Steve Hilberg, longtime Illinois CoCoRaHS State Coordinator is now part of the CoCoRaHS Headquarters team. Steve brings his weather and climate expertise as well as CoCoRaHS observing wisdom to us through his "TIPS" via our message of the day. Here are some to share with you.
Hilberg's Tips -- Winter Precipitation Types
Do you remember the difference between different types of winter precipitation? Here's a review.
Snow is small white ice crystals formed when supercooled cloud droplets freeze. Snow crystals can have different shapes usually dictated by the temperature at which they form.
Snow pellets, also called graupel, are white, opaque ice particles round or conical in shape. They form when supercooled water collects on ice crystals or snowflakes. They typically bounce when they fall on a hard surface and often break apart.
Snow grains are very small, white opaque particles of ice, more flattened and elongated than snow pellets. Snow grains can be thought of as the solid equivalent of drizzle, or as I like to call it, "snizzle".
Ice pellets, or sleet, are small balls of ice. They form from the freezing of raindrops or the refreezing of melting snowflakes when falling through a below-freezing layer of air near the earth's surface.
For measurement purposes, all four are treated as frozen precipitation and snow measurement procedure should be followed.
Freezing rain occurs when rain occurs and the surface temperatures is below freezing. The raindrops become supercooled as they fall through the layer of cold air near the surface and freeze upon impact with surfaces below freezing. Freezing rain is liquid precipitation and should be measured as you would measure rain, after you have melted the ice in your rain gauge (don't worry about any ice on the outside surface of the cylinder). You can report the thickness of ice on surfaces in you observation comments.
Hilberg's Tips -- The Basics: Measuring Snow and Reporting it Correctly
Measuring snow during the winter requires a few more steps to complete than just measuring rain.
There are five basics steps to remember:
- 1) Melt the snow that falls in your outer cylinder and measure the melted water. This is what you report for your daily precipitation.
- 2) Measure the depth of new snow on your snowboard, or other flat surface that is well-exposed and not subject to drifting. Measure to the nearest tenth of an inch, e.g. 4.3, 2.1, 0.8, etc. and report this in the new snowfall field (NOT the daily precipitation field).
- 3) If possible, take a snow core from your snowboard using the outer cylinder. Melt and measure this amount of water, and report it as the water equivalent of new snow. If you do not take a core, then leave this field NA.
- 4) Measure the total depth of snow and ice on the ground (new snow plus old snow) and report it to the nearest 0.5 inch. This is a measurement you should take every day there is snow on the ground.
- 5) At least once a week (preferably on Monday) or on days on which new snow has fallen, please take a snow core of the total snow and ice on the ground. Melt and measure this core, and report it as the “Melted Value from the Core” in the Total Snow and Ice on the ground section.
Also, if you observe flurries, but nothing accumulates on the ground or ends up in the gauge, you should report a Trace for precipitation AND a Trace for new snowfall. If there is any snow showing on the ground at observation time but it is not measurable, then also report a Trace for Total Snow and Ice on the Ground.
If you are measuring snow during the winter, it is a good habit to enter a zero for new snowfall each day when you do not have snow and if you did have precipitation. (If your precipitation is zero, snowfall is automatically set to zero.) Total Snow and Ice on the Ground should also be a daily observation, whether or not it has snowed in the past 24 hrs. This is the total amount on the ground at your observation time. If there is no snow on the ground, enter zero. If there is less than one half inch or coverage is less than 50 percent, then enter a Trace for Total Snow and Ice on the Ground.
Some observers choose to not measure the depth of new snow during the winter. If you are not measuring snow, then leave the New Snowfall field as NA. A zero in any field implies a measurement.
Finally, be sure to take some time to view the CoCoRaHS training animations on snow measurement on the CoCoRaHS YouTube channel . They are short, entertaining, and cover the techniques and procedures you need to know to successfully measure snow.
Hilberg's Tips -- Reporting Snow with the Mobile App
Reporting snow with the mobile app is not much different than using the web site. There are a couple of things to remember, however. As with the web site, DO NOT enter your snowfall in precipitation field. This is for the melted water. If you are unable to melt what's in your gauge at observation time but did measure the snow, click the NA box on the screen to enter NA for precipitation. (You cannot submit an observation with zero precipitation and "greater than" zero snowfall). Then, proceed to enter your snowfall information.
