Data Collection and FAQs

Participate in Mountain Rain or Snow in three steps: 

Location: The app needs your location to submit an observation, so make sure that your device’s location permissions are set to ON. 

Reach a member of the team: If you have questions, you can directly reply to your most recent text message from us (855-909-0798) at any time. 

Send observations while out of service: If you do not have cell service/Wi-Fi when you submit, the app will save your observation for you to manually upload later. 

Classifying precipitation types

How do I recognize mixed precipitation? 

Mixed precipitation might look like slushy snow, or rain that is crystallizing.  As it falls, it might look part solid and part liquid.

If the precipitation is liquid as it falls, call it rain. If the precipitation is solid as it falls, call it snow (unless it’s hail or sleet - see below). If it’s changing too fast to be sure, call it mixed. If there are some fully solid and some fully liquid pieces falling at the same time, call it mixed as well.

Be sure to only report what is currently falling, rather than what is accumulating on the ground. Check out the precipitation phase classification guide below for a visual aid. 

If you have questions about classifying mixed precipitation, feel free to send us a message at 855-909-0798.

How should I classify graupel (snow pellets)?

Graupel is classified as snow for the purposes of this project. While there are many types of snow, we don’t need further specificity for the scope of Mountain Rain or Snow’s research question. 

Graupel and snowflakes form by different processes high in the atmosphere, but the conditions that both experience between the cloud and the ground fall into our “snow” category. Graupel looks like snow pellets. It has a softer texture than hail and is always smaller than 0.2 inches (about 5 millimeters).

How should I classify hail and sleet? 

Do not send an observation if you see hail or sleet.  

Here’s why: hail, although solid, forms by a very different process than snow, and sleet, also solid, forms by yet another process altogether. The conditions that allow for either hail or sleet to fall are too complex to have a meaningful role in determining the rain-snow transition for the purposes of this project.

If you see mixed precipitation that looks like it might include sleet (some fully solid, clear pieces falling at the same time as fully liquid droplets, OR clear ice pieces falling that are partially melted), send an observation of mixed precipitation. If you aren't sure whether it is mixed or just sleet, skip the observation or text us first at 855-909-0798.

For fun, here’s how to tell the difference between hail and sleet. Hail consists of frozen balls of ice and falls at warm temperatures. Sleet also looks like frozen balls of ice, but it falls at cold temperatures and is usually more clear than opaque. This page briefly discusses how hail and sleet form: Severe Weather 101: Hail Types (

How should I classify freezing rain? 

Freezing rain is liquid water that freezes when it hits the surface. 

Freezing rain is classified as rain in this project. We are concerned with the water’s journey through the atmosphere. The fact that it is a liquid while in the air is the key information for this project, even though it freezes when it hits the ground. 

For more information, visit this page on freezing rain and sleet

Precipitation phase classification guide

If you need help determining if it is rain, snow, or mixed precipitation, check out this guide: 

Times and places to send observations

How often should I send observations?

Send observations whenever you notice that it has started to precipitate, or if you notice that the type of precipitation has changed. 

You can send observations as frequently as you remember while it is precipitating, down to 15 minute intervals. This is because the other variables that we use for data analysis that are matched to the time and location of the observation are tracked at 15 minute intervals.

When do you send weather alerts?

We send out text alerts for forecasted storms between November and May, because this is when the temperature outside is most likely to be in the range of interest for this project (about 28°F to 50°F). However, you can send observations any time of the year - you aren’t required to wait for a text alert from us to send an observation.

Should I report rain/snow/mixed even if you didn’t send an alert? 

Whether or not we have sent out a text alert, if you make an observation, send it! We send alerts as reminders before storms that are forecasted to be in the temperature range of rain vs. snow uncertainty. Sometimes we miss a storm, or the forecast might be wrong, which is another reason why having observers like you ground-truthing observations is so important.

What is the ‘season’ for sending observations?

Send observations at any time of year. 

The temperature range of most interest for this project tends to occur between November and May, so we only send out text alerts during these months. However, you can submit observations at any time of the year, and they will still be included in the analysis. Storms near freezing can happen outside of November to May, so feel free to send observations whenever you notice precipitation.

Up to what temperatures do you want observations? 

Submit observations any time it is precipitating. 

We are most interested in observations in the temperature range with the greatest uncertainty for rain and snow, which is between about 28° to 50°F (-2°to 10°C). In this range, models have the hardest time accurately predicting rain vs. snow. However, we don’t remove any observations simply based on the temperature, so feel free to submit observations any time that it is precipitating.

Do you only want observations when I am in the mountains? 

Send observations at any altitude! The project focuses on mountainous regions because that is where rain vs. snow models struggle the most, but receiving observations from a wide range of altitudes helps us verify that our models are correct. 

Also, the temperature of the rain-snow transition changes a lot based on where you are in the world and your altitude, so receiving observations from non-mountainous locations as well helps us to better predict precipitation phase for a range of locations.

Indicating when the storm changes

How can I indicate that the precipitation transitioned from one phase to another? 

If the precipitation phase changes, just submit a new report as soon as you notice the change, as long as it's still precipitating in real time. This helps us figure out what temperature the rain-snow transition occurs for your location. 

How often should I report if the conditions continue as the same type, like snow, for hours? 

It is helpful to receive repeated observations for the same precipitation type at consistent intervals. For example, submit an observation of an unchanged phase at whatever interval you can manage (they do not need to be any more than every 15 minutes). Even one observation during the entire storm is very helpful! 

