National Weather Service Forecast Discussion

Dicussion provided by the National Weather Service Forecast Office located in San Diego, California

FXUS66 KSGX 240452

Area Forecast Discussion
National Weather Service San Diego CA
930 PM PDT Thu May 23 2019

Clouds will gradually decrease through Friday as the low pressure
trough moves to the east of the area. Warmer weather will occur
Friday and Saturday. Another low pressure system from the north will
bring showers and cooling Sunday with warming and decreasing shower
chances Memorial Day. Drier weather with a slow warming trend will
return Tuesday through Thursday as the low pressure trough weakens.



Skies were partly cloudy over the region, with the greatest cloud
cover over the valleys and coastal mountain slopes. Fog continued in
some mountain locations. Current guidance, including the latest
local WRF, continue to show a gradual decrease in clouds through
Friday, and any chances of showers Friday over the mountains look
minimal given that instability and moisture appear insufficient.
With 850 MB temps increasing to around 11 deg C Friday and less
cloud cover, we should be considerably warmer than today, though
still below average in most areas, especially the deserts as Palm
Springs will have a high around 86 degrees, versus an average high
of 98. West of the mountains, temperatures will only average around
5 degrees below normal. Saturday should be similar, except slightly
warmer in the deserts.

00Z NAM has more precipitation than previous runs and considerably
more than any of the GFS or ECM solutions, including GFS ensembles.
The track of the closed low for Sunday is also farther south (SoCal)
than the GFS or ECMWF ensembles. 00Z NAM has some locations having 1
1/2 inches of rain in the mountains. Given about 300 miles (north-
south) uncertainty among the ensemble solutions, the range of
possibilities is 1/2 to 1 1/2 inches of rain in the mountains, and
current messaging of up to one inch possible is probably best. If
the cold core low moves over SoCal, there could be thunderstorms as
well, mainly Sunday afternoon and evening. Lower elevations could
receive 1/4 to 1/2 inch of rain. Strong winds are likely in the
mountains and deserts as well. Snow levels will likely start out
high, above 7000 feet, but could fall to 6000 feet Sunday night,
with some accumulating snow possible.

Ensemble solutions are not in the best agreement after Sunday, but
the most likely scenario right now is for some lingering precip into
Monday followed by fair and somewhat warmer weather under weak
cyclonic flow Tuesday and Wednesday, with temperatures possibly
approaching average. Some solutions show additional troughing from
the north later in the week.


240400Z...Coast/Valleys/Mountains... SCT-BKN low clouds with bases
2500-3500 ft MSL through tonight. BKN low clouds likely at KONT and
KSBD, but low confidence of BKN low clouds at coastal TAF sites.
Higher terrain will be obscured by clouds overnight. Scatter out
expected after 17Z Friday.

Deserts...Mostly clear with unrestricted vis through Friday.


No hazardous marine weather expected through Monday.


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





NWS SGX Office Area Forecast Discussion