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|01-04-2002 07:14 AM
Noaa Marine Weather Images
I feel some frurther information re my prior post re Noaa marine weather images could be helpful.
Here is a list of reasons why I think having forecast synoptic images for the Gulf of Mexico and Caribbean is important, as important as they are for the Atlantic and Pacific oceans.
#1. In lower latitudes a small isobaric pressure differential dramatically
produces more wind than would the same pressure differential across the same
distance in the upper latitudes. From a table comparing isobaric pressures,
across a set distance of say 150 nm between say 4 mb isobars, and then the
resulting wind speeds, consider the following: At 10 degs lat a 4 mb
pressure differential across a 150 nm distance produces a wind speed of 88
knots. At 20 degrees lat = 45 kts, 30 degs lat = 30 kts, 40 degs lat = 25
kts, and 50 degs lat = 20 kts.
#2. Any High pressure region to the north of the Caribbean which starts
shifting south dramatically increases the normally low pressure
differential, causing a subsequent increase in winds. As an example: Working
from an isobar vs wind speed table, in the northern Caribbean ie at 18
degrees North latitude, using 4 mb isobar spacing, a pressure gradient
increase of 4 mb across 300 nm to 4 mb across 250 nm, produces an increase
in wind from 28 knots to 35 knots.
#3. Generally year round, there is more wind on any givend day in the
Caribbean, especially in the Eastern
and Southern Caribbean, than there is around the South East US, ie the Gulf
of Mex, Florida, the Northern and Central Bahamas, Georgia, Carolinas, etc.
#4. The Gulf of Mexico is an entirely different body of water than the
Caribbean, especially in the fall, winter and summer months, and the
argument doesn''t even apply to the Gulf of Mexico. Cold fronts can be wicked
in the Gulf of Mexico.
#5. There are a ton of boats underway in the Caribbean at any one time, more
so than in any other comparably sized body of water. Many boats in the
Caribbean must anchor very near "steep-too" islands in deep, and are
susceptible every night to slight changes in wind, wave and swell direction.
We are talking about Noaa adding just six images to the current list of images available for the Gulf of Mexico and Caribbean. These would be 00Z and 12Z for each forecast interval 24 hours, 48 hours and 96 hours. Surely this would be no great burden. They would add immeasureably to the weather awareness of mariners in the affected bodies of water.
I think the images can and should be added as soon as possible to the suite of products available online via the Noaa web and FTP
servers, and if possible by juggling the NMG broadcast schedule, be added to the radiofax schedule. In my opinion forecast synoptic images are more valuable than the USCG "Highseas" and "Offshore" voice broadcasts. The problem with voice broadcasts is they cover too wide an area. The result is they loose applicablity to specif locations within these wide areas.
2. If as is presently done by the MPC, small, light font wind barbs can be added to forecast synoptic charts, I think that makes for a better presentation method than presenting just wind/wave charts or just isobaric charts.
#3, if Noaa lacks the necessary budget or staff time to create these additional forecast synoptic charts, while the MPC on a different budget has the necessary budegt or staff time to create them, then I think
that the MPC could or should be considered as a source for the forecast charts for the Gulf of Mexico and Caribbean.
Thank you. Again, if you would like to weigh in on this issue or would like to get in touch with myself or Noaa, you may email myself or the person in charge at Noaa, Chris Burr. My email address is CaptCook@Ocean-Pro.com. Chris Burr''s email address at Noaa is Burr@nhc.noaa.gov.
|12-24-2001 05:40 AM
Noaa Marine Weather Images
I would like to call attention to an area for improvement in the marine weather images which Noaa makes available on it''s web site, via FTPmail and via radiofax.
Noaa''s latest Marine Weather product suite for the Gulf of Mexico and Caribbean, both before and after the latest product suite revision of Dec 4th, does not include "forecast synoptic Surface Charts for
these two important ocean regions.
All three of Noaa''s primary marine weather image distribution methods, the Noaa web site, the FTP Mail
server, and USCG weatherfax broadcasts from NMG, show only
past synoptic "Surface Charts" for the "past 24 hours". These consist of eight
images. Four of them now show the "West Half of the Tropical Atlantic" at 00z,
06 z, 12z and 18z. and four show the "East Half of the Tropical Atlantic for
00z, 06z, 12z and 18z. These images give a mariner a look back in time but
not a look forward! I believe we need "forecast" synoptic images for the next 24, 48, and 72 or 96 hours for the Gulf of Mexico and Caribbean. I have been in communication with Noaa about this subject for months without success.
There are no forecast synoptic "Surface Charts" for the Gulf of Mexico and
Caribbean showing the forecast synoptic situation 24 hours, 48 hours, or 72
or 96 hours from the present. There are "Wind/Wave charts for the past 24
hours, and the next 24 and 48 hours. They show wind, waves, and any fronts,
but do not show HIGHS, LOWS or isobars, or the anticipated movement of these
features. I think this is a serious ommission of important weather data for
By comparison, Noaa''s product suites available via their web site, FTP mail
and for broadcast via USCG weatherfax do show forecast synoptic Surface
Charts" for 24, 48, and 72 or 96 hours for the two other primary Ocean
regions, the Atlantic Ocean and the Pacific Ocean. These are represented by
the images broadcast by USCG station NMF in Boston, Massachusetts; and by
USCG station NMC in California.
I absolutely do not understand why forecast synoptic Surface Charts are not
made available for the Gulf of Mexico and Caribbean. I think it is a serious
ommission of weather information for mariners. I would like to see Noaa do whatever it takes to add these images!
Capt Bob Cook
USCG Captain, 100 ton vessels
Offshore Sailing Instructor
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