As a Cincinnati native, I find it very surprising that so many people that live in the Tri-State – including many natives – that don’t expect the temperature to drop near freezing in late April or early May. Hope springs eternal? Perhaps. While many cheer for warmth all spring, flowers almost always start blooming before the last 32° or 36° temperature of the cold season comes.

While a temperature to or below 32° is scored as a freeze, frost can develop at various temperatures. The temperature at eye-level can be 40°, but there can still be frost at your feet. At local airports (where the meteorological standard is used), the temperature is measured 2 meters (or roughly 6.5 feet) above the ground:

Because relatively cold air sinks and relatively warm air rises, the temperature of the air below the temperature sensor’s height is likely below the temperature of the air at the temperature sensor’s height. If a plant was planted below the temperature sensor at an airport, it may be damaged or killed on a morning where the temperature sensor above it recorded a low of 35° to 40°. This is why Frost Advisories are issued when the temperature drops into the mid and upper 30s.

When does history suggest you’ll be able to plant your flowers and completely forget (well, virtually) about a killing frost or freeze? A sign at Natorp’s Nursery Outlet in Mason says:

…but historical records suggest otherwise!

The latest freeze of the spring in Cincinnati typically comes in April, but we have gone the entire month of April without a freeze and had to wait until late May to get the last freeze of the season:

A freeze (hitting 32° or below) will kill plants very sensitive to the cold and severely damage plants sensitive to the cold. A frost, however, will damage – in full or part – plants sensitive to cold. Using a temperature of 36°, Cincinnati’s last frost of the spring typically comes in late April; historically, it has come as early as late March and as late as late May:

Mother’s Day is usually a save bet for planting flowers; more specifically, looking at the forecast on Mother’s Day to make sure the temperature won’t drop below 40° is a save bet for planting flowers. Since 1871 (not including 1872 because those spring records are missing), the historical odds of the last spring frost (using a temperature of 36°) occurring during May in the Queen City is 32.8%. In other words, the last frost of the year comes before May begins two out of every 3 years.

So…back to the big question…when does history suggest you’ll be able to plant your flowers and completely forget about a killing frost or freeze? Based on records back to 1871, you’ll have to wait to late May to completely avoid a freeze and June 1st to avoid frost:

Happy planting! But seriously, wait until Mother’s Day.

All weather is local.

Sure, patterns and cycles in the atmospheric impact the oceans, the patterns and cycles of the ocean affect the atmopshere, the larger scale features affect the smaller-scale features, and the smaller-scale features can effect the large scale features. But – ultimately – you care about the current conditions and the forecast for where you live. Not a state to the west, not a county to the west, not a city to the west, but where you live. And that’s why all weather is local. As a meteorologist, you must think globally and forecast locally.

A forecast for where you live is more likely to be accurate when we know the current conditions where you live. As George Carlin said, “I don’t know anybody who lives at the airport.” While reliable instruments for measuring atmospheric conditions – including the temperature – are often located at airports, the weather must also be understood away from airports. There are several airports in the Tri-State, but there are hundreds of thousands of people in our area that don’t live within 5 miles of an airport (and weather conditions can be dramatically different over a 5 mile span).

One of the most common ways to showcase local weather conditions is a temperature map. Rain or shine, people always care about the temperature. Here’s a typical temperature map you’ll find on Local 12:

Regardless of the source, it is incredibly likely that your community or one nearby is represented on this map. Nearly all counties are represented, and some counties have 2 or 3 temperatures listed. It is impossible to get all of the weather stations in the Tri-State on this map; this is about as full as it can get.

But what is the source of this temperature data? The simple answer is: “there are multiple sources.” The more complex answer is below.

