Category Archives: Weather

Severe weather is possible Sunday, Aug 6, including a tornado.

This map from today’s SPC Day 4 Severe Weather Outlook indicates an area (shaded in yellow) that has a 15% probability of severe weather on Sunday, August 6. It includes the entire state of Indiana.

TLDR: The National Weather Service Storm Prediction Center issued an outlook early this morning that indicates a probability of all forms of severe weather throughout Indiana Sunday, including tornadoes; damaging straight-line thunderstorm winds; and large hail. People should pay attention to reliable sources of weather information as Sunday nears, especially people who are planning outdoor activities Sunday afternoon and evening.

How we know this is possible

The Storm Prediction Center (SPC) is a branch of the U.S. National Weather Service (NWS) that’s responsible for providing timely and accurate forecasts and watches for severe thunderstorms and tornadoes over the contiguous United States. Every day, it issues severe weather outlooks for the current day (Day 1) and for days two (tomorrow), three, four, five, six, seven and eight.

Accurately predicting severe weather more than two days in advance is difficult. So, if the SPC indicates a possibility of severe weather in an outlook for three days from now, it’s wise to pay attention.

In the outlook for Sunday that SPC issued this morning (Aug. 3), it indicated a 15% probability of severe weather, including tornados, damaging straight-line thunderstorm winds and large hail, within 25 miles of any point in Indiana as well as parts of neighboring states.

Tornadoes, damaging straight-line winds and large hail are all possible in Indiana Sunday.

Why is 15% a big deal?

As percentages go, 15% looks pretty small. But that’s because severe storms don’t happen all the time. The SPC, in collaboration with another branch of the NWS, the NOAA National Severe Storms Laboratory (NSSL), analyzes historical weather data to determine the normal probability of severe weather on any given date (based on how many times it happened on that date in the past). That analysis indicates that in Indiana, the normal probability of severe weather on any August 6 is 2% to 3% (depending on where in the state, see graphic below).

SPC/NSSL map showing probabilities of severe weather in various parts of the continental United States on any August 6, based on data collected between 1982 and 2011.

That means Sunday’s 15% probability of severe storms is 5 to 7.5 times what’s normal for that date.

What’s most likely, tornadoes or severe thunderstorms?

Day 4 is too far away for SPC to provide probabilities for specific severe weather hazards, like tornados. Nonetheless, the text of today’s Day 4 outlook implies that tornadoes, damaging straight-line winds and large hail are all possible in Indiana Sunday.

In addition. local NWS offices in Indiana issued their own outlooks today that indicate the possibility of severe weather Sunday, especially in the afternoon and evening. These local outlooks also indicate the NWS might need reports from trained, volunteer storm spotters Sunday.

Tomorrow, SPC will issue a Day 3 outlook for Sunday that will provide a categorical risk level from one to five (five being the greatest risk) and possibly modify the target area based on the latest available weather data.

Saturday, SPC will issue a Day 2 outlook for Sunday that will provide individual probabilities of a tornado, damaging straight-line thunderstorm winds (58 mph or stronger), and large hail (one inch or larger). By then, we’ll have a much better idea of what parts of the state have the highest risk and which hazards are most likely.

What should you do now?

No matter who you are, if you’ll be in Indiana Sunday afternoon and evening, and especially if you plan to be involved in an outdoor activity, pay close attention to a trusted source of weather information as Sunday approaches, such as your local NWS office or professional broadcast meteorologists. If you don’t have a weather alert radio in your home, this would be a good time to buy one.

If you’re a trained Skywarn storm spotter like me, prepare for possible activation Sunday, including charging all your battery-powered devices and reviewing what to look for, what to report, and how to report it. The NWS will likely need your eyewitness reports so they can issue the best warnings and keep people safe.

Tornado strikes NW Allen County July 29

Path of a tornado that touched down just west of the Eel River Golf Course south of Churubusco and tracked rapidly east southeast, crossing US 33 before dissipating in a corn field west of Chase Road. NWS image.

The National Weather Service Northern Indiana weather forecast office (IWX) announced August 2 that it found evidence that a tornado did damage in eastern Whitley County and northwestern Allen County, Indiana at approximately 2:30 a.m. July 29.

“But wait,” you might say, “I never heard about a tornado warning for Allen County that day!” That’s because IWX didn’t issue a tornado warning for this storm. At the time of the tornado, however, a severe thunderstorm warning was in effect that included the words, “tornado possible.”

