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Text Wind Speed Probabilities Forecast
The Wind Speed Probabilities are also issued in the form of two tables, with probabilities for tropical storm-force (34 kt), 50 kt, and hurricane-force (64 kt) winds being experienced at specific locations. The wind speed thresholds are the same as those in the graphical version, following the size forecast.
One wind speed probability table is issued for "selected locations," including named cities and points in water identified by latitude and longitude. A second table is issued for "forecast positions," the latitude/longitude points from the track forecasts - those same points around which the cone of uncertainty is constructed - through the 3-day forecast (72h).
Each table contains two types of probabilities: individual probability is for the onset of those winds during each individual forecast interval (i.e., between one standard forecast time and the next), considered in isolation from all prior forecast intervals. Cumulative probability for any of the standard forecast times is the combined probability those winds will occur anytime from the initial time (0h) all the way through to that time. Cumulative probability for the 72h forecast time thus combines (adds together) the individual probabilities from the 0-12h, 12-24h, 24-36h, 36-48h, 48-72h forecast intervals.
The cumulative probability is given in (parenthesis) next to the individual probability for each forecast period. If an X appears instead of a number, the individual (or cumulative) probability that the specified winds will start (occur) at a location during (by the end of) that forecast period is deemed to be less than one-half of one percent. This notation is described in the product itself:
|
CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT
LEAST PROBABILITIES FOR LOCATIONS ARE GIVEN AS IP(CP) WHERE PROBABILITIES ARE GIVEN IN PERCENT ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME EASTERN DAYLIGHT TIME (EDT)...SUBTRACT 4 HOURS FROM Z TIME CENTRAL DAYLIGHT TIME (CDT)...SUBTRACT 5 HOURS FROM Z TIME |
A sample of the two wind speed probability tables for the same Hurricane Dean advisory - one for SELECTED LOCATIONS and one for FORECAST POSITIONS - are reproduced below, in that order. These probabilities represent the text version of the graphical wind speed probability product, as they are constructed from the same data and convey essentially the same predictive information, though there are a few differences in the level of detail presented.
One important difference is that the graphical product covers only the cumulative probabilities for each forecast period, whereas the text product presents both individual and cumulative probabilities. The text version therefore offers the user specific information as to when the hurricane- or tropical-storm force winds are likely to begin at a location, information that cannot be extracted from the graphical version.
Another difference is that in the graphical version, SELECTED LOCATIONS are not portrayed separately from FORECAST POSITIONS, and none of the locations is pointed to specifically on the map. Rather, it is more fluid to convey the entire set of probabilities on a large contiguous area represented in single map form.
Selected locations in water, as well as forecast positions both on land and in water, are listed in the tables by latitude and longitude coordinates to the nearest one-tenth of a degree, but with the decimal points omitted, such that the in-water location GFMX 270N 960W stands for "Gulf of Mexico, 27.0 degrees North latitude by 96.0 degrees West longitude."
The number following each selected location (first table) or forecast positions (second table) tells the user which wind speed threshold that row of probabilities applies to. The entry CORPUS CHRISTI 34 means that the probabilities in that row are for the storm's 34-kt or tropical storm-force winds starting (occurring) at Corpus Christi, TX, during (by the end of) each of the standard forecast periods, both individually and (cumulatively). A place name followed by 50 would refer to the 50 kt winds, and 64 to the 64 kt or hurricane-force winds. If a selected location, such as Corpus Christi, does not have listings for 50 kt or 64 kt wind fields, it is because the probability of 50 kt or hurricane-force winds occurring there was determined to be too small to warrant a listing. For Hurricane Dean with regard to Corpus Christi, the only probabilities deemed significant at the time this advisory was issued were those pertaining to its tropical storm-force winds.
