Linking Synoptic Climatology to Hydrologic Responses in Upstate New York and Western New England

• Created by:

• David Thomas, University at Albany, SUNY

A COMET project between the University at Albany, SUNY and National Weather Service Forecast Office, Albany N.Y.

February 2003

Location of Stations

625 COOP stations from New York State and adjoining counties were used.

Time Frame:

1951 – 2000 November through April

Elevation of Region

AlbanyNumber of cases with 6 Day SWE loss

1951 - 2000

0 0

9 9

02

7269

5 4

22

85

0

20

40

60

80

100

November December January February March April

Month

Nu

mb

er o

f d

ates

wit

h S

WE

loss 2.00'' and

greater

0.50'' - 1.99''

RochesterNumber of cases with 6 Day SWE loss

1951 - 2000

0 1 3

19

26

16

27

83

106

5

88

0

20

40

60

80

100

120

November December January February March April

Month

Nu

mb

er o

f d

ates

wit

h S

WE

loss

2.00'' andgreater

0.50'' - 1.99''

Definition of Wind Direction:A forecast 6 Day mean 200 hPa

wind with wind direction as follows:

WSW = 236.25 - 258.74

West = 258.75 - 281.24

WNW = 281.25 - 303.74

Definition of Snow Depth Change

• For a particular event a COOP station was considered only if it had a snow depth loss, or no change in snow depth. Any snow depth gains were eliminated from the list.

• If more than 25% of the COOP stations had a snow gain for a particular event, that event was not included in the study.

Definition of Rain on Snow

• Rainfall is defined as at least 0.10 inches of rain over a given day.

• In the event of mixed precipitation a 10:1 liquid water equivalent assumption was made to estimate how much precipitation fell strictly as rain.

Statistics for Snow Depth ChangeAlbany Rochester--Absolute Difference --Absolute DifferenceSnow Depth loss Snow Depth loss

WSW West WNW WSW West WNWCOOP stations COOP stationsused 316 322 330 used 297 341 354MIN 0.33 0.75 0.60 MIN 1.20 0.75 0.43MAX 8.60 11.00 10.80 MAX 14.00 12.87 8.75MEAN 2.96 4.11 4.35 MEAN 5.61 4.85 3.48St. Dev 1.06 1.23 1.38 St. Dev 1.54 1.60 1.36

Albany Rochester--Percent Difference --Percent DifferencePercent of Snow Depth loss Percent of Snow Depth loss

WSW West WNW WSW West WNWCOOP stations COOP stationsused 316 322 330 used 297 341 354MIN 7% 6% 9% MIN 5% 9% 5%MAX 86% 88% 96% MAX 90% 100% 81%MEAN 38% 41% 40% MEAN 40% 47% 34%St. Dev 15% 15% 15% St. Dev 14% 16% 16%

Statistics for Rain on SnowAlbany RochesterRain on Snow Rain on SnowAbsolute Difference of Snow Depth loss Absolute Difference of Snow Depth loss

WSW West WNW WSW West WNWCOOP stations COOP stationsused 297 365 263 used 218 395 257MIN -5.00 -3.25 -1.60 MIN 0.33 -2.75 -1.25MAX 4.14 3.50 5.80 MAX 13.33 5.60 6.20MEAN 0.45 1.01 1.83 MEAN 3.74 1.80 2.26St. Dev 1.25 0.75 1.00 St. Dev 1.45 0.83 0.94

Albany RochesterRain on Snow Rain on SnowPercent of Snow Depth loss Percent of Snow Depth loss

WSW West WNW WSW West WNWCOOP stations COOP stationsused 297 365 263 used 218 395 257MIN -50% -650% -100% MIN 3% -38% -15%MAX 20% 89% 100% MAX 87% 88% 77%MEAN 0% 18% 36% MEAN 33% 27% 27%St. Dev 5% 37% 26% St. Dev 15% 16% 17%

Albanywind: west-southwest

Albany wind: west-southwest

Albanywind: west

Albany wind: west

Albanywind: west-northwest

Albany wind: west-northwest

Rochester wind: west-southwest

Rochester wind: west-southwest

Rochester wind: west

Rochester wind: west

Rochester wind: west-northwest

Rochester wind: west-northwest

Cumulative Frequency Charts

• Based on the 277 events for Albany, New York and 365 events for Rochester, New York, that had 0.50 inches or more of 6 day SWE loss.

• Based on WSW,West, and WNW wind direction.• Not all events had a 2 day rainfall.

Albany Rain on SnowCumulative Frequency

Rainfall Cumulative Chart for Albany, New York104 cases

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.1 0.2 0.3 0.4 0.5 0.75 1 1.5 2 2.5

rainfall in inches

pe

rce

nta

ge

of

ca

se

s

WSW wind direction

West wind direction

WNW wind direction

All cases

Rochester Rain on SnowCumulative Frequency

Rainfall Cumulative Chart for Rochester, New York137 cases

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.1 0.2 0.3 0.4 0.5 0.75 1

rainfall in inches

pe

rce

nta

ge

of

ca

se

s

WSW wind direction

West wind direction

WNW wind direction

All cases

Albany Rain on Snow wind: west-southwest

Albany Rain on Snow wind: west-southwest

Albany Rain on Snow wind: west

Albany Rain on Snow wind: west

Albany Rain on Snow wind: west-northwest

Albany Rain on Snow wind: west-northwest

Rochester Rain on Snow wind: west-southwest

Rochester Rain on Snow wind: west-southwest

Rochester Rain on Snow wind: west

Rochester Rain on Snow wind: west

Rochester Rain on Snow wind: west-northwest

Rochester Rain on Snow wind: west-northwest