Winter is far from over, but the core of the winter season – December, January, and February – was among the snowiest and coldest on record. In fact, meteorological winter 2013-2014 was the 2nd snowiest and the 18th coldest on record in Cincinnati.

To ensure that meteorologists compare apples with apples, meteorological winter is defined as December, January, and February. Astronomical winter’s start and end date varies each year and often ends and begins at a different time each year. Meteorological winter is always 3 months long, so it’s simple to compare seasons.

To measure where a season ranks compared to other years, we must know the average temperature of each day in that season. The average temperature of a day is the high and low temperature divided by two; the average temperature of a season is the average of all of the daily average temperatures in a season. When you crunch these numbers for the winter of 2013-2014, it ranks as the 18th coldest:

Meteorological winter of 2013-2014 ranks as the 2nd snowiest on record in Cincinnati; we were close to the number one spot of 1977-1978!

While those are the two most common ways to measure a winter’s might, there are other ways. Ranking as the 14th coldest, the average low temperature this winter in the Queen City was 4.4° below average, but it was nowhere near as cold as 1976-1977:

The number of nights where we dropped below 10° in meteorological winter was double the average but well short of the record set in 1976-1977:

Cincinnati dropped below 0° 7 days between December 1st and February 28th. This is over three times the average, but 10 days short of the record:

While the days were cold, records show that the number of days in December, February, and January where the high was below 32° was about average and not even close to matching the record:

One big record was set this winter: the most number of days (32) in meteorological winter with measurable snowfall. This beats the previous record set in 1977-1978 of 30 days:

One Tornado Warnings and seven Severe Thunderstorm Warnings were issued in February 2014. The Tornado Warning was the first issued in the Tri-State during February since National Weather Service Forecast Office in Wilmington records began in 1995. The tornado confirmed by the National Weather Service in Ripley County was the first February tornado in the Tri-State since February 15, 1967.

Even after the brutal cold of meteorological winter 2013-2014, nearly all records of snowfall and cold still belong to 1976-1977 or 1977-1978. Rounds of snow and ice are far from over in the Ohio Valley. Cincinnati averages 3.1″ of snowfall each March; some in the Tri-State may see more than that Sunday into Monday!

If you thought January 2014 was cold and snowy, you’re right. January 2014 was the 4th snowiest and 12th coldest January on record in the Queen City. Considering official weather records for January in Cincinnati go back to 1871, making it in the top 20 lists for snow and cold in January is impressive. When you have winters like 1976-1977 and 1977-1978, however, it is very hard to get to or near the top spot of the coldest and snowiest month of the year (on average).

January’s snowfall total at the Cincinnati/Northern Kentucky International Airport of 20.4″ was over three times the average amount of snowfall in January, but it fell well short of the January 1977 snowfall total:

The snow that fell in January felt like even more of a burden after a very snowy December. December 2013 (with a total of 10.4″ of snowfall) was the 9th snowiest December on record in the Queen City:

December’s 2013 total was 1/2″ short of January 1977’s total, and over 7″ below the December 1883 snowfall total. The National Weather Service says official snow records began in 1893; if you accept that as the start of official records (and not when other records like temperature and precipitation began in November of 1870), December 2013 was the was the 7th snowiest December on record.

January 2014 was also snowier than average by the number of days with measurable snowfall in Cincinnati:

January 2014 was also a very cold month. In meteorology, the ranking of cold is determined by calculating the average temperature of the month. The average temperature of any given day is average of the high temperature and low temperature; the average temperature of the month is calculated by averaging daily average temperatures for the entire month (did you get all of that?). By this measure, January 2014 was the 12th coldest January since official records began (in November 1870):

The average high temperature in January 2014 was colder than the 30-year average but well above of the average high temperature in 1977:

It was the same story with low temperatures: January 2014’s average low temperature was below the 30-year average but above the average low temperature of January 1977:

The temperature frequently dropped below 10° in January 2014, but the record of January nights with a low temperature below 10° went unchanged this year:

We also dropped below 0° 7 days in January 2014, but we dropped below 0° more frequently in 1977:

The cold of January 2014 was not just felt at night; we had several days where the temperature didn’t get above 32°. Despite being above the average, our count of days with a high temperature below 32° fell way short of the 29 days with a high below 32° in January 1977:

Regardless of how you measure it, January was a very cold, snowy month; the king of cold and snow continues to be 1977. More waves of snow and cold are on the way in the month ahead. Our snowfall total since last summer now stands at 33.7″; we need need just over 20″ to get to the all-time fall/winter/spring snowfall record set in – you guessed it – 1977 through 1978.

