# Presentation: 000181

## Tropical Cyclone Winds in IFPS in Pacific Region

- IFPS Methodology Workshop
- April 2004
- Ken Waters

## Outline

- Pacific Region ORD
- TCM Tools
- Rankin Vortex Work
- What’s Next?

## Pacific Region ORD

- ORD August 3rd to September 15th
- IOC October 15th
- TCM grids
- Appropriate 3 hourly TCM grids required
- OB3 required for TPC TCM solution
- Test grids prior to ORD
- TCM Grids within GFE 30 minutes after issuance from Centers
- IFPS 16.0 timing
- National implementation immediately after ORD
- Backup Issues
- WFO MTR, WFO HFO & WFO GUM
- VTEC Issues???

## Pacific Region ORD

- BOTTOM LINE
- Pacific Region stated our #1 most important issue and potential IOC-breaker was.....

-  THE NEED FOR TROPICAL CYCLONE INITIALIZATION WIND GRIDS:
- In a timely manner
- Sufficient resolution
- Reasonably representative of the structure of the tropical cyclone as best as we know

## Pacific Region ORD

- Initial Results appear very promising
- Communication tests sending TPC grids to PR mostly successful
- FSL tool successfully run at WFO Guam, PRH, and WFO Honolulu
- Can only be fully evaluated using a real storm when it comes into either Guam’s or Honolulu’s domain
- Both tools seem to show good potential to be used
- One big drawback to the TPC tool is the 6-hour resolution

## FSL TCM Solution

## TPC TCM Solution

## Rankin Vortex Work

- Work started in 1997 at WFO Guam
- The Original Goal: To give forecasters aid to translating text warnings into hourly forecast for point locations for use in TAFs and determining temporal “breakpoints” for determining periods of destructive winds
- WFO Guam had 31 warning points/islands and frequently had more than one tropical cyclone to warn on in their coverage area

## Rankin Vortex Work

- Basic Concept
- Start with the warning positions (lat/long/max wind)
- Interpolate hourly position and intensity
- Develop a Rankin vortex centered on each interpolated hourly position
- Using this model calculate wind speeds for both points (islands) and at regularly-spaced gridpoints
- Adjust wind speeds/directions by adding/subtracting vector storm movement

## Rankin Vortex Work

- Issues
- Determination of Radius of Maximum Wind (RMW) --- not part of forecast but input to the formula
- Determination of the exponential “shape” factor
- How rapidly does wind speed fall off as one moves away from center?
- Variances include spectrum from huge storm down to “midget” typhoons
- Inherent dangers with using a highly deterministic approach to describe difficult-to-predict tropical cyclone movement and intensity

## Typhoon Sudal Apr 9, 2004

- SYMMETRIC MODEL PREDICTED WINDS FOR:
-       Koror    Ngulu    Yap      Taipei   Hong Kong
-  0    340 25   334 56    59 69    47  9    33  8
-  1    339 26   330 59    66 73    47  9    33  8
-  2    338 26   325 62    74 77    47  9    33  8
-  3    337 27   319 66    84 81    48  9    33  8
-  4    336 27   312 69    95 84    48  9    33  8
-  5    335 28   304 72   106 84    48  9    33  9
-  6    334 28   296 74   118 83    48  9    33  9
-  7    333 29   286 76   128 80    48 10    33  9
-  8    332 29   277 76   136 76    48 10    33  9
-  9    330 30   267 75   144 72    49 10    34  9
- 10    329 31   259 73   150 68    49 10    34  9
- 11    327 31   251 70   154 64    49 10    34  9
- 12    326 32   245 67   158 61    49 10    34  9
- 13    324 32   241 63   164 59    49 10    34  9
- 14    321 33   238 59   169 56    49 10    34  9
- 15    319 33   236 56   173 54    49 10    34  9
- 16    316 33   234 53   176 52    49 10    34  9
- 17    314 34   232 50   180 50    49 10    34  9
- 18    311 34   231 48   182 48    49 10    34  9
- 19    309 34   230 46   185 46    49 10    34  9
- 20    306 34   229 44   187 45    49 10    34  9
- 21    303 34   228 43   188 43    50 11    34  9
- 22    301 34   227 41   190 42    50 11    33 10
- 23    298 34   226 40   191 41    50 11    33 10
- 24    296 34   226 39   193 40    50 11    33 10

**HOURLY POSITION/CLOSEST POINT:**
** ****#  Lat   Lon    Wind      Mvmt         Dstnc/Dirctn from (naut mi)**
** ****0   8.8  138.5 110.0      282  8        55 SSE Yap      **
** ****1   8.8  138.4 110.4      282  8        50 SSE Yap             **
** ****2   8.9  138.3 110.8      282  8        45 SSE Yap             **
** ****3   8.9  138.2 111.2      282  8        42   S Yap             **
** ****4   8.9  138.0 111.7      282  8        40   S Yap             **
** ****5   8.9  137.9 112.1      282  8        40 SSW Yap             **
** ****6   8.9  137.8 112.5      282  8        42 SSW Yap             **
** ****7   9.0  137.7 112.9      282  8        44  SW Yap             **
** ****8   9.0  137.6 113.3      282  8        48  SW Yap             **
** ****9   9.0  137.4 113.8      282  8        50   N Ngulu           **
**10   9.1  137.3 114.2      282  8        53   N Ngulu           **
**11   9.1  137.2 114.6      282  8        56 NNW Ngulu           **
**12   9.1  137.1 115.0      282  8        61 NNW Ngulu           **
**13   9.2  137.0 115.4      305  9        69 NNW Ngulu           **
**14   9.2  136.9 115.8      305  9        77 NNW Ngulu           **
**15   9.3  136.8 116.2      305  9        86  NW Ngulu           **
**16   9.4  136.7 116.7      305  9        94  NW Ngulu           **
**17   9.5  136.6 117.1      305  9       103  NW Ngulu           **
**18   9.6  136.4 117.5      305  9       111   W Yap             **

- Paper to be presented May 2004 at AMS Tropical Conference

## What’s Next?

- Direct Comparison in Pacific Region
- Same storm
- Same warning
- Analyze effect of difference in temporal resolution (e.g., interpolated 6 hr TPC grids to 3 hr vs. FSL 3 hr)
- Analyze effect of differences in spatial resolution

## What’s Next?

- Decision by wind team on which tool to use
- Not efficient to support two tools other than in a test environment
- Possible enhancements?
- Asymmetric wind structure (moving storm)
- Environmental blending (e.g., SW monsoon flow)
- Verification (using...? QuikSCAT? Recon?)

## Questions?