April Showers…
April 20, 2009
Better bring some May flowers, because I am tired of sailing in the rain. Of course all of these low pressure systems sure bring good wind and a chance to learn a little bit about weather systems and how they influence the wind we use.
This past weekend I was fortunate enough to sail with clients Friday, Saturday and Sunday and witnessed a fairly regular weather system change.
Monday through Thursday a low pressure system pounded the Chesapeake Bay with big breeze (from the East) and lots of cold rain. Then a high pressure system swept in, brought big wind initially and lots of sunshine. For the Annapolis area with the sun came warmer temperatures and a bit of sea breeze (water temperature in the Bay is 52 degrees) and some great sailing conditions. But by Sunday a new system was moving in and the wind and weather changed pretty radically.
I had predicted that the weather system would arrive late in the day on Sunday – but instead it showed up around 1130 and conditions changed from light and variable to NE and building, and finally settled into an easterly 12-16kts.
In fact in the race on Sunday we went from 10-20kts of appartent wind in about 15 minutes. WHOA! Looking at my notes from that race there were some pretty clear indicators. Patchy clouds at 0900 gave way to steady cloud cover at 1045. Swinging ships with at least a 100 feet more “air draft” began swinging, long before we felt the shift at the surface – yet it was obvious enough that I wrote it down.
All in all it was a great lesson that I hope I can apply to a race situation again in the future.
I have posted a current surface map for the Mid-Atlantic region in this post. You should be able to click on it and view a larger version. Here is some information on how to read that map.
How to Read a Surface Map
Surface maps depict the large-scale elements of the weather. These elements include high and low pressure systems, cold and warm fronts, and precipitation areas.A high pressure system is an area of relative pressure maximum that has diverging winds and a rotation opposite to the earth’s rotation. Fair weather is typically associated with high pressure.
A low pressure system is an area of relative pressure minimum that has converging winds and rotates in the same direction as the earth. This is counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Stormy weather is often associated with low pressure systems.
A cold front is the leading edge of an advancing cold air mass that is under running and displacing the warmer air in its path. Generally, with the passage of a cold front, the temperature and humidity decrease, the pressure rises, and the wind shifts (usually from the southwest to the northwest in the Northern Hemisphere). Precipitation is generally at and/or behind the front, and with a fast-moving system, a squall line may develop ahead of the front.
A warm front is the leading edge of an advancing warm air mass that is replacing a retreating relatively colder air mass. Generally, with the passage of a warm front, the temperature and humidity increase, the pressure rises, and although the wind shifts (usually from the southwest to the northwest in the Northern Hemisphere), it is not as pronounced as with a cold frontal passage. Precipitation, in the form of rain, snow, or drizzle, is generally found ahead of the surface front, as well as convective showers and thunderstorms. Fog is common in the cold air ahead of the front. Although clearing usually occurs after passage, some conditions may produce fog in the warm air.
Current surface maps are updated every hour. Forecast surface maps are updated once each day.
If you are looking for more resources on weather, wind and forecasting. Give us a call or contact us.
April 12, 2009
Tides.Info: Tide Predictions for Annapolis, Maryland
Building the Ark
April 1, 2009
Spring has arrived and I know that there are plenty of folks who are eyeing their savings accounts and the brokerage pages thinking about a great season on the water. I can’t think of a better bad idea. Boats make very little sense – except for all those times you are on them. DO IT!
About me
I am the owner of Gale Force Sailing and write about all things related to coaching, instruction and team building. contact me>>