This first table (below) is for SELECTED LOCATIONS. It includes known place names such as cities, as well as locations in water, which are identified by their basin and latitude/longitude coordinates.
| TIME PERIODS | FROM 18Z MON TO 06Z TUE | FROM 06Z TUE TO 18Z TUE | FROM 18Z TUE TO 06Z WED | FROM 06Z WED TO 18Z WED | FROM 18Z WED TO 18Z THU | FROM 18Z THU TO 18Z FRI | FROM 18Z FRI TO 18Z SAT |
| FORECAST HOUR | (12) | (24) | (36) | (48) | (72) | (96) | (120) |
| LOCATION KT |
- | - | - | - | - | - | - |
| CORPUS CHRISTI 34 |
X | X( X) | X( X) | 1( 1) | 2( 3) | X( 3) | X( 3) |
| GFMX 270N 960W 34 |
X | X( X) | X( X) | 2( 2) | 2( 4) | X( 4) | X( 4) |
| BROWNSVILLE TX 34 |
X | X( X) | X( X) | 5( 5) | 4( 9) | X( 0) | X( 0) |
| GFMX 250N 960W 34 |
X | X( X) | 2( 2) | 10(12) | 5(17) | X(17) | X(17) |
| GFMX 250N 960W 50 |
X | X( X) | X( X) | 2( 2) | 1( 3) | X( 3) | X( 3) |
| LA PESCO MX 34 |
X | X( X) | 1( 1) | 17(18) | 11(29) | X(29) | X(29) |
| LA PESCO MX 50 |
X | X( X) | X( X) | 3( 3) | 5( 8) | X( 8) | X( 8) |
| TAMPICO MX 34 |
X | X( X) | 4( 4) | 31(35) | 16(51) | X(51) | X(51) |
| TAMPICO MX 50 |
X | X( X) | X( X) | 11(11) | 12(23) | X(23) | X(23) |
| TAMPICO MX 64 |
X | X( X) | X( X) | 3( 3) | 6( 9) | X( 9) | X( 9) |
| TUXPAN MX 34 |
X | X( X) | 7( 7) | 35(42) | 13(55) | X(55) | X(55) |
| TUXPAN MX 50 |
X | X( X) | 1( 1) | 14(15) | 9(24) | X(24) | X(24) |
| TUXPAN MX 64 |
X | X( X) | X( X) | 3( 3) | 5( 8) | X( 8) | X( 8) |
| VERACRUZ MX 34 |
X | 1( 1) | 9(10) | 19(29) | 4(33) | X(33) | X(33) |
| VERACRUZ MX 50 |
X | X( X) | 2( 2) | 6( 8) | 3(11) | X(11) | X(11) |
| VERACRUZ MX 64 |
X | X( X) | X( X) | 2( 2) | 2( 4) | X( 4) | X( 4) |
| FRONTERA MX 34 |
X | 13(13) | 30(43) | 4(47) | X(47) | X(47) | X(47) |
| FRONTERA MX 50 |
X | 2( 2) | 11(13) | 2(15) | X(15) | X(15) | X(15) |
| FRONTERA MX 64 |
X | 1( 1) | 3( 4) | 1( 5) | X( 5) | X( 5) | X( 5) |
| MERIDA MX 34 |
3 | 49(52) | 8(60) | 1(61) | X(61) | X(61) | X(61) |
| MERIDA MX 50 |
X | 15(15) | 4(19) | X(19) | 1(20) | X(20) | X(20) |
| MERIDA MX 64 |
X | 4( 4) | 1( 5) | X( 5) | X( 5) | X( 5) | X( 5) |
| COZUMEL MX 34 |
50 | 19(69) | X(69) | X(69) | X(69) | X(69) | X(69) |
| COZUMEL MX 50 |
6 | 7(13) | X(13) | X(13) | X(13) | X(13) | X( 13) |
| COZUMEL MX 64 |
1 | 2( 3) | X( 3) | X( 3) | X( 3) | X( 3) | X( 3) |
| BELIZE 34 |
20 | 42(62) | X(62) | X(62) | X(62) | X(62) | X(62) |
| BELIZE 50 |
3 | 14(17) | X(17) | X(17) | X(17) | X(17) | X(17) |
| BELIZE 64 |
1 | 5( 6) | X( 6) | X( 6) | X( 6) | X( 6) | X( 6) |
