fxus66 ksgx 201011 

Area forecast discussion 
National Weather Service San Diego California 
310 am PDT Sat Oct 20 2018 

offshore flow and warm weather will continue today, with gusty 
easterly winds near the foothills. Cooler on Sunday as the winds 
weaken and turn onshore. Some coastal marine clouds may return as 
well. Moisture moving in from the southeast will bring some clouds 
over the mountains and deserts Sunday into Monday, and there may 
even be an isolated shower or two, but most areas will stay dry. The 
marine layer will deepen early next week, allowing low clouds to 
spread a little farther inland. This will be followed by warming 
during the latter half of next week as high pressure over the 
eastern Pacific expands eastward. 


Discussion...for extreme southwestern California including Orange... 
San Diego...western Riverside and southwestern San Bernardino 

At 2 am PDT...skies were clear across the County Warning Area. Moderate offshore sfc 
pressure gradients near 9 mbs (sw Nevada to ksan) continued to support 
gusty easterly winds along the coastal foothills at 15 to 25 miles per hour 
with gusts over 35 miles per hour in the more wind-prone areas. 

A Rex block over the West Coast will break down and be replaced by a 
broad trough as the southern low lifts NE and opens. At the same 
time moisture will be drawn northward, setting the stage for 
scattered showers and possible thunderstorms, mainly to our north 
and east. Some isolated activity is not out of the question for 
northern portions of the cwa, but does not look significant at this 

It will be another warm day today with temperatures running from 5 
to 10f degrees above average west of the mts....then cooler on 
Sunday as the sfc pressure gradient turns back onshore for a cooler 
afternoon. The somewhat cooler days will continue through the first 
half of next week under the weak trough, then warmer for the latter 
half of the week as high pressure over the eastpac builds eastward 
across socal. 

Some low clouds/fog may return Sat night into Sun morning, but 
cyclonic flow aloft and a possible eddy should help to limit fog and 
very low ceilings. 


200830z...areas of NE-east winds with sfc gusts 20-30 knots and pockets of 
low level wind shear will continue below the passes and near the coastal foothills 
through about 18z, then weaken through the afternoon. Areas of low 
clouds with bases near 500 ft mean sea level and vis 2sm or less developing 
along the San Diego County coast after 21/05z and spreading north 
along the coast and up to 10 mi inland overnight. Vis below 1sm is 
possible at ksan, kcrq, and ksna at times overnight, but confidence 
is low on timing and duration. Otherwise few-scattered clouds in the 7000- 
10000 ft layer beginning this afternoon. 


no hazardous marine weather is expected through Wednesday. 


Fire weather... 
there has been some modest relative humidity recovery overnight, but as the sun 
heats the airmass, once again relative humidity levels will be marginally critical 
as easterly winds remain gusty along the coastal slopes, through the 
passes and over foothill areas at 15 to 25 mph, with higher gusts 
this morning in wind-prone areas. Widespread critical fire weather 
conditions are not expected, although some areas may reach those 
levels for a few hours later this morning into midday. The offshore 
flow will weaken this afternoon. Onshore flow and a shallow marine 
layer will return late Saturday into Sunday, bringing greater 
humidity recovery. 


Skywarn activation is not needed. 


Sgx watches/warnings/advisories... 


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