Most severe thunderstorm warnings do not automatically create alerts on your cell phone.

It’s not unusual for the kind of storm we had Saturday morning (a bowing “squall line”) to spawn weak tornados that appear and disappear before the National Weather Service can issue a warning. That’s why, when they warn us of a severe thunderstorm that could contain such tornados, they mention that a tornado is possible.

Weather radar loop slowing the bowing squall line that moved across Indiana early July 29.

It’s also one reason that it’s so important to know about and react appropriately to severe thunderstorm warnings, including those the National Weather Service issues in the middle of the night, when you’re sleeping. But that requires extra effort on your part, because most severe thunderstorm warnings do not automatically create alerts on your cell phone.

If you’ve ever been someplace covered by a tornado warning, you probably received a Wireless Emergency Alert (WEA) on your phone, even if you never installed a weather app. That’s because all modern smartphones come with WEAs enabled and all tornado warnings prompt WEAs.

The only severe thunderstorm warnings that trigger WEAs, however, are those in which the National Weather Service includes a “destructive” damage threat “tag.” They do that for storms that have either hail that’s at least 2.75 inches in diameter (baseball-sized) and/or 80 mph straight-line thunderstorm winds. According to Saturday morning’s severe thunderstorm warning, meteorologists expected winds of up to 60 mph and no large hail. That warning therefore did not trigger a WEA.

So, how can you know if a storm like Saturday’s is headed toward your home in the middle of the night, while you’re asleep? I know of two really good ways:

  1. Buy a weather alert radio and keep it near enough to your bedroom to wake you.
  2. Install a weather alert app, like Storm Shield, and configure it to alert you to severe thunderstorm warnings.

When the NWS issues a severe thunderstorm warning for your location, the best way to be safe is to do the same thing you’d do in a tornado warning. Move to the most interior room on the lowest level of your house. This will provide the best protection from a brief tornado, like the one that touched down July 29 and from straight-line thunderstorm winds dropping a tree limb on your house, which is what killed a woman in Ohio City, Ohio July 20.

How much snow would a blizzard bring?

Blizzard conditions along a highway. South Dakota Highway Patrol photo, 2020.

National Weather Service meteorologists from the Northern Indiana office and elsewhere have used the “B word” when writing about the winter storm that’s forecast for Indiana later this week.

For example, a winter storm watch that the Northern Indiana office issued today includes the phrase, “blizzard conditions possible.”

When I was a kid, depictions of blizzards in movies and TV dramas led me to think of a blizzard as a very bad, very dangerous storm that drops huge amounts of snow.

It wasn’t until much later that I learned that the meteorological definition of “blizzard” has nothing to do with accumulation!

What really defines a blizzard is how strong the wind is and how far you can see through the snow and blowing snow. The National Weather Service website defines “blizzard” as “blowing and/or falling snow with winds of at least 35 mph, reducing visibilities to a quarter of a mile or less for at least three hours.”

This means that if the wind is strong enough and the forward visibility is low enough, you can have blizzard conditions without large accumulations!

Travel in northern Indiana could be extremely dangerous Friday, no matter how much snow falls, because strong wind could cause white-out conditions. Making the situation even more dangerous will be extreme cold, which would be especially bad for anyone who slides off a road and gets stranded in a ditch.

It’s wise, therefore, not to focus too much on accumulation forecasts with this storm. The wind, visibility and cold could be dangerous even in areas where accumulation is relatively light.

Here’s why real meteorologists don’t yet know how bad the coming winter storm will be

A winter storm is coming to Indiana and will likely impact travel Thursday night and Friday, December 22 and 23.

Some areas could get a lot of snow. Some could get mostly rain.

As of this morning, the expert meteorologists at the National Weather Service’s Northern Indiana Office can’t forecast where the heaviest snow will fall.

The biggest reason is that meteorological science isn’t capable yet of forecasting the exact track of a low pressure system four days in advance.

I’m not a meteorologist, but I’ve spent enough time collaborating with meteorologists to develop a fair understanding of their work. So, I’ll try to explain here what I know about the coming storm, based on what the pros have published.

First, it helps to know how low pressure systems affect winter weather. Typically, the heaviest snow falls to the north and northwest of a low pressure system. Areas to the east and northeast usually get mostly rain. Areas to the southeast can get clear skies with little or no precipitation.

