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Area forecast discussion 
National Weather Service San Francisco Bay area
632 PM PDT Sat Mar 28 2015

Synopsis...warming trend is expected into Sunday with mostly
clear skies. A cooling trend is then forecast for Monday through
Wednesday. Dry weather is expected to persist through the forecast
period.

&&

Discussion...as of 2:45 PM PDT Saturday... visible satimg shows
mostly clear skies over California with just a few high clouds
present over the area. A weak dry cold front slid across
northern/central California earlier today in the wake of the
previous ridge. The strong northerly gradient that helped clear
stratus from the coast is gradually weakening this afternoon...
dropping from -6.7mb to -5... but is still strong enough to
generate breezy conditions over the coastal waters this afternoon.
Temperatures are running much warmer today versus
yesterday... especially along the coast... where the lack of
clouds (relative to yesterday) is not inhibiting maximum diurnal
heating. Ksfo is 11 degrees warmer as of 2pm today than 2pm
yesterday (73 vs 62f) and is forecast to rise a few more degrees
this afternoon. The only locations showing cooling trends are those that
were directly the ridge the last few days... ie southern San
Benito County. Weak ridging rebuilds into tomorrow South Dakota temperatures
will trend warmer with middle 70s to around 80 forecast for most
inland locations.

Temperatures are expected to cool through midweek next week. Cool
is a relative term however as temperatures will still be a few to
several degrees above normal. In case you missed it... 2015 has
been the warmest winter on record for California (as of the end of
February... and March is on pace to be the warmest as well). The
cooling will come as a low pressure system passes well to the
north of our forecast area. No precipitation is expected through
the end of the month in our area at this time.

Long term models are trending towards a low pressure system
sweeping into norcal and spreading precipitation through our area
around April 5-6. The Euro is the most bullish in this scenario...
however the Euro has overanalyzed the southward amplification of
troughs and associated precipitation production for most of the
winter/Spring so far... so leaning more on GFS for guidance at
this time.

&&

Aviation...as of 6:20 PM PDT Saturday...VFR. 24 hour trends indicate
much drier conditions due to northerly winds. The onshore gradient
sfo-SAC is presently 2.2 mb and the acv-sfo and uki-sts gradients
are 7.3 mb and 2.5 mb respectively. The sfo-SAC gradient will probably
weaken tonight while the wmc-sfo gradient increases to 7 mb by Sunday
morning per the 18z NAM model run...which initialized well on the 18z
run. Dry northerly winds are expected to continue into Sunday with an
onshore wind component returning by afternoon...and as the larger scale
wmc-sfo gradient is forecasted to scale back to neutral. A dry northerly
wind persists into Monday morning but sea-breezes are likely to be a
bit more robust in the area by Monday afternoon.

Vicinity of ksfo...westerly wind gusts to 25 knots until 04z. VFR.
High confidence forecast.

Sfo bridge approach...VFR.

Monterey Bay area terminals...high confidence VFR holds into the
evening hours...but there is lowering confidence regarding low cloud
and/or fog potential very late tonight. There could be a few brief
very small patches of either low clouds or fog Sunday morning per
recent model forecasts indicating higher boundary layer humidity
Sunday morning along the southern half of the Monterey Bay...but
believe it's not enough to include IFR in the tafs. 00z tafs maintain
optimistic approach with VFR for the overnight hours.

&&

Marine...as of 02:12 PM PDT Saturday...a strong northerly surface
pressure gradient will maintain moderate northwesterly winds
across a majority of the coastal waters through middle week. These
gusty northwesterly winds will generate steep fresh swell. A
moderate period westerly swell will begin to build into the waters
Sunday night.

&&

Mtr watches/warnings/advisories...
... Pt to pt pinos 0-10 nm until 3 am
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm
Small Craft Advisory...pt Arena to pt Reyes 10-60 nm
Small Craft Advisory...pt Reyes to Pigeon pt 10-60 nm
Small Craft Advisory...Pigeon pt to pt pinos 10-60 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 10-60 nm
Small Craft Advisory...Monterey Bay until 11 PM

&&

$$

Public forecast: drp
aviation: canepa
marine: rww

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