Binghamton Severe Weather Climatology
|Fujita Tornado Scale||Wind Speed||Damage Description|
|Table 1; Source: Fujita (1981)|
e) deaths and injuries
Fortunately, there have been very few deaths or injuries from
tornadoes in Central New York and Northeast Pennsylvania. In the 51 year period
of record (1950-2001), there have been 7 deaths and 74 injuries
These deaths and injuries were caused by a total of 16 of the 130
tornadoes. This means that for this area, the percentage of tornadoes with
deaths or injuries as a percentage of all tornadoes is about 8%. This is probably
largely due to the fact that there has never been a violent tornado experienced
in this area. Interestingly, none of the deaths or injuries reported were
caused by an F0 tornado, even though one-third (33%) of the tornadoes that
have occurred in this area have been classified as F0. The F1, F2, and F3
tornadoes that have occurred have caused roughly the same number of deaths
and injuries per category, even though 44% of tornadoes have been classified
as F1 and only 9% have been F3. This is surely a testament to the strength
of a "severe" versus a "moderate" tornado (see Table 1).
a) yearly distribution
Large hail (>3/4 inch diameter) is a fairly common occurrence throughout the CWA, with reports observed in most years since the 1960s and in every county (Fig 8.)& (Fig 9.). The number of reports has been increasing significantly since the implementation of the NWS warning verification program in 1980. Nationally, a study by Sammler (1993) has shown that hail reports more than doubled in the decade 1981-1990 from the previous decade, due in large part to this verification program.
b) monthly frequency
The climatology for large hail shows a peak frequency in May, a bit earlier than the June tornado maximum (Fig 10.). The number of events rises drastically from April to May, then drops off steadily until the onset of cooler fall weather. Due to the lack of thunderstorms during the cold months in this area, large hail is almost never seen during the late fall through early spring.
c) hourly occurrence
Like tornadoes, the greatest number of hail events occurs during the afternoon through the early evening hours with a slight peak at 4 o'clock (Fig 11.). The least likely time for hail is during the overnight into the mid morning hours.
d) hail size
Table 3 depicts the size estimation guide that the National Weather Service uses to obtain hail size information from spotters, law enforcement, and the public. The NWS uses a hail size of 3/4 inches or greater to verify a severe thunderstorm. As Figure 12 shows, the large majority of the CWA's hail events have been made up of large hail reports (3/4-1.74 inch diameter). The doubling of hail reports in the last decade, as discussed earlier, has been due to a dramatic rise in the smaller hail category (1 inch or less) since 1980. However, the amount of hail reports greater than 1 3/4 inches has remained nearly constant since 1970. While prior to 1983 the highest percentage of hail reports were in the 1 inch to 1 3/4 inch category, since 1983 hail sizes of 1 inch or less have ballooned to where they now account for over 50 percent of all hail reported (Sammler, 1993).
Hail Size Estimate
|1.75 inch||Golf Ball|
During July, the dominant severe weather type in the CWA shifts to wind damage (Fig 13.). Nationally, the number of severe wind reports peaks in June and July (Doswell, Kelly and Schaefer, 1983). The National Weather Service defines severe thunderstorm winds as those of 50 knots (58 mph) or greater. As is the case with hail, severe thunderstorm winds are not an uncommon occurrence throughout this area and have occurred in every county in the CWA (Fig 14.). The number of reports has increased significantly since the assumption of CWA responsibility by the Binghamton forecast office (Fig 15.). Like the verification for tornadoes, the verification for severe thunderstorm winds is quite subjective. Most often, verification is made by reports of damage rather than actual measured wind speeds.
The same pattern holds true for wind damage as with all the
other types of severe weather. The greatest number of severe thunderstorm
wind events occurs in the afternoon through early evening hours (peak 4 p.m.),
while the least number occurs during the overnight hours
The purpose of this study was to determine the severe weather climatology across the Binghamton, NY CWA. During the past 20 years, a distinct increase in the number of severe weather events has been reported to the NWS. The increase has been most pronounced in the number of severe wind and hail events. This fact is likely attributable to the increased sensitivity of the WSR-88D radar versus the old radar systems, and to the increased awareness of the NWS, local emergency managers, spotters, and the general public to these events.
It was shown that the occurrence of tornadoes and hail is most frequent from the mid spring to the early summer months of May and June, while the peak time for damaging winds occurs during July. The decrease in tornado events during the peak summer months can likely be attributed to the main westerlies shifting north of the area, and thus decreasing the amount of vertical wind shear. The gradual decrease in hail events during the summer can be attributed to the increase in the height of the freezing level, hence making the atmosphere less favorable for hail development.
Severe weather during the heart of summer (July) in this area is most often due to wind damage. This is most often associated with pulse-severe type thunderstorms that produce locally strong microbursts. As expected, the peak time for all types of severe weather occurs during the afternoon through the early evening hours.
It is hoped that this study will give the staff at NWS Binghamton a better understanding of the severe weather that occurs in the Binghamton forecast area. It is hoped that this, along with future study of severe weather events in this area will help improve the forecast and warning program of NWS Binghamton.
Doswell III, C.A., D.L, Kelly and J.T. Schaefer: A Preliminary Climatology of Non-Tornadic Severe Thunderstorm Events. Preprints, 13th Conference on Severe Local Storms, St. Louis, Amer. Meteor. Soc., 25-28.
Fujita, T. T., 1981: Tornadoes and downbursts in the context of generalized planetary scales. J. Atmos. Sci., 38, 1511-1534.
Grazulis, Thomas P., 1993: Significant Tornadoes 1680-1991. Environmental Films, 1326pp.
Ostby, Frederick P., 1993: The Changing nature of tornado climatology. Preprints, 17th Conference on Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc., 1-5.
Sammler, William R., 1993: An updated climatology of large hail based on 1970-1990 data. Preprints, 17th Conference on Severe Local Storms, St. Louis, Amer Meteor. Soc., 32-35.
|National Weather Service
Binghamton Weather Forecast Office
32 Dawes Drive
Johnson City, NY 13790
Page last modified: August 1, 2006.