It is easy to be caught off guard during the season’s first heat wave – the year’s first transition of the weather from comfortably warm to intensely hot. Perhaps your heat pump needs a few hours to adjust to cooling mode, and you must endure a steamy night. Maybe the sunscreen and swimming suits are still in winter storage or, even worse wherever they were last placed after that last warm day back in the fall! If you can see a Midwest heat wave coming, it’s going to look like multiple days above 90 degrees with dewpoints in the 60s or higher, especially when night time lows remain at or above 75 (see the hourly forecast image below for an example of this).
Two-story houses often present a challenge for keeping upstairs bedrooms cool without excessively chilling the downstairs. Those who sleep in a basement bedroom may be bundled up through the night, as I was in June of 2019 while visiting my new grandson and his family. I took refuge from the family cat in the refreshingly cool basement sleeping quarters!
The Late Spring Tipping Point
In May or early June there often seems be a “late spring tipping point” prior to which the air masses are generally comfortable – both cool and dry. Then, as though a switch had been flipped, the middle part of each day becomes oppressively hot whenever the sun is shining. Two things are at work in late spring across the primary row crop areas of the central and eastern US – the increasing sun angle, and the increasing humidity. This is one reason for a trend seen with daily record temperatures in recent years – for much of the spring, new record highs have tended to be set much more often than record lows. By early June, the crops in the fields usually have established a green layer above the darker colored soil and until early fall will provide a continual supply of moisture to the low-level air. After getting used to the spring coolness, we are thrust right into the summer heat and humidity. Neither our bodies nor our minds have had opportunity to make a transition and it’s easy to become overwhelmed by the heat. It is good to bring out the lighter clothing, the cooling bands, and your protective hat a couple weeks before you think they will be needed. Notice the forecast low temperatures, the amount of sunshine and whether your house seems to be holding onto the heat through much of the night. Most importantly of all, pay attention to what your body is telling you, remembering that we’re all a year older since the last time summer heat was in place!
After a Heatwave – Is it Really Over?
I’ve always had a bit of trouble after a heatwave with summer cool fronts that fail to cool me. What happens right near a cool front is that any cooling breezes can drop off to near calm and the dewpoint will INCREASE. If this is happening toward the middle of the day (when clouds and rain can be at their daily minimum) you end up more uncomfortable than had there been no front. I remember being absolutely wiped out playing golf one day when a weak cool front delivered no relief. To make matters worse, it was before I had developed weather wisdom regarding the sun’s power. I not only had parked my car in the sun but, even worse, with the driver’s seat exposed to the direct sunlight.
Hourly forecasts now are quite good at showing you when the wind direction will shift to the north or northwest, and when the dewpoint will start to improve. Short-term forecast models aren’t always very good with cloud cover but often will give you at least some idea of what’s possible. So be alert to the signs of the season’s first heat wave. Taking a few steps to prepare can improve both your physical and mental endurance of this annual event!
The summer-long question!
Now that we’re getting into real summer weather across the northern states, more areas have seen strong thunderstorms recently. We know that just about everyone else will see strong to severe thunderstorms within the next few weeks.
The stormy time of year overlaps with a lot of our outdoor events. Precipitation is a lot harder to forecast in the summer because the weather systems are more subtle than cold-season storms that bring constant rain or snow across a broad area for many hours. Thunderstorms start out as isolated cells and sometimes develop into lines or complexes, other times staying rather spotty. The image below is from early Sunday afternoon of Memorial Day weekend.
When you want to be outside HOW do you determine where and when those first areas of rain will spring up? What direction will they move? How widespread will they be, and if it does start raining, how heavy will it be and how long could it last?
One great clue comes from your local NWS forecast at weather.gov. Don’t just read the written forecast, but go to see the hourly details. On the image below, I could see that the highest probability of rain was forecast around mid-morning and in the mid to late afternoon.
Oh, and be sure to check back every so often during the day because the forecast can and will change as short-term trends unfold! That’s because new weather models that represent the expected patterns hour by hour are run frequently.
For those on Twitter or Facebook, some of the NWS offices are very good about providing short-term model forecast details in their social media feeds.
