Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service San Francisco Bay area
526 PM PDT Tuesday Jun 30 2015

Synopsis...hot weather expected once again tomorrow...especially
across inland portions of the forecast area as high pressure
continues to build over the western United States. Cooler
temperatures are anticipated on Thursday as the center of the high
pressure shifts position. Upper level moisture will also make its
way toward our area Wednesday and Thursday which could lead to a
few showers and isolated thunderstorms.

&&

Discussion...as of 3:30 PM PDT Tuesday...hot temperatures are
being reported in many inland locations this afternoon. So far
Livermore has hit 106...Concord is 98 and Gilroy 98. Along the
coast temperatures are quite a bit cooler with Monterey at
67...Santa Cruz 81 and downtown San Francisco 72 degrees. The
marine layer is right around 1000 feet deep with relatively light
onshore flow. This onshore flow will provide cool overnight
temperatures along the coast with some patchy fog.

The current satellite water vapor image continues to show a low
pressure system in the Gulf of Alaska with moisture rotating
around a dome of high pressure centered over the Great Basin area.
The 1800z gfs40 and 1200z European model (ecmwf) have initialized well with the
current synoptic pattern and remain in good agreement through the
Holiday weekend. Both models continue to build a dome of high
pressure over the western states which is resulting in hot
temperatures across the inland areas of our County Warning Area.

The 1800z gfs40 continues to show 850mb temperatures over the
inland portions of the County Warning Area warming to 26 to 27 c on Wednesday.
With light winds beneath the dome of high pressure and these hot
850mb temperatures expect surface temperatures to reach the upper
90s to 108 in some inland locations once again tomorrow. Earlier
today we issued a heat advisory for the North Bay area...East Bay
area and the Santa Clara Valley valid today into Wednesday. This
message looks to be verifying well today and should also verify
tomorrow as well. Along the coast expect a gentle sea breeze once
again tomorrow which will maintain another comfortable at the
areas beaches.

Temperatures are expected to cool a few degrees by Thursday as the
center of the dome of high pressure shifts to the northwest. With
the repositioning of the high a shot of monsoon moisture will
push into the area Wednesday into Thursday bringing up the
possibility of showers and isolated thunderstorms.

For the Holiday weekend it looks like the center of the high will
shift back towards The Four Corners states...bringing cooler
temperatures to the forecast area. Along with the cooler
temperatures expect a return of the marine layer at the coast.

&&

Aviation...as of 5:00 PM PDT Tuesday... high pressure over the
area will maintain mainly clear conditions across area terminals
and will continue to compress the marine layer. Coastal terminals
such as kmry...ksns...khaf...kwvi.Will be the only terminals to
see ceilings tonight. The shallow marine layer will keep low clouds
confined to the coastline. Light to moderate onshore flow will
continue through the forecast period.

Vicinity of ksfo... VFR. Onshore winds to 15 knots this afternoon
easing to around 5 knots overnight.

Ksfo bridge approach... similar to ksfo.

Monterey Bay area terminals...IFR ceilings returning after 06z with LIFR
visibility/ceilings possible between 11 to 16z Wednesday. Moderate onshore
flow will ease becoming light and variable overnight.

&&

Climate...record highs for June 30 and July 1 for selected
locations.

Sf Bay area.................June 30............July 1
Kentfield..................106/1972...........103/1996
San Rafael..................98/1999............99/1991
Napa.......................105/1972...........103/1972
San Francisco...............93/1996............92/1991
sfo Airport.................92/1996............99/1985
Oakland downtown............90/1972............92/1984
Oakland Airport.............90/1950............90/1985
Richmond....................91/1996............97/1985
Livermore..................112/1972...........110/1950
Mountain View...............91/1972............97/1985
San Jose...................100/1996...........102/1985
Gilroy......................98/1999...........108/1972

Monterey Bay area............June 30............July 1
Monterey....................89/1996............96/1985
Santa Cruz..................98/1996............99/1970
Salinas.....................94/1996............85/1996
Salinas Airport.............97/1996............88/1991
King City..................109/1950...........105/1985

&&

Marine...as of 11:03 am PDT Tuesday...northerly winds gradually
decrease today from south to north with some gusty winds lingering
north of pt Reyes into the evening. Winds will continue to
decrease Wednesday through Friday as the weather pattern shifts. A
weak disturbance will move through the region on Thursday bringing
a chance of showers and thunderstorms to the region.

&&

Mtr watches/warnings/advisories...
... Advisory...North Bay area...East Bay area and the
Santa Clara Valley.
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm until 3 am
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm until 3 am
Small Craft Advisory...sf Bay until 9 PM

&&

$$

Public forecast: Larry
aviation: CW
marine: drp
climate: Bell



Visit US at www.Weather.Gov/sanfrancisco

Follow US on facebook and twitter at:
www.Facebook.Com/nwsbayarea
www.Twitter.Com/nwsbayarea

National Weather Service Glossary of Abbreviations