Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 03/16/20

Area Forecast Discussion

National Weather Service San Diego CA

 818 PM PDT Sun Mar 15 2020

.SYNOPSIS...
Cyclonic flow aloft over the West, coupled with onshore flow and
a deep marine layer, will keep the weather cool and somewhat
unsettled much of this week, with periods of rain and mountain snow.
More organized storm systems will move over Southern California
Tuesday through Thursday, and again early next week, with some
moderation in temperatures late this week.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

Satellite imagery showed most of the cloud cover along the coastal
slopes and foothills this evening. Precipitation had largely ended
for now, but some spotty, light precip could break out again
overnight with the best chance of accumulation along the coastal
slopes where gusty upslope winds are adding lift. Onshore sfc
pressure gradients were running 4-8 MBS (KSAN to the deserts) and SW
winds were 20 MPH with peak gusts around 35 MPH in the wind-prone
mtn areas. Based on MDCRS soundings from around KONT, the moist
layer was in excess of 7K FT deep.

The latest hires models indicate the potential of isolated light
showers again tonight, but most areas should remain dry ahead of a
storm system spinning off the NoCal Coast. The forecast was updated
earlier in the afternoon, and no further updates are planned this
evening.

From previous discussion...

Numerical models continue to be in good agreement through
Thursday with respect to the track and timing of the low pressure
system off the coast of northern CA. The low pressure system is
expected to continue moving southward through Tuesday night with
the upper low pressure center remaining off the coast. On Wed, the
low will begin to move east over northern Baja, becoming an open
wave over northern Mexico/southern AZ by Wed evening.

A shortwave trough rotating around the low center will bring
widespread, organized rainfall and mtn snow, beginning Monday
evening and continuing through Tuesday morning. Current precip
estimates during this time are for: one half to two thirds inch at
low elevations west of the mtns, one to 1.5 inch in the foothills
and mtn slopes. Snow levels will be mostly above 5000 feet,
falling to around 3,500 feet Tuesday morning, and about 3-5
inches of snow could fall above those elevations. Above 7,000
feet, 10 inches or more could accumulate.

On Wed as the low moves east over Baja and the coldest air moves
over SoCal, the bulk of precip will fall to our south and east
while we enjoy a period of relatively mild weather with periods of
scattered showers. However, we will remain in cyclonic flow aloft
with a second low to our north. Although most of the energy has
moved east with the first low, enough moisture and instability
remains to produce periods of showers through Friday. The colder
air will keep snow levels down around 3,500 feet on Wed morning,
after which it gradually goes back up to around 5,000 feet on Fri.
Thunderstorms could develop on Wed, but probabilities are very
low.

This system will also produce periods of strong and gusty
southwest to west winds, mainly in the mtns and adjacent desert
areas. Winds will peak Mon night/Tue morning with wind gusts to 40
mph possible in the favored areas.

Beyond Friday, the forecast remains highly uncertain but current
indications are for mostly fair weather next weekend before
another low pressure system moves in from the northwest late
Sun/Mon morning.

&&

.AVIATION...
152015Z...Coast/Valleys/Mountains...BKN clouds with variable bases
between 2500-5000 ft MSL will continue through Monday evening, with
unrestricted VIS except for mtn slopes obscured by clouds. RA
developing near 00Z Tue, give or take a few hours, at KSNA/KONT.
Precipitation will spread from NW to SE Monday evening, reaching San
Diego County 2-4 hours later. Bases will lower during frontal
passage to around 1000-2500 ft MSL, with periods of VIS 1-4SM
expected during showers at any of the terminals. Expect an increase
in southerly surface winds ahead of the front (near 15Z Mon at
KSNA/KONT, and 18Z at KSAN), with potential gusts to 25 kts for
several hours.

Deserts...SCT-BKN high clouds at/above 15,000 ft at times with
unrestricted visibility through Monday night.

&&

.MARINE...
Wind gusts to 20 knots are possible over the coastal waters Monday
and Wednesday, mainly during the afternoons and evenings. Otherwise,
no hazardous marine conditions are expected.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Storm Watch from Monday evening through Tuesday morning
     for Riverside County Mountains-San Bernardino County
     Mountains-San Diego County Mountains.

PZ...NONE.

&&

$$

PUBLIC...10/PG
AVIATION/MARINE...Rodriguez