*Annual Rainfall is based on the California Water Year,|
which runs from October 1 through September 30.
FXUS66 KSGX 190435 AAA
Area Forecast Discussion
National Weather Service San Diego CA
930 PM PDT Thu Aug 18 2022
The summer doldrums will continue through next week with warm and
humid weather. A weak monsoonal flow will maintain a chance for
mainly afternoon and evening thunderstorms over the mountains and
deserts. The greatest chances for thunderstorms will be Friday and
Saturday, and again around the middle of next week. Patchy night and
morning low clouds and fog will spread inland each night, and then
burn back offshore each morning, along with periods of higher clouds
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
No updated were needed this evening. Very limited convection
occurred today within our area, there were just a couple of cells in
the Santa Rosa Mountains, just west of the Coachella Valley.
Convection was probably limited due to subsidence along the eastern
periphery of the East Pac High Pressure ridge. There may be a little
better chance for convection Friday afternoon, but still only
isolated coverage is expected for Friday afternoon and early
evening. Nonetheless conditions will remain very warm and humid
across SoCal, and any storms that develop could contain brief heavy
downpours and slow storm motion.
Remainder of Previous Discussion (issued at 148 PM PDT):
High pressure aloft will remain in control over the SW through the
weekend and next week. Shifting and repositioning of the axis of
high pressure will determine the direction of our weak flow aloft,
and ultimately, moisture availability. Through the coming weekend,
we will remain on the edge of some very deep tropical moisture that
is smothering NW MX and the Lower Colorado River Valley of SE CA.
Any convective systems that develop there, could influence our
weather, due to outflow and convective debris. Forecasting those
details beyond anything more than 12-24 hours will be difficult to
impossible, so expect forecast adjustments.
Based on the various ensemble projections, more show greater
precipitable water values at various places in the CWA Friday into
Saturday, with drier solutions predominating early next week,
followed by another increase in moisture mid next week. Following
the PW trends gives us some variation in the POPS, but nothing
concrete. Bottom line...We remain in a weak monsoon pattern well
into next week, which favors afternoon, mountain convection, and to
a lesser extent, the deserts. As of now, we don't see a good chance
for any of this activity to make it to the coast, but it wouldn't be
surprising if something didn't develop next week for a few hours.
Except for periods of extensive cloudiness from the east, and/or
precipitation, daytime temperatures will be close to mid summer
190400Z...Coast/Valleys...Areas of low clouds will continue
developing along the immediate coast through 08Z Fri and spread up
to 20 miles inland by 13Z Fri. Bases will be 1000-1200 ft MSL with
tops to 1400 ft MSL. Local vis 3-5 miles will occur in the coastal
valleys 10Z-15Z. Most areas will clear 15Z-17Z with mostly SCT
clouds at/above 15000 ft MSL Fri afternoon. Areas of stratus will
develop near the immediate coast again Fri evening.
Mountains/Deserts...SCT-occasional BKN clouds at/above 15000 ft MSL
will continue through Fri evening with mostly unrestricted vis.
There is a slight chance of TSRA Fri afternoon/early evening with
bases 8000-10000 ft MSL and tops to 40000 ft MSL along with strong
up/downdrafts and local gusty surface winds.
No hazardous marine weather is expected through Tuesday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.