The path a low pressure system takes therefore has a major impact on where the biggest winter storm impacts will occur.

The main way meteorologists predict a system’s path is by monitoring the output of special computer programs known as numerical weather prediction models. These programs run on supercomputers, because they ingest massive amounts of weather observation data and apply complex equations in their attempts to create reliable, mathematical simulations of the atmosphere. Several such programs exist, all written differently. It’s not unusual for the various models to produce different solutions, which typically come out every 12 hours.

Meteorologist Megan Dodson at the Northern Indiana NWS office wrote in an Area Forecast Discussion this morning that they’re watching the outputs of at least four different models. They’re paying attention to how much consensus exists between the solutions of the various models and how consistent each model’s output is with previous output from the same model.

As of this morning’s forecast discussion, these models indicated that the low pressure system would move from the southwest to the northeast and that the path it follows would be farther west than previous model runs indicated. The image below, published by the Indianapolis NWS office, shows three possible paths for the system. One model, known as the Global Forecast System (GFS), is an outlier, forecasting the most westward path. If it’s right, and the center of the low stays west of Indiana, the Hoosier state won’t get much snow. Other models forecast more easterly paths.

Graphic published by NWS Indianaolis showing possible tracks of a low pressure system associated with a forecast winter storm

All the models could still be wrong!

Numerical weather prediction is not perfect, but the closer the low pressure system gets to Indiana, the more the models will align and the better the forecasts will get.

As I write this, the system is still over the Pacific Ocean, so it should be understandable that it’s too early for the models to accurately predict how it will track over the Midwest.

For now, it’s important to understand that a winter storm will very likely occur somewhere, but as much as you’d like to know exactly where the most snow will fall (and where the most travel impacts will be), it’s just too early to know.

That said, because it’s also too early to rule out big impacts in any part of northern Indiana, it’s wise to prepare for such impacts. For example, you might shop for Christmas dinner ingredients a day earlier than you originally planned, just in case.

It’s also important to realize that some people who are not meteorologists post official-looking but unscientific forecasts on social media. Often, they choose the single model output that looks the most dramatic (even though it’s an outlier), rather than create legitimate forecasts based on a full understanding of model limitations and model consensus. Often, the main goal of such posts is to create bigger audiences for advertisements. Keep that in mind the next time you see a dramatic snow forecast for any time that’s more than a few days away.

High probability of very severe weather in Indiana today

Probabilities of damaging, straight-line winds or gusts.

Damaging, straight-line thunderstorm winds — the kind that can knock down whole trees and cause widespread power outages and road blockages — are likely in Indiana this afternoon and evening, especially in extreme southwestern counties (shaded purple in the map above), according to a convective outlook that the National Weather Service (NWS) Storm Prediction Center issued at 9 a.m. ET today.

The 45% probability indicated on the map above compares to “normal” or “average” probability for this time of year of only 1%, acccording to climatology (weather history) data from the National Severe Storms Laboratory.

And in a large part of southern Indiana (shaded gray on the map below), any severe thundertorms that form could create wind gusts of 75 mph or stronger. That’s the same as a category one hurricane. The probability of that happening is 10 percent, or approximately 100 times the climatology norm of 0.1%

Probability of gusts of 75 mph or stronger.

Tornadoes are also possible throughout Indiana and once again, the greatest risk is in the southwest (shaded yellow on the map below), where the probability is 10%, or about 25 times the climatology norm. The 5% probability in the rest of the state is about 12.5 times the norm for this time of year. So even though 10 and five are small numbers, they’re important in this context.

Probability of a tornado.

Any tornadoes that form in southwestern Indiana (shaded gray on the map below) have a 10% probability of doing damage rated EF-2 or higher on the enhanced Fujitsu scale. That’s about 50 times the climatology norm.

Probability of a significant tornado doing damange of EF-2 or greater.

The entire state also has a risk of one-inch or larger hail, but as the map below indicates, the hail risk is lower than the straight-line wind risk.

Probability of one-inch or larger hail.

It’s important for anyone in Indiana to have multiple ways to receive severe thunderstorm and tornado warnings today. Unfortunately, the Indianapolis NWS office reported this morning that three NOAA Weather Radio transmitters in southern Indiana were inoperative.

NWS Indianapolis tweet about inopertive weather radio transmitters

Update: The Indianapolis NWS office reported at 11:44 a.m. ET that all three transmitters had returned to service.

