We’ve all seen a watch or a warning issued when severe weather hits. And, because we’ve seen these calls before, we assume we know what they mean. But have you ever stopped and thought about how forecasters and meteorologists come to their conclusions?
If you live in an area that often experiences severe weather, knowing the difference between weather watches and warnings could aid in your response to the event.
So let’s answer this question: What are the differences between watches and warnings for different types of weather events, and how can you prepare and respond to each?
General Differences between Watches and Warnings
Each kind of weather event has a specific set of criteria for watches and warnings.
But, generally speaking, watches and warnings can be summed into two respective definitions.
Watches mean that the atmospheric conditions could generate severe weather (of course, those conditions vary depending on the type of event). A watch typically spans a large area as well. Watches are often issued to a swath or counties, or maybe even multiple states. A watch is not necessarily an endorsement of the weather happening, however; there is still a possibility the type of weather event the watch is issued for may not occur.
A warning is a sure bet. If a warning is issued by officials, it means that type of weather event is occurring. Before issuing a warning, however, authorities wait for confirmation. Either a witness reports the weather, or it’s confirmed by Doppler radar. Compared to a watch, a warning’s area of effect is often much smaller. The scope is more targeted, helping those who are surely in the path of the severe weather to prepare and respond appropriately.
Thunderstorms
Thunderstorms are the most common type of severe weather experienced in the US. They occur more often in the East and the Midwest thanks to the abundance of moist air that the oceans and air currents provide. These storms do occur across the country, however, so everyone should be prepared for one to hit.
How do these events occur?
Warm, moist air rises into the atmosphere as it interacts with colder air surrounding it. Typically this occurs when two opposing fronts meet each, but this isn’t always the case. As the warm air rises higher into the atmosphere, the moisture condenses and the signature dark clouds form. When the clouds get too heavy, rain begins to fall towards the earth’s surface.
The activity of the condensing and freezing moisture within the cloud generates the thunder. This also causes an electrical imbalance in the cloud; positive particles aggregate at the top of the cloud, while negative ones collect at the bottom. The lightning occurs within the cloud, and if enough positive particles are near the earth’s surface, the electricity discharges and lightning strikes. Positive particles on the surface also tend to gather around taller objects, and why lightning often strikes trees and other tall objects.
Thunderstorms: Watches vs Warnings
Keep the general rules we outlined above for watches and watches in mind. The definitions of those two classifications mirror the criteria for thunderstorm watches and warnings most closely out of all weather events.
Watches, as you can probably guess, cover counties and large areas. The atmospheric conditions when a thunderstorm watch is issued are favorable for these storms. Again, a watch isn’t a guarantee that a storm will occur.
A warning serves a smaller area, and means a person, or radar, has confirmed that a thunderstorm is occurring. A thunderstorm can be confirmed if one of the three following conditions is true:
- Hail larger than one inch in diameter
- Wind gusts over 57.5mph (92.5km/h)
- The presence of a tornado
How to prepare
Thunderstorms are gambles. They can serve as the spurs for other types of dangerous weather events. Tornadoes, strong winds, flash floods, and wildfires can all result from thunderstorms.
You should prepare for all of these possibilities. Certain events within a thunderstorm may be more rare than others, but being ready to respond to whatever the weather throws your way is imperative.
First, create a personal emergency preparedness kit (which you can do with the help of this blog post). Make sure you and anyone else you’re responsible for has their needs covered by the contents of your preparedness kit.
You should also have evacuation routes already laid out. Have a couple different options too, if possible. There’s no telling what roads will be blocked by the weather that’s in the pipe. And be ready to move at a moment’s notice as well. Thunderstorms, and the possibilities they contain, can be sudden. If the events of a storm ground you, know where in your home you stay safe. Note where in your home you can take shelter if a tornado sweeps through, for example.
Snow, Ice, and Blizzards
While thunderstorms are common during the spring and summer, they can form at any time of the year. Different storms, exclusive to the winter months at higher latitudes, also warrant watches and warnings from meteorologists and officials.
Compared to thunderstorms, the cautions meteorologists dole out for winter weather are much more complex. A primary reason for that type of winter weather isn’t as uniform as thunderstorms.
Winter storms can bring ice, sleet, snow, and destructive winds, either by themselves or in combination. The amount of snow, or the contents of the storm, can also change how meteorologists caution people about the weather coming their way.
How snow, snowstorms, and blizzards form is similar to thunderstorms. When moist warm air meets cold dry air, it rises into the atmosphere and the moisture condenses. Ice crystals in the clouds stick together, and if the air is colder than 35.6ºF (2ºC), the precipitation falls as snow.
Ice storms are a weird exception, as they form when warm moist air is sandwiched by two fronts of colder dry air.
The speed and intensity of the warm air’s movement influences accompanying winds, and the air temperature affects the density of the snow. Warmer moist air creates heavier snow, generally speaking, and colder dry air creates what many describe as “powder.”
Winter Weather: Watches, Advisories, and Warnings
Winter weather has a lot of faces, and because of that, their watches, advisories, and warnings have a lot of criteria.
Here’s a breakdown of the headlines:
Watches
Winter Storm Watch: Conditions favor a winter storm.
Blizzard Watch: Conditions favorable for a blizzard (a prolonged period of visibility of .25 of a mile (400m) and 35mph (56km/h) winds).
Advisories
Winter Weather Advisory: If any, or a combination, of the following criteria are met:
- 3-5″ of snow in 12 hours
- Sleet greater than .5″
- Freezing rain with sleet or snow
- Blowing snow
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Freezing Rain Advisory: Ice accumulation greater than .25″.
Warnings
Winter Storm Warning: Heavy snow of 6″ in 12 hours, or 8″ in 24 hours.
Ice Storm Warning: Ice accumulation of .25″ or more
Blizzard Warning: Blizzard conditions lasting for at least 3 hours.
The National Oceanic of Atmospheric Administration (NOAA) and the National Weather Service (NWS) say watches are only that. Typically, this means the described conditions have a 50% chance of occurring. Advisories and warnings have an 80% chance; while advisories mean the weather will inconvenience travel, warnings mean travel will be next to impossible, if not totally so.
Prepare for Winter Weather
Winter weather paints a landscape drastically different from that of thunderstorms. Preparedness, despite the event on-hand, always hits on the same few chords, though, so some of what thunderstorms require will come into play here.
As always, have an adequate personal emergency preparedness kit. Winter weather is very capable of cutting off power or trapping you where you are. Even if these circumstances have a low likelihood of happening, it’s best to have a response to them ready.
Avoid travel if you can as well. Advisories and warnings alike create dangerous conditions for travel. Roads under all outlined conditions will be in poor conditions. Traveling also risks exposure to extreme conditions.
Keep an Eye on the Forecast
Weather watches and warnings are markedly different, and knowing the difference can keep you safe during these events. Both thunderstorms and winter weather, and the events they can cause, deserve your time and attention. Keep this information in mind an announcement comes through so you can respond appropriately to what’s on the horizon.