There are eight airports in the Tri-State that have an Automated Airport Weather Station (ASOS) or Automated Weather Observing System (AWOS) that share data with the FAA directly. These observations are taken under strict standards; for example, temperatures are measured 2 meters above the ground and wind speeds are measured 10 meters above the ground. These sites also report the visibility. Outside of maintenance and occasional power outages, these sites share observations 24 hours a day, 7 days a week, and 365 days a year:

While those sites are very reliable, Remote Automated Weather Station (RAWS) sites are also run 24 hours a day but report just basic weather conditions (temperature, winds, dewpoints, etc.). These RAWS sites are run by the U.S. Forest Service and Bureau of Land Management to monitor wildfire potential in and near national forests. These sites always report once or twice an hour with no exceptions (including special reports for strong winds or severe weather). There are three RAWS sites in the Tri-State (Crittenden, Big Oaks Refuge, and Shawnee National Forest):

The Shawnee National Forest RAWS is not displayed to make room for West Union’s temperature (see below).

Roadway Weather Information System (RWIS) sites are operated by state transportation departments, including the Indiana Department of Transportation, the Ohio Department Of Transportation, and the Kentucky Transportation Cabinet. These sites measure atmospheric conditions as well as pavement conditions (wetness, temperatures, etc.):

The Kentucky Mesonet is the official climate network of Kentucky and is operated by Western Kentucky University. Most counties in Kentucky have a site, and they are positioned to measure temperatures, wind speeds, rainfall amounts, and dewpoints in areas away from airports and other major observing sites:

The Kentucky Mesonet site in Burlington is not shown to make room for the Cincinnati/Northern Kentucky International Airport and Union weather station data.

The temperature map is pretty full with temperatures already, but there are several communities we have left out so far. To fill in the gaps, we use personal weather station data. More specifically, owners of a personal weather station (that they bought) have configured their weather station software to share data with us. With the exception of Lebanon and Falmouth, the data shown on Local 12 from these sites come from personal weather stations:

Temperatures listed for Falmouth and Lebanon come from the AWOS at the Gene Synder Airport and the Lebanon Airport, respectively. These observations, however, are not sent directly to the FAA and the NWS through a certified channel; they are sent to us through a secondary data stream NOAA operates called MADIS, or the Meteorological Assimilation Data Ingest System.

Remember, the temperatures on the maps above are just the ones that fit on the map. There are dozens of other sites in our area that we monitor.

With ASOS, AWOS, RWIS, RAWS, and Kentucky Mesonet sites in the Tri-State, why is there a need for personal weather station data? It all comes full circle: all weather is local. Personal weather station data shows us small-scale wind, precipitation, and temperature changes. These personal weather station stations can and have verify Severe Thunderstorm Warnings and Flash Flood Warnings. Also, higher-resolution, modern computer forecast models analyze local weather station data and may incorporate the data into the model.

If you own a personal weather station, please consider sharing your data with the Citizen Weather Observer Program. If you use software to upload your weather station data online, odds are good that you can share your data with CWOP. Step-by-step directions for sharing data from popular weather stations and their software to CWOP can be found here: http://www.srh.noaa.gov/epz/?n=cwopepz. Many towns and cities don’t have a weather station reporting at this time.

If you have any questions about which weather station to buy or how to share data with CWOP, please don’t hesitate to ask in the comment section of this post.

There are numerous misconceptions and myths about thunderstorms. “Lightning only strikes tall objects,” “people struck by lightning carry an electrical charge,” and “it is okay to showers during a thunderstorm” are some of the common misconceptions. I am not here to discuss these; instead, I want to highlight some of the challenges meteorologists face during active and severe weather. While reports are valuable to us, there are a lot of beliefs about storms and reporting storms that are not true, such as:

While radar is a powerful tool, it is not a pair of eyes. Radar can but often does not confirm tornadoes. Radar suggests where damaging straight-line winds are likely, but it doesn’t confirm them. Radar data suggest where heavy rain has fallen, but it doesn’t replace what a rain gauge measures. Simply put, radar, models, satellite, and weather balloon data are great, but it doesn’t always verify the conditions where you live. In fact, your report is more important than anything a meteorologist can access at his or her fingertips. Please don’t assume someone else has reported what you are seeing because you may the only one seeing what you are seeing. Always report out-of-the-ordinary weather.