I have good news if you feel that changing forecasts toss you first in one direction and then the other. All the weather forecast models are limited by simplifying assumptions about the vast atmosphere they represent. That is one reason that the results can change over time. But often, changes to the forecast are made incrementally, so they need not surprise you. To help you plan for travel and outdoor events, let’s look at three weather trends to watch.
Weather Trend Number 1: How Much Will it Rain?
The amounts will change as the event gets closer and forecasts become more refined. Forecasters make their best forecast at each step of the process, and confidence in the results usually will increase as the event gets closer. The most useful forecasts will present the probability of measurable rainfall (percentage chance) for each hour and the amounts expected for each three to six hour time frame.
Weather Trend Number 2: How Warm Will it Be?
The location and strength of weather systems affecting your area will determine how warm or cold it gets. The amount of sunshine, cloud cover and rainfall are the key ingredients “baked into” the forecast high and low temperatures. Especially if you are sensitive to heat or cold, watching this trend will point your outdoor plans in the right direction! The most useful forecasts will depict the expected temperature for each hour of the day and night — for the next three to seven days.
Weather Trend Number 3 – How Windy Will it Be?
While it’s easy to see that the wind directly affects certain outdoor activities — sports, grilling, or that ancient spring pastime of kite flying — not everyone fully appreciates how much the wind affects your perception of warmth or chill. Wind speed can make or break an otherwise ideal weather day. The wind can also influence the way in which you’ll want to regulate indoor temperatures (opening the windows or running the air conditioner).
Keeping in mind these three weather trends to watch, try looking for your best times to be outdoors. Next week, we’ll look at one of my favorite sources of weather forecast information.
One evening this week provides an example of practicing severe weather wisdom. While getting ready for bed I received a text message from our daughter in Ohio informing me that they were hearing tornado sirens. We had been communicating back and forth via Twitter and text message regarding the severe weather risk for the area, so the sirens came as no surprise. (Though living 900 miles away, I remain her most trusted meteorologist.)
When I looked at their local county warning map on the NWS website, the depiction was remarkable. There were tornado warnings covering the areas just north and south of my daughter’s location, with her suburb lying in the middle of a 4-mile wide gap in between these tornado-warned areas! I quickly sent a re-assuring message, not implying that there was no risk, but that the highest potential for damaging weather would pass just to their north. I later learned that my daughter and her family went to the basement anyway. This shows how well she has learned my severe weather wisdom principle of being more cautious than seems necessary around unpredictable events like thunderstorms! My caution was enhanced with a family of nine all sleeping on the second floor of a country house in Iowa. I vowed to be vigilant against a situation of having to awaken and rush so many sleepers down two flights of stairs to the basement in the midst of extreme weather.
A Timely Resource
This is Easter weekend and because time is precious I now provide a link to a timely and valuable resource — one of my best posts on severe weather. This will explain both the ways the Storm Prediction Center presents its forecasts of severe storm risk categories, and also the manner in which the National Weather Service depicts warnings on their local county maps. Though warnings generally come on a county basis, using these maps will give you a better idea of your exact level of risk when the weather radio alerts you to severe weather.
Though many of our customary “rites of spring” are cancelled or postponed this year, we can still work in the garden. In many areas of the central US, winter was mild, but the wet weather of recent months has brought a slow start to spring fieldwork and gardening. Once your soils have dried out sufficiently, you have a decision to make for deciding when to plant seeds in the ground. While a packet of seeds is inexpensive, it’s always desirable to get the most for your investment of money and time. So the timing of planting is a relevant question as the new growing season gets started.
The earliest I ever planted garden seeds was while living in central Iowa during the early spring of 2000. At the end of February we had true spring weather so I planted peas along the fence row in the front yard – on Leap Day. I recall that those peas germinated fairly quickly because March remained quite warm. That planting did not end up thriving, perhaps due to drier than normal spring weather, or that the early season wasn’t cool enough for that particular variety.
The more certainty we have of favorable warmth continuing, the more confidence there will be to proceed with this type of early planting. Unless the pattern flips to unusually cold, temperatures often won’t be your main problem. Spring sunshine is strong enough to warm the ground even when air temperatures are relatively cold, but there is no remedy for cold soils produced by wet and persistently cloudy weather. Even though it has been mild to warm in much of the Northern US during the early spring, try to assess how cloudy and showery it’s likely to be in the 6 to 10 days ahead and use that as a guide to timing your early planting.