In Cincinnati, the month by which all cold or snowy months are measured against is January 1977. Those who have lived in Cincinnati for decades – regardless of when they were born in the 20th century – will tell you the winters of 1977 and 1978 were the coldest and snowiest. The average high temperature that month was 22°; the average low temperature was 2°. In January 1977, the low temperature dropped below 0° 16 days, and the high temperature didn’t even get to 0° one of those days. Over 30″ of snow fell that month, and 13 days of that month began with 10″+ of snow on the ground. It was cold.

That cold has stood the test of time. 37 years later, 3 of the top 4 coldest early morning low temperatures in Cincinnati were set in January 1977:

In the mid 80s and 90s, sharp cold shots and a deep snowpack over the Ohio Valley allowed the temperature to dip to -20° or colder, but those cold blasts were not as prolonged as the cold of January 1977.

Two of the coldest daily low temperatures on record in Cincinnati were set on consecutive nights. The all-time coldest low temperature for Cincinnati was set on January 17, 1977 (-24°); the following night – January 18, 1977 – the temperature dropped to -25° at the Cincinnati/Northern Kentucky International Airport, which was the new all-time coldest low temperature recorded. Prior to these days, the all-time record low for Cincinnati was -19°, set on January 24, 1963.

The official climatological summary from the National Weather Service shows the all-time record low from January 18th (yellow) and all-time record lowest average temperatures from January 17th and 18th (red) highlighted with an asterisk:

Using the average temperature as a measure, January 16th, 17th, and 18th of 1977 is the coldest 3-day stretch on record in Cincinnati.

-25° still stands as the all-time record low temperature for the Queen City to this date. Several spots in the Tri-State were just as cold as the International Airport that mid-January morning, but others were not as cold:

The all-time record low temperature was also set at Fernbank (in western Hamilton County) that morning. Other all-time records in the Tri-State, however, were not set that morning. Here is a small sampling of when all-time record low temperatures were set at several Tri-State locations:

Several all-time low temperature records were set in January 1994, especially on the 19th. The all-time low temperature in Cincinnati was almost matched that day:

5-10″ of snow covered the Tri-State on January 19, 1994. Maysville’s all-time record low temperature was set that morning, but January 17th and 18th, 1977 weather records from Maysville are missing…when it may have gotten colder than in 1994.

While the numbers tell a story, the photos from January 1977 tell more. Many did what may never be possible again in our lifetimes; they walked across the frozen Ohio River.

Frozen Ohio River in January 1977; photo courtesy of Edith Suttle

National Weather Service records show navigation up and down the Ohio River past Cincinnati was suspended from January 25 to February 2, 1977. The photo above shows travel across the river by foot was easier than down the river by boat.

Frozen Ohio River in January 1977; photo courtesy of Cathy Lang

The several party boats were stuck along the shore for days. The Showboat Majestic was surrounded by ice.

Not everyone remembers tornadoes, floods, or hail storms; those weather events often affect a select group of people and don’t always leave a large footprint. Perhaps more than any other Tri-State weather-related event, those who lived through the snowiest, coldest January on record or walked over the Ohio River remember it.

While models have wobbled more than usual with the handling of weather systems recently, the latest computer model runs all suggest a large piece of arctic air will drop into the Ohio Valley next week. The specifics about the timing and strength of the cold plunge are nowhere close to being finalized, but a signal of very to extremely cold temperatures should be taken seriously.

There is already a lot of hype about next week’s cold blast on social media. Some models are producing very cold temperatures for the Tri-State next week, while others are suggesting we’ll come close to setting all-time record low temperatures. These same models may change their tune later this week and over the weekend, but for now, they all agree that cold (in some form) is coming soon.

