Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 182141

Area Forecast Discussion
National Weather Service San Diego CA
241 PM PDT Sun Jun 18 2017

High pressure aloft over the southwest states will bring well
above normal high temperatures through mid week...peaking Tuesday
and Wednesday. A shallow marine layer and weak onshore flow will
moderate the heatwave towards the immediate coast with areas of
night and morning coastal low clouds and patchy dense
fog...diminishing Tuesday and Wednesday. High pressure may weaken
slightly the latter part the next week with cooling spreading
into the valleys Thursday...with slight cooling spreading farther
inland on Friday and Saturday.



Stronger marine layer in place for the time being and will see
another round of very low clouds and fog closee to the coast
tonight and into early Monday morning. The marine layer should
become too shallow and weak as the high shifts a bit west Tuesday
and Wednesday.

Excessive heat forecast remains on track through Thursday. The
most intense period of the heatwave will be Monday through
Wednesday, likely Wednesday will be the hottest day as warmest
temps aloft and the ridge begins to shift. Many daily records will
be broken Monday through Wednesday with the all-time record at
Palm Springs could be tied on Tuesday or Wednesday.

Brief return flow next weekend will bring some cumulus buildups
over the mountains and slightly cooler temperatures.

It is becoming quite clear that abnormally warm conditions...maybe
not continued excessive heat levels...but still well above normal
temperatures will persist away from the coast into next weekend
and early the following week. The EC continues to reestablish the
ridge over the SW and California by next weekend although not
quite as what we`re likely to see early this week. Nonetheless the
forecast will reflect well above normal conditions persisting.


182030Z...Coast...Local BKN stratus will occur this afternoon along
the beaches with bases 800-1000 ft MSL. Vis will be unrestricted
through at least 04Z. Stratus will spread 7-12 miles inland tonight
with patchy dense fog. Confidence is high for occurrence of low
stratus/fog, but confidence of timing is low, with onset probably in
the 05Z to 09Z range, and likely affecting KSAN, KSNA and KCRQ. Cigs
will be in the 500-1000 ft MSL range with tops to 1200 ft MSL. Areas
of vis 2-4 mi will occur with local vis below 1 mi which could
affect KCRQ. Most areas should clear by 16Z Mon.

Valleys, mountains, deserts...Clear skies with unrestricted
visibility will prevail through Monday. For density altitude
concerns, PSP has a projected high temperature of 115 today and 119


Patches of fog with visibility 1 mile or less will occur over the
coastal waters at times through Thursday, mainly during the early
morning. Otherwise, no hazardous marine weather is expected through


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


CA...Excessive Heat Warning until 9 PM PDT Thursday for Apple and
     Lucerne Valleys-Coachella Valley-San Diego County Deserts-
     San Gorgonio Pass Near Banning.

     Heat Advisory until 9 PM PDT Wednesday for Riverside County
     Mountains-San Bernardino County Mountains-San Bernardino
     and Riverside County Valleys-The Inland Empire-San Diego
     County Mountains.

     Heat Advisory from 11 AM Monday to 9 PM PDT Wednesday for Orange
     County Inland Areas-San Diego County Valleys-Santa Ana
     Mountains and Foothills.



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