A typical date for first garden plantings in southern Minnesota would be at the start of April. Such was the case in 2018 when a seasonable planting date coincided with the Opening Day baseball game at Target Field. While the rest of the family was gone to visit relatives, I enjoyed an afternoon off work and perfect planting weather while listening on the radio to the baseball game. The advantage of seasonable planting dates is that in April and May you are more likely to see the right mix of moisture and temperature for the cool season plants. Plant a month early and you have up to two months when a late cold snap can set your efforts back. Plant a month late and hot dry weather can arrive in time to hinder the fruit-bearing of plants (like lettuce and edible-pod peas) that produce better quantity and taste when it’s not too warm and sunny.
This year, our snow melted fairly early in March, and I have been looking for a window of opportunity to start planting spinach, carrots, and other things that do well in the coolness of early spring. I have continued to wait as each warm spell has been followed by a well-forecasted chilly and cloudy stretch of days. I was glad that nothing was planted ahead of this week’s freezing rain event which was followed by almost 48 hours below the 30-degree mark! If I see that it’s going to be only a little cool and damp for a day or two, that will prompt me toward starting the garden during the next warm spell.
I am even more sensitive to the appropriate time for planting fragile plants from the nursery such as tomatoes, squash, and green peppers. Even when it’s warm enough to plant these things, a brisk wind or vivid sunshine can beat down and dry out the new plantings. Ideally, I like nursery stock to have a two or three-day window of mixed sun and clouds with a few light showers (or regular hand watering) and little wind to acclimate to life in the garden. Once they are off to a strong start for a few days, bright sun, stronger wind, and even harder rain is usually not a problem. Confidently deciding when to plant allows enjoying these first days when we can work outdoors, while looking forward to the fresh produce we’ll gather during the summer and fall months.
While threats of severe weather raise the anxiety level of those immediately at risk, the current health crisis creates an epidemic of stress and uncertainty throughout the land. It reminds me of occasions in my own life when stress increased amid uncertainty regarding the future. At every one of those difficult times, I have been an eager an avid follower of the daily weather patterns. Watching the weather has always been my calming action in a stormy time.
One such time was during a personal health scare ten years ago. I was so relieved that the physical misery I was experiencing turned out to be far more uncomfortable than serious. The worst part of the suffering lasted only a few weeks but during those lowest days the simple activities of daily life brought the most comfort – trimming and collecting branches with the children in our large yard, shopping for food that would enhance my health, and my lifelong consolation of watching the sky and savoring the changing of seasons. Within a year of that health challenge I was in a much better place both health-wise and professionally than I could have anticipated. In an upcoming e-book I will talk more about the simple ways in which I have long enjoyed watching and taking delight in the weather and how that has comforted me amid the storms of life.
This time of year, changes in the weather can be very frequent, and sometimes quite entertaining. Enjoying those changes may even help to calm frayed nerves and anxious hearts. If you currently have either extra time or unsettled thoughts, it is my hope that by watching the skies a bit more you might experience some rest and consolation. Let me now offer a few ideas for enjoying the change of seasons as fully as possible.
Increase your Knowledge
Cloud charts like this one help you match what you’re seeing out the window to its proper name and even get some idea of what is causing that type of cloud. If you have a particular interest in severe storms and have never been to a free Skywarn Spotter Training class, it will be easier than ever to attend this year because most of the classes which typically are offered in-person were cancelled or moved to an online format. Search for classes offered by the National Weather Service in your local area.
Watch a Movie…. Out Your Window
Clouds are parading by, people are out walking, and especially in the northern states, the landscape is changing with new bird songs, greener grass, and final snow melt. Even if you can’t be outside yourself due to illness or quarantine, that parade of clouds and change of seasons doesn’t stop. More than ever before, forecasts show what’s likely to unfold hour by hour, and help us to anticipate the “playlist” in the sky. Forecasts are usually accurate, but even when they are not, the wide availability of weather information online can allow us to anticipate those times when a change in the forecast will happen. If you don’t have a great view from your own window, look for a live webcam view either from your local area or even a different part of the country.
