7 Habits of a Highly Effective Marine Weather Forecaster
1 Start by looking at relevant Satellite maps:
a. Infrared Eastern North Pacific the big picture2. Read the weather forecast discussion for SF Bay and surrounding regions--Sacramento--Every area of the state is covered. At first it's hard to read but just read through it and try to understand what you can. See Glossary
b. Satelite Animator What direction is the flow? How fast or slow is it?
c. Visible SF Bay Area
d. Wind and water vapor shows the true circulation pattern
3. Look online or listen to the weather radio to get Pacific buoy information. Click on the buoy for a 24 hour record of various weather records; wind, waves, air & water temps, and barometric pressure. For SF Bay.
In the Spring and Summer, a persistence (the next day will be the same) weather forecast can be used; see if you can determine the daily trends in the winds.
4. Look or listen (with a weather radio) to NWS SF Bay marine forecast the Pacific Coast NWS marine forecasts
5. Look online at the current Pacific Analysis and pay particular attention to the arrows since these indicate the direction and flow of the wind and the waves. Check out the North Pacific briefing. Read the North Pacific Forecast Discussion.
6. Look online at Stormsurf's Quickcast
7. Look online at the 7 day wind forecasting. Look for trends over the 7 days.
Meteorology is an inexact science; there are too many variables to be entirely accurate (although the butterfly effect may be a myth), so don't expect to be able to do an exact forecast. An example to consider is to forecast how much money you've got in your pocket. Occasionally you guess exactly how much you have. More often, you've got a ballpark figure, but don't know the exact amount. I look for such ballpark figures when reviewing weather information. I look for the best and the worst conditions I can expect.
Local Weather Tips
Higher barometric pressure moving inland (which can happen any time of year) usually brings the best kayaking conditions--sunny and warm--to our coast. Compare the barometric pressure readings at SFO San Francisco International and SAC Sacramento International Airports. Usually the pressure gradient pattern is described in the forecast discussion. If it isn't mentioned, you can determine the gradient at the bottom of this page. This is a good general guide for wind direction and barometer.
Our 3-4 day heat waves are usually followed by a Southerly Surge of cooler marine air.
colder our nearshore waters, the thicker our fog bank will be. In
the spring and summer, upwelling
lowers our nearshore water temperatures to the low 50s--and if the upwelling
is strong, to the upper 40s.
Conversely, if the upwelling stops, the water temps reach the mid 60s; in the lower 70s in pockets of protected waters along the Pacific coast, the fog bank disappears--it needs the colder water to form. Daily fog and clouds forecast
Gales occur 1-2 percent of the time inside SF Bay, most often in Dec/Jan.
The prevailing wind on SF Bay North of the Bay Bridge is West/SW; South of the Bay bridge it is North/NW. See current wind chart
If the major ebb tide falls in the afternoon, there is a much better chance of clearing as (relatively) warm water flows out the gate. I have noticed many times that the fog bank clearing reflects the plume of warmer water moving out the gate. And conversely if the major flood occurs in the afternoon the colder ocean water will inhibit the clouds from clearing.
Adverse conditions result when you have:
Smoother conditions result when you have:
The edges of low clouds have the highest surface winds.
the winds are out of the south on the open coast, the low cloud and
fog areas are expanding or increasing. If the wind is out of the
northwest, the low cloud and fog areas are contracting or decreasing.
Some consider San Francisco Bay weather to have the least variety in the lower 48 states.
South wind: High to your South and a Low to your North
West wind: High to the West with a Low to the East
North wind: High to the North with a Low to the South
East wind: High to your East with a Low to the West
The Highs and Lows are
closely related and can only be as strong or as weak as each other.
Storm fronts push through every 7-10 days except for a dry spell which happens every winter when the Pac High moves North and blocks the storms for a 2-4 week period.
Fog blows the other way East to West from the Central Valley down the delta through the Carquinez Straits and then down Sf Bay and all the way out the Golden Gate.
