Rain Transitioning To Snow, Gusty Winds Tonight

Good afternoon! A well advertised storm system will affect the Ohio Valley over the next couple of days. Simply put, rain will transition over to snow tonight, and winds will continue strengthening over the next several hours. I have broken down this blog post into sections to focus on each threat specifically:

Precipitation

Early morning model runs are in good agreement about the strength and positioning of the low pressure (the driving force) at 7am Friday morning:

dec20-12zmodels

The 7am model runs all have low pressure centered over Michigan tomorrow morning. The heaviest, most intense precipitation with this system will be to our east by early tomorrow morning, but models all suggest precipitation (snow, given temperatures in the 20s) will be falling in the Ohio Valley at that time.

While rain will fall in many Tri-State locations through dinner time, rain will gradually transition over to snow approaching late evening. The latest run of the HRRR model suggests many will have a slushy inch or more of snow by 1am tonight:

dec20-hrrr6z

Of course, this is just one model’s forecast snowfall accumulation, but the HRRR model tends to do well with snow events like these. Notice higher snowfall accumulations north and west of Cincinnati. There will likely be some other areas north and east of Cincinnati with locally higher amounts as an upper-level disturbance moves through overnight.

Fayette, Union, Franklin, and most of Ripley County, Indiana along with Butler, Warren, Clinton and most of Highland County will likely receive 1-3″ of snow from this evening through tomorrow afternoon. Totals will be closer to 1-2″ from southern Ripley County to southern Butler County back down to northern Adams County. Less than 1″ of snow is forecast in the southern third of the Tri-State. Local 12 Meteorologist John Gumm posted this storm total accumulation graphic this morning, and his thinking is nearly identical to my thinking for now.

Snow will partially melt tomorrow as temperatures struggle to reach into the low 30s. Roads tomorrow morning in and around Cincinnati may be slick or partially covered with slushy snow. I’m cautiously optimistic road crews will keep up with snow overnight, but I’m confident there will be more accidents than usual during the Friday morning commute.

Temperatures

The chart below shows model temperatures trends in the week ahead:

dec20-temps

Temperatures will drop rapidly through the 40s, 30s, and 20s over the next several hours. We’ll likely be in the mid to upper 20s early tomorrow morning. The warmest Tri-State locations tomorrow will top out in the mid 30s. We’ll be back down in the 20s early Saturday morning.

Wind Chills

The chart below shows model wind chill trends in the week ahead:

dec20-windchills

The “feels like” temperatures late tonight will likely be in the single digits and teens. It will feel just as cold early Saturday morning. Wind chills will be in the teens most of Friday morning and afternoon.

Winds

The chart below shows model wind trends in the week ahead (solid lines are sustained winds, dashed lines are wind gusts):

dec20-winds

Wind chills will be well below temperatures tonight, Friday, and Friday night. Winds will gust as high as 65mph tonight and tomorrow; sustained winds will be between 20-40mph out of the southwest early this evening, then veering to the west by early Friday morning. Winds will be strong out of the northwest tomorrow.

Some will experience power outages tonight and tomorrow; light home damage also will be possible. I strongly recommend you secure any outdoor holiday decorations soon before gusty winds hit this evening; this includes any inflatable snow globes you have in your front yard!

Be safe tonight and tomorrow! Strong winds, arctic air, and accumulating snow promises to travel challenging in the next 36 hours!

Quick Thoughts On Snow Tonight

I’m on vacation, so I’m going to keep this short…plus I have a lot of Christmas shopping to do!

A quick glance through the latest computer model runs shows they are more aggressive with snow chances tomorrow. As of yesterday afternoon up to 2″ of snow appeared likely north and west of Cincinnati Thursday night and Friday; models are now more aggressive with bringing snow farther south.

Here’s what the latest model runs have to say about snowfall amounts tonight in Cincinnati:

This morning’s (7am) NAM: 0.9″
Last night’s (7pm) GFS: 1.0″
Last night’s (7pm) ECMWF: 1.0″

Even the SREF model probabilities for 1″+ of snow in our area have gone up. The SREF model trends are usually accurate, so this is a telling signal. Here’s a comparison of yesterday’s 4pm and this morning’s 4am SREF model runs for the potential of 1″+ of snow:

Image

Notice higher probabilities of 1″+ of snow are higher in the Cincinnati area. With low temperatures tonight in the mid 20s and highs tomorrow only in the low 30s, this snow will be more slushy than powdery.

For now, I’m thinking storm total snowfall will look something like this…(remember, these numbers may change!):

Connersville, Liberty: 1-2″, isolated 2.5-3″ amounts
Brookville, Middletown, Lebanon, Wilmington, Hamilton, Penntown: 1-2″, isolated 2.5″ amounts
Cincinnati, Versailles, Fayetteville, Hillsboro, Alexandria, Batavia, Aurora: Around Or Just Under 1″
Vevay, Owenton, Williamstown, Falmouth, Foster, Maysville, Georgetown, West Union, Peebles: 1″ Or Less

I’ll try to get another update in later today…

A Call To Action: One Thing Every Television Meteorologist Should Do

Data is the food of a meteorologist. Dozens of weather balloons are launched each day in this country and across the world. Satellites and radars can scan the globe and the sky on the order of seconds. High-resolution models can provide forecast data in 15 to 30 minute intervals. The best forecasts – especially in active weather patterns – require an understanding of this data; unfortunately, trying to get a handle on all of this data is a lot like drinking from a fire hose.