It’s precipitating very lightly. Should I still send an observation? 

Yes, send observations for very light precipitation. Even though only a small amount of precipitation is falling, this information helps build the model for whether or not snow or rain will fall in those conditions. 

Should I report when precipitation stops?

Do not send a report when precipitation stops. But if it changes to a different type, submit that! This is because the main goal of the project is to help us differentiate between solid/liquid/mixed precipitation. 

Don't you need more information?

Why do you have only three categories of precipitation phase? 

We only give three options (rain, snow, or a wintry mix) because these three options tell us everything we need to know to answer this particular research question about the processes happening in the atmosphere. The forecast algorithms that we are trying to improve (used by NASA Global Precipitation Monitoring satellites) report a computed probability of the precipitation being liquid. Whether or not it is liquid is the information needed from community observers.

If you’d like to know more about how the satellites that we are trying to improve classify precipitation, check out the third FAQ on this page from NASA: IMERG: Integrated Multi-satellitE Retrievals for GPM | NASA Global Precipitation Measurement Mission. We also explain these satellites' rain-snow prediction method in this report-back article.

Why don’t you have a field for me to enter precipitation that fell in the past? 

There isn’t an option to submit an observation of precipitation in the past because there is no way to make sure that the time and location are completely accurate. For each observation that is submitted, information from meteorological models and measurements (from satellites, nearby weather stations, etc.) is matched up to the observation’s exact time and location. So, we need to make sure it is precipitating in real-time when you send the observation. 

For more information, check out the “Quality Assurance and Quality Control” section of the Methods in this article published about Mountain Rain or Snow from previous seasons: Frontiers | Enhancing Engagement of Citizen Scientists to Monitor Precipitation Phase (

Why don’t you want observations on the intensity of the precipitation? 

Mountain Rain or Snow doesn’t ask about the intensity of the precipitation because we don’t need to know how hard it is precipitating (or for how long) in order to figure out the point when falling snow turns to rain. We simply need to know if the precipitation has reached the ground as solid, liquid, or mixed precipitation in order to build a model for the behavior of precipitation in the near-freezing temperature range. 

Why don’t you have a field for me to enter the temperature?  

We don’t have a field for observations of temperature because the project uses temperature values from existing meteorological models to match your observations to the modeled temperature at your location. The scientific community has high confidence in modeled temperature data. 

Also, Mountain Rain or Snow is trying to improve the accuracy of rain-snow models which already use modeled temperature - we just need to know if, for the value the models use, they’re predicting snow versus rain correctly. 

For more information, check out “Quality Assurance and Quality Control” in the Methods section of this publication about Mountain Rain or Snow from 2021: Frontiers | Enhancing Engagement of Citizen Scientists to Monitor Precipitation Phase (

App issues and troubleshooting

How can I open the app more easily?  

You can install the app so that an icon appears on your phone’s home screen. This won’t take up much storage space and it will update automatically. To install the home screen icon, open this link in your phone’s browser app: and follow the instructions.

I'm having trouble installing the app. What should I do?  

First, please make sure that this app is open in your device's browser app (Safari or Chrome). If you opened the app by clicking a link in your email, you will need to copy and paste the link into your browser app instead. 

If you’re using an iPhone and you still don't see the option to Add to Home Screen, click "Edit Actions..." at the bottom of the menu and look there.

If you are using a different browser and you receive a message that you must use Safari or Chrome, you will need to switch browsers in order to install the app. This is because the platform we use to make the app installable isn’t compatible with all browsers on some older devices, and not at all for Firefox. You can still use the app in any browser that you’d like, it’s just installing the home screen icon that may require a certain browser.

Help with location services: iPhone or iPad  

1. Open the app in Safari then click on the “AA” symbol. Open website settings from this menu, then allow location for the website.

2. In your general phone settings, open Privacy, then Location Services. Make sure the toggle at the top is on.

3. Below the Location Services toggle is a list of apps. Scroll through these apps until you find Safari, then open it and allow location access. 

4. If you are using the app from the home screen icon and having issues with location (an error message pops up or the location is just a comma), open Safari and open the app in a new tab, then start again from the top of these instructions. You can use the app from the home screen icon after this, but first you will need to set up the settings in Safari. If you did this before installing the app, you'll probably need to do it again. Copy and paste this link into Safari:

5. If you are seeing just a comma without latitude and longitude even after steps 1-4 above, it may be that the location is found but it needs a moment to load. Give it 30 seconds or so and the coordinates may show up.

6. Still having trouble? Try restarting your phone. You can also text us at 855-909-0798 if you have an unresolved issue.

Help with location services: Android  

Are you seeing just a comma? If steps 1-4 don't work, it may be that your location is found and the text is just loading slowly. Give it 30 seconds or so and the coordinates may show up.

If you continue experiencing issues with location, text us at 855-909-0798.

How can I fix an incorrect report?  

Send us a message by texting 855-909-0798 (you'll reach a real person, and we'll respond in 24-48 hours).

How can I report a bug or formatting issue for the app?  

We appreciate your help finding issues with the app so that we can make it easier to use and more scientifically rigorous. Report app problems by texting us at 855-909-0798.

How can I reach a real person with questions about the app or how to use the technology? 

You can talk to a real person that works on the Mountain Rain or Snow project by texting your question to 855-909-0798. (This is the same phone number we use to send out reminders.) We can respond to any questions that you send to this phone number. We’ll do our best to respond within 24-48 hours.