Our windiest season The cool Pacific air rushes in to replace the warm rising air inland. The temperature and air pressure differences are the greatest this time of year
Late spring and summer season are our fog and low cloud season Aug. and Sept. are the foggiest but are the least windiest.
Sept. and Oct. are the warmest months on the beach. Indian Summer conditions result when High Pressure builds inland.
Some of the best kayaking weather conditions can be found during this season.
Worst times to paddle the coast for particular weather conditions:
Best time to paddle the Bay: In between Winter storms and during the Fall when high pressure moves inland.
Best times to paddle the Pacific Ocean: Any time of the year when surface High pressure moves inland into the Great Basin. When this happens we usually get 2-3 days of great conditions year round.
Understanding our Sea Breeze
The sea breeze usually peaks in the afternoon/evening but can go all night usually by morning it is weaker. A good summer forecast is persistence; look up the wind reports and see if you can determine a pattern.
This gradient starts out very small in the desert Southwest in March as the continent starts to warm under the increasingly strong rays of the sun. By summer it is massive, covering thousands of square miles of the desert Southwest, peaking around the Summer solstice. As summer progresses an upper level high called the 4 corners High moves on top of the desert thermal Low making it expand out underneath the High.
Sometimes it expands Westward and rolls over us and heads out to sea completely reversing the flow from onshore to offshore and ending the seabreeze. We get a heat wave and under the Low the winds are light and air is warm, providing great kayaking conditions.
This year 8-2003 the High was so big and strong that it created a SE to NW flow of Pacific Ocean water in front of the Central Calif. Coast. This reversal of the usual pushed water temps into the mid 60's and we didn't have a fog bank the first half of August.
Gradually the gradients relax as the air masses mingle and become more like each other. As the continent slowly cools in the Fall with the shorter days, the Thermal Low weakens and eventually disappears in November. The continent becomes cooler than the ocean and the pressure gradient pattern is reversed, with Highs on land and Lows out at sea.
Storms have thousands of miles of unimpeded progress as they cross the Pacific. As they approach the West Coast, the continent gets in their way and they are squeezed to get through. You can see the storms hit this High pressure pocket of air and start to stagger, hence the reason the timing is usually off on when the rain or winds will start. Sometimes the storm is almost completely dissipated.
air (relative) moving over (relatively) cooler water creates the fog.
The cooler the water, the thicker the fog
Fog and low clouds have a daily/weekly/yearly cycle.
The fog moves in in the afternoon and then gets evaporated by the sun the next morning. The last places to fill are usually the first to clear.
If a fog bank is strong, it will cool the hot interior valleys and weaken the hot air machine that feeds it. Once weakened, the valleys warm again and the process is repeated over and over.
Nearshore water temps are the key. If nearshore water temperature measurements get above 60 degrees, expect less fog. If temps stay in the low 50s or upper 40s, expect a thick fog year.
Bay fog in the summer is rarer than the winter because as the fog flows inland, it hits the warmer waters of the bay and gets lifted by the time it gets over to the East Bay.
Just like in the spring, in the fall the fog comes back in low on the water. This is the time of year to look for fog falls as fog flows over a hill and runs down the far side.
an inversion, the normal conditions (cooler air as you go up) is reversed.
This is the major reason we don't get summer thunderstorms very often.
With warm air above the cooler air, the air is very stable.
A big change is coming about how the general public can access weather forecasts
The NWS is about to undergo a fundamental change; instead of waiting for weather forecasts to be issued every 6 hours, we will be able to make our own digital weather forecasts
This is the future of weather forecasting!
If you want to pay for your specialized forecasts try these sites:
I use a guide that works for my experience and skill level: 10-30-3
10 stands for 10-foot waves
30 stands for 30-knot winds
3 stands for 3-knot current
Anytime these these (or higher) conditions are reported or forecasted, I know that my skills could be overwhelmed. I know I can't fight these conditions for long but I can still go kayaking and go with these conditions or paddle in protected areas.
I would encourage all kayakers to develop their own weather/condition guides tailored to their skill and experience levels.
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