Look Forward to Better Weather
Changeable spring weather brings the advantage that even the most foul weather usually doesn’t last too long. I think in terms of two levels of bad weather days. Some spring weather bears truly hazardous potential while often it’s merely unpleasant. Many areas of the country will experience more days with significant severe weather risk between now and early summer. While you’ll definitely want to take appropriate caution and heed local warnings, remembering that these episodes are usually very short lived and often localized helps ease the worry. It’s rare for severe weather to produce widespread destruction, so we can be hopeful while anticipating the calmer weather to come. Keeping that perspective is my calming action in a stormy time. Sometimes, the “bad days” might simply mean weather which doesn’t suit my preference. For example, where I live, the last few days have been persistently cloudy. Tomorrow that will change dramatically and temperatures will also be warmer. Today, I am planning for how to use that time and savor the brighter skies!
Plan for the Good Days
Someday soon, we will be more able to spend long stretches in the yard and garden, or at the park, doing things that for the past few months could only happen in our dreams. It’s not too late to order garden seeds or make your wish list for this year’s garden. When you see those warmer and drier days arrive it will be a time of great enjoyment inspiring hope for the entire growing season.
Looking at the long-term record temperature trends both on a daily basis and a monthly basis can bring a helpful perspective. I have found this Climate at a Glance site to be a wonderful resource for monthly comparisons of historical temperatures and precipitation. In the central US, we can choose almost any state or city and find that the average temperatures in winter have reflected a warmer trend over time.
Monthly Trends Echoed Daily
How do these monthly differences translate to daily weather and what can be noted? A closer look at daily data confirms that, at places such as Minneapolis and Des Moines, it has become rare for daily record low temperatures to be broken in the wintertime. These locations were among 60 US cities examined in a spring 2017 study which looked at record temperatures in not just the winter months but for all months of the year. To ensure that the results were not skewed by having too few years of data, all sites chosen were required to have weather records extending back to at least 1895. The study noted that from January of 2010 through April 2017, record highs across the US overall occurred at five times the rate of record lows. In some western Cornbelt locations like Des Moines and Minneapolis that ratio has been closer to eight to one! That’s why it seemed remarkable when late January of 2019 brought an episode of record cold to the Upper Midwest.
Explaining the Disparity with Data
Here’s one perspective on why the distribution of records is so skewed. The 30 year periods from which our normal temperature values are calculated have been warming. Our normals are adjusted every ten years to reflect the latest 30 years of data. We’re now using normals based on the last three full decades (1981-2010). At the last update in 2011, we added the warm decade of the 2000s and dropped the very cold decade of the 1970s. With this higher average temperature, you still have the typical ups and downs as daily readings vary over time in response to passing weather systems. Though the normals are reset every 30 years (after all, we want to capture what’s normal now, not 50 or 100 years ago) the record temperatures continue to be carried from the entire period of observation – often 120 years or more. Many of the record lows were set before observations began to be taken at airports, and before there was much of an Urban Heat Island effect. A key point here is that the normals shift over time but the set of record highs and lows does not get an adjustment. As a result, the fluctuations need to be that much bigger than usual in order to reach the low temperature records, many of which were set in a colder era.
A Couple Degrees = Real Differences
So is there a disparity in variations of the record highs and lows from the normals? Can the effect of shifting normals with time be seen in the data? I averaged the number of degrees from normal highs to record highs and from normal lows to record lows at Marshall, MN for the month of January. On a monthly average basis, the daily low temperature must fall 29 degrees below the normal low to reach the daily record. The daily high temperature, on an average basis must surpass the normal high by 27 degrees to reach the daily record. While that two degrees’ difference may not sound like much it turns out to be quite significant. Think of how often just a degree or two determines whether we merely come close to the record or whether we tie or set a new record. For March the average reach from normal to record temperatures is 29 degrees for highs and 31 degrees for lows – again showing a two-degree difference.