Hilberg's Tips -- The Difference between the Rain Gauge Amount and Snow Water Equivalent (SWE)
If you measure snow, there are five (yes, five) potential separate measurements you can make:
- 1) The melted precipitation in your rain gauge (daily precipitation).
- 2) The depth of the new snow that has accumulated in the past 24 hours (since your last daily observation) to the nearest tenth of an inch.
- 3) The liquid water equivalent of the new snow, obtained from taking a snow core then melting and measuring the water. THIS IS NOT THE AMOUNT FROM YOUR RAIN GAUGE!
- 4) The total depth of snow and ice on the ground, old and new, reported to the nearest half inch.
- 5) The liquid water equivalent of the total snow on the ground, obtained from taking a snow core then melting and measuring the water. In the instance where new snow is the only snow on the ground, then 2 and 4, and 3 and 5 could be the same.
We see too many observers copying their precipitation amount into the new SWE field. SWE is a separate measurement! If there has been rain followed by snow, or snow changing to rain, the amount in your rain gauge does not represent the liquid water equivalent of the snow. In windy situations where gauge catch may be poor, SWE from a snow core will likely be a more accurate measurement of the precipitation. In such a case, you can enter the SWE as your precipitation with a note in the comments about the situation and what was in your rain gauge. Here is a recent example. I had an inquiry from an observer who found her liquid precipitation in the gauge was 1.03" and that from a snow core from her from her snow board was 1.16". It was windy during the storm and she wondered if perhaps the wind had prevented all of the snow from making it into her gauge. Yes! The 4-inch gauge is not a great collector of snow in windy situations, so a correctly done snow core is more accurate. In this case, she should enter her SWE as the daily precipitation amount and indicate, in the comments, her gauge amount and that it was likely affected by the winds.
MAIN POINT: If you don't take a snow core and melt and measure the water, then leave "Melted value from the core to the nearest hundredth" as NA.
You can view a short video on how measure SWE on YouTube
Hilberg's Tips -- Snow Measurement Reminder
While we would like every observer to measure new snowfall we realize that not all observers want to or are able to make this measurement. The snowfall entered on your daily form should be a measurement, not an estimate. The measurement is made by using a ruler or snow stick to measure the depth of the new snow on a snowboard or other level surface. The depth of snow should never be measured in the rain gauge itself. Snowfall should also never be calculated using a snow-to-water ratio or a temperature/snowfall chart. If you don't measure snow but want to provide an estimate of what has fallen, enter NA for new snowfall and include the estimate in your comments. Again, if you are measuring snow please review the online snow measurement videos - they are short and are great for a quick review.
Hilberg's Tips -- Measuring and Reporting Total Snow and Ice on the Ground
I've had a few questions on how to report total snow on the ground when there are large patches of bare ground. If there is any natural snow on the ground at observation time (i.e. not man-made piles from shoveling, etc.) then you should report the Total Depth of Snow and Ice on the Ground (old snow plus any new snow) every day there is snow on the ground. The total depth of snow on the ground is reported to the nearest half-inch. If less than 50 percent of the ground is covered with snow, then report the total snow depth as a Trace, and a Trace should be reported each day until the snow has melted, assuming there is no new snow. Review this short CoCoRaHS animation for more information: TOTAL DEPTH
Hilberg's Tips -- Snow - Trace, Zero or NA?
Here are a couple of things to keep in mind about snow measurements the next time you see flakes fly.
If you observe flurries at your location, but nothing accumulates on the ground or ends up in the gauge, you should report a Trace for precipitation AND a Trace for new snowfall. Remember, if you observe it's a trace - it doesn't have to fall in the gauge. If there is any snow showing on the ground at observation time but it is not measurable, then also report a Trace for Total Snow and Ice on the Ground.
