A strong cold front will sweep through the heart of the U.S. and the Ohio Valley tonight, Wednesday, and Thursday. There is still uncertainty about the exact timing and strength of storms in the Tri-State late Wednesday night through Thursday evening, but the threat for severe weather will be higher southwest, west, and south of Cincinnati through Thursday night.

In addition to the cold front, the driving force behind the severe weather threat Thursday will be a large upper-level disturbance moving in from the west. This morning’s GFS model has that upper-level disturbance (in orange and red) to our west early Thursday morning:

This disturbance is a lifting mechanism, so showers and thunderstorms will be likely ahead of it. This morning’s GFS model has this upper-level energy to our north and east by Friday morning, as the cold front pushes east:

The future radar product from this morning’s WRF model suggest showers and thunderstorms will be staying to our north, northwest, and west at 2am Thursday:

By 8am Thursday, the WRF morning suggests showers and thunderstorms will be approaching the Tri-State from the west:

In this particular radar snapshot, more green and yellow colors over orange and red colors suggests showers and storms will arrive in a weakening mode as temperatures drop overnight.

The severe weather threat, however, will continue through Thursday early evening. The cold front will slow down as it moves through the Tri-State Thursday, so strong and severe storms remains a possibility Thursday afternoon and early evening. This morning’s WRF model shows showers and thunderstorms energizing – especially east of Cincinnati – late Thursday afternoon and early evening:

When you break down the severe weather threat by day, the Storm Prediction Center has placed areas northwest of Cincinnati under a SLIGHT risk of severe storms Wednesday night (through 8am Thursday):

SPC has southern, southeastern, and eastern parts of the Tri-State under a SLIGHT risk for severe storms from 8am Thursday through Thursday night:

Damaging straight-line winds and large hail will be the main severe weather threats Wednesday night and Thursday. The tornado threat is in play, but it is the lowest of the main three severe weather threat.

Compared to last winter, this winter has been very cold and very snowy. Compared to average, however, this winter overall was warmer but snowier than average. The lingering cold is getting warm weather lovers antsy for spring and summer.

Most in the Tri-State dropped into the low and mid 20s early Monday morning. The luckier spots only dropped into the upper 20s:

Monday’s early morning low of 22° at the Cincinnati/Northern Kentucky International Airport is a new record low temperature. Another low temperature will likely be broken Tuesday when we drop to 21° (the current record low temperature is 23°, set in 1992).

It is unusual to be this cold in April. 62% of all days so far in 2013 have featured a high temperature below average in Cincinnati. We’ve had over 2′ of snowfall since last summer in the Queen City. With all of this being considered, it could and has been a lot worse.

When you take the high and low temperature each day and average them, you get the “average temperature.” When you take the average temperature for each day so far this year and average them, you get the year-to-date average temperature. When you take this year’s year-to-date average temperature and compare it to other years, 2013 (so far) is only the 47th coldest year (to date) on record:

This graph suggests we have have a lot to be thankful for this year…46 reasons! Those of you know who remember the winters of 1976-1977 and 1977-1978 know true cold.

Part of this year being the 47th coldest year-to-date can be blamed on a colder than average March. In fact, March 2013 was the 13th coldest March on record in Cincinnati (average temperatures in the graph are rounded to the nearest tenth):

14 of 31 days in March 2013 had a high temperature 10° or more below average. Brief spikes in warmth did little to curve the average up.

While below average temperatures have been common since the year began, there have been relatively few brutally cold nights. We’ve only dropped to 7° twice this year in Cincinnati. Our coldest night of the fall, winter, or spring – including i the last several years – is often near or below 0°:

There’s no doubt this year has been colder than average so far. We got spoiled last year with the second warmest March on record, a very mild winter, and very little snow. Spring is a season of transition, and this year’s transition from cold to warm will be gradual and come in spurts. Warmer air is coming later this week, and before we all know it, we’ll be complaining about the heat and humidity.

Meteorological spring began on March 1st, but astronomical spring begins Wednesday morning at 7:02am eastern time. Despite what the calendar shows, it won’t feel like spring tomorrow or any day in the near future.

The colder-than average stretch we’ve been on for a couple of weeks is likely to last at least two weeks more.

NOAA’s Climate Prediction Center issued a forecast Febuary 28th suggesting that there was an equal chance of a warmer or colder than average March. This forecast is unlikely to verify:

The last several days of March will likely be colder than average based on the latest guidance. This morning’s GFS model run suggests temperatures will be well below average (blue and green colors) Thursday morning over much of the nation:

The latest ECMWF ensemble model also suggests below average temperatures (blue and purple colors) for most of the nation early Thursday morning, including in the Tri-State:

If we fast-forward to next Wednesday morning, it’s more of the same. This morning’s GFS model suggest temperatures will be colder than average (blue, green, and purple colors) for the eastern two-thirds of the nation:

The latest ECWMF ensemble model agrees with the GFS model regarding below average temperatures (blue and purple colors) next Wednesday morning:

Based on this model data, it seems unlikely that a significant warm-up anytime in late March. This morning’s GFS, however, suggests a ridge of warmth may be building into the heart of the nation during the last week of March:

This is a promising sign for those of you looking for a warm up. The strength and positioning of this ridge, however, is very uncertain; in turn, there is no guarantee that a warm-up is coming in early April.

