Snow MeasurementsSnow Measurements

NOAA/NWS Current Standard Observing Practices

ASOS, Snow Paid and Snow Spotters

NOAA/NWS Current Standard Observing Practices

ASOS, Snow Paid and Snow Spotters

Thomas TownsendRegional Observations Program Manager

NWS Central RegionMay 25, 2011

Snow MeasurementsSnow Measurements

A short history

LCD record stations

Snow Paid observers

ASOS

NWS Spotters

A short history

LCD record stations

Snow Paid observers

ASOS

NWS Spotters

Snow MeasurementsA little history

Snow MeasurementsA little history

For many years up until the Modernization of the National Weather Service in the early and mid 1990’s the NWS Offices measured snow at the four synoptic times and at midnight, producing high quality records at about 230 Local Climatological Data (LCD) stations.

The FAA Flight Service Stations also measured snow at the four synoptic times and at midnight, producing high quality records at many more Local Climatological Data (LCD) stations.

Bringing the total to about 273 LCD station.

For many years up until the Modernization of the National Weather Service in the early and mid 1990’s the NWS Offices measured snow at the four synoptic times and at midnight, producing high quality records at about 230 Local Climatological Data (LCD) stations.

The FAA Flight Service Stations also measured snow at the four synoptic times and at midnight, producing high quality records at many more Local Climatological Data (LCD) stations.

Bringing the total to about 273 LCD station.

Snow MeasurementsSnow Measurements

Following ASOS commissioning and the movement of NWS away from many LCD airports and taking of aviation observations and augmentation of ASOS, the NWS struggled to fill the LCD snow records using volunteers and cooperative data, etc.

The NWS closed half of offices and moved about half of the remaining 122 offices off of airports.

Estimated data was not allowed into the observation record (Data is data).

Aviation Service Levels were negotiated between the FAA the Air Transport Association, FAA contract observers at A and B level stations provided 6-hourly snow depth reports and snow increase remarks at all Aviation Service Level A and B locations. Snowfall was no longer a requirement at aviation stations.

Following ASOS commissioning and the movement of NWS away from many LCD airports and taking of aviation observations and augmentation of ASOS, the NWS struggled to fill the LCD snow records using volunteers and cooperative data, etc.

The NWS closed half of offices and moved about half of the remaining 122 offices off of airports.

Estimated data was not allowed into the observation record (Data is data).

Aviation Service Levels were negotiated between the FAA the Air Transport Association, FAA contract observers at A and B level stations provided 6-hourly snow depth reports and snow increase remarks at all Aviation Service Level A and B locations. Snowfall was no longer a requirement at aviation stations.

Snow MeasurementsSnow Measurements

Snow Measurements2002-03 Winter Season: Major

Snowstorms/Customer Ire

Snow Measurements2002-03 Winter Season: Major

Snowstorms/Customer IreBoston –

A snowfall of 27.6 inches was measured at Logan Airport from Feb. 16-17, 2003. If accurate, this would be a new 24-hour Boston snowfall record. 41.6 inches of snow was measured for February, a new monthly record.

Snowfall measurements were taken on a non-standard slatted wood bench approximately four feet from a 3-story high building. The prevailing strong northeast winds (22 MPH with gusts to 39 MPH) during the storm likely resulted in inflated snowfall totals as the downwind site likely received deposition from wind blown roof snow. Snow depths were also likely reduced by the exposure and strong winds.

BALTIMORE/WASHINGTON

A four day snowfall total of 28.2" was measured at BWI resulting in a reported all-time record snowstorm total. The hourly observations imply that hourly snowfall was reported. However, the Committee was unable to confirm this fact in addition to determining the representativeness of the snowfall observing site.

Boston –

A snowfall of 27.6 inches was measured at Logan Airport from Feb. 16-17, 2003. If accurate, this would be a new 24-hour Boston snowfall record. 41.6 inches of snow was measured for February, a new monthly record.

Snowfall measurements were taken on a non-standard slatted wood bench approximately four feet from a 3-story high building. The prevailing strong northeast winds (22 MPH with gusts to 39 MPH) during the storm likely resulted in inflated snowfall totals as the downwind site likely received deposition from wind blown roof snow. Snow depths were also likely reduced by the exposure and strong winds.

BALTIMORE/WASHINGTON

A four day snowfall total of 28.2" was measured at BWI resulting in a reported all-time record snowstorm total. The hourly observations imply that hourly snowfall was reported. However, the Committee was unable to confirm this fact in addition to determining the representativeness of the snowfall observing site.

Snow MeasurementsSnow Measurements

There had been a loss of about 50 percent of the snowfall data since automation of surface observations at LCD airport locations. LCD snowfall data have, for decades, provided the nation with the bulk of its near real-time 6-and-24 hourly snowfall observations.