For the sake of simplicity, I’ll focus on next Tuesday morning (January 7th). This morning’s GFS model pushes temperatures to around 0° in Cincinnati that morning:

The GFS model ensemble members averaged together suggests we’ll drop between 5 and 10° above zero:

This morning’s ECMWF model says the Tri-State will drop between -10° and -25° below zero Tuesday morning:

Meanwhille, the ECMWF model ensembles averaged together drops Cincinnati between 0° and -5°:

The Canadian model ensembles averaged together – which tends to do well with extreme cold – drops the temperature to around 10° in Cincinnati early next Tuesday morning:

Clearly, there is a large spread on overnight lows from one model to the next. Long range forecasting can be very tricky, especially when dealing with the timing of disturbances more than a week out.

Long range forecasting is especially hard this time of the year because:

– The lack or depth of a snowpack can have a large influence on temperatures
– Models tend to overdevelop areas of low pressure in the winter, and – thus the amount of cold air behind departing behind them
– Cloud decks are also tough to forecast more than one week out, especially stratus decks and low-level inversions/stable layers of air aloft

For these reasons and others, forecasting temperatures for next week now is difficult at best. While models may not agree with each other, they are sending a signal of brutal cold. Here’s a list of how many times Cincinnati has dropped below certain temperatures in January since 1871:

What are the historical odds that the low temperature on any given January day in Cincinnati will drop below these same temperatures?

On average, Cincinnati drops below 0° two days each January. There have been many years where we didn’t hit 0°, but there have also been years where we hit or dropped below 0° frequently (16 days in January 1977).

A lot is needed to get a temperature well below zero in Cincinnati. Notice that all of the top 10 coldest mornings on record in Cincinnati had at least two inches of snow on the ground:

The presence and amount of snow on the ground in Cincinnati has a big impact on how cold we get at night. The presence and amount of cloud cover at night has a impact on how cold the Tri-State gets. The amount of snow to the north and west of Cincinnati (even as far back as the Plains and Dakotas) can have a big impact on how low temperatures go. Just as drought begets drought and wet begets wet, cold and snow begets cold and snow. A dense snowpack from the Ohio Valley to the Plains is often a major contributor to record cold, as arctic air from Canada “holds together” better when it travels south.

Simply put, we are getting signals from recent computer model runs about a significant surge of arctic air next week. Some models suggest we will see near-record cold, but this is highly dependent on the extent of cloud cover and snow cover in the Ohio Valley in the coming days. Stay tuned for what could be one of the biggest – if not the biggest – polar plunges we’ve had the Tri-State in the last couple of years!

Did Saturday’s weather seem unusual to you? It was. In fact, it was very unusual by several different measures. Heavy rain is not common in December, and severe weather isn’t either. We had plenty of both this weekend, fueled by an abundance of warmth and low-level moisture.

How does one measure the weirdness of weather? The easiest way to do this is by variable.

It was hard to ignore the rain this weekend, especially with Friday, Saturday, and Sunday being some of the biggest travel and shopping days of the year.

Rainfall totals varied from one community to the next, but most fell into a 1-3″ range; some were just outside the range:

While 1-3″ is a significant amount of rain, it doesn’t always lead to problems. For this event, however, it caused widespread flooding thanks to one of the snowiest starts to December on record and temperatures in the 40s, 50s, and 60s before, during, and after rain was falling. Tri-State soils were wet to soaked before rain fell in many communities, and 1-3″ of rain on top of a saturated ground means flooding is imminent.

The 2.29″ storm total at the International Airport is about 68% of the average amount of precipitation (rain + melted down snow and ice) Cincinnati gets in the entire month of December. 1.86″ of that total fell between midnight Saturday and midnight Sunday, making Saturday, December 21st the 15th wettest December day on record (since 1870) in the Queen City:

A surplus of low-level moisture and a surge in warmth helped to support the widespread rain and storms that passed through the Tri-State Friday, Saturday, and Sunday. Since reliable hourly weather records began in Cincinnati in 1939, the highest dewpoint recorded in Cincinnati during the month of December was 65°. At the Cincinnati/Northern Kentucky International Airport, the dewpoint hit 63° several times Saturday. A dewpoint of 63° is abnormally high for Cincinnati in December and almost tied the dewpoint “record” set in 1948:

Temperatures were also well above average, helping to create some instability. Our high of 68° was 1° from matching the record high of 69° set in 1967. Here’s a map of Tri-State high temperatures Saturday:

Oddly enough, the weather setup in 1967 (when the record high was set) was similar to Saturday’s. After a dry morning and a rapid warm up from the 40s into the 60s on December 21, 1967, a cold front came through that unloaded 1.06″ of rain; the following day featured a low in the 20s, a high in the 40s, and some flurries in the morning. Similar  to those days in 1967, we’ll start tomorrow around 30°, finish in the upper 30s, and have some flurries and sprinkles in the morning.