Thank you for your report. Seriously! We need to know what you are seeing! Radar doesn’t always tell us the story. When you submit your report, however, please be specific about what you are seeing and where. Where are you located? Are you in a town, and how far/what direction are you relative to that town? A photo of hail or damage is great, but a photo with a detailed description of where you are (i.e. “I’m 2 miles west of Oxford, Ohio”) is FAR more helpful. In addition to knowing where you are, I want to know what you are seeing specifically. If you are seeing hail, how large is the hail compared to a coin? Why do I ask this? Because coins are all the same size; a quarter in California is the same as a quarter in Ohio. I need to know how big your hail is compared to something absolute in size. I don’t know how big your hand is. I don’t know how big your finger is. I do, however, know how big a golf ball is.

Also, please let me know what time severe weather occurred. Sending me a photo at 5:30pm of damage that occurred at 5:25pm is helpful, but sending me a photo at 5:30pm of damage that occurred at 2:30pm is not as helpful, especially if there are numerous rounds of storms; I don’t know what storm likely caused the damage unless you can confirm when the damage occurred.

You might. If you’re seeing a violently rotating cloud extending from the base of a thunderstorm that’s connected to the ground, you are seeing a tornado. If you’re not seeing this, you’re probably not seeing a tornado. You may be seeing a tail cloud, a funnel cloud, a wall cloud, or another type of cloud. After going through spotter training, you’ll know the difference between these types of clouds. There are a lot of tornado look-alikes. There’s actually a “Scary Looking Cloud Club.” While these clouds may look like tornadoes, they are not.

I am sorry. I really am. I don’t want to have to interrupt your program to tell you there is a threat for damage. I don’t want to cut into your favorite show to tell you there may be a tornado coming towards you or one of your neighbors. But if it’s a life threatening situation, I have to cut into your program. It’s not just a standard set by television station managers, but it’s also the right thing to do.

I understand you may not be in the warning, but someone nearby is; they deserve the warning just as much as you do should your town been placed in the warning. Please understand that my job – ultimately – is to make sure you stay safe. If you’re going to see severe hail, severe winds, or a tornado, you not only deserve to know, you should want to know. Big Brother, Survivor, the Olympics, the World Series, the NBA Finals, or any other program is not as important as a meteorologist telling you that you or your stuff is in danger.

In my March 31st blog post, I said that the Tri-State had not gone the entire month of January, February, and March without a Severe Thunderstorm Warning being issued (since 1995 when the National Weather Service in Wilmington opened).

Boy, did our luck suddenly run out. Or as Ron Burgundy put it:

The first Severe Thunderstorm Warning of the year in the Tri-State was issued in Owen County at 4:35pm on April 2nd. Another was issued at 5:10pm that day, and other was issued on the afternoon of April 7th. From April 8th through April 10th, however, a whopping 33 Severe Thunderstorm Warnings were issued in the Tri-State, bringing the monthly total up to 36 warnings; this total puts the Tri-State into second place for the most number of Severe Thunderstorm Warnings during April:

All of these warnings were issued in the first 10 days of the month. Between 1995 and 2014, an average of 14 Severe Thunderstorm Warnings were issued in the Tri-State each April; with 2015 included, that average now goes to 15.

On average, April is the 3rd most common month for severe storms in the Tri-State behind June and May.

While getting 34 Severe Thunderstorm Warnings in two days is impressive, the number of times certain counties have been placed under warnings so far this month is also impressive:

The Severe Thunderstorm Warning count for so far this month for Clermont, Brown, Pendleton, and Adams County are new records for April. Grant and Owen have tied their records for the most number of Severe Thunderstorm Warnings in a single April.

While there will be waves of rain and storms in the week ahead, this week does not look exceptionally stormy. The warning count for most if not all Tri-State counties will remain the same through the upcoming weekend.

Opening Day is upon us, and the long-awaited start of the baseball season is here! Showers will be scattered today, and high temperatures will be near average. While you may be bummed about the chance for rain, it will not be widespread, and it the weather has been MUCH worse on Opening Day!

To celebrate the beginning of the 2015 season, here’s some Cincinnati Reds Opening Day weather trivia:

Play ball!

