FXUS66 KMTR 192139
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
239 PM PDT Sun Apr 19 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 935 PM PDT Sat Apr 18 2026

 - Seasonally warm temperatures Sunday

 - Cooler temperatures, beneficial rainfall, and isolated
   thunderstorms expected Monday through Wednesday

&&

.SHORT TERM...
Issued at 235 PM PDT Sun Apr 19 2026 
(This evening through Monday)

Pleasant end to the weekend for the Bay Area and Central Coast 
weather wise with filtered sunshine and seasonably mild 
temperatures. Max temps today will peak in the 60s to mid 70s 
with a few interior spots making a run at 80 plus. 

Stepping back and taking look at the bigger picture reveals a 
system lurking off the coast. In fact, pretty impressive looking
visible satellite imagery this afternoon. A discernible
circulation is spinning off the PacNW with a band of clouds
wrapping around the system and stretching along the West Coast.
The circulation is an anomalously deep upper low. At the surface 
is a double barrel low pressure system with a marked frontal 
structure. The surface low and front will begin to inch its way 
eastward Sunday evening and Sunday night. The advancing cold front
will bring increasing clouds and a few scout showers to the 
northern coastal waters and far northern Sonoma county. Not 
expecting much in the way of accumulating precip with these 
leading showers through Sunday night. 

More widespread precip is expected on Monday as the highly
amplified upper jet begins to phase off the CA coast. Light to 
moderate rain will begin across the North Bay toward the end of 
the AM commute. Rain will spread S and E through the day with the 
passage of the cold front. Expect the evening commute to be pretty
messy with wet roads.

In addition to the rain on Monday, southerly flow will ramp 
thanks to a tightening surface gradient. Winds are initially
strongest over the waters before hitting the coast and inland
areas by the afternoon. Not strong enough for a wind advisory, but
general gusts in the 30-40 mph range seems reasonable. Given the
southerly flow, initial rain chances for some areas will be eaten
thanks to downslope flow and rain shadowing. 

As for temperatures, despite a pattern change temperatures will 
be mild since the region will be in a warmer sector until fropa. 
Given the solid S flow think there could be some enhanced 
downslope warming - thinking Monterey. 
  
&&

.LONG TERM...
Issued at 238 PM PDT Sun Apr 19 2026 
(Monday night through next Saturday)

Monday looks wet, but Tuesday may end up being a little more
dynamic thanks to convection. A few things we'll be watching for
Tuesday: cold pool aloft behind the front destabilizing the 
atmosphere, approaching upper low, position of left exit of jet 
aloft, and wind profiles relating to low level shear. While those
pieces varying from model to model, enough of a signal is present
to justify having thunderstorms in the forecast for Tuesday. 
Putting things into better context, the ECMWF Extreme Forecast 
Index has strong signal for CAPE over the coastal waters giving 
more confidence to thunderstorms. SPC Day 3 outlook does have the 
entire region in a general mention of thunderstorms. 

Monday's rain and Tuesday additional shower activity should be
mostly beneficial rain, but given the convective nature local 
ponding/minor flooding is possible. Lingering showers will 
continue into Wednesday afternoon thanks to a trailing shortwave 
behind the departing upper level low/trough.

Warmer and drier conditions there after.


&&

.AVIATION...
(18Z TAFS)
Issued at 1152 AM PDT Sun Apr 19 2026

High clouds are building across the area with moderate winds 
building into the afternoon. Winds become light into the evening and 
into the night with mostly variable to southerly winds expected. The 
next cold front begins to enter the region from the northwest into 
the late night and early morning. Southerly winds build ahead of the 
front with light prefrontal showers. Rain and winds increase along 
the front with gusty southerly winds expected. Rain and winds 
continue well beyond the TAF period, with increased rain rate 
predicted further into Monday.

Vicinity of SFO...VFR through the TAF period. High clouds will build 
through the day with moderate west to southwest winds. Winds weaken 
and turn slightly more southerly into the night. Light showers arrive 
along with moderate southerly winds into Monday morning. Gusty south 
winds build into the late morning on monday as rain rates begin to 
increase.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period. High clouds 
continue to build into the areas with moderate to  breezy winds 
expected this afternoon and through the evening. Winds reduce into 
the night and become light. Southeast winds begin to build at SNS 
into mid Monday morning. Showers and increased winds arrived beyond 
the TAF period.

&&

.MARINE...
(Today through Friday)
Issued at 1152 AM PDT Sun Apr 19 2026

Expect breezy and gusty winds to build  ahead of a slow moving
cold front that arrives on Monday. Rain will accompany the cold
front starting Monday and lingering into early Wednesday. Chances
of thunderstorms will move through the waters for much of Tuesday.
Dry weather returns late in the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Monday for SF Bay N 
     of Bay Bridge.

     Small Craft Advisory from 9 AM Monday to 3 AM PDT Tuesday for 
     Mry Bay.

     Small Craft Advisory from 3 AM to 9 PM PDT Monday for Pigeon Pt 
     to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena 
     to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory from 3 AM Monday to 3 AM PDT Tuesday for 
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras 
     Blancas 0-10 nm.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...Murdock
MARINE...Murdock

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Prepared by Boulder-Creek.com Weather at: Sun Apr 19 16:30:02 PDT 2026