| PUERTO BARRIOS 34 |
1 | 4( 6) | X( 6) | X( 6) | X( 6) | X( 6) | X( 6) |
| GUANAJA 34 |
30 | 3(33) | X(33) | X(33) | X(33) | X(33) | X(33) |
| GUANAJA 50 |
3 | X( 3) | X( 3) | X( 3) | X( 3) | X( 3) | X( 3) |
| CP SAN ANTONIO 34 |
4 | 3( 7) | X( 7) | X( 7) | X( 7) | X( 7) | X( 7) |
| ISLE OF PINES 34 |
2 | 1( 3) | X( 3) | X( 3) | X( 3) | X( 3) | X( 3) |
The second table (below) is for FORECAST POSITIONS. It contains wind speed probabilities for each of the forecast points that make up the track forecasts issued through 72 hours. Each forecast position represents where the storm's center was projected to be at the end of each of the six forecast periods that constitute the 3-day track forecast. The entry 12 185N 867W 34 means that the probabilities in that row represented the probabilities - both individually and cumulatively - that Dean's 34 kt or tropical storm-force winds would occur at the location described by the 12-hour track forecast coordinates, 18.5 N latitude by 86.7 W longitude.
| TIME PERIODS | FROM 18Z MON TO 06Z TUE | FROM 06Z TUE TO 18Z TUE | FROM 18Z TUE TO 06Z WED | FROM 06Z WED TO 18Z WED | FROM 18Z WED TO 18Z THU | FROM 18Z THU TO 18Z FRI | FROM 18Z FRI TO 18Z SAT |
| FORECAST HOUR | (12) | (24) | (36) | (48) | (72) | (96) | (120) |
| HR POSITIONS KT |
- | - | - | - | - | - | - |
| 12 185N 867W 34 |
98 | 1(99) | X(99) | X(99) | X(99) | X(99) | X(99) |
| 12 185N 867W 50 |
90 | 6(96) | X(96) | X(96) | X(96) | X(96) | X(96) |
| 12 185N 867W 64 |
62 | 16(78) | X(78) | X(78) | X(78) | X(78) | X(78) |
| 24 193N 902W 34 |
4 | 72(76) | 11(87) | X(87) | X(87) | X(87) | X(87) |
| 24 193N 902W 50 |
X | 48(48) | 13(61) | X(61) | X(61) | X(61) | X(61) |
| 24 193N 902W 64 |
X | 24(24) | 7(31) | X(31) | X(31) | X(31) | X(31) |
| 36 202N 936W 34 |
X | 9( 9) | 58(67) | 12(79) | 1(80) | X(80) | X(80) |
| 36 202N 936W 50 |
X | 1( 1) | 36(37) | 14(51) | 1(52) | X(52) | X(52) |
| 36 202N 936W 64 |
X | X( X) | 19(19) | 8(27) | 1(28) | X(28) | X(28) |
| 48 210N 970W 34 |
X | X( X) | 10(10) | 39(49) | 11(60) | X(60) | X(60) |
| 48 210N 970W 50 |
X | X( X) | 1( 1) | 17(18) | 9(27) | X(27) | X(27) |
| 48 210N 970W 64 |
X | X( X) | X( X) | 6( 6) | 6(12) | X(12) | X(12) |
| 72 215N 1030W 34 |
X | X( X) | X( X) | X( X) | 13(13) | X(13) | X(13) |
| 72 215N 1030W 50 |
X | X( X) | X( X) | X( X) | 3( 3) | X( 3) | X( 3) |
| 72 215N 1030W 64 |
X | X( X) | X( X) | X( X) | 1( 1) | X( 1) | X( 1) |
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