The term “Smog Alert” has been a phrase used for decades on days where air quality was relatively poor in Cincinnati. Beginning today, however, the Southwest Ohio Air Quality Agency will no longer issue “Smog Alerts.” Instead, they will issue an “Air Quality Advisory.” This change involves more than just the title of the alert. The chief aim of this rebranding is to re-engage you about local air quality.

The Southwest Ohio Air Quality Agency measures the concentration of the six pollutants to U.S. Environmental Protection Agency health-based standards for Butler, Clermont, Hamilton, and Warren County. Under the current U.S. EPA standards, if ozone or particulate matter causes the Air Quality Index to exceed 100, the Agency will issue an Air Quality Advisory (beginning today). This is a message that encourages at-risk individuals (those with asthma and other pulmonary issues, young children, and older adults) to avoid strenuous outdoor activity until air quality improves.

When an Air Quality Advisory is issued, it will be in effect for Butler, Warren, Hamilton, Clermont, Boone, Kenton, and Campbell County (just like Smog Alerts).

The Air Quality Advisory is issued by Southwest Ohio Air Quality Agency the day before elevated ozone and/or particulate matter levels are anticipated. The decision is made around 2pm (usually Monday through Friday, but occasionally on weekends if ozone or particulate matter levels are forecast to be high) and includes a review of current and historic weather patterns.

Calculating the Air Quality Index is not easy. In fact, it’s horribly messy. The technical explanation how the AQI is calculated is here: http://www.epa.gov/airnow/aqi-technical-assistance-document-dec2013.pdf (beginning on page 16). Before the overall AQI is calculated, the AQI must be calculated for each pollutant (O2, O3, NO2, SO2, PM10, PM2.5). A calculator for doing this can be found at: http://airnow.gov/index.cfm?action=resources.conc_aqi_calc. Again, it’s a total mess. However, once that AQI is measured or forecast, the determination for a “Air Quality Advisory” will be made.

The weather plays an important part of that decision to issue or not issue. Here’s a graphic showing some weather factors that may trap pollutants near the ground and cause an “Air Quality Advisory” day to be issued:

Notice that high dewpoints, a center of high pressure nearby, weak winds, and a temperature inversion (temperature increasing with increasing altitude, creating a stable layer of air aloft) help elevate air pollution levels. With time these conditions change, and air quality levels improve.

The main driver for an elevated AQI in the summer is ozone. The main driver for an elevated AQI in the winter is particulate matter. Smog alerts were almost always issued during the summer in the past; going forward, Air Quality Advisories may be issued at any time of the year, including during the winter.

Air Quality Advisories will likely be issued more frequently than Smog Alerts were. The current national standard for ozone is 75 parts per billion (ppb). The U.S. EPA is proposing a new standard of 70 or 65ppb and possibly 60ppb; the EPA will likely adjust the standard this fall. How many Air Quality Advisories we get will depend on how strict the standard is.

For example, no Smog Alerts were issued in 2013 or 2014. Had the Air Quality Advisory program been in effect those years, an advisory would have been issued 2 days in 2013 and 4 days in 2014 due to ozone levels exceeding the standard of 75ppb:

That’s the current EPA ozone standard. The standard will likely become more strict later this year. Suppose it was set at 70ppb in 2013 and 2014 (like it likely will be later this year); during the last two years, there would have been 31 days with Air Quality Advisories in effect:

Suppose it was even more strict and set at 65ppb. There would have been 109 Air Quality Advisory days in 2013 and 2014:

Lastly, if the EPA had lowered the standard to 60ppb for 2013 and 2014 with the Air Quality Advisory program in effect, an Air Quality Advisory would have been needed 239 days in the last two years:

We are just barely meeting the ozone standard in Cincinnati now:

Courtesy: Southwest Ohio Air Quality Agency

While ozone concentrations in the air we breathe have dropped significantly in the last few decades (the blue line above), we are just under the current standard (the green line above).

Again, this is just for the ozone standard. We also have to meet particulate matter, sulfur dioxide, nitrogen dioxide, and carbon monoxide standards. In addition to ozone, we are barely making sulfur dioxide and some particulate matter standards.

