Text-Based Probability Product


The example below is a portion of a strike probability issued for Hurricane Georges in 1998. The rows in the table are the locations, some of which are given in latitude and longitude and others by name. The different columns (labeled "A","B", "C", "D") are probabilities at various forecast times (listed at the bottom of the table in red). The column labeled "E" is the sum of the probabilities in the four periods.

According to this example, Key West FL had the highest probability (99%)of the hurricane passing within 75 mi (65 NM) and it was forecast to hit sometime between 11 a.m. EDT on Friday, September 25 (the current time) and 8 a.m. on Saturday, September 26. There was a 2% chance that the hurricane would hit the location GULF 29N 87W before 8 a.m. Saturday, but a 25% chance it would hit sometime between 8 a.m. Saturday and 8 p.m. Saturday . The 2% probability is low for a 24-hour forecast, but the 25% chance at about 36 hours is about as high as is possible.

ZCZC MIASPFAT2 ALL
TTAA00 KNHC DDHHMM
HURRICANE GEORGES PROBABILITIES NUMBER 41
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT FRI SEP 25 1998

PROBABILITIES FOR GUIDANCE IN HURRICANE PROTECTION
PLANNING BY GOVERNMENT AND DISASTER OFFICIALS

AT 11 AM EDT...1500Z...THE CENTER OF GEORGES WAS LOCATED NEAR
LATITUDE 24.3 NORTH...LONGITUDE 81.7 WEST

CHANCES OF CENTER OF THE HURRICANE PASSING WITHIN 65 NAUTICAL MILES OF LISTED LOCATIONS THROUGH 8AM EDT MON SEP 28 1998

LOCATION

A

B

C

D

E

  LOCATION

A

B

C

D

E

26.7N 85.3W

54

X

X

X

54

 

APALACHICOLA FL  

8

14

1

1

24

28.1N 86.7W       

16

18

X

1

35

 

PANAMA CITY FL

3

17

3

1

24

29.6N 87.9W

X

15

11

1

27

 

PENSACOLA FL     

X

11

12

2

25

MUHA 230N 824W

16

X

X

X

16

 

MOBILE AL

X

4

16

3

22

...

 

 

 

 

 

 

 

 

 

 

 

 

KEY WEST FL     

99

X

X

X

99

 

GALVESTON TX

X

X

X

3

3

MARCO ISLAND FL

56

X

X

X

56

 

GULF 29N 85W       

20

9

1

X

30

FT. MYERS FL

39

X

1

X

40

 

GULF 29N 87W

2

25

2

1

30

COLUMN DEFINITION PROBABILITIES IN PERCENT
A IS PROBABILITY FROM NOW TO 8AM SAT
FOLLOWING ARE ADDITIONAL PROBABILITIES
B FROM 8AM SAT TO 8PM SAT
C FROM 8PM SAT TO 8AM SUN
D FROM 8AM SUN TO 8AM MON
E IS TOTAL PROBABILITY FROM NOW TO 8AM MON
X MEANS LESS THAN ONE PERCENT

RAPPAPORT

The information above is also available in a graphical form.