Weather Service Report


530 
FXUS66 KMTR 202046
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
146 PM PDT Fri Jul 20 2018

.SYNOPSIS...Seasonably warm daytime temperatures will persist
through the weekend with marine air keeping conditions cooler near
the coast. A more robust warming trend is then expected for next
week, especially across inland areas, as as strong ridge of high
pressure builds over the region.

&&

.DISCUSSION...as of 01:41 PM PDT Friday...Similar to yesterday, 
the deeper moisture in the 700- 500 MB layer split to our west and
to our east with drier conditions aloft over our region. This, 
along with less than forecast instability, resulted in little to 
no high-based convection over our region. However, there was a 
shower that moved over the Delta and then another cell with 
lightning detected east of the region near Stockton. Otherwise, 
temperatures today are not nearly as warm (in most areas) as those
yesterday due to the ridge aloft shifting eastward away from the 
region.

Overall, similar conditions are likely into Saturday with still some 
higher level moisture over the region that will diminish throughout 
the day as southwesterly flow develops aloft. Cannot rule out a 
rouge shower or brief thunderstorm over the San Francisco Bay Area 
Saturday morning, yet chances are marginal enough to keep a mention 
of convection out of the forecast at this time. Little change is 
expected as we head into Sunday as well with temperatures near 
seasonal averages and the presence of a marine layer. This should 
result in low clouds near the coast penetrating inland each night 
and lasting into the early morning hours before dissipating by late 
morning. This too will keep conditions coolest at the coast while 
inland areas warm into the 80s and 90s. 

A more robust warming trend is then forecast for early next week and 
lasting into at least midweek. The greatest heat appears to stay 
over interior as well as southern portions of the state with 500 MB 
heights forecast to approach 600 DAM. However, onshore winds are 
forecast to persist over our region which will help limit overall 
heating across much of the Central Coast and San Francisco Bay Area. 
The exception will be far inland areas and those in higher 
elevations of the region where we could see temperatures range in 
the 100 to 105 deg F range (especially for the interior). We'll 
continue to monitor the potential for heat risks in the coming days, 
however widespread concerns do not appear likely at this time for 
urban areas. Stay tuned...

&&

.AVIATION...As of 10:41 AM PDT Friday...All terminals becoming 
VFR as of this writing. NE winds at SFO pushed in some cigs 
briefly, but otherwise it has been similar to the last few 
mornings. VFR this afternoon. Will bring cigs back in again 
tonight. SFO will be borderline again, LVK/SJC VFR with cigs 
elsewhere.

Vicinity of KSFO...VFR through the forecast. Some cigs will be
lurking around tomorrow morning, but confidence is low on impacts
a this point. Westerly wind gusts to 20-25 knots possible this 
afternoon and early evening.

SFO Bridge Approach...VFR today. Otherwise similar to KSFO.

Monterey Bay Terminals...VFR this afternoon. Not conf on strong SW
flow keeping MRY clear. Therefore, brought back cigs to MRY and
SNS this evening.

&&

.MARINE...as of 09:18 AM PDT Friday...A weak disturbance over the
coastal waters will result in gusty northerly winds over the 
northern outer waters and lighter variable to southeasterly winds 
elsewhere. Northwesterly winds will redevelop over the coastal 
waters early next week. Gusty onshore winds will redevelop north 
of the Bay Bridge to the Delta later today and again later 
Saturday. A long period southwesterly swell arrives by early next 
week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm until 9 PM
             SCA...SF Bay until 9 PM

&&

$$

PUBLIC FORECAST: RGass
AVIATION: MM
MARINE: MM

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Western Regional Climate Center, wrcc@dri.edu