A look at the remarks section of the observation page along with the Xs in the fog column highlight

1
The Problem
A look at the remarks section of the
observation page along with the Xs in the fog
column highlight the feature of the month fog
and lots of it! 28 fog days were counted at the
NWSCS. That is, 28 days with one or more hours
of horizontal visibility limited to six miles or
less. The July 2005 fog days featured fog for
many, many hours/day, with visibilities less than
three miles (and often a quarter mile or less) on
more than 60 of the fog days. The number of fog
days is not a July record. There were 31 fog
days in July 1996. Although local records on
extent and duration, coupled with intensity, do
not exist, this observer rates July 2005 as one
of the foggiestduration, extent, intensity
combined -- in recent memory. The Marina
observer reported sixteen days with dense fog (lt
¼ mile visibility) a near record for some 20
years of July observing.
From SUMMARY of the JULY 2005 WEATHER ON THE
MONTEREY PENINSULA http//www.weather.nps.navy.mil
2
Patterns
20050720 2145
20050718 2155
20050719 2100
20050723 2035
20050721 2050
20050722 2130
3
Camera Locations
4
Del Monte Beach 23 July 1424PST
5
Sand City Camera 1 23 July 1429PST
6
Sand City 23 Camera 2 July 1429PST
7
Fort Ord (Stillwell) Camera 1 23 July 1435PST
8
Fort Ord (Stillwell) Camera 2 23 July 1435PST
9
Marina Camera 1 23 July 1400PST
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Marina Camera 2 23 July 1400PST
11
Marina Camera 4 23 July 1410PST
12
Marina Camera 5 23 July 1420PST
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What accounts for these persistent fog patterns?

• First, consider the observations of wind speed,
  direction and temperature- does anything stand
  out?
• Next, determine if 3km COAMPS can resolve these
  small-scale differences.
• A slope in the boundary layer?
• Split flow?
• Small area of subsidence?

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Observation Stations Topography
M0
SNS
ORD
M1
R07
M2
R30
MRY
MBA
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Temperatures at Del Monte Beach increased
throughout the afternoon in sunshine.
No sustained seabreeze-related increase in wind
speed..
Wind varied between NW and NNE- sometimes from
water, sometimes from land
18
Temperatures at the airport increased throughout
the afternoon in sunshine.
No sustained seabreeze-related increase in wind
speed..
Wind veered from NW (water) to NE (land).
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Temperatures at Fort Ord decreased throughout the
afternoon in fog.
Significant increase in wind speed- seabreeze.
Wind backed from WNW to WSW and then veered back
to WNW.
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3km COAMPS Temperature 05, 08,11,1400PST
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COAMPS Temperature- Results

• No along coast pattern evident

25
3km COAMPS Winds 05, 08,11,1400PST
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COAMPS Winds- Results

• NE winds at Del Monte Beach and airport not
  evident
• Seabreeze-related increase in wind speed at Fort
  Ord not evident
• No split flow evident

27
3km COAMPS Theta 05, 08,11,1400PST
28
COAMPS BL- Results

• No apparent slope in the BL along a cross section
  running from the SE Bay through the airport

29
3km COAMPS Vvel 05, 08,11,1400PST
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COAMPS Vertical Velocity- Results

• No subsidence evident anywhere

31
Conclusions

• There is a persistent pattern to the fog along
  the coast of Monterey Bay specifically, there is
  a clear pocket that extends from Del Monte Beach
  to Sand City and inshore to the airport.
• From observations, it would appear that this
  could be due to a shift from NW to NE winds in
  this area.
• There were no patterns evident in the COAMPS data
  to explain this phenomena- probably on a scale
  smaller than 3km (2 miles).

32
Acknowledgements

• Richard Lynd- observational data
• Mark Orzech- camera images
• Professor Nuss- COAMPS and advice
• Professor Wash- NRL MODIS imagery
• Bob Creasey- COAMPS