Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 272045
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
145 PM PDT WED JUL 27 2016
Hot and mostly dry weather will continue through Thursday. Below
seasonal temperatures this weekend into early next week, with a
chance of showers and thunderstorms in the mountains and deserts.
Night and morning low clouds and fog will be patchy through the
end of this week, and become more widespread along the coast early
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
At 1 PM PDT, water vapor satellite imagery displayed an upper-
level ridge centered over the NV/UT/AZ border, with southeasterly
flow aloft. The 27/1200 UTC KNKX sounding showed a more stable
atmosphere compared to yesterday morning, and calculated 1.35
inches of precipitable water. Lingering moisture may develop a
light shower over the high peaks of the San Bernardino County
Mountains this afternoon.
The aforementioned upper-level ridge will remain in place through
Friday, with H500 heights peaking today and Thursday around 597
DM. H850 temperatures will reach near 31 C over the deserts, which
will help highs rise to around 114-116 F in the low deserts and
Coachella Valley and 104-109 F in the High Deserts today and
Thursday. Highs over and west of the mountains will be fairly
close to seasonal normals through the period. A Heat Advisory
remains in effect through 8 PM Thursday for the desert areas. A
shallow marine layer will keep night/morning stratus and fog
patchy and along portions of the coast and coastal valleys through
The ridge will slightly weaken and move southeast this weekend
into early next week. Lowering upper-level heights will allow high
temperatures to lower to near to or slightly below normal Saturday
through mid next week, and allow night/morning low clouds and fog
to move more into the inland valleys. Upper-level flow will also
allow monsoonal moisture to enter the region through the period,
creating a slight chance to chance of afternoon/early evening
thunderstorms in the mountains and deserts. Dry lightning will be
possible this weekend before atmospheric moisture increases to
1.50 inches early next week. There is a greater possibility of heavy
rain and isolated flash flooding early next week where strong and
nearly stationary storms develop.
272000Z...Coastal areas...Patchy low clouds with bases 800-1100 ft
MSL lingering at the beaches this afternoon. Otherwise, mostly clear
with unrestricted visibility. Patchy stratus will redevelop along
the coast after 07Z Thu. Bases will be around 900-1300 ft MSL.
The only TAF sites that may be impacted are KSAN and KCRQ, but
confidence is low that any impacts will last for 2 or more
hours in a row. Expect clearing by 16Z Thu.
Valleys/Mountains/Deserts...Cumulus clouds will develop over the
mountain crests late this morning and dissipate shortly after
sunset. Otherwise a few clouds at/above 15000 ft MSL and
unrestricted vis through Thu morning.
No hazardous marine weather is expected through Monday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Heat Advisory until 8 PM PDT Thursday for Apple and Lucerne
Valleys-Coachella Valley-San Diego County Deserts.