We’ve all heard, at one time or another, one or both of our parents yell at us when we were about to do something wrong: ” You watch out, I’m warning you!” Did we then understand what that really meant? Well, in todays “weather world” there are watches and warnings and many people don’t really know the difference. It is sort of like when people go on an airplane trip. You go through the security, board the plane, and find your seat.
As the plane is gaining altitude one of the flight attendants stands up, grabs a microphone, and drones on about the safety features of the plane. At least that’s the way it looks to some people. The time it becomes important, no vital, is when a serious problem erupts and those oxygen masks spring out of the overheads and extend down in front of you. You think to yourself “What do I do now? Am I supposed to push, pull, or what to make it work? Do I put it on my child first or should I put it on me first?” I think what this shows is that under many circumstances we ignore someone who says “Watch Out!!” or gives you a warning until we think the situation directly relates to us and is dire.
In meteorology there are watches and warnings about many things. When I worked in other parts of the country, particularly in what is called “Tornado Alley” I would produce and air on TV a half hour severe weather special before the storm season began and remind the viewers what the terminology meant and what actions they would need to take to protect themselves.
In some markets I would break that information down into 7 parts and we would air one a night for a week. Both ways got the people prepared for the storm season that was inevitable and coming soon. Here in the South Willamette Valley we don’t see severe weather very often. If you were shown a half hour program or even a week of news stories about weather safety the chances are you would have already forgotten what you saw and heard so many weeks or months before an actual weather event occurred.
Well, I’m not limited any more to that half hour program or 7 shorter segments that are seriously limited in the time they are allotted. So I am going to lay out for you, step by step, many of the rules of weather safety so you will know what they are and how to use them if and when you need them. All of the quoted definitions that follow are courtesy of the National Weather Service Glossary.
We’ll start with the two words I already mentioned “watch” and “warning. The subject matter may change but the words will always mean what they say. A “watch” means literally that we are watching out for whatever weather event is stated. A “warning” means that the event is occurring right now and you need to take the appropriate action immediately. If you don’t listen to those words and take the proper actions you could be taking a serious risk to your life and the lives of your family members.
Let’s start out with some of the simpler examples. A Severe Thunderstorm Watch means that conditions are right for the formation of severe thunderstorms and you should be prepared to go indoors to safety.
What exactly is a severe thunderstorm? The National Weather Service (NWS) defines a severe thunderstorm as one that “produces winds of at least 58 mph, and/or hail at least 1 inch in diameter.” A Severe Thunderstorm Warning means that a severe thunderstorm, already defined, is in progress and has been spotted through visual observation by National Weather Service personnel, or reported by other authorities or someone from the public, or indicated by WSR-88D radar (Weather Service Doppler Radar).
Now we get to a subject we hardly ever hear about in Western Oregon tornadoes.
The National Weather Service defines a tornado as: ” a violently rotating column of air pendant (hanging) from a cumulonimbus (cloud), with circulation reaching the ground.” The difference between a “funnel cloud” and a “tornado” is that the funnel cloud is still airborne and not touching the ground. A Tornado Watch means “conditions are favorable for the development of tornadoes in and close to the watch area.” A Tornado Warning means that “a tornado is indicated by WSR-88D radar (Weather Service Doppler Radar), or spotted by spotters, therefore people in the affected area should seek safe shelter immediately. They can be issued without a Tornado Watch being already being in effect. They are usually issued for a duration of around 30 minutes.”
A Flood Watch is issued when the “hydrometeorological conditions are such that there is a threat of flooding, but the occurrence is neither certain or imminent.’ In other words the chance of flooding exists, but is not happening yet. If you live near a river or stream you need to be prepared to evacuate to higher ground if a warning is issued. A Flood Warning is issued ” to inform the public of flooding along larger streams in which there is a serious threat to life or property.”
A flood warning will usually contain river stage (level) forecasts.” In other words flooding is already in progress and you should be prepared, if you live near a river or stream, to get to higher ground immediately. In what sounds like a directly related situation, but really is not, a Flash Flood Watch and a Flash Flood Warning mean respectively that flash flooding is possible in the watch area and is occurring in the warning. The important difference is the word “flash.” A Flash Flood is defined as “a rapid and extreme flow of high water into a normally dry area, or a rapid rise in a stream or creek above the predetermined flood level, beginning within six hours of the causative event (e.g., intense rainfall, dam failure, ice jam).” In other words a flash flood is a rapid flow of water caused by heavy rainfall or a serious event like a dam breach. There can also be Urban and Small Stream Flood Advisories which are meant to let the public know there is a possibility of street flooding or small stream flooding due, usually, to sudden heavy downpour of rain.
During our Summer months we have a Heat Advisory which is issued “within 12 hours of the onset of the following conditions: heat index of at least 105 degrees F but less than 105 degrees F for less than 3 hours per day, or nighttime lows above 80 degrees F for 2 consecutive days. There is an Excessive Heat Warning which means: “a heat index of at least 105 degrees F for more than three hours per day for 2 consecutive days or heat index more than 105 degrees F for any period of time.” The Heat Index or Apparent Temperature is “an accurate measure of how hot it really feels when the Relative Humidity is added to the actual air temperature.” There can be other Weather Statements concerning Summer weather, but as mentioned before we would not have many opportunities to have them issued.
Now we get to the Winter season. A Winter Storm Watch means “there is a potential for heavy snow or significant ice accumulations, usually at least 24 to 36 hours in advance.” On the other hand, a Winter Storm Warning means a winter storm ” is producing or is forecast to produce heavy snow or ice accumulations.” A Heavy Snow Warning means “a snowfall of 6 inches (15 cm) or more in 24 hours is imminent or occurring. These criteria are specific to the midwest and may vary regionally.” Of course for the WIllamette Valley area it takes much less snowfall potential to issue a heavy snow warning due to the steep hills and low valley floor in which travel would be extremely hazardous with less than 6 inches of snow in 24 hours.
Anytime of the year we can have excessive winds and the following could be issued. A High Wind Watch is issued “when there is a potential of high wind speeds developing that may pose a hazard or is life threatening.” A High WInd Warning is issued “when high wind speeds (currently or imminently taking place) pose a hazard or are life threatening.” Again the specific wind speed criteria vary from one part of the country to another. The potential wind speeds expected will be given when the bulletin is issued.
There are various advisories, watches, and warnings that can be issued for the offshore and coastal waters of the Oregon, but they effect only coastal interests so they will not be dealt with at this time.
As previously mentioned, these are not all of the statements that can be issued by the National Weather Service, but they are ones most likely to be issued in our area. What I hope you take away from all of these definitions is not necessarily the memorization of all of them, but a familiarization with their meanings so that if and when the bulletins are issued you won’t be completely in the dark as to what they mean and what you should do in response to them. It is the responsibility of those relaying the bulletins, meaning TV stations, radio stations, and online news outlets (including EDN), to explain what the bulletin means and what you should do in response to it. You need to be given both the alert and your response options. I may go into detail at a future date to discuss my thoughts on emergency bulletin dissemination. In the meantime just remember to be aware and listen when you hear an alert and do what you are told. Your life might just depend on it.
Let me know what you would like me to talk about or explain. You can email me at: [email protected].