Hourly data on whether it is snowing for a particular location (NYC)

Question

I am trying to get hourly information on whether it is raining/snowing in a particular location at that point in time (NYC to be exact).

Currently, I am looking at NOAA's QCLCD hourly weather data from the NYC Central Park weather station. The data contains a WeatherType column that states if there is rain or snow. However in a previous question, I asked about inconsistencies with the HourlyPrecip column - there are instances where the WeatherType would indicate rain, but the HourlyPrecip would show 0 inches - and it turns out that the WeatherType is a 3-hour summary of conditions.

The HourlyPrecip column is therefore what I need for the presence of rain. However, there is no corresponding column for snowfall. I took a closer look at the dataset and found that there are some >0 entries for HourlyPrecip when the weather condition indicates "Snow" (SN). Does that reflect the hourly snowfall (ie does HourlyPrecip reflect the hourly snowfall as well as rain)?

Here is a small slice of the data that illustrates my point (T= trace amount):

Date Time WeatherType DryBulbCelsius RelativeHumidity WindSpeed HourlyPrecip 20130302 2011 -SN 0.6 75 9 20130302 2049 -SN 0.0 82 11 20130302 2051 -SN 0.0 79 10 T 20130302 2056 -SN 0.0 79 7 20130302 2151 -SN -0.6 78 10 T ... 20130318 1851 +SN FZFG -0.6 96 8 0.11 20130318 2051 -SN BR -0.6 92 8 0.12 20130318 2103 -SN BR -0.6 96 10 20130320 2351 -SN 2.8 55 0 T 20130325 1249 -SN 3.0 76 14 20130325 1251 -SN 2.8 76 17 T

I have emailed NOAA to enquire about this but their only contact email on the site appears to be geared towards ordering climatological data from them, so I am not sure if I will get a response. Wondering if anyone here has experience with this.

Answer 1

The live weather feeds for weather stations, reporting to the NWS, in the State of New York can be found here at the link below. Each station has its own update interval. The XML feed is really HTML, so you will have to parse it as a HTML table.

http://w1.weather.gov/xml/current_obs/seek.php?state=ny&Find=Find

Answer 2

NASA has a project called Precipitation Measurement Missions. In theory, this is a 3-hourly dataset of precipitation for any location within 60° of the equator, based on satellite data. You can find more information here.

In theory it does both snowfall and rainfall. However, spaceborne remote sensing of snowfall is difficult — if you are interested in one particular location, and that location happens to have a weather station, you are most likely going to get more reliable data from the ground.

Meanwhile, enjoy this awesome video animation.

Answer 3

As it turns out, the NOAA did respond (rather quickly too i might add)!

Regarding snowfall measurement and positive precipitation observations during snow (edited excerpt of email exchange):

"The ASOS systems don't measure snowfall, so you won't find it there. You will have liquid equivalent precipitation (the rain gauges are heated). However, even that becomes suspect during significant snow events due to the gauge become clogged or frozen if snowfall rates are high or temperatures are quite low.

Therefore, **don't use QCLCD for snowfall levels **. Stick with daily data such as the edited LCD or GHCN-Daily.

However, if all you need to know is whether it is snowing at that particular time, you may use the present weather, or 'weather type' to determine that, since its precipitation discriminator is independent of accumulation.

The WeatherType is also hourly, not 3-hourly. It's a spot determination at the time of observation."