In summary, it is too early to speculate on when a warm-up is coming. Confidence is fairly high, however, that the rest of March and at least a few days in early April will be colder than average.

The active weather pattern we have been stuck in for the last several days will not be going away anytime soon. Several disturbances are forecast to move through the Ohio Valley between now and next weekend. Some will be weak, while others will have punch. Some disturbances have little uncertainty surrounding them, while others are very uncertain.

While much of the evening will just be cloudy to mostly cloudy, showers and isolated thunderstorms will develop nearing midnight. A rapidly developing area of low pressure approaching from the west tonight will likely spark clusters of showers and thunderstorms later tonight. This morning’s WRF model has rain and thunderstorms in our area by 2am Saturday:

Given the amount of cold air aloft, small hail and brief gusty winds will be possible with any thunderstorms that form. Confidence is high that showers and thunderstorms will diminish Saturday morning, and much of Saturday will be cloudy to mostly cloudy. Precipitation, however, is likely to return by 8am Sunday morning, as this morning’s WRF model shows:

If you look closely, the model has the 32° isotherm/line in our area when precipitation is falling. With temperatures at and above the ground near freezing early, snow may mix in with rain in the morning. By afternoon, we will have just rain in our area with temperatures approaching 40°. This morning’s WRF model has rain in our area Sunday evening as well:

Greater uncertainty in the forecast comes for Monday as yet another area of low pressure sweeps across the Plains. Given modest instability, there will be a risk for thunderstorms Monday morning, afternoon, and night. There is still some uncertainty on how strong thunderstorms will be Monday and Monday night. The Short Range Ensemble Model suggests the best instability in our area will be in the early afternoon and focused over northern Kentucky:

Given modest instability coupled with the strength and positioning of low-level moisture, upper-level energy, and wind shear, the Storm Prediction Center has placed sections of the Ohio and Tennessee Valley under a risk for severe storms Monday morning, afternoon, and night:

Two weaker disturbance passing through the Tri-State will give us a chance for flurries Tuesday and Wednesday morning.

More energy will move in late next week, bringing rain and perhaps snow showers to the Ohio Valley later next week. The timing and strength of this system is very uncertain.

New long range data has come into the weather center over the last week, and it looks like any warm-ups for the rest of March will be short-lived.

This morning’s GFS model is very similar to the last several runs before it, keeping colder than average temperatures around through the weekend, next week, and the week after next. While there will be some warmth into the start of this weekend, this morning’s GFS model has colder than average air (purple and blue colors) over much of the Midwest and Ohio Valley by next Tuesday:

The GFS model also suggests that cold air sticks around into late March, including for Monday, March 25th:

Northwest flow and a persistent snowpack in southern Canada means reenforcing shots of cold air will keep coming for the second half of March.

A new ECMWF Weekly model run came in this afternoon. Like the GFS, it suggests below average temperatures will dominate for late March and early April. This afternoon’s ECMWF Weekly model says temperatures will be below average (blue colors) from this past Tuesday through next Monday:

The model also says temperatures will be below average in the Ohio Valley from next Monday through March 25th:

…and from March 26th from April 1st:

…and from April 2nd to April 8th (although not as cold as previous weeks):

The theme is clear: cold air will be a clear winner over warmth for the next few months. It is still too soon to make an outlook on the summer.

We may be nearing mid-March, but we aren’t done with the threat of accumulating snow in the Tri-State. While the disturbance coming through late tonight and early tomorrow isn’t particularly strong, it will be strong enough to create snow showers and flurries around and after midnight.

Recent model runs have hinted at the possibility for localized bursts of snow for a few days now. Once of our in-house models, Microcast, has been very consistent with the timing and strength of this incoming disturbance. By midnight tonight, Microcast paints snow showers and flurries in and around the Tri-State (in blue):

Microcast is also painting some shades of purple and pink, suggesting rain will mix with flurries. While this is possible, it is not likely given the forecast temperature profile of the atmosphere.

By 7am Wednesday morning, Microcast has several clusters of snow showers and flurries in the area:

The ground and air near the ground will be cold enough to support a chance for accumulating snow at this time. With the morning commute in progress, slick or partially snow-covered roads, sidewalks, and driveways are a concern. Many will just see flurries and little to no accumulation while others that see snow showers may see 1/2″ to 1″ of snow by early Wednesday afternoon.

The risk for snow showers and flurries will drop dramatically by Wednesday afternoon. The latest run of Microcast has only widely scattered snow showers and flurries in our area by 5pm Wednesday:

This morning’s Microcast run gives nearly all of the Tri-State 1/10″ of snow accumulation or less through Wednesday afternoon:

While I agree with this model output overall, isolated 1/2″ to 1″ totals can’t be ruled out overnight and tomorrow morning in the heavier bursts of snow. The best chance for these isolated higher totals will be on elevated, grassy surfaces; accumulation on roads, however, is also possible in the next 24 hours.