Another Notable Pattern
This disparity in frequency of record lows and highs is just one feature of the recent past climatology in the central US. Another of the record temperature trends that is less intuitive is the rarity of seeing record highs in the summer months. As our summer climate has become rainier and more humid, we’ve consistently seen much warmer summer nights. That higher humidity also works against extremely hot daytime temperatures. We might look at that more closely in the future.
I wrote a few weeks ago regarding the Accumulated Winter Season Severity Index (AWSSI) which has been developed to measure a winter severity using a combination of total snowfall and departure from normal temperature. At that time, winter was running remarkably mild in much of the East and near to more severe than average over the Northern Plains into the central Rockies (see image below as of February 1st, 2020).
With the winter of 2019-2020 now approaching its end, most areas of the Nation have seen little change to the Index since I wrote about the “minimal winter” at the start of February. The main exceptions are found in a few places across the central US. With temperatures running close to monthly normals and minimal snowfall during February into early March, the AWSSI did become slightly milder since late January from Nebraska southwestward to much of the southern Rockies. Below are the February maps reflecting those weather patterns.
February patterns in most of the Nation were not dramatically different from those earlier in the winter, with the result being that the Winter Severity Index (see current Index map here) has changed little in locations where the winter started off well into the mild category.
I think it’s really important to note how our perception of even a mild winter is affected by its effect on the human body. The amount of cloud cover and wind are two primary influences on how cold it actually feels to our senses, but these are not measured by the Winter Severity Index. My perception from a southern Minnesota vantage point (where the Severity Index has remained in the moderate or average categories) was that our February was much less wintery than January. I’ll now compare the two months and reveal the likely reasons for that difference. The average temperatures in absolute terms were strikingly similar between the two months at places like Minneapolis, because while January was quite mild our February temperatures were closer to the 30-year normal, making for no real difference overall. Snowfall amounts were also similar between the two months and not too far from normal, but there was a difference to note here. What was the distribution of snowfall like? Looking at details for my location in southwest Minnesota, January had a couple significant snowfalls and several smaller events. Each time it snowed, it seemed more snow fell within a few days. By contrast, almost all of February’s snow fell on a single day with a generally dry pattern in the rest of the month.
Now let’s look at a comparison of wind and cloud cover. Average wind speed was quite similar between the two months, but February was a MUCH sunnier month. After a near record-setting January for lack of sun at Minneapolis- Saint Paul(fifteen cloudy days and two clear days), the February ratio of clouds to sun nearly reversed – to three cloudy days and eleven clear days! Along with less cloud cover, the astronomical calendar also helped. With more than an additional hour of daylight compared to January, even the partly cloudy to cloudy days seemed a lot brighter in February! So while the Winter Severity Index did not move much for southern Minnesota over the past few weeks, the two main factors in making for a much nicer February were far fewer days with snowfall and much more sunshine!
Finally, the length of winter at the back end has seemed dramatically shorter this year compared to last year in southern Minnesota. This year, several brief warm spells already had melted a lot of the snow in time for March sunshine to keep temps mild. That’s a lot different than last year when the snowpack was still growing through March and stuck around well into April with temperatures languishing below normal (with even the daytime temperatures only a few degrees above the freezing mark).
So when considering winter severity, be aware that some influences can be measured with an Index like the one I have shown, while other influences will only be uncovered by a closer look at the day to day weather, assisted by some perspective on what an average winter is like. An important part of this perspective includes what we’ve come to expect – what feels normal – based on recent history!
The early March Nashville tornado event serves as a reminder that it is very much the time to be ready for severe weather events. For most of the US, severe storms are usually the most numerous and intense during the four months of March through June. The three main areas to which we need to attend are preparation (including gathering the right information), equipping ourselves (including framing our thoughts correctly), and taking the right actions (doing the right things at the right time).
Preparation is Key
My primary source for severe weather information is the National Weather Service office closest to me. NWS issues official watches and warnings as well as other statements and updates related to severe weather risks. NWS meteorologists also conduct storm surveys after tornadic events and compile damage reports. The map below shows locations of the various NWS offices and counties for which each is responsible.
