saturday will range from a few
degrees below average near the coast to 10 to 15 degrees above
average, mostly in the 90s for the inland valleys and 108 to 114
for the lower deserts.

The Excessive Heat Warning will continue for the lower deserts
for Friday and Saturday. Night and morning coastal low clouds will
continue to spread into the western valleys late each night.
Through Saturday, high temperatures for a few locations each day
could be near record levels for the lower deserts. Yesterday, Palm
Springs tied the existing record high temperature of 114 set in
1947 with that high of 114 exceeding the 99th percentile of the
NBM.

&&

.LONG TERM (Sunday through Wednesday)...
A weak low pressure system is expected to move to near the
California coast on Sunday with not much change in high temperatures
for the coast and western valleys with the mountains and deserts a
few degrees cooler. Low pressure will weaken across southern
California on Monday and Tuesday with a warming trend with high
temperatures on Tuesday ranging from a few degrees above average
near the coast to 12 to 18 degrees above average for the mountains
and deserts. High temperatures on Tuesday will range from the mid
70s near the coast to the mid 90s to 102 for the inland valleys with
108 to 114 for the lower deserts.

By Friday of next week, there are large differences among the
deterministic runs of the ECMWF, GFS, and Canadian models with
the placement and amplitude of a low pressure system across the
eastern Pacific and West Coast, however with cluster analysis
showing a similar distribution of solutions for the ensemble
members of each ensemble system. While a cooling trend is expected
for the latter half of next week, there is greater spread with
the timing and amount of the cooling.

&&

.AVIATION...
260930Z...Coasts/Valleys...Low clouds will continue to develop and
extend into portions of the valleys through 14Z. Bases will be 900-
1200 feet MSL with tops to 1700 feet. Isold vis reduced 0-5SM on
higher coastal terrain and in valleys. Scatter out 16-19Z, but with
only partial or intermittent clearing at the immediate coast in San
Diego County. Low clouds will redevelop and push inland after 00Z in
San Diego County and after 06Z in Orange County tonight, extending
not as far into valleys overnight into Friday. Bases/vis will be
slightly lower.

Mountains/Deserts...Clear today and tonight.

&&

.MARINE...No hazardous marine conditions are expected through
Monday.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning from 10 AM Friday to 8 PM PDT Saturday
     for Coachella Valley-San Diego County Deserts.

PZ...None.

&&

$$

PUBLIC...17
AVIATION/MARINE...MM