If you are measuring snow during the winter, it is a good habit to enter a zero for new snowfall each day when you do not have snow and if you did have precipitation. In fact, it's a good idea to do this year 'round. (If your precipitation is zero, snowfall is automatically set to zero.) Total Snow and Ice on the Ground should also be a daily observation, whether or not it has snowed in the past 24 hrs. This is the total amount on the ground at your observation time. If there is no snow on the ground, enter zero. If there is less than one half inch or coverage is less than 50 percent, then enter a Trace for Total Snow and Ice on the Ground.
Some observers choose to not measure the depth of new snow during the winter. If you are not measuring snow, then leave the New Snowfall field as NA. A zero in any field implies a measurement.
Hilberg's Tips -- Reporting Hail
As you know "hail" is part of the CoCoRaH S name. Spring is prime time for hail, especially the large variety, but it falls in different parts of the country during various seasons. We often see observers mention hail in their comments, but then forget to submit a separate hail report. When you observe hail, please submit a hail report as soon as possible with as much information as you can provide (you can always go back and add to or edit your report later). As soon as you submit the hail report it is also transmitted to your local National Weather Service office. These reports are critical in severe weather situations and may be one of the triggers for a severe thunderstorm warning, for example. You can find the link to the hail report in the left hand menu once you log in.
Once the hail report displays, fill out as much information as you have at the time, but be sure to include the date, time, and size of the hailstones. Note that often there will be larger hailstones among a fall of smaller stones. For example, you may be observing many 1/4 inch stones (pea-size), and at the same time may see a few larger hailstones falling as well. Again, you may go back and update your report, for example, after you have had a chance to see if there was any damage. Note that the Hail report is NOT yet available on the mobile app.
Safety is of critical importance! Observe from the safety of a building. DO NOT run outside to pick up or measure large hail stones in the middle of a storm. Stay away from windows, especially if the wind is blowing and/or there is lightning.
Hail size is easy to estimate by comparing the hail to the size of common objects, from coins to softballs. Not all hailstones are round. Some look like oblong potatoes or have jagged spikes protruding. When measuring hail or estimating its size, use the measurement along its longest axis.
You can download this handy pocket hail size guide from the Illinois CoCoRaHS web page. The rule on the bottom is to scale and fits on a 3x5 card. Make multiple copies and keep one at home, in the car, or at work.
Finally, review hail measurement procedures by viewing our CoCoRaHS hail measurement training animation.
Hilberg's Tips -- The Importance of Significant Weather Reports
Significant Weather Reports (SWR's) submitted by CoCoRaHS observers are a huge help to the National Weather Service. All SWRs are automatically routed to the local NWS office, and forecasters use these reports to monitor the progress of storms. Questions we get from time to time are "What is significant weather?" and "How often should I submit a Significant Weather report?". First, Significant Weather Reports are supplementary reports and DO NOT replace your Daily Report nor should it be submitted in lieu of a Daily Report. The SWR is great for updating rainfall after your regular observation time. You should not be updating your daily report once it is submitted, except to make a correction or add additional information.
What is "significant weather"? In general, it is heavy rain (falling at a rate of an inch an hour or more), snow accumulations, high winds, icing from freezing rain, or flooding. However, you are not limited to this list - use your best judgment. How often should you report? You should report as often as needed to convey what is happening. Comments included with your Significant Weather report are very useful.
Hilberg's Tips -- Editing Your Observations
We sometimes get questions from observers on how to edit their data. You can edit any report you submit. To edit your Daily Precipitation Report, for example, log in and then select LIST/EDIT MY REPORTS. Click on the pencil icon next to the report you need to edit, and go from there.
This same procedure can be used for any report you submit, including Multi-Day reports, Significant Weather Reports, etc. Mobile users can also edit your data, although the procedure is different. You access the editing function through the station history option in the app. Select the menu in the upper left-hand corner, and select History for a list of your recent daily reports. Touch any of the reports on the screen, and a dialog will pop up asking if you want to edit this entry.
Hilberg's Tips -- Forgot Your Login and/or Password?
Most of us probably save our login and password to web sites we visit often because it's a lot easier to access the web site each time However, after a period of time you might forget your password, especially, since you don't see it except as a series of dots or stars. Inevitably something will happen where you will have to enter everything again (computer crash, new web browser, new phone, etc.), and for the life of you you can't remember your CoCoRaHS password. What do you do? After so many times logging in you may not notice it, but there is a a way to retrieve your login info right there on the login page.