In my opinion, what make Saturday unique – or perhaps historic in some ways – was the presence of severe thunderstorms. From the time the National Weather Service Forecast Office in Wilmington first started issuing warnings for the Tri-State in 1995 to the start of this month, only 4 Severe Thunderstorm Warnings had been issued in the Tri-State during the month of December; all of them were issued on December 1, 2006 when a line of storms traversed the Ohio Valley. In this same time period, no Tornado Warnings and only 3 Flash Flood Warnings were issued in the Tri-State.

Last night, 8 Severe Thunderstorm Warnings, 6 Flash Flood Warnings, and a Tornado Warning were issued in the Tri-State. In other words, more Severe Thunderstorm, Tornado, and Flash Flood Warnings were issued in the Tri-State last tonight (both individually and added together) than in all December days from 1995 to 2012 combined.

After a very quiet spring and summer severe weather season, here are the latest warning totals for 2013 compared to the yearly records and averages:

Saturday’s severe weather event and the severe weather event that hit in the Tri-State on Halloween were unique in that damaging straight-line winds were caused more by showers than thunderstorms. Radar data showed a well-defined, narrow line of showers and isolated thunderstorms entering the Tri-State just before 9:30pm last night:

…and east of the Tri-State around 1:30am:

Showers and storms were moving quickly (50+ mph) last night, and their speed and outflow alone was enough to cause damage. In real-time, there was no strong indication that warnings were verifying. The peak wind gust map from last night (including observations from local airport and weather stations) suggests there was little to no damage (60+ mph winds are usually needed to cause damage):

When the sun came up and flooding concerns eased some overnight, people found more damage, but most that got damage just had trees or limbs down.

When you get off the beaten path, even more complex weather records were set on Saturday. The precipitable water (atmospheric water content) value measured by Saturday night’s weather balloon launched at the NWS Wilmington around 7pm set a December record (records began in 1948). In the graphic below, the green line represents the monthly records, and the “X” shows last night’s value broke the December record (and was 321% of the December average):

Regardless of how you measure Saturday’s weather, it’s hard to say it wasn’t unusual, atypical, or just plain weird. As a meteorologist who has worked for several years in the Ohio Valley, you never quite know exactly what you’ll see any given year. After a record number of tornadoes last year, this year has been quieter than usual and with nearly all of our severe weather coming late in the year.

Thankfully, the next few days look quiet with some bouts of flurries and near or below average warmth.

There are several things about this weekend’s weather setup that are troubling. First, waves of heavy rain are forecast this weekend, this after a couple days of snow melting to saturate the ground. Second, there is a threat for strong and severe storms this weekend in the Ohio Valley; after a quiet spring and summer, this fall and now winter has been very stormy. Severe weather events in the Tri-State during the month of December are very rare.

Several disturbances will affect the Ohio Valley Friday through Sunday; the thinking on the strength and timing of each has not really changed in the last 24 hours.

The latest computer forecast model runs all have widespread light to moderate rain in the Tri-State Friday morning and afternoon:

This initial round of rain is not going to cause widespread problems, but it will help to saturate the ground. Models have widespread moderate to heavy rain moving in Saturday afternoon and evening:

Moderate to heavy rain continues into early Sunday with the center of low pressure to the northwest of Cincinnati:

Given the dewpoints in the 50s and 60s, temperatures in the 50s and 60s, the positioning of the jet stream, and modest instability, thunderstorms are forecast from Saturday afternoon through Sunday. In addition to the threat of thunderstorms, there is also support for strong and severe storms in the Tri-State Saturday night and early Sunday. Being south of the warm front and east of the cold front puts us in the “warm sector,” or the warm, moisture-rich airmass that will support storms. Specifically, there is a concern for damaging straight-line winds early Sunday morning.

