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Area Forecast Discussion (AFD)

Issued by San Diego, CA (SGX)

                            
000
FXUS66 KSGX 251643 CCA
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
945 AM PDT Sun Aug 25 2019

.SYNOPSIS...
Unusually strong high pressure over the western states is expected 
to continue to slowly strengthen over the next week. This should 
keep afternoon high temperatures above normal for most areas, but 
closer to normal along the immediate coastline and in the deserts. 
Some night and morning low clouds and fog can be expected near the 
coast, with mainly just afternoon clouds over the mountains and 
deserts. There is a slight chance of showers and thunderstorms 
southern mountain areas today however, but no showers or 
thunderstorms are forecast for any of the SoCal regions after today. 

&&

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

Stronger than normal upper level high pressure continues to threaten 
the southwest as heights build over the region. This should keep 
afternoon high temperatures above average into at least next 
weekend, except at the immediate coastal regions and possibly the 
Coachella Valley. There should still be some night and morning low 
clouds at times near the coastline. Coachella Valley high 
temperatures should be moderated, at least for a few days, by a 
surge of cooler, low level moist air surging in from the gulf of 
California. 

A peek at the ensemble data and local WRF shows very little change 
in the upper level pattern and in the mid-upper level moisture for 
at least a week. Some remnant mid level moisture from decaying 
Tropical Storm Ivo will be around for the next couple of days with a 
slight chance of thunderstorms in the San Diego County Mountains, 
but only interesting looking mid and high clouds for the rest of the 
area. 

Heights continue to very slowly climb through Tuesday, and 
temperatures could  peak in the lower deserts and The Coachella 
Valley around 109-113 degrees midweek or so, dependent on whether 
the low level moisture hangs around there or not.  

The upper high will be centered near SoCal late in the week, 
although this does not seem to be intense enough for excessive heat 
concerns, especially with some remnant moisture likely to linger 
over the area.

&&

.AVIATION... 
251530Z...Coast/Valleys...Mostly clear skies expected 
through early afternoon. Clouds at/above 10000 ft MSL will be on the 
increase late afternoon into this evening as Tropical Depression Ivo 
moves northward. Confidence on the low end for stratus impacting 
coastal TAF sites tonight with cigs between 700-1000 ft MSL and 4-6 
sm vis. May be patchy after 04Z, but looking to stick more between 
11Z-16Z Monday.

Mountains/Deserts...SCT-BKN cigs 2000-5000 ft MSL possible over 
portions of the low desert through 19Z today. Low confidence of 
slight chance for tstms over the mountain crests during the 
afternoon, dissipating in the evening. Otherwise increasing clouds 
at/above 10000 ft MSL throughout the day.

&&

.MARINE... 
No hazardous marine weather is expected through Thursday. 

&& 

.BEACHES...
South-southeast swells from 160-170 degrees with a 12-13 second 
period, generated by the now Tropical Depression Ivo, will generate 
elevated surf through Monday morning. Isolated surf up to 6 ft is 
possible on the south facing beaches of Orange County. Main impacts 
on west facing beaches will be longshore currents. A Beach Hazards 
Statement remains in effect for Orange and San Diego county beaches 
through Monday morning.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Monday morning for Orange 
     County Coastal Areas-San Diego County Coastal Areas.

PZ...NONE.
&&

$$

PUBLIC...SMALL
AVIATION/MARINE/BEACHES...APR