We have a lot of work to do on air quality. I haven’t met a person who doesn’t want cleaner air. All of the same air quality tips you heard for Smog Alerts will apply to Air Quality Advisory days. In case you’ve forgotten them (I understand, it has been a while), here they are:

– Taking the bus, carpooling, biking or walking instead of driving
– Refueling your vehicle after 8 p.m.; do not top off when refueling and tighten the gas cap
– Not idling your vehicle
– Combining trips or eliminating unnecessary vehicle trips
– Keeping your vehicle maintained with properly inflated tires and timely oil changes
– Avoiding use of gasoline-powered lawn equipment on Air Quality Advisory days
– Avoiding use of oil-based paints and stains on Air Quality Advisory days
– Never burning leaves or other yard trimmings
– Always burning clean, seasoned wood in outdoor fire pits, fireplaces and wood stoves
– Not using fire pits or fireplaces for non-essential home heating on Air Quality Advisory days
– Conserving electricity

There have been no Severe Thunderstorm Warnings issued in the Tri-State so far this year. That is an incredible statement to make in late March.

As I mentioned in my March 17, 2015 blog, the first Severe Thunderstorm Warning of the calendar year in the Tri-State, on average, is issued on Valentine’s Day:

Note that the latest first Severe Thunderstorm Warning of the year and in the Tri-State was on March 31, 2007. There will be no severe thunderstorms in the Tri-State today, and there will be no severe thunderstorms tomorrow; this means – using the first Severe Thunderstorm Warning of the year as a measure – this will be the latest start to the severe weather season on record (since the National Weather Service forecast office opened in 1995).

Reading that statement doesn’t really do it justice; you have to see it. Here’s the total number of Tri-State Severe Thunderstorm Warnings issued in January, February, and March by year:

Since 1995, there have been 3 years with 1 Severe Thunderstorm Warning issued in the first 3 months of the year. One could make the argument that we are barely setting a new record, and that is true. The argument I make here is that a record is a record.

On average, 5 Severe Thunderstorm Warnings are issued in the Tri-State each March:

It is common to go through March without severe storms, but it is uncommon to go through the first 90 days of the year without at least onr severe storm. On average, 2 Severe Thunderstorm Warnings are issued each January, and 3 are issued each February. We have beat the odds for three straight months.

This stretch (since the beginning of the year) is not the all-time stretch between two Severe Thunderstorm Warnings. The last Severe Thunderstorm Warning issued in the Tri-State was issued on the afternoon of December 24, 2014 for Highland and Adams County (about 98 days ago). The record for the longest period of time between two warnings in the Tri-State is 216 days (between warnings issued on August 27, 2003 [Clinton County] and March 30, 2004 [Adams County]).

While strong storms are a possibility later this week, we are not currently set in a severe weather risk. This may change; if it does, this change in the pattern will be overdue. Be prepared!

There is a problem in the weather community that no one really discusses. Of all of the problems that the weather enterprise needs to tackle, this is far from a #1 priority; this issue, however, is important.

It’s about high clouds.

High clouds are often written off as decorative clouds. They often produce no precipitation and just filter sunshine. Thin, wispy cirrus clouds form usually form due to upper-level winds tearing off the tops of showers and storms that extend tens of thousands of feet into the atmosphere. High-level clouds often go where low- and mid-level clouds can’t survive, including right through areas of high pressure; this is because sinking air associated with a surface area of high pressure is usually focused well below jet stream level (where high-clouds live). High-level clouds typically last longer and travel farther than low- and mid-level clouds because vertical motion and friction closer to the ground allows dry air to mix with lower-level clouds more easily.

So why care about these clouds if they just filter starlight, filter sunlight, and rarely produce precipitation? Because a forecaster’s reputation is on the line every time he or she sits in the chair.

High clouds matter, and here are some examples why.

