FXUS66 KMTR 310036
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
436 PM PST Mon Jan 30 2023

.SYNOPSIS...Frost and freezing temperatures are likely away from 
the coast and are even possible for some coastal areas through mid
week. Warming by late week with rain chances returning. 

...Frost and Freezing Temperatures Many Areas Tonight...

.DISCUSSION...as of 12:04 PM PST Monday...

This Evening through Wednesday:

Upper ridging will build into the region as surface high pressure 
centers over the central Great Basin. This will set up a north to 
northeast wind pattern this evening with breezy conditions in the 
North Bay hills. A consensus of the high resolution model guidance 
then suggests these winds should weaken between 12-15Z (4-7 AM). So 
while the breeze should keep things somewhat mixed during the first 
portion of the night do expect winds to settle a bit heading towards 
morning. This setup once again implies some complexity to the 
temperature forecast and to which areas will fall, and how fast. 
Before getting into the details let's first state that it will be 
cold. Lows for most places will drop into the 30s, with 20s for the 
coldest interior valleys. So these readings will be hazardous to 
unsheltered individuals, pets, and sensitive plants. Most areas 
(outside of the warmest places immediately adjacent to the coast and 
bays) will see frost potential (below 35 degrees) with a freeze 
expected for some. Right now the highest confidence in seeing more 
widespread freezing temperatures is across San Benito County, within 
the Santa Clara hills, across the Santa Lucia range, and across far 
southern Monterey County. However freezing temperatures are also 
expected within wind sheltered locations (primarily inland) across 
the Monterey and San Francisco Bay areas, and within the Santa Cruz 
Mountains. Frost/freeze products are out to cover the temperature 
threat in a broad sense but do be aware given our complex terrain 
that results may vary locally with some spots dipping to freezing 
while others remain just a bit above. The key message is to check on 
people and pets, and cover or bring sensitive vegetation indoors. 

For tomorrow high pressure will dominate at the surface and aloft 
with quiet weather. High temperatures will warm a few degrees from 
Monday with low elevation highs generally in the upper 50s to around 
60. The higher terrain will remain chilly with highs in the 40s. 
Look for a repeat on Wednesday with a frosty night followed by 
afternoon warming. Winds do appear a little lighter so lows 
Wednesday morning could even be a few degrees colder in the 
sheltered valley locations. So another night to protect people, 
pets, plants and pipes from the cold. 

Friday through Sunday:

A progressive upper flow pattern will prevail with the storm track 
focusing a bit to our north. However we'll remain close enough for 
some rain chances, with the greatest potential across the North Bay. 
The first system should move through on Thursday night into Friday 
bringing modest rain amounts to the region. Portions of the Sonoma 
Hills and Santa Cruz Mountains may receive over 0.5 inches of rain 
with much lighter totals elsewhere. This system will quickly depart 
with another arriving on Saturday night into Sunday. This system 
also looks to bring modest amounts with the greater totals across 
the North Bay. Temperatures appear seasonal into early next week.

&&

.AVIATION...as of 04:36 PM PST Monday...For the 00Z TAFs. VFR 
through the TAF period. Building high pressure is resulting in 
clear skies area-wide. Light to moderate winds generally out of 
the E to NE. Another burst of NE winds aloft tonight could bring 
some stronger gusts to North Bay terminals and possible LLWS. 
Other areas will continue to experience light offshore flow.

Vicinity of KSFO...VFR. Winds have been remaining easterly and
have diminished AOB 10 kt at KSFO and other area terminals.
Expecting winds to remain offshore tonight, but may become more
northerly later tonight, so overall low confidence in direction.
Moderate confidence in winds staying AOB 10 kt tonight. Clear
skies continue through the period. 

KSFO Bridge Approach...Similar to KSFO.

Monterey Bay...VFR. Winds light and E to NE this evening, but NW
may develop at KSNS. SE drainage winds overnight tonight into 
Tuesday morning. NW winds develop Tuesday afternoon. Clear skies
prevailing. 

&&

.MARINE...as of 02:42 PM PST Monday...Gusty winds over the 
southern waters again tonight, and will begin to diminish into 
Tuesday morning. Winds remain relatively light through mid week, 
increasing again and becoming southerly on Thursday. Seas 
gradually diminish Tuesday into Wednesday, with a new 
northwesterly swell along with a storm system arriving Thursday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...Frost Advisory...CAZ502>504-508-512-528>530
             Freeze Warning...CAZ506-510-513>518
             SCA...Pt Reyes to Pigeon Pt 0-10 nm until 3 AM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM

&&

$$

PUBLIC FORECAST: SPM
AVIATION: Lorber
MARINE: Behringer

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