Please use caution on area roads during Wednesday morning’s commute!

A Winter Storm WARNING has been posted for Fayette, Union, Franklin, Butler, Warren, and Clinton County from late Tuesday morning through 1pm Wednesday:

The rest of the Tri-State will be under a Winter Weather Advisory from 6pm Tuesday to 1pm Wednesday:

Light rain (especially after midnight) will mix with flurries tonight, and Tuesday’s forecast calls for mainly rain with some flurries in the morning. With ground temperatures at or above freezing tonight, accumulating snow is not a concern; accumulating snow, however, is likely late Tuesday night and early Wednesday.

For being this close to the Tuesday night/early Wednesday event, there is still great uncertainty about where the heaviest snow will fall in the Ohio Valley. The latest model data have trended farther south with the axis of heavier snow. Last night, it appeared the heaviest snow would be in northern Ohio and Indiana; that axis of heavier snow now looks to set up closer to I-70.

I will show you the latest model runs not to highlight specific amounts but instead to show you model uncertainties and where the heaviest snow – at least for now – will fall. Remember, this is NOT a forecast!

Our in-house model Precisioncast gives a wide range on totals from north to south; it suggests the southern-most communities in the Tri-State will see minor accumulations while many north of the Ohio River see at least a couple of inches of snow through Wednesday evening:

Another one of our in-house models, Microcast, gives most in the Tri-State about an inch of snow, but also blasts some Tri-State communities with snow:

This morning’s ECMWF model – which has consistently been the most aggressive with snowfall amounts Tuesday night and early Wednesday – gives the Tri-State anywhere between a couple and a few inches of snow:

The latest outlook from NOAA’s Hydrometeorological Prediction Center gives the northernmost parts of the Tri-State a moderate risk of seeing 4″+ of snow through 7am Wednesday morning; according to this forecast, the rest of the Tri-State has a slight risk for seeing 4″+ of snow:

My Latest Forecast

For now, I’m thinking we’ll get a couple inches of snow Tuesday night and early Wednesday. The highest snowfall totals will likely be north and northeast of Cincinnati, and the lowest totals will be focused south and southwest of the Queen City. Visibilities will likely be reduced by snow falling early Wednesday. Snow will likely be wet and slushy instead of dry and powdery with this event.

This blog will be updated tomorrow…or as needed!

Like I’ve done every snow event this season, I will hold judgement on specific amounts until we get much closer to the event. For this bout with wintry weather, we’ll get a rain/snow mix Monday night through Tuesday and snow Tuesday night and early Wednesday. No ice is forecast in our area with this mid-week system.

It is important to note that three different areas of low pressure will move through the eastern 2/3rd of the country between now and Thursday. Here is a plot showing the track of each low pressure system, as analyzed by NOAA’s Hydrometeorological Prediction Center:

The area of low pressure tracking out of southwest Canada will die before ever making it here. A different area of low pressure that develops over the Mid-South and Mississippi Valley will sweep through the Ohio Valley Monday, Tuesday, and early Wednesday. This area of low pressure will also die, and another area of low pressure will develop in the Carolinas Tuesday night and track just east of the Mid-Atlantic states Wednesday afternoon and Wednesday night. The low tracking through the Ohio Valley will be the driving force behind our threat for accumulating snow.

A rain/snow mix will develop in the Tri-State Monday evening  and continue through Tuesday. Very minor accumulations are possible early Tuesday, but rain will likely be the main precipitation type Tuesday afternoon with temperatures in the mid to upper 30s. Rain and snow Tuesday afternoon will transition to all snow Tuesday night. My forecast low for Wednesday morning in Cincinnati is 29°. Accumulating snow would be a much bigger threat if low temperatures were forecast to drop into the low to mid 20s. Nonetheless, our main window for accumulating snow will be late Tuesday night and early Wednesday.

I will share the latest model snowfall forecasts in this blog with you not in an effort to pinpoint specific amounts but instead to show uncertainty and where the focus for heavy snow will be.

Sunday morning’s NAM model keep the focus for heavy snow accumulations through Wednesday afternoon north of the Tri-State:

Notice the NAM’s forecast of 20″+ for the Washington D.C through 7pm Wednesday. This morning’s GFS model brings the threat for accumulating snow closer to Cincinnati but keeps heavy snow over northern Indiana and Ohio:

Sunday’s morning’s ECMWF model is the most aggressive model with snow Tuesday night and early Wednesday:

The ECMWF brings a swath of 5-10″ of snow up to the edge of the Tri-State. This model is an outlier, and – for now – I do not believe this is where the heaviest axis of snow will set up.

NOAA’s Hydrometeorological Prediction Center gives the Tri-State a 10% of seeing 4″+ of snow from 7pm Tuesday through 7am Wednesday, but chances for 4″+  of snowfall accumulation ramp up quickly northwest and east of Cincinnati:

For now, plan on accumulating snow Tuesday night and early Wednesday. The Tri-State is fair game for an inch or more of snow and potentially more if temperatures trend cooler than forecast early Wednesday morning.

I’ll update this forecast Monday afternoon!