That makes multiple alerting methods even more important. People in that area shold probably keep a TV on, turned up, and tuned to a local station (i.e., not ESPN or Netflix!). Another idea is to install the free FEMA app on smartphones.

If your phone and other rechargeable devices are not fully charged, start charging them now.

If you’re a volunteer Skywarn storm spotter, prepare for activation this afternoon or evening.

NWS needs storm spotter photos

National Weather Service SKYWARN Storm Spotter Jay Farlow W9LW using ham radio
WFFT image.

The National Weather Service (NWS) is preparing to revise the web page for its Skywarn® storm spotter program. The agency is seeking photographs to use on the revised web page.

Photographs should depict real-life, safe and responsible spotter activities. Examples include a ham radio operator holding a handheld radio while looking at the sky, or a spotter typing a message on a smart phone, etc. The ideal photos imply action (vs. portraits) and are set outdoors. Due to government policies, NWS declines to use photos of spotters sitting behind the steering wheel of a vehicle while using a mobile radio.

Skywarn volunteer Jay Farlow is gathering photos for a contact at NWS, so contributors should send the photos to arsw9lw@gmail.com by March 31. Contributors should provide contact information of each photographer, so the NWS can confirm it has permission to use the photos.

NWS Northern Indiana conducts partner webinar on coming winter storm

The Northern Indiana office of the National Weather Service (IWX) conducted a webinar for its partners at 3:30 p.m. ET Monday, January 31, to discuss a winter storm forecasted to hit its area in the following days. Here is a summary of the information shared during the initial briefing and subsequent question-and-answer session.

Update: IWX later published on YouTube a recording of the briefing given during the webinar described here.

IWX meteorologist expected to upgrade the existing winter storm watch to a winter storm warning for at least part of the IWX forecast area by 3:30 p.m. ET Jan. 31. Update: IWX issued a winter storm warning for some of its counties at 3:21 p.m. ET. Visit the IWX web page for details.

IWX plans to issue a new multimedia briefing via YouTube Wednesday morning and conduct a second partner webinar Wednesday afternoon.

Forecast timeline of expected winter storm weather

Forecasters expect the event to begin with a light wintery mix in South Bend Tuesday evening, with rain elsewhere, eventually changing to heavy snow in all areas, as indicated by the timeline graphic above.

Forecaster confidence on winter storm timing is high. Uncertainty is in the transition from rain/sleet/freezing rain to heavy snow, especially along and south of U.S. 24.

Snow accumulation forecast for first round of snow Tuesday night through Wednesday.

IWX shared the graphic above regarding snowfall total for the first of two rounds of snowfall and cautioned partners that the forecast accumulation numbers are very likely to change between now and the beginning of the storm.

Probabilities of exceeding snowfall thresholds.

IWX shared the graphic above regarding probabilities of heavy snowfall and commented that the storm could be on the order of a one-in-five-year or one-in-ten-year event.

Winds are not forecasted to be significant during this first round of snow Tuesday night and Wednesday. That snow will be fairliy wet and heavy and therefore unlikely to blow and drift.

High winds, blowing and drifting snow are likely Wednesday night through Thursday.

IWX forecasts a lighter, drier snow Wednesday night through Thursday. Combined with wind gusts forecasted to reach as high as 35 mph, significant blowing and drifing of snow is forecast, especially on east-west roads in rural and open areas. Whiteout conditions are possible. Roads could drift back over shortly after snow plows pass through on Thursday.

Wind chills are forecasted to be below zero by Thursday night, causing a potential hazard for any motorists stranded in snow.

IWX forecasts ice accumulation to be brief in most areas, and not a great impact. Ice amounts will be less significant than heavy snow.

NWS Northern Indiana Conducts Jan. 8 Web Briefing on Potential Flooding

The northern Indiana office of the National Weather Service conducted a webinar briefing for partners this afternoon, regarding the potential for moderate to major flooding, beginning later this week.

Meteorologist Chris Roller explained that the office has forecast three to four inches of rainfall throughout the office’s 37-county warning area late Thursday through early Sunday. Some areas could get up to six inches. The heaviest rainfall is forecast to begin during the day Friday and to diminish on Saturday.

Roller said that the Wabash and Maumee River Basins have the greatest potential to receive flooding. He added that flooding has the potential to continue from late this week into next week and that some rivers could crest early next week due to runoff.

