Hail in California, March 25 to 26, 2020

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1044 AM PDT Wed Mar 25 2020

.SYNOPSIS...A cold upper level system over the Bay Area today
will keep temperatures below normal with showers and isolated
thunderstorms. Cold overnight lows tonight with frost in the North
Bay. Residual showers for the Central Coast on Thursday while the
Bay Area dries out as the trough exits the region. High pressure
briefly builds on Friday with dry and mild weather. Quick hitting
cold front approaches Northern California later Saturday into
Sunday with a chance of light rain showers, mainly north of the
Golden Gate. High pressure builds early next week with dry
conditions forecast.

&&

.DISCUSSION...as of 09:20 AM PDT Wednesday...Isolated showers
persist over the northern portion of the region while more
scattered showers spread inland over the Central Coast this
morning. Reports of small hail have come in within heavier
showers, yet thunderstorms have yet to develop. Expecting this
activity to continue through the day with the potential for
isolated thunderstorms this afternoon/evening. Regardless of
thunderstorms, small hail will be likely within heavier rain
showers that move inland over the region given the very cold air
mass aloft. Additionally, snow levels appear to range from 3,000
feet over the north and around 3,500 feet over the southern
portion of the region. Thus, expecting high elevation snowfall to
be occuring within these showers, especially over the Santa Lucia
and southern Diablo Ranges. With this said, the ongoing forecast
remains on track with no updates anticipated at this time.

&&

.PREV DISCUSSION...as of 3:08 AM PDT Wednesday...Numerous rain showers
still rotating across the region early this morning with cold
upper trough overhead. Some of the showers last evening were
overproducers with places like Watsonville reporting seven tenths.
IR satellite indicates plenty of cold air cumulus over the ocean.
As these move onshore and hit the coastal range today they should
be efficient rain producers. Snow levels around 3000 feet with
small hail likely in the heavier showers. Storm prediction center
has our eastern areas in the general t-storm outlook and forecast
grids will carry a chance of isolated t-storms with small hail
this afternoon. 500 mb temps very cold from -25 to -30 by late
this afternoon will allow for steep lapse rates. Daytime highs
will stay in the 50s with the cold airmass aloft, even for
locations where the sun is poking out with cool daytime highs in
the 40s for the hills.

Most shower activity will end as the sun goes down. As the North
Bay dries out temperatures will fall to around freezing with some
concern for frost and impacts to the agriculture community up
there. Have issued a Frost Advisory for tonight into Thursday
morning to cover this. In contrast, enough cyclonic onshore flow
overnight to allow for a few rain showers along the Monterey
coastline. On Thursday morning a final shortwave will take aim
towards the Central Coast and keep shower chances going for the
Monterey Bay region while the rest of the Bay Area dries out but
remains seasonably cool.

High pressure builds on Friday bringing a dry day with
temperatures back into the lower 60s for daytime highs.

The weekend forecast has changed some in the last 24 hours as
another fast moving shortwave now looks to take aim on Norcal by
Saturday afternoon/evening. Rain chances look best for the North
Bay and Bay Area with increasing clouds keeping temps cool as
light rain chances increase. Precip winds down by midday Sunday as
fast moving system ejects to the east. Model trends now suggest
high pressure builds Monday and Tuesday with a return of dry
weather while longer range trends still keep the storm track
focused on the West Coast with perhaps enough troughiness for some
more light rain chances into early April.

&&

.AVIATION...as of 10:44 AM PDT Wednesday...For 18Z TAFs.
Scattered showers prevail across the Bay Area and the Central
Coast this morning under partly cloudy skies. Brief periods of
IFR vsbys will accompany heavier showers otherwise cigs will
remain VFR today. Isolated thunderstorms remain possible this
afternoon into early evening. Light and variable winds will turn
increasingly onshore and strengthen by this afternoon.

Vicinity of KSFO...VFR cigs will prevail with scattered showers
likely through the day. Brief periods of IFR vsbys possible with
heavier showers. Isolated thunderstorms remain possible this
afternoon into early evening. Light and variable winds will turn
increasingly onshore and strengthen by this afternoon. Expect
stronger gusts in the afternoon as the cold front moves through.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR cigs will prevail with scattered
showers likely through the day. Brief periods of IFR vsbys
possible with heavier showers. Isolated thunderstorms remain
possible this afternoon into early evening. Light and variable
winds will turn increasingly onshore and strengthen by this
afternoon. Expect stronger gusts in the afternoon as the cold
front moves through.

&&

.MARINE...as of 8:54 AM PDT Wednesday...Rain showers continue
over the coastal waters as the next weather system moves
southward. Northwest winds will become gusty this afternoon and
into the evening. With this system, there is also a slight chance
for thunderstorms for this afternoon. The moderate northwest swell
prevails and gradually lowers through the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pt Arena to Pt Reyes 0-10 nm from 2 PM
             SCA...Pt Reyes to Pigeon Pt 0-10 nm from 2 PM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm from 2 PM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm from 2 PM
             SCA...Pt Arena to Pigeon Pt 10-60 nm from 2 PM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 2 PM
             SCA...Mry Bay from 2 PM

&&

PUBLIC FORECAST: RGass/RWW
AVIATION/MARINE: CW

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