Once you click that, you will be asked to enter your email address or your station number. Your login information will be sent to the email address you registered with (if you don't see the message be sure to check your spam/junk folder). One issue you might encounter is if you have changed your email address and you have not updated in your CoCoRaHS record. In this case, the email is sent to your old and possible defunct email address and you will never see it.
To update your email address, click on My Account in the top line menu and then select EDIT. Change your information and save it. Of course, this only works if you can login. If all else fails and you can't get your login information please contact firstname.lastname@example.org and we'll help you retrieve it.
Hilberg's Tips -- How to Correct a Multi-Day Amount Submitted as a Daily Amount?
Situation: you are gone for the weekend, and on Monday morning you need to report your weekend precip accumulation. In an early morning fog you log on to CoCoRaHS, enter your precipitation amount, and click Submit. Gaackk!! You realize you just entered your weekend accumulation as a daily amount. So, you pull up the multi-day accumulation report, enter the dates and your amount, and click Submit. The screen lights up in red text: Errors: This multi-day report would overlap with daily report on 2/11/2018. Failed to save the Multiple Day Precipitation Accumulation Report. Great.....now what?
As long as you have a valid amount on the conflicting daily report you will get an error. In order to submit the multi-day report, FIRST edit your daily report and set your erroneous daily report amount to NA, then Submit. Now, you can go ahead and enter the multi-day report without generating an error. There is one last step you need to do to make this a clean operation. Send me an email with your station number and the date of the NA'ed daily report. We will make sure the daily report is removed from the database. If it is not, then your observations will not list correctly when you list your data using the Station Precip Summary or Station Snow Summary.
Hilberg's Tips -- To "NA' or not to "NA"...
When you pull up your Daily Report form on the web, all fields except for the precipitation field are set to "NA". "NA" in our case means "Not Available" or missing. If there is no precipitation, then zero is the correct report. "NA" does not mean "no precipitation". Also, please do not submit NA reports with no data. If you do not have an observation for a particular day, then there is no need to enter anything at all. One situation that occurs frequently is that an observer may submit a multi-day accumulation as a daily report, then realize they needed to submit a multi-day report. In order to do that, the incorrect daily report must be set to "NA", or you will get an error message when you try to enter the correct multi-day report. That's because two observations for the same day cannot exist in the database. Each day must be represented by a daily accumulation, or part of a multi-day accumulation. The daily report which is now "NA" must be deleted from the CoCoRaHS database. If not, then it will affect the correct listing of your data in data summaries. To have the record deleted, be sure to email me with your station number and data of the record to be deleted and I will take care of it.
A situation where "NA" is allowed for precipitation is when reporting snowfall. If it is still snowing at observation time and you cannot bring in your gauge to melt and measure, you can still measure and report the depth of the snow. To do this, enter "NA" for your precipitation, and then enter your snowfall in the New Snow section of the report. The Daily Report will not allow a zero for precipitation and a non-zero amount for snow because, after all, snow is precipitation. You can report your melted precipitation and total snowfall the next day using the Multi-Day Accumulation form. Feel free to contact me if you have questions about any of this.
Hilberg's Tips -- Back to Basics - Observation Time
When you signed up for CoCoRaHS you selected an observation time. This is the time that automatically appears in the Observation Time field on the Daily Report form, and for the many of us this is 7:00 a.m. The time is automatically entered into the field as a convenience since we assume that's when you will regularly take your observation. However, if for some reason you make your observation at an earlier or later time other than the "standard" time you chose, be sure to enter that actual observation time in the Observation Time field. This is especially important when we have rain occurring at the time of observation. A difference of 30 minutes could make a big difference between what you measure and what surrounding stations measured 30 minutes earlier. So if your observation time is more than 5 minutes either side of your chosen time, enter the actual observation time in the field. Also, the observation time is the time you make your measurement, NOT the time you enter it on the web. For example, if you make you measurement at 7:00 a.m. but don't enter it on the web until 3:00 p.m., your observation time remains as 7:00 a.m.
