Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 231130

Area Forecast Discussion
National Weather Service San Diego CA
430 AM PDT Wed Aug 23 2017

A trough off the California coast will bring seasonally warm August
weather today and Thursday, along with a fairly deep marine layer.
The weather will start heating up Friday and Saturday as high
pressure begins building over the Southwest. The hottest days will
be Sunday through Wednesday as stationary high pressure aloft
dominates our weather.



Marine layer stratus cover the San Diego Valleys and the far western
sections of the I.E. this morning including Temecula and Murrieta.
Cloud bases were 1000 feet with tops near 2000 feet, perhaps deep
enough for areas of mist or drizzle in the coastal zones this

Scattered midlevel clouds near 10kft were associated with a weak
shortwave rounding the West Coast trough. Midlevel SE flow pulled in
a narrow band of moisture in the 650-800 mb layer, but the deepest
moisture will remain over Arizona and the Lower Colorado River
Valley where isolated afternoon t-storms may form.

The trough along the West Coast will remain in place tonight through
Thursday morning with a deep marine layer in place. Patchy mist or
drizzle will again be possible tomorrow morning. Then from Thursday
afternoon through Friday morning the trough fills and gradually
dissipates over the CA coastal waters.

Our weather will turn hotter over the weekend as strong high
pressure builds over the Four Corners region. The ridge then
strengthens and expands into a 596 dm high over the Great Basin
Sunday afternoon. The stagnant weather pattern will remain in place
through Wednesday, enveloping the entire Southwest under a dome of
hot air. With temperatures forecast to be 5-10 degrees above average
next week, Heat Advisories or Heat Warnings may be needed. Highs
will range from 100-110 in the Inland Empire and the High Deserts,
and from 110-115 in the Lower Deserts.

Southeast flow around the Great Basin high draws in modest amounts
of mid level monsoon moisture next week for possible isolated
convection over the mountains midweek.


230900...Coast/Valleys...Low clouds with bases 1100-1800 ft MSL
continuing to spread 25 mi inland through 15Z, possibly reaching
KONT after 12Z. Local vis 3-5 SM where clouds near higher terrain in
the valleys. Low clouds slowly clearing inland 16-18Z, with only
partial clearing along the coast 18-20Z. Low clouds beginning to
move back inland around 25/00Z and spreading into the valleys
overnight. Bases will be near 1500-2000 ft MSL.

Mountains/Deserts...FEW afternoon cumulus over the ridges and
unrestricted visibility through Thursday morning.


No hazardous marine weather is expected through Sunday.


Skywarn activation will not be needed on Wednesday.





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