Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 290949

Area Forecast Discussion
National Weather Service San Diego CA
245 AM PDT Thu Jun 29 2017

A stable and relatively stagnant weather pattern will remain in
place through the fourth of July. Temperatures will be seasonally
warm through the period. No hazardous weather conditions are
expected through the holiday.



The marine layer was 1500-2000 feet deep this morning and stratus
streamed farther into the San Diego Valleys overnight with low
clouds as far inland as Valley Center, Ramona and Harbison Canyon.
Low clouds also made it to the far western sections of the Inland
Empire near Chino Hills and Temecula.

Changes in the synoptic pattern will be minor through the middle of
next week. A weak trough passing by to the north today will be
followed by a weak ridge Friday and Saturday for a degree or two of
warming. On Sunday into Monday another weak trough will bring a
degree or two of cooling. The marine layer depth will go through
minor daily fluctuations, but be deep enough to reach into the
western valleys most nights. Breezy at times in the mountains and
deserts, mainly in the afternoons and evenings.

Long Range Outlook: The first signs of a weak monsoon pattern appear
in the ECMWF and GFS next Wednesday through Sunday (July 5-9). On
Wednesday a 594 dm high forms over the Four Corners, then drifts
west and steadily strengthens into an expansive 599 dm high over the
Great Basin by next Saturday. There will be some increase in
monsoonal moisture aloft late next week, and this small moisture
flux coupled with any weak impulses in the southeast flow merit a
brief discussion on the monsoon potential. For now the long range
progs are only showing modest increases in mid level moisture over
SoCal, and very little QPF. But it`s something to watch during this
quiet weather period that will continue through July 4th.


290930Z...Coast/Valleys...Stratus will cover most areas within 25-30
miles of the coast and will extend into some west/south parts of the
Inland Empire this morning. Bases will mostly be 1200-1600 ft MSL
with tops to 2000 ft MSL, and clearing times will mostly be 15Z-18Z.
Areas of vis 3-5 miles in fog will occur through 18Z, plus some
smoke in Orange County, and local vis 1-2 miles in the valleys.
Stratus will spread inland again tonight, mostly after 01Z, with
similar bases, and local 1-3 mile vis due to fog in the valleys.

Mountains/Deserts...Clear skies with unrestricted vis will prevail
through tonight. West winds will locally gust to 25 kt late this
afternoon and tonight on the desert mountain slopes into adjacent
desert areas.


No hazardous marine weather is expected through Monday.


Breezy west winds again this afternoon and evening in the mountains
and desert slopes, but critical RH/wind combinations will become
more localized and last for only a few hours in any one spot through
the weekend. The wildfire risk will remain elevated at times over
the back country through the holiday weekend due to the dry fuels
and gusty winds.


Skywarn activation will not be needed today.




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