Roller focused his briefing on four river locations:

  • Tiffin River at Stryker, Ohio
  • Auglaize River at Defiance, Ohio
  • Eel River at North Manchester, Indiana
  • Ottawa River near Kalida, Ohio

Roller said, however, that flooding is also possible on the Maumee River at Fort Wayne, Indiana.

The orange area in the graphic above indicates the range for the most likely outcomes along the area rivers. The charts above indicate the possibility of major flooding on the Tiffin, Auglaize and Ottawa Rivers and moderate flooding on the Eel River.

NWS makes specific information for individual gauges on any river available at https://water.weather.gov/ahps/.

Roller said forecasters have high confidence in a heavy rain event occurring with three to four inches and locally higher amounts to six inches possible. He said river flooding and flooding in normal flood-prone areas is likely.

Roller encouraged citizens to report to NWS Northern Indiana visual evidence of flooding along the rivers, saying that data can be more valuable than river gauge readings.

The office plans an updated briefing Thursday afternoon.

NWS to shut down northern Indiana radar for maintenance

NWS photo

The northern Indiana office of the National Weather Service announced today that it will shut down its Doppler weather radar system for approximately five days beginning Oct. 21 for maintenance.

According to a news release the office issued, technicians will replace old breakers and cables original to the radar with modern fuses and new cables. The NWS said this will help keep the 20-year-old radar operating smoothly for another 20 years.

This transmitter update is the second major project of the NEXRAD Service Life Extension Program, a series of upgrades and replacements designed to keep the nation’s radars viable into the 2030’s. NOAA National Weather Service, the United States Air Force, and the Federal Aviation Administration are investing $150 million in the seven year program. The first project was the installation of the new signal processor. The two remaining projects are the refurbishment of the pedestal and equipment shelters. The Service Life Extension Program will complete in 2022.

During the downtime, usable adjacent radars include: NWS Chicago (KLOT), NWS Grand Rapids (KGRR), NWS Indianapolis (KIND), NWS Detroit (KDTX) and Terminal Doppler Weather Radars located at Detroit (TDTW), Midway (TMDW) and Dayton (TDAY). For direct access to any of these surrounding radar sites, go to the following web page: https://radar.weather.gov/index.htm.

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Two education opportunities for Fort Wayne-area storm spotters

SKYWARN storm spotters and future spotters prepare for training Feb. 16, 2016 at the Public Safety Academy of Northeast Indiana, Fort Wayne
SKYWARN storm spotters and future spotters prepare for training Feb. 16, 2016 at the Public Safety Academy of Northeast Indiana, Fort Wayne

Storm spotters can refresh and increase their knowledge at events in this month and next. One is the official spotter training that the National Weather Service plans to conduct in Fort Wayne October 22. The other is the annual Indiana Storm Chaser’s Convention Nov. 16.

NWS spotter class

As Allen County HamNews reported last month, the Northern Indiana office (IWX) of the National Weather Service (NWS) will conduct a storm spotter class, beginning at 7 p.m. in the auditorium of the Public Safety Academy, 7602 Patriot Crossing. That’s behind the Walmart and Menards stores, off Lafayette Street, south of Tillman Road.

IWX needs spotter reports year-round. Autumn classes like the one in Fort Wayne October 22 will cover late-season severe weather as well as winter weather types and reporting methods.

Even if you attended a spotter class last spring, I recommend attending this October class. It will give you a chance to see what changes IWX has made to its curriculum, refresh your knowledge for the autumn severe weather season, and prepare you to be more helpful during the winter weather season. I plan to attend and hope to see you there. Register online at www.weather.gov/iwx/Spotter_Event_List.

Indiana Storm Chaser’s Convention

Every year, serious storm chasers from around the Midwest gather in the Indianapolis area for a day of learning about severe meteorology and other topics related to their hobby. Unlike chasers, storm spotters might not be interested in driving all over the Plains in the hope of seeing a tornado. The information imparted at the Indiana Storm Chaser’s Convention, however, can help any storm spotters be more effective at protecting their communities.

The Convention unfortunately conflicts with the first day of the Fort Wayne Hamfest. But for storm spotters who are eager to increase their knowledge of severe meteorology, it can be worth attending, even if it means missing the first day of the Hamfest. Learn more about the Indiana Storm Chaser’s Convention at www.indchasercon.com.