1999 NWS TAUNTON SEVERE WEATHER STATISTICS
| A) TOTAL # OF WARNINGS ISSUED: |
111 |
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| B) # OF WARNINGS THAT DID NOT VERIFY: |
41 |
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| C) "WARNED SEVERE EVENTS": |
78 |
|
[ Verified Warnings = 70 |
(A-B) |
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+ Multiple Severe Events |
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within same warning:= 8 ] |
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|
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| D) # OF SEVERE EVENTS WITHOUT WARNING: |
32 |
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| E) TOTAL SEVERE EVENTS: |
110 (C+D) |
The numbers above are used to calculate severe weather
statistics, which give a measure of an office’s performance. There are 3 statistics
used in severe weather verification. The first is False Alarm Ratio, or FAR,
which is the ratio of unverified warnings to the total number of warnings issued. The
lower the FAR the better, since it expresses the number of "false alarms"
issued. Probability of Detection, or POD, is the ratio of warned severe
events to total severe events. A high POD is best, since it shows the skill an office has
in warning for severe weather events. The Critical Success Index, or CSI,
takes both FAR and POD into account to give a measure of performance that includes both
verified and unverified events. As with POD, a high CSI is best. Finally, an average lead
time was calculated for all warnings issued this year. Lead time is defined as the
time elapsed from when the warning was issued to the time of the first severe weather
occurrence in the warned county.
FALSE ALARM RATIO (FAR):
| (0 is best) |
UNVERIFIED WARNINGS |
= |
41 |
= |
36.9 % |
|
TOTAL WARNINGS |
|
111 |
|
|
PROBABILITY OF DETECTION (POD):
| (100% is best) |
WARNED SEVERE EVENTS |
= |
78 |
= |
70.9 % |
|
TOTAL SEVERE EVENTS |
|
110 |
|
|
CRITICAL SUCCESS INDEX (CSI):
| (100% is best) |
WARNED SEVERE EVENTS |
= |
78 |
= |
51.7 % |
|
TOTAL SVR EVENTS + UNVER
WRNGS |
|
110+41 |
|
|
AVERAGE LEAD TIME: 19.8 minutes
HOW DO THESE NUMBERS COMPARE TO RECENT
YEARS and NATIONALLY?