NWS Forecast Area Discussion - San Francisco Area

FXUS66 KMTR 071200

Area Forecast Discussion
National Weather Service San Francisco Bay Area
500 AM PDT Thu Jul 7 2022

.SYNOPSIS...Without a well defined marine layer, a mix of low and
mid level clouds continue today. Morning coastal drizzle may be
possible in areas with lower clouds. A gradual warming and drying
trend begins by midweek, however, below normal temperatures
persist today through Friday for the afternoon highs. By Saturday,
the region warms more becoming near to slightly above normal
conditions through Monday.

&& of 4:55 AM PDT Thursday...Low clouds continue to
fill in around the cwa this morning. 24 hour trends show temperatures
are a few degrees cooler and dewpoint temperatures are ranging in
the lower to mid 50s. Last evening`s Oakland sounding precipitable
water (pw) had lowered to 0.85" which is gradually drying out
since early in the week when the pw peaked at 1.36". With the
recent decrease or loss of northwest coastal waters winds and
subsequent decrease in cold water upwelling, sea surface temps
jumped upwards ranging in the 50s. This corresponded to very
similar timing to the passage of a warm front and much higher
humidity from the subtropics, which slowly drifted through the cwa
with milder maritime influences holding temperatures up higher
than prior to the warm front/boost in humidity. It`s been dry
inland, however along the coast since early July there`s been
periodic light measurable drizzle and rain. More recently, ill-
defined cooling is gradually filtering in on west winds also
helping produce periodic light precipitation on the coast.

July`s high sun angle and subsequently strong surface warming over
the interior of the western CONUS is trying to link up with a
strengthening and retrogressive 500 mb high pressure system.
Meanwhile, along the west coast the upper level trough is steadily
becoming more nebulous of a feature at our latitude as 500 mb
heights steadily rise to 580+ decameters (as the low weakens) and
then by the weekend rise to 590+ decameters. The jet stream winds
across the northernmost CONUS typically retreats to the north in
the summer with a varying sized high pressure system located over
a fair amount of the CONUS. Since 500 mb heights are forecast to
strengthen over our cwa through late week and weekend, with
redeveloping subsidence inversions and generally clearer skies,
daily surface temperatures will enter a warming trend best chances
of this well inland in the usual hot temperature spots that reach
the 90s/100. For most locations including inland the heat risk is
projected to stay in the low risk category through the weekend
and early next week. Of course it`s always a good idea to stay
properly hydrated and out of the sun as much as feasibly possible,
using sun protection, etc. Global model output with regard to the
location and strength of the aforementioned high pressure system
has oscillated a bit west to east in model trends, nonetheless
it`s expected to basically take root closer to and over the western
CONUS as is usually what occurs with some lower latitude retrogression
expected. Monsoonal moisture from Mexico is forecast to continue
entering the southwestern states, and possibly by July 14th if the
500 mb high sets up over AZ/UT it could bring a period of monsoonal
moisture close to our cwa.

&& of 4:44 AM PDT Thursday...For the 12Z TAFs.
Widespread MVFR with a few areas of IFR will last into the mid to
late morning with light to moderate winds. Widespread VFR returns
with mid clouds in the late morning and early afternoon with
winds becoming moderate to breezy. Cloud cover will struggle to
move inland Thursday night, keeping VFR conditions through the
night for all but the more coastal terminals and the SF Bay.

Vicinity of KSFO...MVFR/IFR with light winds through the late
morning. Expect VFR for the afternoon with breezy westerly winds
peaking around 16 kts with 24 kt gusts. These winds will ease into
the night but stay moderate. The late night and early Friday morning
offers moments of IFR as low clouds fail to stay consistent over the
SF Bay terminals.

KSFO Bridge Approach...Similar to SFO.

Monterey Bay...MVFR through the late morning with moments of IFR and
mist around MRY in the mid morning. Winds will be light but become
more moderate and breezy for the afternoon as VFR returns. Expect a
breezy afternoon followed by lighter winds into the night. MRY looks
to have a brief period of IFR CIGs and mist into early Friday

&& of 2:52 AM PDT Thursday...Winds will be breezy over
the coastal waters into the late morning with strong winds south
of Pigeon Point and Point Sur. Winds will gradually build over the
coming days. Small craft advisories have been issued for the near
shore waters during this time.


     .Tday...SCA...Mry Bay from 9 AM
             SCA...Pt Arena to Pt Reyes 0-10 nm from 9 AM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm from 9 AM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm from 3 PM
             SCA...SF Bay from 9 AM



MARINE: Murdock

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NWS MTR Office Area Forecast Discussion