Strong Wind in California, April 16, 2019

Area Forecast Discussion
National Weather Service San Francisco Bay Area
155 PM PDT Tue Apr 16 2019

.SYNOPSIS...This afternoon will feature cool temperatures and
breezy conditions under partly cloudy skies. A warming trend is
forecast for Wednesday and Thursday, with temperatures expected to
climb well above normal by Thursday with widespread 80s for
inland locations. A cooling trend is forecast to begin on Friday
and continue into the weekend. Generally dry conditions are
expected over the weekend and early next week.

&&

.DISCUSSION...as of 01:55 PM PDT Tuesday...Showers have exited
the region with dry conditions in all areas this afternoon.
Sunshine and low level moisture are creating widespread
stratocumulus clouds, especially over the higher terrain. A
subsidence inversion is forming about 5000 feet MSL limiting the
vertical development of these clouds. Temperatures this afternoon
are on the cool side, ranging from the upper 50s along much of the
coast to the middle 60s inland. Our region is situated between a
surface high to the west and a surface trough to the east, and as
a result breezy northwest winds have developed this afternoon.
These winds will become strong at times through the evening along
the coast where gusts up to 30 mph are possible. Overnight
tonight, areas of stratus are likely to develop along the coast.

On Wednesday, an upper ridge currently over the eastern Pacific
will begin to move overhead. This will bring a warmer airmass and
weaker onshore flow, resulting in about 10 degrees of warming
inland and up to 5 degrees along the coast. The ridge will
continue to shift east on Thursday, when the ridge axis is
expected to transverse the region. A surface trough will develop
along the coast on Thursday as high pressure develops over the
Great Basin, resulting in weak offshore flow. Thursday is expected
to be the warmest day of the week with widespread 70s at the coast
and 80s in the inland valleys. The warmest locations, such as the
southern Salinas Valley, are forecast to reach the upper 80s with
a 90 degree reading not out of the question. These high
temperatures are about 7-15 degrees above normal for mid-April.
These warm temperatures are expected to remain several degrees shy
of record highs. For reference, the record high on Thursday for
Downtown San Francisco is 83 and San Jose is 91 degrees, which we
are not expecting to approach.

On Friday, a cutoff low will move onshore over southern
California, and onshore flow will increase. Cooling will be most
pronounced along the coast, while some inland areas could see
temperatures similar to Friday. Additional cooling is expected on
Saturday as a Pacific trough brings with it a cooler airmass.
Highs are expected to range from the mid 60s to the mid 70s, or
about a 10 degree drop from Thursday. Precipitation chances with
this system will be minimal with showers expected to remain to our
north.

Another weak shortwave trough will move through the area on
Sunday, with continued minimal chances of precipitation. A low-
amplitude ridge of high pressure will then replace the trough on
Monday and Tuesday with warming temperatures expected. With a
return to ridging, the forecast looks to remain dry through the
end of the forecast period.

&&

.AVIATION...as of 10:50 AM PDT Tuesday...VFR. Low clouds continue
to lift and dissipate this morning with FEW/SCT clouds between
500-3,500 ft lingering. Otherwise, look for onshore winds to
increase and become locally gusty (up to 25 kt through coastal
gaps such as near KSFO) this afternoon and evening. Winds diminish
overnight with low confidence of lowering ceilings toward
Wednesday morning.

Vicinity of KSFO...Breezy west winds through this evening, with
sustained winds 15-20 kt and gusts 20-25 kt possible.
Redevelopment of MVFR ceilings possible early Wednesday morning,
low confidence.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Breezy onshore winds 10-15 kt with gusts
up to around 20 kt through the afternoon. Redevelopment of MVFR
ceilings possible early Wednesday morning, low confidence.

&&

.MARINE...as of 08:22 AM PDT Tuesday...Northwest winds are
forecast to increase and become gusty by the afternoon in wake of
an overnight frontal passage. These gusty winds will prevail
through early Wednesday morning, primarily along the coast and
just offshore. Moderate northwest swell will continue through the
forecast period.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Mry Bay until 11 PM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm until 11 PM
             SCA...Pt Reyes to Pigeon Pt 0-10 nm until 3 AM
             SCA...Pt Arena to Pigeon Pt 10-60 nm until 3 AM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM
             SCA...Pt Arena to Pt Reyes 0-10 nm until 3 AM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM

&&

PUBLIC FORECAST: ST
AVIATION: RGass
MARINE: RGass

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