Replies to Best Track Change Committee - March 2009
Notes on the Best Track Committee Meetings 1/27/2009 to 2/6/2009
Responses to the committee's comments are indented.
The committee met to discuss the responses provided by the re-analysis
project for the storms from 1921-1925. For the most part, the committee
agrees with the responses. However, there are a few meteorological
aspects that still need clarification, and a few minor corrections to be
made in the write-ups.
: The committee accepts the submitted track. Is a
position available for the 50 kt ship report on November 21? Also, is
anything available from Cuban records on this system?
Yes-as provided in the excel spreadsheet, the position for the
ship is 23.7°N 74.4°W. Analyses from Cuban meteorologists at the
time (Ramon Perez, personal communication, 2008) suggested that this
system was a tropical depression at landfall in Cuba. The observed gales
were located well-removed from the center northwest of the cyclone,
suggesting that the system had some subtropical storm characteristics.
At landfall in Cuba late on the 22nd, the cyclone's peak winds had
weakened to around 40 kt, primarily occurring in the Florida Straits and
: The committee chair has forwarded some additional
information on the impact of this storm on Bermuda. This does not appear
significantly different than the Bermuda data already available but could
be noted in the September 21 write-up. There is a 944 mb pressure
observation on September 25 in the summary section that needs to be added
to the daily September 25 section.
Data and commentary from Port Prospect Observatory as reported in
the Royal Gazette and Colonist Daily (provided by Mark
Guishard) are added into the writeup and the excel database. The 944 mb
observation is added into the daily section for September 25th .
The committee has an issue with the 95 kt intensity as an extratropical
system on September 25. Could you please re-examine this? While there
are extratropical cyclones of this intensity, most 944 mb or lower
extratropical cyclones do not have winds this strong.
Agreed. Winds reduced to 75 kt during the duration of this
strong extratropical cyclone portion of the system.
1922 new #3
: The committee accepts this system. However, it
would like more detailed analyses of the frontal structure and
Reanalyzing the structure of this system indicates that the
temperature gradients were very small from the 18th onward,
but that it still had a somewhat asymmetric structure on the
18th . (Perhaps instead of fronts in the HWM, this could have
better been shown as trough lines.) There was a prominent ridge of high
pressure to the north of the cyclone from the 18th to the
22nd , which did cause an enhancement of winds on the north
side of the cyclone.
: Is a time available for the 60 kt ship report on 16 October?
Unfortunately, no. The MWR of the era typically had times for
minimum pressure reported by ships, but not times for maximum winds.
: The committee accepts the new track. It should be noted
that the 70 kt observation at Bermuda is 70 n mi or more from the center
if the track is correct. This implies the system was a very large hurricane.
So noted now in the metadata.
: The landfall intensity is stated as 70 kt and 983 mb
based on data from two ships just offshore from the landfall point.
However, if the Morgan City low pressure of 990 mb is a central pressure,
this suggests some filling occurred after those ship reports. The
committee suggests changing the landfall intensity to 65 kt and 987 mb.
After further analysis, it does not appear that the 990 mb is a
central pressure (especially as two ships just offshore had 50 kt/987 mb
and 65 kt/989 mb and Vicksburg did have a central pressure of 991 mb
several hours later). Thus we prefer to retain the 70 kt and 983 mb at
: In the 27 October write-up, use 'position' instead of
1923 old #4 removed
: Please change 'well-defined core' to 'not
well-defined core'. This system may have had a structure similar to
Tropical Storm Frances of 1998, but was not of tropical-storm strength.
You may want to modify the final paragraph of the write-up accordingly.
The paragraph did not successfully convey what was intended.
Here is the revised wording in the metadata: "In our assessment, this
cyclone had a large circulation with peak winds below gale-force and with
no well-defined center. However, it is possible that a well-defined
center did exist embedded within the large circulation envelope, but that
it was just not sampled from the available observations. The system (if
we are correct that no well-defined center was present) is likely
somewhat analogous to Tropical Storm Frances in 1998, but without gale
force winds present."
: Please note in the metadata and summary why the track
was shifted northward near the northeastern coast of Mexico.
This track shift was primarily due to the report in the MWR of a
1005 mb pressure reading in Tampico, MX on the 20th. This is added to
the metadata daily and summary writeups.
: Please include the comments about the weakness of the
temperature gradient that were provided to the committee in the final write-up.
: The committee has reservations about the decreased peak
intensity. The data on 25-26 August supports the suggested decreased
intensity, but this decreased intensity has been included for 22-24
August where there are no core observations to support it. If no core
observations can be found for 22-24 August, the committee suggests
blending the current major hurricane status of those days with the
reduced intensities of 25-26 August. This would likely result in a
Category 3 peak intensity.
Agreed. Best track winds so adjusted.
Do the observations justify adding in a Category 1 impact for Virginia?
Probably not. The peak corrected wind from the state was Cape
Henry's 52 kt (adjusted downward from 63 kt from the high bias of the
instrument). However, it is a marginal call as to whether Virginia
should be included.
: Is there enough pressure data to justify adding central
pressures to the record for this storm?
Yes, at 12 UTC on the 29th a ship with 25 kt and 1002
mb suggests a central pressure of 999 mb. Early on the 30th ,
the center of the (now) extratropical cyclone went over Savannah, which
recorded 1001 mb. Both of these central pressures are now added to
: There is a reference to the developing hurricane in the
Caribbean as storm #9. Please change this to #10.
: Please make sure an updated metadata entry is in the
: The committee accepts the current proposed new track.
Given the potential historical importance of this storm (the latest
hurricane of record to strike the United States), it is recommended that
a search be conducted for Florida newspapers that would provide
additional information on this system. This search would be for possible
future re-examination, and not before the current 1921-1925 revisions are
incorporated into HURDAT.
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