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Area forecast discussion 
National Weather Service San Diego California
930 PM PDT Tuesday Jun 30 2015

Synopsis...
moisture in southeast flow aloft and an upper level disturbance will
bring a chance of thunderstorms late tonight through Wednesday over
the entire region. Brief heavy rain...gusty winds and cloud-to-
ground lightning strikes will be possible. Otherwise...humid
conditions will continue with very warm to hot weather through
Wednesday. A slight cooling trend will occur starting
Thursday...mainly west of the mountains...and thunderstorms chances
will decrease. By the weekend...dry weather should prevail with
temperatures near seasonal normals. Low clouds will return to
coastal areas by Thursday and continue through early next week.

&&

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

Things calmed down after late afternoon as the upper wave moved west
and an area of subsidence occurred behind the wave. Temperatures
spiked as the sea breeze was interrupted...resulting in Miramar
reaching 91 at 6 PM and John Wayne Airport reaching 86 at 8 PM. At
mid-evening...a mesoscale convective complex was moving west over
Sonora and far southern Arizona...with scattered thunderstorms over
central Arizona and isolated cells in far eastern San
Bernardino/Riverside counties which should drift west. There is some
weakening of the Arizona/Sonora storms...but the mesoscale convective system appears to be
holding together well enough to send outflow into southeastern
California. The Yuma observation the next few hours will be critical
for possibility of gusty southeast winds and/or blow dust in our
deserts. This could also result in thundestorm development late
tonight over our area along the leading edge of the outflow...and
another wave moving west through Sonora/southern Arizona late
tonight and into northern Baja California early Wednesday could result in further
activity. Exact location of thunderstorms is difficult to
determine...but they again could occur anywhere from the coastal
waters east to the deserts. If cloud cover is low enough...there
could be additional afternoon convection Wednesday over the
mountains and desert slopes as near and a little east of the
mountain crests is where the surface convergence will be. Main
threats will be brief heavy rain...gusty winds and lightning
strikes...much like today. The middle-level winds will continue to be
rather strong...20-25 knots...so flash flood threat will mostly be
low...though any training...or any thunderstorms over the lake fire
burn area in San Bernardino County...could result in isolated
flooding. It should be hot again in most areas Wednesday...though
some places will cool a few degrees west of the mountains as a
precursor to a more notable cooling trend Thursday.

Thunderstorm chances should lower Thursday/Friday as the middle-level moisture
dercreases...and 00z NAM indicates probably no thunderstorms will occur at
all Friday. Also...the surface convergence lines shift further east
each day and will be well into the desert by Friday as onshore flow
increases. In fact...gusty winds will occur in some mountain/desert
areas...especially through San Gorgonio Pass and on the desert
foothills. Right now...the weekend looks dry as the flow between the
trough to our west and the ridge to our northeast will result in
mostly dry south-southwest flow. Some model runs have shown monsoonal flow in
our eastern areas earlier for Sunday/Monday...but most solutions are
trending drier now. Overall...temperatures look seasonal over the weekend
and early next week...and with onshore flow prevailing and the
trough to our west...there should be moderate amounts of marine
layer stratus...though probably not extensive due to the
renewed rise in local sea surface temperatures.

&&

Aviation...
010300z...scattered clouds at or above 150...becoming broken-ovc150 after 08z with scattered
-shra and isolated thunderstorms and rain possible with tops to fl300 after 10z. Confidence
in marine stratus development overnight is low and has been removed
from the coastal taf sites...but patchy clouds with bases 600-900 feet
mean sea level and tops near 1k feet mean sea level are still possible near the coast...
along with local visible restrictions in br/haze after 10z through 15z.
Confidence is low for placement and timing of showers/thunderstorms through
Wednesday...but development is possible any time after 09z tonight. The
best chance for thunderstorms will be with daytime heating Wednesday afternoon.

Through and below the San Gorgonio Pass...west winds 20 knots with
gusts to 35 kts through 11z with associated low level wind shear and uddfs.

&&

Marine... 800 PM...slight chance of thunderstorms late tonight and
on Wednesday...otherwise no hazardous marine weather is expected
through Friday.

&&

Beaches... 800 PM...there will be another chance of thunderstorms
at the beaches on Wednesday. Cloud-to-ground lightning strikes will be
possible.

&&

Skywarn...
Skywarn activation is requested for San Diego County. Skywarn
activation may be necessary for the other counties this afternoon.

&&

Sgx watches/warnings/advisories...
California...none.
Pz...none.

&&

$$

Public...Maxwell
aviation/marine/beaches...jad

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