The rainfall your report each morning is the total that has accumulated since the previous day's observation. The total is reported on the day of the observation, not necessarily the day the rain fell. For example, let's say you had 1.23 inches rain on the afternoon of April 1st, and your next regular observation is the morning of April 2nd. Your observation for the morning of April 2nd would be 1.23 inches, representing all of the rain that fell since your last regular observation (the morning of April 1st). It would be helpful if you noted when the rain fell in your comments.
Hilberg's Tips -- Please Don't Ignore Email About Your Observation
There are many eyes looking at the CoCoRaHS data to ensure that it is correct. Our quality control procedures may cause your observation to be flagged for further investigation. Sometimes it is because there may be an error, such as an incorrect time of observation, a typo, or the ever-popular decimal error. In fact, most errors we find are not measurement errors, but reporting errors. Sometimes we want to verify an observation as valid. For example, a very high rainfall value surrounded by significantly smaller amounts will stand out and may very well be correct (such as from an isolated heavy thunderstorm). You may be contacted to verify that observation so that it is NOT flagged in future quality control processing. So, please respond to email you receive from CoCoRaHS or your local coordinator asking about an observation. The intent is not to be critical - we want to ensure the data is as good as possible, and we need your help to do that. If you make the correction to your observation, please let the coordinator who contacted you know that you have done so. That way we can "close out" the quality control ticket that was submitted for the observation. Thanks!
Hilberg's Tips -- Weighing Your Precipitation
Illinois CoCoRaHS state coordinator, Steve Hilberg has spent many hours preparing tips for CoCoRaHS observers in his state. Throughout the seasons of 2019 we would like to share them with you. We'll just call them "Hilberg's Tips" for now. So let's begin . . . . Here's one on weighing your precipitation.
The "melt and measure" method of dealing with snow and ice in the gauge in the winter is sometimes time-consuming, and there's always a chance that you could spill the contents as your pour from outer cylinder into the inner measuring tube. There is a much easier way to deal with snow and ice in the rain gauge, and the snow collected in snow cores that involves no melting and is very quick to do. The alternative is to weigh your outer cylinder and the contents, and convert that measurement into inches of precipitation. You can view the two-minute CoCoRaHS training animations on how to do this WEIGHING, but here's a quick description on how to accomplish this. You will need a decent kitchen scale that measures to the nearest gram. The first step is to weigh your empty, dry outer cylinder without the inner tube or funnel. Write down the weight. It's also a good idea to write the weight on the bottom of the cylinder with a permanent marker. The next time it rains or snows, bring in your outer cylinder. Be sure to wipe off the outside of the cylinder to remove any excess water. Then, weigh the cylinder and its contents. Subtract the weight of the cylinder from the total weight. Divide the result by 201, and you will have the amount of precipitation in inches. (An inch of water weighs 200.8 grams). Here is an example.
Your outer cylinder plus the snow in it weighs a total of 510 grams. The outer cylinder weighs 445 grams. The weight of the snow in the gauge is 510-445 = 65 grams. 65 g divided by 201 g/inch = 0.32 inch of precipitation.
Not only is this great during the winter, but you can also use this for any heavy precipitation you receive where the inner cylinder overflows. This eliminates the need to pour and measure multiple times and the risk of spilling. Pour the contents of the inner cylinder into the outer cylinder, and then weigh the outer cylinder plus the precipitation. Be sure the outside of the cylinder is dry before you weigh.
Hilberg's Tips -- Please keep your email address updated
Communication is a very important part of the "community" in CoCoRaHS, and our primary means of communicating with observers is through email. If your email address is not up to date, then you will not receive monthly editions of The Catch and other important communications from CoCoRaHS headquarters or your state and local coordinators. Typically you will receive only one two messages a month.
It's easy to update your email address in your CoCoRaHS record. After you log in, select My Account in the top line menu.
On the next screen, click the edit button on the far right side of the My Information section.
When the My Information screen displays, update your email address, and then click Save.
That's all there is to it! . . . or just send us your new email address along with station number to email@example.com