Tropical Depression 18W

Passive Microwave (PMW) Intensity Information
Advanced Dvorak Technique
Version 9.1


       --Overpass--              --ARCHER--   Ring  Ring            Eye              BT   -Forecast-  
       Date    Time      Sat     Lat    Lon   Diam   Pct  TbDiff   Score  Meaning   Vmax  Lat    Lon                 
     20240924 034821     AMSR2   27.7  134.4   N/A   N/A     N/A     N/A      N/A   30.0  28.1  135.1 Analysis Plot     
     20240924 185954       GMI   28.1  135.1   N/A   N/A     N/A     N/A      N/A   30.0  28.1  135.1 Analysis Plot     
     20240924 210739  SSMISF17   27.5  134.6   168   12%    2.24   -2.24      N/A   30.0  28.3  135.1 Analysis Plot     
     20240925 082844       GMI   27.7  133.6   N/A   N/A     N/A     N/A      N/A   35.0  28.2  133.7 Analysis Plot     
     20240925 195407  SSMISF18   28.0  132.5   201    3%    2.48   -2.48      N/A   30.0  28.0  132.6 Analysis Plot     
     20240925 221048  SSMISF16   28.5  132.1   223    4%    0.93   -0.93      N/A   30.0  28.1  132.4 Analysis Plot     
     20240926 071208  SSMISF18   28.0  131.8   135    6%    0.61   -0.61      N/A   30.0  28.4  131.9 Analysis Plot     
     20240926 092905  SSMISF16   27.9  132.0   146    6%    1.65   -1.65      N/A   25.0  28.1  132.3 Analysis Plot     
     20240927 065821  SSMISF18   29.4  132.8   101    3%    2.43   -2.43      N/A   25.0  29.4  132.8 Analysis Plot     
     20240927 083915       GMI   29.0  133.3   N/A   N/A     N/A     N/A      N/A   25.0  29.5  132.9 Analysis Plot     
     20240927 091531  SSMISF16   29.1  133.5   N/A   N/A     N/A     N/A      N/A   25.0  29.8  133.1 Analysis Plot     
     20240927 182803       GMI   29.9  132.9    34   N/A    7.48   -7.48      N/A   20.0  29.8  133.0 Analysis Plot     
     20240927 192515  SSMISF18   30.9  134.0    46   N/A    0.61   -0.61      N/A   20.0  30.8  134.0 Analysis Plot     
     20240927 214203  SSMISF16   31.0  133.9   223    3%    1.94   -1.94      N/A   20.0  31.0  134.3 Analysis Plot

Legend

  - Overpass Date/Time are determined from satellite overpass of targeted TC (position determined from Best Track Lat/Lon position). Date is YYYYMMDD and time in HHMMSS (UTC).

  - Forecast (Best Track) and ARCHER positions (deg) of the TC center at overpass day/time. Positive/Negative: Latitude = North/South Hemisphere; Longitude = Eastern/Western Hemisphere.

  - BT Vmax is the concurrent ATCF Best Track (BT) wind speed intensity estimate (Vmax) value from either NOAA/National Hurricane Center (NHC) (North Atlantic and Northeast Pacific), NOAA/Central Pacific Hurricane Center (CPHC) (North-central Pacific) or Joint Typhoon Warning Center (JTWC) (Northwest Pacific, Indian Ocean, or Southwest Pacific).

  - Sat is the satellite descriptor providing the overpass. Currently the satellites used are the DMSP/SSMIS-16/17/18, GPM/GMI, and GCOM/AMSR2.

  - Ring Diam (km) indicates the estimated surface eyewall diameter if one is analyzed in the PMW imagery. The value listed is the average PMW-estimated inner eyewall edge diameter minus 10 km for eyewall slope. N/A indicates no appreciable eyewall is analyzed.

  - Ring Pct is the percentage of the analyzed "ring" (eyewall inner boundary) that is 1) colder than the eye Tb (the "hot spot" -- warmest eye pixel) by at least 20K, or 2) that is colder than 232K and colder than the eye Tb by 10K, whichever is greater. Values are red if Ring % ≤65,yellow/brown if Ring % ≤85 and green if Ring % >85. N/A indicates no appreciable eyewall is analyzed. A value over 85% is used in the intensity score by adding 15 points to it.

  - TbDiff is the difference between the warmest eye pixel and the warmest pixel on the eyewall. This value is used in the Intensity Score. N/A indicates no appreciable eyewall is analyzed.

  - Eye Score values are based on the strength and organization of the convective/eyewall signatures in the PMW imagery, and based on the ARCHER center location. They normally range from 0 to 100 with empirically-determined thresholds related to intensity (Vmax) in the "Meaning" column (≥20 suggests ≥65kts; ≥60 suggests ≥85kts). Scores are listed as negative, and not used by the ADT, when the NHC, CPHC, or JTWC Best Track Vmax is <55 kts in order to filter out occasional "false eye" cases. A value of -920 is used when the warmest eye pixel is <200K to prevent false positives; -930 means edge of overpass and <85% of eyewall is captured and therefore can't fully be analyzed.