Scientific Forecaster Discussion
fxus66 ksgx 192115
Area forecast discussion
National Weather Service San Diego California
115 PM PST sun Nov 19 2017
high pressure aloft along the West Coast will bring unseasonably
warm weather this week. High temperatures will be 15 to 25 degrees
above average Wednesday and Thursday. Cooling will gradually spread
inland Friday through next Sunday as high pressure aloft weakens and
onshore flow returns.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
The Holiday week weather is looking warm and dry with no travel
concerns in Southern California.
This morning started out cool in the wind sheltered valleys where
temperatures fell into the mid 30s at Riverside and San Pasqual
Valley. In contrast, temperatures were some 20 degrees higher in the
windy areas like Rancho Cucamonga and Fallbrook where the early
morning temperatures were 58f. The coldest air settled over the San
Bernardino Mountains and high deserts. Morning lows were in the
upper 20s and low 30s at Victorville, Hesperia and Phelan, with the
coldest spots in the mountains at Baldwin Lake (13f) and the big
bear Airport (14f).
The weather will turn warmer through Wednesday as 500 mb heights
steadily increase as a high amplitude upper ridge builds over the
southwest. This strong ridge aloft combined with weak offshore low
level flow will bring greatest warming Tuesday through Thursday with
highs in the 90s in the lower deserts and the valleys. Coastal zone
highs will be in the 80s, and mountain highs will be in the 60s and
70s. Both Wednesday and Thanksgiving day will be exceptionally warm
days with record highs likely.
Friday through Sunday...the ridge aloft weakens and onshore flow
will return to Southern California. Cooling will spread inland but
temperatures will still be a little above average through next
192105z...coast/valleys...p6sm vis and few-scattered clouds at or above 20000 ft
msl through 20/0300 UTC. 20/0300-1500 UTC, patchy dense fog/very low
stratus may develop again within 5 sm of the coast, with bases 100-
400 ft msl, tops around 500-700 ft msl, and local vis 1/4 sm or
less. Taf site most likely to be impacted would be ksan, but
confidence is very low on occurrence and timing. Thus, mostly p6sm
vis continuing with scattered-broken clouds at or above 20000 ft msl.
Mountains/deserts...p6sm vis through Monday morning with few-scattered
clouds at or above 20000 ft msl becoming scattered-broken after 20/0000 UTC.
slight chance for patchy dense fog to occur again late tonight into
Monday morning. Otherwise, no hazardous marine conditions are
expected through Friday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.