Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
FXUS66 KMTR 242037
Area Forecast Discussion
National Weather Service San Francisco Bay Area
137 PM PDT Fri Mar 24 2017
.SYNOPSIS...Showers can be expected into the evening behind a
departing cold front. A break in the rain is expected Saturday
with showers anticipated to return starting late on Sunday as a
low pressure system moves through.
.DISCUSSION...as of 1:40 PM PDT Friday...Widespread rainfall
across our CWA today as a moderate cold front quickly advances
through our region. So far rainfall reports have generally been a
bit lower than forecast in most locations which has meant fewer
hydro reports than expected. Even when the main band of moderate
rainfall went through the Bay Area late a couple of hours ago,
reports of roadway flooding or hydro issues were less than what we
typically would typically see. One possible reason is as expected
the front went through at an ideal time between the morning rush
and evening commute -- typically when traffic is quite a bit less.
Regardless, still decent values that will add to our impressive
totals for the winter of 2016/17.
Winds also increased as the front approached, however outside of a
few isolated spots, speeds have been lower than advisory criteria.
Latest analysis suggests that the peak winds have already
occurred, so the wind advisory was cancelled for all locations.
Post-frontal Scattered showers can be expected into tonight
especially for far southern portions. However, amounts will
generally be very light -- less than 1/10" for urban locations
with locally up to 1/4" for higher elevation spots.
Dry weather will return for Saturday through most of Sunday as a
weak ridge of high pressure builds back to the coast. Highs will
mostly be in the upper 50s to mid 60s on Saturday with a few
degrees of cooling on Sunday as the ridge flattens out. At the
same time a minor system will drop down from the north and
quickly move through our region. Scattered showers can be expected
with the majority of the rain over the North Bay. In fact, many
locations south of the Bay Area will likely see a tenth or less.
Light showers will mostly come to an end by Monday morning.
Continues to look like next Monday through the following weekend
will be fairly quiet as a ridge of high pressure builds to the
coast and is then replaced by a dry northwesterly flow. Models
show possibly two shots at getting light scattered showers,
however any associated precipitation should be very light.
Temperatures will range from near normal to a bit above normal.
.AVIATION...As of 10:55 AM PDT Friday...For 18Z TAFs. A heavy band
of showers is moving across the Bay Area at this hour resulting in
decreased vsbys and IFR to MVFR cigs to area terminals. As the
band of rain slides south terminals currently ahead of the band
will begin to see lowered vsbys and cigs. Improving conditions
expected behind this band of showers later this afternoon and
Moderate southeasterly winds with locally stronger gusts will
continue across the forecast area. Wind gusts could reach 25-30 kt
at times through about 00Z, as a cold front passes.
Moderately high confidence.
Vicinity of KSFO...MVFR cigs with periods of moderate rain and
gusty winds expected through 00z. Moderate southeasterly winds
with gusts around 25 kt or more expected through the afternoon
and early evening.
SFO Bridge Approach...Same as KSFO.
Monterey Bay Terminals...VFR cigs prevail at this hour with cigs
expected to lower to MVFR around 20z with the arrival of the rain.
Southeast winds will turn increasingly to the south by the
afternoon, with gusts around 20 kt possible.
.MARINE...as of 10:49 AM PDT Friday...Occasional gale force gusts
are possible through the day today as a storm system impacts the
region with strong southerly winds and rain. Seas will be rough
with the frontal passage...but should begin to decrease by this
evening. Expect northwest winds to return by Saturday morning
before briefly becoming southerly on Sunday as another weak
system moves over the waters.
.Tngt...SCA...Mry Bay until 9 PM
SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 9 PM
SCA...SF Bay until 5 PM
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 5 PM
SCA...Pt Arena to Pt Reyes 0-10 nm until 3 PM
SCA...Pt Reyes to Pigeon Pt 0-10 nm until 3 PM
PUBLIC FORECAST: Bell
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