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Best Track Committee Responses to the Re-Analysis Project Proposed Revisions to 1931-1933

[Responses to the Committee are in boldface – Hagen/Landsea – February 2012]

            The committee concurs with the majority of the comments, changes, and correction that have been made.  The committee still has some issues included in the points below.

            The committee notes the finding of the decoders for the 1930Õs coded ship reports and the impact it had on the various 1933 cyclones.  This is most welcome and very good work!

Thank you.

            1931 General comment #1: The loss of the EDADS web site is an increasing problem in the committeeÕs reviews of the re-analysis submissions.  There are several storms, both in the 1931-1933 time frame and in other years, where Original Monthly Record (OMR) data would be very valuable to the committee in its deliberations.  Not having the OMRs available slows the pace of the re-analysis and opens up the process to criticism that it has not been as thorough as it could have been.  Please expedite the efforts to obtain all the necessary OMRs, including those for landfalling tropical storms.  This effort should not only cover years that have not yet been re-analyzed, but also the years which have been analyzed that the committee has not yet taken up (e. g. 1944-1953).

            As an example, there are these unfulfilled requests for additional OMRs in the 1931-1933 period:

á      1931 Storm #2 (Louisiana, Mississippi, Alabama, Florida Panhandle)

While the Original Monthly Records are not available, other sources have been identified that provide much of the same information.  The Daily Weather Maps (DWMs) and Monthly State Climatological Data from the four states have now been obtained.  The Monthly Local Climatological Data for Vicksburg, MS was obtained.  The Daily Weather Maps commentary from 15 July agrees with the most recent analysis of a landfall in the vicinity of Morgan City during the morning of the 15^th.  Strong rains and gusty winds extended to the coastlines of MS and AL, but these winds and rains were much less in the Florida panhandle.  Local Climatological Data states the minimum pressure for the month at Vicksburg, MS was 1008 mb on the 16^th.  On the 16^th at 13Z, the pressure was 1010 mb at both Vicksburg, MA and Shreveport, LA.  Although there is some new data from these sources that have been recently accessed, none of the data suggests that the analyzed track and intensity needs any further changes.

á      1931 Storm #4 (San Juan)

Text from the DWMs was obtained.  Also climatological information from NCDC was obtained from the West Indies and Jamaica.  All 3 sources are consistent in mentioning the system as a weak tropical disturbance and that no gale force winds were recorded with it.  At 13Z on the 17^th, the pressure at San Juan was 1011 mb with winds 5 kt NW.  We could not obtain any additional information for San Juan.  None of the new data obtained provides evidence for any additional track or intensity changes to this system.  We believe that there is not enough evidence to remove this system from HURDAT even though there were no gales observed because of the very sparse nature of available observations. 

á      1932 Storm #3 (San Juan)

á      1932 Storm #8 (Louisiana, Mississippi)

á      1933 Storm #6 (Brownsville)

á      1933 Storm #11 (Brownsville)

á      1933 Storm #17 (San Juan)

The responses to these will be provided in the 1932 and 1933 replies.

            A related note regards observations from Mexico.  While the committee recognizes that Mexican data will be far sparser than U. S. data, it is wondering if more can be obtained than has been so far?  Previous discussions mentioned that Mexican observations were being added to EDADS before it went down, and those have been used in the re-analysis.  These obs have to have a source other than EDADS.  Can they be obtained directly from NCDC?  Is there any Mexican equivalent to NCDC that might provide this data?

We obtained some Mexican synoptic maps and once daily 13Z observations from several stations from the Mexican NCDC website for the following storms and printed out synoptic maps and obs from the following storms:  1931 storm #s 1, 3, 6 (originally 5), 7 (originally 6).

            1931 Storm #6: Has the Meteorological Service of Belize been able to provide more information on the 952 mb pressure observation and the passage of the eye over Belize City?  Please keep digging on this, as there should be at least some additional information available on this standout event for Belize City.

No additional information on this system was available from the Meteorological Service of Belize. 

            1931 Storm #9 (late addition): The committee concurs with adding this storm to HURDAT.  Please provide the maps for the binder and all the necessary updates for the metadata.

The HWM maps from 12-16 October have been printed out and placed in the binder.  A sentence was added to each of the 12, 13, and 14 October paragraphs to state that there were no gales or low pressures observed on those days.

            1931 Storm #11: The committee would like to see the thermal analyses for this system.  Also, there is a concern regard the gale wind reports: These are all a considerable distance from the center, and one of them (45 kt observation at 0600 UTC 3 November) reports a northwest wind at a location northwest of the center.  Please review the ships data to see if these reports were associated with a cold surge, or whether this system had perhaps the characteristics of a subtropical or monsoon cyclone.

Additional thermal analyses have now been provided for this system and they have been placed in the binder.  It is noted that there may have been some funneling of winds and slightly cooler air along the east coast of Central America on the 2^nd to the 4^th in association with this system.  However, a distinct minimum in wind speed occurred in the winds north of the system near the Yucatan Channel, western Cuba, and south Florida, suggesting that the cyclone was a separate entity producing (at least in part) the numerous tropical storm force winds.  Observations during much of the systemÕs lifetime show that winds on the southeast side of the cyclone were light compared to the other quadrants, but there are enough observations to analyze a closed circulation.  Additionally, the thermal structure was analyzed, which indicated relatively isothermal for the four days the system had tropical storm force winds.  Since a closed circulation is analyzed along with numerous observations of gale force winds from at least five separate ships and the isothermal structure, this system is added to HURDAT. In general, these gale force winds were 75 to 200 nm from the center suggesting that the system did have some subtropical cyclone characteristics.         

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