This is the weather system where we see a few squalls or thunderstorms and then a dramatic wind shift into the NW. During the Spring, Fall, and Winter, we can see much colder temps and frequently we see a gusty, unstable wind of 20-30+ kts after this weather system passes. Cold fronts are by definition,

1. a transition from a warm, moist air mass into a colder, drier air mass
   a) during the summer months, it may not be cooler, but it will be drier
2. rising surface pressures
3. in the northern hemisphere, winds frequently shift S and SW into the W and NW
   a) occasionally winds will shift into the N and NE – this is very common between 20 and 25N and can also occur with the notorious “back door cold front” in the northeast U.S.

On a surface weather map, a cold front is depicted as a line with solid triangles on the warm side of the line. On color charts, the cold front is represented as blue and the warm front as red Cold fronts are frequently accompanied by or preceded by a squall line.


The squall line can be

1. a brief band of showers and a few scattered gusts to 20-30 kts or
2. a serious line of severe thunderstorms

1. the showers and thunderstorms develop on the leading edge of the cold front, where the cold air undercuts the warm moist air
   a) the warm air rises and condenses into the clouds, showers, and thunderstorms
2. once developed, the clouds, showers, and thunderstorms will move at the speed and direction of the winds aloft, which is frequently faster than the cold front is moving
   a) this means the showers and thunderstorms can be as much as 2-4 hours ahead of the actual cold front. This can be very important during a race!
3. the showers and thunderstorms can cause a premature wind shift into the W and NW, along with wind gusts 20-30 kts or more
   a) many think this is the actual cold front, but it is just a squall line, preceding the cold front
   b) once the squall line passes, winds will diminish dramatically and wind shift back into the WSW or SW, since the actual cold front has not passed!
   c) this also means, you can get a 2nd squall line, if there is enough heating and moisture along the actual cold front for another squall line to form
   d) just because you get a squall and a wind shift, you do not get a cold front
   
   
4. To be certain a cold front has passed and winds will stay W or NW or continue to clock
   a) wind speeds do not diminish, after the squall passes or better still, increase as the skies clear. This can be very tricky on land or right next to the shoreline, as the rain cooled land may prevent the stronger winds aloft from mixing down to the surface, but
   b) over the ocean, 1-2+ miles away from land, it is simple – if the squall ends and wind speeds are the same or increasing, the winds will remain W or NW and may continue to clock and the cold front has passed.

Back Door cold front

1. This is a cold front that originates over eastern Canada or the Gulf of Maine, especially during Spring and early Summer, when the ocean temps are still cold, especially relative to land temps
2. They are most common when land temps are much warmer than normal
3. The front develops when high pressure moves into eastern Canada or the northern Gulf of Maine
4. The cool air over the Gulf of Maine or Gulf of St Lawrence surges to the SE, S, and SW
   a) much stronger N and NE winds will accompany this surge of cool, moist ocean air
5. The various weather models do a very poor job of forecasting this type of cold front
   a) winds are much stronger than forecast by the weather models – I have see NE and ENE winds behind a “back door cold front” up to 30-40 kts in Long Island and S of Newport
   b) the front pushes further S than any weather model suggests
   c) yes, you can get a squall or thunderstorm preceding this front and they arrive from the N and NE, not the more typical W and NW direction
6. What to look for,
   a) when very warm in the Spring or early Summer, watch for increasing high pressure over eastern Canada
   b) the front 1st develops on the Maine coast as a NE and E wind, which could look like a sea breeze
   c) it then spreads to the SW, 1st to the east coast of Massachusetts, then Cape Cod, and Buzzards Bay
   d) frequently pushes W and SW across coastal Rhode Island and into Long Island and Long Island Sound
   e) on rare occasions the front will reach coast New Jersey and Delaware
   f) this is purely a Spring and early Summer weather phenomena

Three time J/24 World Champion Mauricio Santa Cruz testing his new sails in a light breeze at Primo Cup 2011, finished second out of 28 boats.

February is a traditional sailing month for Monaco, starting the season with the Primo Cup. The three day event, started on February 4th 2011.

Twenty-eight J/24s from Monaco, Italy, Sweden, Hungry, England, France and Brazil were looking forward to some top notch racing, but we did not have much luck with the wind gods. There was almost no wind and the Race Committee only managed to run one race.

Unfortunately just after the committee shortened the one-and-only race, the wind shifted 30 degrees to the right, which moved Alessandro Cominelli Nois from Monaco ahead of us. He took first and we finished second in the race and the regatta.

Even with that result, I am more than satisfied with the new sails; they showed outstanding performance in all conditions. The next J/24 event will be in Texas, on March 19th and 20th, at the Austin Yacht Club where I'll be answering all questions regarding our new UK-Halsey Santa Cruz sails and tuning tips. The sails are produced by UK-Halsey Texas and Mauricio Santa Cruz’s designs and construction standards. For more info you can contact:

UK-Halsey Santa Cruz
Estrada General Eurico Gaspar Dutra, 211,
Jurujuba, Niteroi / Brazil CEP: 24370-375
+ 55 21 3611-1161
santacruz@ukhalsey.com
Mauricio Santa Cruz

UK-Halsey Texas
2031 Anders Ln., Suite J
Kemah, TX 77565 USA
Tel: 281-334-3464
Fax: 281-334-3874
texas@ukhalsey.com
Pedro Gianotti