1998-1999 WINTER WEATHER VERIFICATION STATISTICS

WINTER STORM WATCHES:

Number of Watches issued: 94
Watches with an event: 50
Watches without an event: 44
Events without a Watch: 55
Events 105
Average Lead Time: 33 hours

WINTER STORM WARNINGS:

Number of Warnings issued: 117
Warnings with an event: 95
Warnings without an event 22
Events without a Warning: 10
Events 105
Average Lead Time: 18 hours

WINTER WEATHER ADVISORIES:

Number of Advisories issued: 235
Advisories with an event: 134
Advisories without an event: 101
Events without an Advisory: 17
Events: 151
Average Lead Time: 10 hours

HIGH WIND WARNINGS:

Number of Warnings issued: 71
Warnings with an event: 17
Warnings without an event: 54
Events without a Warning: 36
Events: 53
Average Lead Time: 16 hours

WIND ADVISORIES:

Number of Advisories issued: 306
Advisories with an event: 102
Advisories without an event: 204
Events without an Advisory: 22
Events: 124
Average Lead Time: 9.5 hours

Abbreviations are as follows: Winter Storm Watch (WSA), Winter Storm Warning (WSW), Winter Weather Advisory (WWA), High Wind Warning (HWW), Wind Advisory (HWA), False Alarm Ratio (FAR), Probability of Detection (POD), Critical Success Index (CSI)

WSA WSW WWA HWW HWA
FAR
(0 is best)
47% 19% 43% 76% 67%
POD
(100% is best)
48% 90% 89% 32% 82%
CSI
(100% is best)
34% 75% 53% 16% 31%

WHAT DO THESE STATISTICS SHOW?

It’s tough to make specific judgments of our office’s performance, namely because the 1998-99 winter season was the first year these statistics were nationally implemented, and there isn’t much to compare it to from previous years.

Overall, however, the winter season was low with respect to the number of storms (there were only 7)! There were only a few "true" snowstorms in southern New England, most notably the ones in mid January, mid February, and mid March. It is apparent that we did not issue many Winter Storm Watches as opposed to Winter Storm Warnings, which indicates low confidence by our forecasters in using computer guidance forecasts beyond 24 hours in the future. Wind verification scores were not exceptionally high, but this can be attributed to two factors. First, wind verification is difficult to obtain, since many spotters do not have access to accurate wind speed measurements. We normally rely on automated stations, such as ASOS, for much of our wind verification. While ASOS stations are well distributed thoughout southern New England, there are still "gaps" where we don’t have wind data. Second, as noted above, we simply don’t have other years to compare this data to. We don’t know if a CSI of 50% for wind verification can be considered exceptional, considering the verification process for wind events, or if it’s no good at all. Keeping these statistics over the next few years will begin to help us out in that regard. We’ve also been active in adding volunteers with approved wind equipment to our spotter network, to help "fill in the gaps" with reliable wind observations.