Friday, February 20, 2015

Tampa Bay Weather Analysis - Feb 20 Review & Feb 21 Forecast

Today on Tampa Bay brought extremely challenging conditions.  Breeze started at 10-13 for race one, but spend the next 3 races less than 10 knots.  The wind forecast we posted yesterday held very true, although the system moved more quickly and racing occurred in a NE breeze instead of the NW expected as an early part of the St. Pete cycle.

Here's the expectations we had:
  • Expect unsteadiness in wind speed
  • Expect local differences in speed across the course
  • Little predictability in oscillations
  • Boats who sail for more pressure typically win
  • Continuous short-term unsteadiness in direction superimposed on long term oscillations
  • Look for changes in wind speed - this is where the advantage is
  • Do not believe if a shift seems persistent over an entire leg...likely just too long of an oscillation to go back on that leg
  • Can recover from a gamble gone bad by using short term shifts
The short answer for reality is that the first race had more breeze and direction and speed were mostly equally important.  For the next 3 races the breeze was 10 or less and pressure won over direction almost always.  Oscillations were completely unpredictable and you could lose out bad on one leg, but by not declaring it would do the same the next leg and looking for pressure you could make back much of the losses.  

It was extremely shifty, gusty, and unpredictable.  The scores indicated that.  With our finishes of 3, 4, 15, and 9 we are in 7th place, 3 points out of 2nd (with 3 MWE Thistlers on board!).  Overall, the scoring matrix and expectations worked extremely well today and helped us not chase a false persistent shift, allowing us to go from 26 to 6 in one windward leg.

February 21 Forecast and Expectations

  • Air temp: 70-75
  • Water temp: 64 degrees
  • Wind type: Breeze (10-18 SE)
  • Breeze Type: Gradient and and/or Sea Breeze
  • Pressure System: High Pressure

The result is High Pressure (3), Gradient and/or Sea Breeze (1 or 2), Air Warmer than Water (3), which is a score of 6 or 7. Those scores say for our expected conditions:

  • If air warmer than water expect modest & unpredictable changes in direction w/ little change in speed
  • If some regular veers or backs occur expect them to break into irregularity - stay defensive

If it's a sea breeze, it should come from the SE.  If cumulous clouds form over St. Pete it's hard for sea breeze to generate until the clouds are gone, but it's a good indicator the sea breeze will try to form.  Oscillations are much quicker in a sea breeze, from 5-10 minutes (2-6 minutes going to windward) and they are much more regular.  It will typically veer (shift right) as the day goes on.  If significant puffs and lulls occur it IS NOT a sea breeze and treat it as a gradient breeze.

If it's a gradient breeze (which is a possibility based on the surface pressure map) then the wind speed should be pretty steady (unless land within 2 miles to windward).  In this breeze, direction wins out and tracking the angles and shifts is extremely important.  Tack as soon as your number crosses your median.  Keeping clear air should be very important, as well as the ability to tack when oscillations occur.

As always, contact us if you have any questions.

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