I went to the Cincinnati/Northern Kentucky International Airport on the evening of Sunday, March 15th to pick someone up after a flight. I noticed the coverage of clouds varying a lot driving from Ohio to Kentucky. As a meteorologist, I want the forecast to be right. After parking in the cell phone lot, I took these pictures of the sky. Here was the sky looking south:

…and west:

…and north:

…and east:

…and straight up:

The weather station at the airport about 5,000 yards away from where I was standing produced the following report at the time the photos above were taken:

KCVG 152252Z 28007KT 10SM BKN250 17/01 A3019 RMK AO2 SLP223 T01670011

Unless you’re a pilot, a meteorologist, or a weather enthusiast, you probably can’t understand that report. When it comes to the report of clouds in this case, we are focused on the part of the report that begins with BKN:

What are “broken clouds?” To understand this, you must understand how sky cover is measured. A number between 0 and 8 (in units of okta) are used to describe how much of the sky is covered with clouds. If the sky cover is reported as 0 oktas, the sky is clear. If the sky cover is reported as 8 oktas, the sky is completely covered in clouds. There can be a few different layers of clouds in the weather observation, and each has a unique opacity. The weather station at the International Airport that measures cloud cover and other meteorological variables is called an ASOS, or Automated Surface Observing System. The cloud cover mentioned in the report is averaged over time and is not a “right now” measurement. Per the NWS’ ASOS users guide, here’s the scale the ASOS uses for converting the sky cover it measures in okta to text:

Using the table, the weather report at the time the photos above were taken says the sky was more than 4/8 (50%) but less than 8/8 (87%) covered with clouds. Many computer algorithms (non-technical weather websites, smartphone apps, etc.) will convert a BKN cloud cover report to be “mostly cloudy.” If a forecaster said the sky would be “partly cloudy,” that forecast would be scored as inaccurate by most computer algorithms. The device used to measure cloud cover is pointed straight up at the sky. While the human observer at the International Airport can adjust the weather observation, the cloud cover part of the observation is rarely adjusted.

Does the sky look mostly cloudy to you in the photos? It depends on which direction you look. You could make the argument that the sky was mostly sunny or partly cloudy in spots.

Here was the visible satellite snapshot around the time of the observation:

Cincinnati is the red dot. Does it look cloudy to you? Based on the satellite image, you could make the case for a mostly cloudy sky at times.

Here’s another example from Sunday night (March 22, 2015)…broken clouds at 25,000 feet above the ground were reported at the airport just before 6pm:

KCVG 222152Z 06010KT 10SM BKN250 10/M07 A3013 RMK AO2 SLP204 T01001067

Remember, broken clouds were reported at the same altitude around the same time on the previous Sunday. A visible satellite snapshot at the time showed clouds overhead at the time:

A minute after the weather report came down from the airport, the sky over Cincinnati looked like this:

The view didn’t look much different from 600 feet above Cincinnati at the same time:

Remember, these are high-level clouds. Who cares, right? Comparing both case studies shows “broken clouds” is a vague description. “Broken clouds” can look partly cloudy or mostly cloudy. But as meteorologists, the quality of a forecast is often measured against surface weather reports at the International Airport.

…or – more importantly – the general public. A meteorologist going on TV and calling for a “partly cloudy sky” when it looks cloudy (or is cloudy) out the window does not bode well for a meteorologist’s reputation.

The negligence of a forecaster to consider the coverage or thickness of high-level clouds can not only harm his or her image, but it can also affect the quality of the forecast. High-level clouds absorb and re-emit radiation, including radiation that comes from the ground or underneath a cloud. The temperature of the air is directly related to the solar radiation that is absorbed by the air and also the ground (because the ground absorbing radiation causes it to warm, which in turn warms the air with which it is in contact). Because clouds can absorb and re-emit radiation directed back at the ground (that would otherwise go out to space), mostly sunny days are often warmer than sunny days (given no other significant differences in weather conditions between the two days).

The lack of frequent weather reports from local airports must also be considered here, but this is a whole different can of worms and a blog post for another day.

High-level clouds are a bigger deal than we make them. While they are often forgotten, ignored, or considered unimportant by forecasters, meteorologists, the weather enterprise, scientists in related fields, and even those not particularly interested in meteorology, they are an important part of weather.

There are various ways to measure the depth of a severe weather season. You can count the number of warnings, damage reports, or tornadoes. You can count the number of days between warnings, or you could count the number of days between the first warning of the year and the last warning of the year.

Comparing the start of the severe weather seasons to another is much easier. The date of the first warning issuance is essentially the starting gun being fired at start line of race.