The latest NAM model run has 60-100+ mph winds 5,000 feet above the Ohio Valley at 1am Sunday:

This morning’s GFS model run has the strongest winds positioned differently but just as strong early Sunday morning:

This fast moving zone of winds just above the ground is called the low-level jet. It typically strengthens before and during severe weather events, but these speeds are abnormally strong for late December. Mathematically speaking, these wind speeds are 3-5 standard deviations above average for this time of the year. Simply put, these wind speeds are rare to very rare for December. Winds 5,000 feet above the ground are often transferred to the ground – in part or whole – when heavy rain is falling. With moderate to heavy rain forecast as these winds are coming through, there is a concern for severe winds Saturday night and early Sunday morning.

While instability can often have a big influence on the chance for thunderstorms, it isn’t as important this time of the year. If thunderstorms are likely (which they are Saturday night and Sunday), the SHERB parameter or index can be very helpful to a meteorologist in the colder months when looking a threat for severe weather. The SHERB parameter is helpful for getting a handle on a severe weather threat in the colder months because it focuses on temperature changes near the ground, lift in the atmosphere, and wind shear instead of instability (instability tends to be low in the winter even when we get severe weather).

Why is SHERB important? Unlike summer severe weather events which are driven by high instability and less of everything else, cold season events are driven by everything else and not often by instability. SHERB is a special blend of “everything else” that is important when gauging a severe weather threat…which makes it valuable when we don’t have summer-like heat and humidity. When SHERB values are high and the chance for rain and storms is high, severe weather is often a concern.

SHREB values on Saturday night and early Sunday morning are elevated in the Ohio Valley. This morning’s NAM model has SHREB values that are high (yellow) and support a Tri-State severe weather threat (Cincinnati is the black dot):

SHERB tells us that instability isn’t really necessarily to get rough storms Saturday night and early Sunday. Any instability will only aggravate the atmosphere more than it is already primed.

Plus, there is a threat for heavy rain and flooding this weekend. The Weather Prediction Center has already placed the Tri-State in a MODERATE risk for excessive rainfall from 7am Saturday to 7am Sunday:

A Flood WATCH is likely coming for most if not all of the Tri-State later today. It will likely be in effect most if not all of Saturday and Sunday.

Here is how much rainfall various models are forecasting from 7am Friday to 7am Monday:

NAM         1.72″
ECMWF: 1.94″
GFS          5.40″

The GFS is clearly overdone, but 1-3″+ of rainfall is likely Friday, Saturday, and Sunday.

Be prepared for flooding and storms this weekend!

Models continue to suggest a significant threat for thunderstorms, strong storms, and severe storms in the Tri-State on Sunday and Sunday night. Since we are still a couple of days out, the exact timing and positioning of this system is still uncertain. There are, however, a lot of similarities in the weather setup for Sunday compared to Halloween night.

Why are we so concerned about the threat for severe weather this weekend? Simply put, the jet stream is strong, it will be warm, it will be rather humid, and there will be a lot of wind shear (changing of the speed or direction of the wind going away from the ground). Notice how I didn’t highlight instability; in the colder months of the year, severe weather events in the Tri-State often happen with little or no instability. The strength of the jet stream, temperatures, lift, and shear are much more important this time of year.

The Storm Prediction Center has placed the entire Tri-State under a SLIGHT risk for severe storms Sunday and Sunday night:

While damaging straight-line winds will be the primary severe weather threat, tornadoes and large hail are still secondary threat with the strongest showers and storms that develop on Sunday and Sunday night. In the forecast model world, there is a consistent signal that that storms will develop to the west and southwest of Cincinnati and move east to northeast with time; this thinking would suggest the main tornado threat will be focused outside of the Tri-State (where storms develop), but – given the amount of wind shear – tornadoes will be possible as showers and storms gradually coalesce into line later in the day and evening.

While it is just one model, Microcast suggests the main threat for severe weather will come Sunday evening. Microcast has a relatively low coverage of showers and thunderstorms Sunday morning at 8am:

Any sun that we get early Sunday will work against us, increase the amount of instability showers and storms will have to work with Sunday afternoon and evening. In this particular setup, sun and instability is not necessarily needed to get strong and severe storms; any sun we get will only bring up the risk for storms.