Over the next few weeks each National Weather Service office will send meteorologists to conduct storm spotter training events throughout its forecast area. These spotter training events are opportunities to refresh the knowledge of experienced storm spotters and to recruit new storm spotters. Search online for “(your city name) NWS spotter training events” and you’ll be able to find details. You’ll often see law enforcement officers and other emergency responders in the audience, but all interested people are welcome at these events. The more people who have knowledge about severe storms and what to look for, the better the reports that the NWS gets from the public in times of severe weather.
Equipping for Success: Accessories and Mindset
There is no substitute for a weather radio with an alarm feature that is activated for significant weather events. Here is information about the programming and locations of weather radio transmitters. Well over 95% of the country’s population is within range of a NWS weather radio broadcast. For those who are not, or would like a wider selection of broadcasts, you can find streaming weather radio broadcasts here.
I actually find on active storm days that the weather radio can be a noisy and inconvenient source of information. To limit the distraction, try utilizing the SAME option so you only receive warnings for your county of interest. A “silent source” allowing you to track incoming storms will be the NWS website. Color-coded watches and warnings show where the activity is most intense. In a previous post, I outlined some strong points of this depiction.
You can then switch to a more active form of monitoring weather info when storms truly get close, entering your neighboring counties to the west or south! Once in the thick of a severe weather event, my preferred source will be any local commercial television or radio station which dedicates their programming to severe weather coverage with a live meteorologist. This is a way to see live radar pictures with emphasis on the areas with the greatest risk of damaging conditions, which may be supplemented by reports from storm chasers and spotters.
Being prepared allows a person to keep calm in the event of a warning. Did you know that it is rare for a person in a fully-enclosed basement or underground shelter to be killed by a tornado? Of course, there are other life-threatening storm hazards from which those inside any sturdy building are largely protected. These include falling limbs and lightning which kill more people each year (and often come with less warning) than tornadoes.
Do the Right Things
Taking the right actions to be ready for severe weather is easier with a list of best practices. Happily, the NWS has a comprehensive page outlining how to prepare for and respond to a wide range of hazards. Separate sections for each hazard describe what to do in a watch (before), in a warning (during), and after the storm. Reviewing these and taking some early preparation steps will make a good short-term project for your household as the weather becomes more turbulent during the coming weeks.
Or for Old Familiar Ones
What do you want to know about the weather patterns in a new town that you will be visiting or to which you are contemplating a move? Many years ago a friend was planning a relocation several states away. He asked me to prepare a comparison of the climate of eastern Ohio compared with the Des Moines area which he would be leaving. I so enjoyed that process that even today, I like to do something similar when planning even a short vacation. Even in the familiarity of my hometown, I want to know how the recent weather patterns compare to normal, and to keep in mind how much the normal values change from beginning to end of individual spring or fall months. It’s just good to have that frame of reference applied to recent weather, and to prepare for what I will experience in the days and weeks ahead.
How Does the Past Month Compare to Normal?
The best place to search for comparisons of recent temperatures to normals is by looking on the National Weather Service site for the area.
Each local NWS office provides daily climate summaries showing high and low temperature and precipitation data as well as the normal and record temperatures for the date. These are provided for official observing sites at airports and Weather Service offices. Because these reports are archived going back several weeks, the daily normal values are accessible for that whole time period.
How do you find this information? Look under the local climate data section as shown in the image below.
In the resulting menu the first two options on the left-hand side (Daily Climate Report and Preliminary Monthly Climate Data) show detailed information for major reporting sites in the region.
The image below shows the position of the various types of data contained within the report.
Farther down the local climate menu you see the options labeled Regional Summary or State Summary (Temp/Precip). These provide basic information from a wider range of locations – including automated observing sites and cooperative observers.
What is Normal for the next Month?
This one can be a little more challenging to answer, but the National Climatic Data Center (NCDC) has provided an excellent resource to show monthly normals and a time series of monthly data. These are available for dozens of cities across the US. Select your city and month of interest at this link. This type of report can also be selected for an entire state, what’s known as a Climatic Division within a state, or on a countrywide basis. Your selection will return a graph of the average monthly values compared to normal (horizontal line), as shown in the sample report below.
Beneath the graph you get a list of the years with the average, the ranking compared to all other years in the period of record, and the departure from normal. It’s easy to look for trends and patterns over time either using the graph or the list!