November 1, 2008

Dear Snow Spotter,

Thank you for your reports last year!  Significant winter weather impacted the Ohio Valley beginning in late January, continuing through the entire month of February, and culminating with the biggest winter storm of the season on March 7-8.  The March 7-8 storm produced crippling amounts of snow along the Interstate 71 corridor, with between 12 and 20 inches reported from Cincinnati to Columbus.  The seasonal snowfall totals at Columbus (45.8”) and Dayton (41.4”) were the second highest over the last 12 winters.  This was the snowiest winter at Cincinnati, Columbus and Dayton since the winter of 2002-03.

Your snowfall/icing reports for the March 7-8 Winter Storm are plotted on a map that is attached to the letter. Note, you can see color copies of these images by viewing this letter on the web at (www.erh.noaa.gov/iln/spotterpage/spotter.htm). Your timely reports throughout the winter helped the Wilmington, Ohio National Weather Service (NWS) provide accurate and timely forecasts.   

If you are new to the NWS Snow Spotter Network – WELCOME!!  We appreciate your willingness to provide valuable winter weather reports.

The reason for having a snow spotter network is to provide our forecasters with near real-time snowfall information (i.e. ground truth).  As with severe weather, our forecasters can infer what is currently going on or what will happen in the near future using various tools (radar, satellite, model data, etc.).  However, knowing how much snow or ice that has actually fallen (“ground truth information”) allows us to monitor the progress of a storm and make critical decisions concerning advisories and warnings for a particular winter storm.

The snowfall information collected is also used in two other ways.  First, it is used to provide a summary of what actually happened for all of our customers and partners (state and local officials, media, and you).  Lastly, this ground truth information will be used to help our meteorologists evaluate their past forecasts, which will help improve their future winter storm forecasts.  This is all thanks to you!!!

As a snow spotter we would like you to report in real-time the following information:

In the fall of 2005, we initiated a web-based reporting program called eSpotter.  eSpotter is a system that allows spotters to easily submit winter or severe weather reports online.  The use of the system is currently available for trained spotters and emergency managers.  Last year we received nearly half of our reports via eSpotter.

If you have not signed up yet and want to, then go to http://espotter.weather.gov/ and click on New to eSpotter? [ Register Here ].  Once you’ve registered then you will get a reply within 10 business days with a temporary password.  Note, once you can log on with a password click on Create a Report in the top left hand corner.  This will take you to a severe weather report form.  Near the top there is a clickable link for a winter weather report form. 

If you don’t have online access to eSpotter, then feel free to call our unlisted number (800) 899-2748.  On occasion, we may give you a call during a snow event.  We will only call during the times that you provided to us on your Severe Weather Spotter application.

Figure 1 – Schematic showing how to measure snow.

Below are some tips for measuring snow:

Measuring snow is a rough art and can be very subjective.  A lot depends on frequency and location of your measurement.  You want a cold flat surface that is somewhat protected from the wind, but not so protected that snowfall measurements will be inaccurate.  On the web at www.erh.noaa.gov/iln/spotterpage/spotter.htm under training you will find a PowerPoint presentation on how to measure snow along with a brief tutorial on the same subject. Below are some helpful hints for measuring snow.  Figure 1 will provide some visual clues for these hints.

• Surface: 
• First choose a convenient spot away from the obstacles such as a house, garage, shed, fence, large bushes, and trees, ideally about 10-12 feet from a 6 foot fence.  These objects aid in the piling up (drifting) of snow near them.  The ideal spot will usually be in the middle of your back or front yard away from trees.
• Ideally a snowboard (simply a piece of plywood cut in about a 2 ft square and painted white), an outdoor table, or a deck are the best measuring surfaces.  If you use a snowboard on the ground, then a flag or some other marker will help you locate it during snowy weather.
• Pavement is OK if it’s cold (below 32 F), but should not be used under milder conditions due to melting.
• Grass is too uneven...especially in the fall and after green up in the spring.  Grass may be used in the middle of winter, if it’s dead and not puffy.
• Bare ground is OK.  Do not mistake an ice layer or crusted snow as the “ground”.
• Picnic table and autos are fine if winds are light. 
• If possible, clean off the surface you are measuring for your next measurement.  If measuring on a surface that already has a covering of snow, then subtract the old snow from the new.
• Wind/Drifting:  If drifting is a problem, take several measurements and average them.  Bare ground will give you a zero reading.  Do not include the largest drifts.
• Frequency:  Do not measure more than once an hour.  Hourly measurements will be extremely helpful when snowfall rates are exceptional (1" or more per hour).  In general, once every several hours (3 to 6) is preferable, unless the snow is melting.
• Total snowfall:  Report to the nearest tenth of an inch.
• Snow Depth:  Report to the nearest whole inch.  Roundup at 0.5 inches.
• The optimal conditions for measuring snow are to find a piece of wood (wooden picnic table or piece of plywood) in an open area where snow will fall unhindered and yet not drift from blustery winds.  After measuring the snow, clean off the piece of wood for your next reading. 

Below are some tips for measuring ice:

• Measure on an outside surface such as a fence, picnic table, car, tree limb, etc.  Make sure that there is no internal heat source.
• When measuring, use a ruler and your eyes to estimate how thick the ice has accumulated.
• Do not measure the length of icicles.

Thanks again for volunteering!  Your time and effort is greatly appreciated.  Feel free to call me at (937) 383-0031 if you have any questions.

Sincerely,

Mary Jo Parker
Warning Coordination Meteorologist                                        
National Weather Service
Wilmington, Ohio