Microcast suggests the coverage and intensity of showers and storms will start ramping up during the afternoon and evening, especially west of Cincinnati. Microcast has most of the storms in the Ohio Valley west of the Tri-State at 4:30pm:

Microcast continues to ramp up the coverage of showers and storms Sunday evening. By early to mid-evening, showers and storms are blowing through the heart of the Ohio Valley:

By midnight, showers and thunderstorms will be diminishing or ending in the Tri-State, as Microcast shows:

Again, Microcast is just one model. Other models are more aggressive with the chance for storms in the afternoon. Know that – for now – the severe weather window begins in the afternoon and continues through the evening.

Why are damaging winds the main threat? Because the low-level jet will be very strong Sunday afternoon and evening. The low-level jet is a stream of air about 5,000 above the ground that usually strengthens ahead of strong areas of low pressure. These winds above the ground can easily be pushed down to the surface with heavy rain or in downdrafts (during showers and thunderstorms). Notice the strength of the low-level jet over the Ohio Valley by 1pm Sunday according to the GFS model (Cincinnati is labeled with a black dot):

Winds in green are over 40mph, and winds in yellow are severe (over 58mph). These winds aloft aren’t necessarily what we will see at the ground, but heavy rain and storms will help to bring these winds above the ground down to the Earth’s surface.

There are still significant uncertainties about the positioning of the jet stream on Sunday; this is a problem, since the positioning and strength of the jet stream often tells us where the strongest rising motion will be in the atmosphere (and thus the strongest showers and storms).

This morning’s NAM model has the strongest divergence (spreading) of air aloft in the red circle by late Sunday afternoon (Cincinnati is in the black circle):

Divergence aloft tends to promote stronger updrafts and, thus, stronger showers and storms. Where their are uncertainties about exactly placement of the jet stream(s), we are in the zone of strong lift, and this means we have more than enough upper-level support for severe weather Sunday and Sunday night.

While instability can often have a big influence on the chance for thunderstorms, it isn’t as important this time of the year. If thunderstorms are likely (which they are Sunday), the SHREB parameter or index can be very helpful to a meteorologist in the colder months when looking a threat for severe weather. The SHREB parameter is helpful for getting a handle on a severe weather threat in the colder months because it focuses on temperature changes near the ground, lift in the atmosphere, and wind shear instead of instability (instability tends to be low in the winter even when we get severe weather).

Why is SHERB important? Unlike summer severe weather events which are driven by high instability and less of everything else, cold season events are driven by everything else and not often by instability. SHERB is a special blend of “everything else” that is important when gauging a severe weather threat…which makes it valuable when we don’t have summer-like heat and humidity. When SHERB values are high and the chance for rain and storms is high, severe weather is often a concern.

SHREB values on Sunday and Sunday night are elevated in the Ohio Valley. This morning’s NAM model is very aggressive with Sunday’s severe threat (probably too aggressive), but it has SHREB values that are high (yellow, orange, and red) and support a Tri-State severe weather threat (Cincinnati is the black circle):

The ECMWF and GFS models suggest SHREB values will be lower during Sunday’s event, but still high enough to support severe weather.

SHREB tells us that instability isn’t really necessarily to get rough storms Sunday. Instability (sunshine) will only aggravate the atmosphere more than it is already primed.

But this discussion is more than just a chance for severe weather on a Sunday; this is a discussion of severe weather on a Sunday where the Bengals are playing and people are outside tailgating and watching the game. It’s much easier to go inside or take cover at home than it is in a parking lot or stadium. I am cautiously optimistic that the Bengals will be actively following the weather Sunday, but you should be prepared for strong and storms Sunday afternoon and evening – especially during and after the game. Ultimately, your safety is up to you. Whether you’re tailgating, going to the game, staying out after the game, or all of the above, you should have a plan to seek shelter if needed. Here is our latest Bengals forecast:

The warmth is welcome by most, but don’t write off the wind or chance for storms.

Now is the time to prepare! Don’t be caught off guard in the stands or tailgating on Sunday. While the timing and other specifics of this event are still uncertain, the threat for damaging straight-line winds, tornadoes, and large hail are all on play Sunday and Sunday night.

I’m working this weekend, and I’ll update you as new model runs complete!