Wet and windy Friday through Sunday
From AFD:
.SYNOPSIS...
Issued at 112 AM PST Fri Mar 1 2024
Expect a nasty couple of days ahead as a second cold front moves
through the Bay Area. Strong winds will pick up this afternoon.
Periods of rain will persist through Saturday with cold weather
sticking around into next week.
&&
.SHORT TERM...
(Today and tonight)
Issued at 112 AM PST Fri Mar 1 2024
The rain forecast is holding steady and gauges overnight are more
or less agreeing with the expected accumulation so far. There are
some exceptions where stronger rain bands were able to persist for
several hours. These include over 1.5" at Ben Lomond and similar
totals throughout the higher peaks in the Santa Cruz Mountains.
The Santa Lucias have also over performed, with several gauges
already over 2". Otherwise, the forecast has been very good so
far. With roughly another 1-2" expected over the next 48 hours,
there are still no major flooding concerns expected this weekend.
That being said, the rain combined with a cold wind will not make
for great picnic weather.
Strong SW winds will increase through the day ahead of the
frontal passage tonight. Gusts to gale force are expected,
especially as the frontal boundary moves through in the afternoon
and early evening. After the front passes, winds will shift to
westerly, but remain strong through the night. A wind advisory is
in effect for the majority of the area from noon today through 10
AM Sunday.
&&
.LONG TERM...
(Saturday through Thursday)
Issued at 112 AM PST Fri Mar 1 2024
Saturday will feel like the Pacific Northwest. In addition to
periods of rain, it`s going to start cold and won`t warm up very
much. The official forecast for San Francisco has a low of 46F
with the high only reaching 53F. While that`s nowhere near the
daily record (lowest max temp) of 45F set in 1896, it`s 9 degrees
below normal and more in line with the average March high temp in
Seattle (54F). The majority of the rainfall looks to be in the
morning, with only scattered showers in the afternoon. Winds will
also be lighter than Friday, but there will still be a stiff
westerly breeze through the day, especially along the Central
Coast. The first real snow of the year is expected in the
mountains as the thickness finally drops low enough during the
tail end of the multiday rain event. There`s some instability,
but the air mass will be drying out in the post-front environment.
The 06Z NAM point sounding for Santa Rosa valid at 10AM Saturday
brings the freezing level to 1465` with 142 J/kg of CAPE. The
problem is the precipitable water is only 0.38" at that time, and
continuing to decrease through the day. A few inches are expected
in the higher peaks of the Mayacamas and Santa Lucias, around an
inch in the Diablo Range, and a possible dusting in the Santa Cruz
Mountains. To be clear, the snow levels will remain above 2,000
ft and will not impact the main mountain passes.
The rain will really taper off Sunday, but the cold temperatures
will linger through the week. Monday morning looks to bring the
coldest temperatures with most areas dropping into the mid to
upper 30s before the sun comes up. The remainder of the week will
have lows in the upper 30s to mid 40s and highs in the upper 50s.
Some light rain is possible mid week. The uncertainty is much
higher than normal beyond Thursday with the global models all over
the place by next weekend.