Since the National Weather Service Forecast Office in Wilmington warning records began in 1995, roughly 230 Flash Flood, Tornado, and Severe Thunderstorm Warnings have been issued in the  Tri-State. None of these warnings have been issued so far this year, and this is unusual.

Of Severe Thunderstorm, Flash Flood, and Tornado Warnings, a Severe Thunderstorm Warning is typically first warning of the year issued. A Severe Thunderstorm Warning has been issued ahead of the first Flash Flood Warning and first Tornado Warning 15 of the last 20 years; a Flash Flood Warning was issued first the remaining 5 years.

On average, the first Severe Thunderstorm Warning of the calendar year in the Tri-State is issued on Valentine’s Day:

Since 1995, there has not been a year in the Tri-State where at least one Severe Thunderstorm Warning was issued before April 1st. Note that severe thunderstorms can occur in January.

The first Tri-State Flash Flood Warning of the year typically comes in the start of meteorological spring:

If a Flash Flood Warning is not issued in the Tri-State before May 20th, a new record for the latest first Flash Flood Warning of the year would be set in 2015. The most common months for Flash Flood Warnings to be issued are April and May.

Tornado Warnings, historically, are the last of the big three warm-season warnings to be issued in the calendar year; the first one, on average, is issued in early May:

Note that it took until November 17th of 2013 to get a Tornado Warning issued. That Tornado Warning did not verify, nor did ones issued on November 18th or for Adams County before sunrise on December 22nd. For the first time since 1988, no tornadoes were confirmed in the Tri-State in 2013. The first Severe Thunderstorm Warning of that year, however, was issued on January 30th.

Colder air is in the process of returning to the Tri-State, and this cold lingering through late March and very early April may mean the slowest start to severe weather season on record based on Severe Thunderstorm Warnings. If that doesn’t convince you, making it through May without a Flash Flood Warning would make 2015 a solid contender for the top spot. If you throw 2013 out, the average first Tornado Warning of the year date drops back to April 28th, and the latest date drops to July 27th (2002).

I can’t recall a time since the year began when there was a cloud-to-ground lightning strike in the Tri-State. For storm lovers, 2015 has been a dud thus far, and they will be waiting for at least a short while to get what they want. For those who dread storms, their prayers have been answered.

There is a great buzz around Cincinnati about the warmer temperatures this week, and there are great reasons for the buzz. People are more inclined to get out and make the most of the day when the sun is out and temperatures are mild. This mild stretch is especially welcome given brutal cold early this month and for most of last month.

We have not seen the last of winter, however. No, there is no immediate threat for snow. Temperatures near or below zero aren’t likely either. This change in the pattern will mean a drop in temperatures though. Right now, the jet stream is positioned to our north, and the influence of an upper-level area of low pressure to our west is minimal:

The pattern we are in now will be changing some this weekend and more drastically next week. Tuesday morning’s European (ECMWF) model shows cold air associated with an upper-level low diving south into New England on Sunday morning:

The ridge over the Rockies and Plains (and it’s associated warmth in red) will mainly hold through the weekend, but the Tri-State will still get a glancing blow of cold Saturday through Monday. Lows will briefly dip into the 30s Sunday and Monday morning.

The biggest blast of cold will come late next week. The large, upper-level area of low pressure moving south out of Canada will not be pushed easily to the east by the jet stream. This area of cold will push the ridge in the Plains back to the west, and this new pattern will likely persist through late March and at least a couple of days into early April:

While the jet stream is to our south later this month, this air mass may bring temperatures back into the 20s at night and 30s to 40s during the day. Some model runs have painted very light snow in the Ohio Valley during this extended period of cold, but there is no specific time when snow more likely than other (if it even occurs at all). Cincinnati averages 0.5″ of snowfall accumulation each April, so don’t think it won’t happen!

In summary, here’s how my latest long range forecast thinking…

Notice that specifics are not a part of this long range prediction. Specifics on timing and positioning of weather systems are rarely resolved well more than one week out. With time, trends will turn to numbers. For now, know our time with above-average warmth is limited.