Tropical Depression 18L

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                 
     20230928 163120       GMI   17.5  -46.0   N/A   N/A     N/A     N/A      N/A   35.0  17.6  -45.1 Analysis Plot     
     20230928 210640  SSMISF17   18.3  -46.3   101    3%    1.73   -1.73      N/A   35.0  18.1  -46.2 Analysis Plot     
     20230929 043047     AMSR2   18.6  -46.7   135    4%    0.32   -0.32      N/A   35.0  18.6  -46.8 Analysis Plot     
     20230929 093953  SSMISF17   18.5  -46.9   212    8%    2.96   -2.96      N/A   40.0  19.0  -46.7 Analysis Plot     
     20230929 153748       GMI   18.6  -47.2   N/A   N/A     N/A     N/A      N/A   40.0  19.5  -47.0 Analysis Plot     
     20230929 191739  SSMISF18   19.9  -47.8   257   N/A    3.39   -3.39      N/A   40.0  19.7  -47.4 Analysis Plot     
     20230929 205412  SSMISF17   19.9  -48.2   N/A   N/A     N/A     N/A      N/A   40.0  19.8  -47.5 Analysis Plot     
     20230930 051245     AMSR2   20.8  -48.0   N/A   N/A     N/A     N/A      N/A   45.0  20.7  -49.4 Analysis Plot     
     20230930 075008  SSMISF18   21.0  -49.5   N/A   N/A     N/A     N/A      N/A   45.0  21.0  -49.6 Analysis Plot     
     20230930 092633  SSMISF17   20.5  -49.7   112    1%    3.23   -3.23      N/A   45.0  21.1  -49.8 Analysis Plot     
     20230930 190418  SSMISF18   22.1  -51.6   135   N/A    3.08   -3.08      N/A   40.0  21.6  -51.1 Analysis Plot     
     20230930 205729  SSMISF16   22.6  -51.6   N/A   N/A     N/A     N/A      N/A   40.0  22.6  -51.5 Analysis Plot     
     20231001 053903       GMI   24.0  -53.3   N/A   N/A     N/A     N/A      N/A   35.0  24.0  -53.4 Analysis Plot     
     20231001 055605     AMSR2   24.2  -53.6   N/A   N/A     N/A     N/A      N/A   35.0  24.2  -53.6 Analysis Plot     
     20231001 073550  SSMISF18   23.2  -53.5   N/A   N/A     N/A     N/A      N/A   35.0  24.4  -53.8 Analysis Plot     
     20231001 092810  SSMISF16   24.6  -53.3   201    7%    0.83   -0.83      N/A   35.0  24.6  -54.0 Analysis Plot     
     20231001 152529       GMI   25.5  -55.0   N/A   N/A     N/A     N/A      N/A   35.0  25.4  -54.9 Analysis Plot     
     20231001 165142     AMSR2   25.7  -55.1   N/A   N/A     N/A     N/A      N/A   35.0  25.8  -55.1 Analysis Plot     
     20231001 204527  SSMISF16   26.3  -55.4    23   N/A    0.96   -0.96      N/A   30.0  26.2  -55.5 Analysis Plot     
     20231001 204535  SSMISF16   26.4  -55.5    68   N/A    1.22   -1.22      N/A   30.0  26.4  -55.6 Analysis Plot     
     20231001 220951  SSMISF17   26.7  -55.2   N/A   N/A     N/A     N/A      N/A   30.0  26.7  -55.6 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.