Despite the latest advances in technology, nothing beats confirmation of knowing what the weather is like (or not like) in a certain area. Radar may suggest a strong storm is moving through a town, but are the winds really as bad as radar indicates? Is it really raining that hard, or is most of the rain evaporating before it reaches the ground? There are only a few ways to know for sure: see it firsthand, get a spotter report, see it on a live camera, or get a weather station report. Meteorologists and spotters can’t be everywhere, and live camera networks are expensive. For these reasons, meteorologists often rely on weather stations across the country to gauge the strength of storms, verify computer model accuracy, and understand weather differences at a city or county level.

Airport weather stations are often most accurate, since they are used for aviation safety and the FAA and National Weather Service help to fund this equipment. However, few people live near airports and extreme or severe weather often happens away from airports. Thankfully, there are thousands of other weather stations in this country that meteorologists can access; most of them are owned by everyday weather enthusiasts.

Outside of major airports, most of the weather data that television meteorologists show on-air comes from NOAA’s MADIS (Meteorological Assimilation Data Ingest System) data stream. Personal weather stations are fed into MADIS through the CWOP (Citizen Weather Observer Program) data stream. Without the MADIS and CWOP data streams, localized temperature differences would be hard to see, especially in real-time.

Background

When I was working for WEHT-TV in Henderson, Kentucky a couple of years ago, I wrote code to bring MADIS data into our on-air system (even before our weather graphics vendor supported it). Localized weather data was important there, and it is important everywhere. Upon moving back to Cincinnati to take a job with WKRC-TV, I took it upon myself to get localized data into our weather graphics system. Here is what WKRC-TV’s temperature map looked like in early November 2011:

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At the time, there were only five personal weather stations on the map (Warsaw, Aurora, Union, Milford and Laurel); all of the other stations were weather stations at airports, owned by the Ohio Department of Transportation, owned by the Kentucky Transportation Cabinet, or were a part of the Kentucky Mesonet. As time permitted, I slowly added new weather stations to the map and shifted things around, but there were still communities left off the map. As a television meteorologist who wants to include viewers from every city and county in the viewing area, what could I do to make sure I could get current weather conditions from as many places as I could?

The Challenge

As a meteorologist, you quickly become familiar with websites that have computer model or weather information. While stumped with where to find other local weather station information, I realized that Weather Underground allowed people with weather stations to freely upload data to their website; in turn, Weather Underground displays these weather stations on their website – including on the WunderMap – and make money through advertising. Weather Underground doesn’t allow you to take weather station data from their website, but it does allow you to message people on the website. After sending out a bunch of messages to people who sent their data to Weather Underground but not to MADIS, I got a couple of replies. I was able to get the people that replied to my message to send their data to CWOP (and therefore MADIS) so we should show it on-air. Unfortunately, only a couple of people replied to my messages. So how could I get the attention of the people that didn’t check their Weather Underground message inbox?

After a while, I figured out a way to contact these weather station owners. On the individual weather station pages, Weather Underground provides the latitude and longitude of each weather station:

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There are several websites – including at stevemorse.org – where you can take latitude and longitude coordinates and get a street address. If I had a street address, I could mail someone a generic “To Whom It May Concern” e-mail about noticing their weather station on Weather Underground, some background about CWOP and MADIS, and my contact information if they were interested in sharing their data with us. At first, I was unsure whether I should send out letters in the mail saying I found their address by finding their latitude and longitude coordinates online. Eventually, I convinced myself to sent out 20 snail mail letters, and I was impressed with the number of replies (especially from rural areas where there was only one known weather station in the county). While not everyone was reporting at the time I pulled this image, here is the temperature map you’ll see often now on WKRC-TV:

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Several stations on the map – including Vevay, Seaman, Peebles, Foster, Brookville, Liberty, Batavia, and Fayetteville – were added as a result of mailing a letter to someone I didn’t know. More stations (that can’t fit on this map) were added in the Cincinnati metro and northeast of Cincinnati along I-71 as result of sending letters out.

Some may look at the map above and say, “it’s busy.” I look at the map above and say, “nearly everyone is covered or is covered more than they were before.” On clear nights, it’s easier to see temperature differences from the river valleys to the higher elevations and areas in the Cincinnati urban heat island. When a line of severe storms is sweeping through the area, it’s nice to have a wind observation from near or in the storm instead of miles away from the storm. For the man or woman that just wants a simple forecast and current conditions on the way to work, it’s nice to show people what the weather is like in their town instead of in the town one county away.

Call To Action

I wish that every broadcast meteorologist in this country would look at Weather Underground’s WunderMap for their area, see which weather stations don’t show up in the MADIS stream (which are displayed in MesoWest), and write a letter to owners of weather stations that aren’t in it. Being the first to reach out to a weather station owner almost guarantees you’ll be the first your viewing area to put that town on the map (and gain the interest of their viewers because the competition won’t know about it). In times of severe weather, you’ll be able to show temperature drops and wind gusts using weather stations the competition doesn’t know about. Television is becoming more and more about local coverage, individual communities, and subdivisions. When it comes to weather on television, highs and lows are helpful, but the hour-by-hour forecast is becoming more and more important. It’s much harder to make a forecast for a town if you don’t know what the weather is like there now.

With time, more weather stations will come online, personal weather stations will become more affordable, and weather will become more and more focused on local conditions. When it comes to the weather, the future – in many ways – is now. Real-time, local weather data is important, and being on the leading edge of this change is the place to be.