 Following the winter of 2002-2003, a snow team was formed under the Extremes Committee of the NCDC to form recommendations to the NWS Corporate Board Operations Committee.

For winter 2003‑2004, NWS requested the FAA to add snowfall measurements and other parameters to their observation requirements at LCD locations, where possible and supported establishment of NWS "Snow Paid" Contracts where LCD sites still lacked snowfall data.

There had been a loss of about 50 percent of the snowfall data since automation of surface observations at LCD airport locations. LCD snowfall data have, for decades, provided the nation with the bulk of its near real-time 6-and-24 hourly snowfall observations.

 Following the winter of 2002-2003, a snow team was formed under the Extremes Committee of the NCDC to form recommendations to the NWS Corporate Board Operations Committee.

For winter 2003‑2004, NWS requested the FAA to add snowfall measurements and other parameters to their observation requirements at LCD locations, where possible and supported establishment of NWS "Snow Paid" Contracts where LCD sites still lacked snowfall data.

Snow MeasurementsSnow Measurements

Snow MeasurementsToday

Snow MeasurementsToday

Nearly all NWS Offices measure and record snowfall and snow depth at the four synoptic times and midnight, and use the data to prepare Daily and Monthly Climate Records.

FAA Contract observers at about 60 locations observe and record snowfall and snow depth at the four synoptic times and midnight, and use the data to prepare Daily and Monthly Climate Records.

NWS has secured the services of individuals and businesses at most remaining LCD locations observe and record snowfall and snow depth at the four synoptic times and midnight, and use the data to prepare Daily and Monthly Climate Records.

Nearly all NWS Offices measure and record snowfall and snow depth at the four synoptic times and midnight, and use the data to prepare Daily and Monthly Climate Records.

FAA Contract observers at about 60 locations observe and record snowfall and snow depth at the four synoptic times and midnight, and use the data to prepare Daily and Monthly Climate Records.

NWS has secured the services of individuals and businesses at most remaining LCD locations observe and record snowfall and snow depth at the four synoptic times and midnight, and use the data to prepare Daily and Monthly Climate Records.

ASOSASOSAll LCD ASOS locations

replaced Heated Tipping Bucket (HTB) with All Weather Precipitation Accumulation Gauge (AWPAG)

Added a 8 ft double Alter shield during the last year

Snow MeasurementsSupplemental ObservationsSnow MeasurementsSupplemental Observations

Various class of supplemental snow observers are trained and used by NWS offices across the nation.

Most offices use CoCoRaHS observers.

Some other sources:

Some “Storm Spotters” in the SKYWARN program also receive snow observation training by NWS and are used for winter weather data

UCOOP stations - Unofficial cooperative stations receive NWS training and call in reports.

Chicago Area Snow Team (CAST) has been in operation for several years. There are about 10 observers currently. These observers are NWS trained.

North Dakota State Water Commission/Atmospheric Resources Board  (ARB) network of observers – 91 snow observers trained by the state.

Central Illinois - Significant Weather Observation Program (SWOP) trained by NWS.

Colorado Avalanche Information Center (CAIC) and La Sal Avalanche Center information regularly.  These folks are considered snow experts in areas including observing, forecasting, snow pits/swe, avalanche monitoring and control, etc. 

Various class of supplemental snow observers are trained and used by NWS offices across the nation.

Most offices use CoCoRaHS observers.

Some other sources:

Some “Storm Spotters” in the SKYWARN program also receive snow observation training by NWS and are used for winter weather data

UCOOP stations - Unofficial cooperative stations receive NWS training and call in reports.

Chicago Area Snow Team (CAST) has been in operation for several years. There are about 10 observers currently. These observers are NWS trained.

North Dakota State Water Commission/Atmospheric Resources Board  (ARB) network of observers – 91 snow observers trained by the state.

Central Illinois - Significant Weather Observation Program (SWOP) trained by NWS.

Colorado Avalanche Information Center (CAIC) and La Sal Avalanche Center information regularly.  These folks are considered snow experts in areas including observing, forecasting, snow pits/swe, avalanche monitoring and control, etc. 

Snow MeasurementsSnow Measurements

CoCoRaHS network has become a great value to the NWS

Snow MeasurementsSnow Measurements

Supplemental observers generally observe and report snowfall and snow depth once daily – in the morning.

Offices locally keep a contact list and metadata for these reporters

NWS occasionally calls the observers for spot reports during a snow storm

Supplemental observers generally observe and report snowfall and snow depth once daily – in the morning.

Offices locally keep a contact list and metadata for these reporters

NWS occasionally calls the observers for spot reports during a snow storm

Snow MeasurementsSnow Measurements

Snow MeasurementsSnow Measurements