Today is going to be fun with summertime instability in a winter cold front.

Be prepared for the passage of an arctic front that will likely bring an intense snow shower similar to a summer thunderstorm and then dangerously cold temperatures. A strong snow band has already formed over Ohio and models are suggesting that it will cross central MD from west to east from about 12 – 2PM. Most areas will see a burst of heavy snow for about 15 minutes and very gusty winds of up to 50 mph that will cause dangerous driving conditions including icy roads and reduced visibility. Behind the front will be an immediate drop in temperatures and strong winds that will make it feel much colder. By evening, temperatures will be in the teens with strong winds making it feel well below zero. The NWS has a Wind Advisory in place for central MD until 6PM, and a Wind Chill Advisory from 9PM tonight until 10AM tomorrow. Overnight air temperatures are expected to just above zero with wind chill temperatures of -15 to -10.

Friday afternoon and evening may bring another round of light snow to the area.

Steady snow, and in some locations, moderate to heavy at times, will continue across central Maryland into the evening hours. Roads are already becoming slush covered in many areas and will continue to deteriorate. Once temperatures fall below freezing early this evening, any untreated surfaces will freeze very quickly. Temperatures will stay below freezing throughout the night and icy conditions will persist into the morning especially on side streets, sidewalks, ramps, and bridges.

During the day tomorrow, models show that an intrusion of arctic air will be preceded by a snow squall. Timing looks to be around noon, and if you’re out during this time, expect a period of very heavy snow, high winds, and extremely reduced visibilities. I’ll send an update out tomorrow morning on the expected intensity and timing.

Some light snow is falling along the MD/PA border this morning, but for central MD the morning commute should be weather-free. Mixed precipitation will develop across the area later this morning and eventually change to snow from west to east during the afternoon. Temperatures will slowly fall and by sunset, most areas will be below freezing which will make for very dangerous driving conditions. The snow will end from west to east from about 8-10PM with total snow accumulations of a coating to the south and east towards the bay, to two inches in the interior areas. North of I 70, 2-4″ is possible.

Some school systems are already announcing two hour early dismissals, and I expect others to follow. If you don’t have to drive this evening, just stay in.

Icy conditions will likely persist into Wednesday morning, and short range models are all picking up a significant snow squall line tomorrow during the late morning or early afternoon. We can discuss that in more detail later today.

Expect very cold temperatures for the remainder of the week, and another small snow disturbance possible Friday evening.

A really tricky forecast for tomorrow because the short range models are now showing some precipitation breaking out before sunrise tomorrow morning in areas to the west of route 97 and along and north of I-70.  A Winter Weather Advisory has been issued for those areas, including all of Frederick and Carroll counties, the western portion of Howard county, and the northern portion of Baltimore county beginning at 4AM.  For the remainder of the 95 corridor, a Winter Weather Advisory begins at 12PM tomorrow.  All areas have the advisory through the evening hours until 9PM or 10PM tomorrow night.

There are still some relatively big differences in the models with the GFS brothers being the most ambitious for precipitation totals and snow amounts, and the Euro and short-range NAM being somewhat drier, but all areas should be prepared for a messy afternoon and evening commute.  It’s not going to take much precip to ice the roads when the temperature falls below freezing.

The morning commute would be a problem if anything falls in the early morning, but that is difficult to predict because the precip looks light. There is some dry air to overcome, so it may never reach the ground.  I’ll be up early tomorrow and make another update.

An approaching arctic front will bring precipitation to central MD tomorrow afternoon and evening that will likely have an impact on roads tomorrow evening and possible Wednesday morning.  Presently, a mix of rain and snow is expected to develop across the 95 corridor during the early afternoon on Tuesday, and then change to all snow around sunset as temperatures fall below freezing.  If that is how things play out, once temperatures get below freezing, untreated surfaces will rapidly ice over. Based on recent model runs, I think the current forecasts look pretty good with a coating – 2″ of snow south of I-70, and 3 – 4″ to the north where less mixing is expected.  However, the main travel concerns are not the amount of snow that falls, but rather the possible relatively fast icing that may occur with the falling temperatures.  Of course, a couple of degrees in either direction would make a big difference on overall impacts, so this will probably be a nowcast event.

I’ll update later this evening or early tomorrow morning with current trends, but for now expect possible travel problems tomorrow evening into Wednesday morning.  After this system crosses the area, blustery and very cold conditions are expected for the remainder of the work week.

The first real cold air of the season is on our western doorstep this morning and will barge in through the day today. Temperatures will drop throughout the day and be in the single digits overnight. There is a windchill advisory for the entire area as it will feel about 10 below tonight and early Monday morning.

An avid reader of the WM wanted to be sure that I remind readers of “a really cool celestial event” tonight. His words, not mine. So after the game tonight, make plans to bundle up and go outside to check out the total lunar eclipse. It starts around 9:30 but will reach totality around midnight. Although it’s going to be frigid, skies should be perfect for viewing. There are tons of sites that explain what’s happening, but I thought this animation was pretty good.

I was surprised yesterday when the NWS issued advisories and warnings for some of the counties along the 95 corridor, and even a bit more surprised that they are still up this morning. There may be some wintry precipitation as the storm starts this afternoon because of some residual cold air, but with strong easterly and southerly winds aloft, it should change to rain pretty quickly. Along the MD and PA border the cold may linger longer, but I think you’ll have to travel well west or north to get any real winter impacts from this system. For most of us the bigger concern is minor flooding overnight and then the bitter cold that builds in behind the departing storm. The cold is legitimate Arctic air as low temps Sunday night and Monday night could be in the single digits with highs on Monday in the low 20’s. Add the wind and there could be sub zero wind chills in some areas. We will have to wait to see how much moisture is around when the cold gets here tomorrow, but right now it looks like there should be time for roads and concrete to dry before freezing temps arrive.

Looking further ahead, I don’t see any real snow potential until Thursday night at the earliest, and that looks unlikely at the this time.

A weak system will cross the area tomorrow night bringing mostly light precipitation, and mainly snow, to central MD Thursday evening and into early Friday morning.  Precipitation will develop from west to east from about 5 to 7PM, and though it may be spotty, there may initially be some snow showers that are moderate in nature.  Temperatures likely will be above freezing during the day tomorrow, but once the precipitation begins, they should fall below freezing rather quickly along and west of I-95.  As a result, depending on when the snow starts and where the heavier snow showers develop, tomorrow evening’s commute may become difficult in these areas.

After the initial burst of snow tomorrow evening, the snow should generally be light and continue into very early morning ending well before sunrise Friday.  Right now, 1 – 3″ is possible, but I’ll update tomorrow if there are any changes.

Looking ahead to the weekend, what looked like a pretty impressive rainstorm a few days ago, may be morphing into a more wintry scenario.   Two pieces of energy that were modeled a couple of days ago to phase causing the storm to pass well to our west and north, now may remain separate.  If they do stay separate, the southern piece of energy may pass to our south which could allow enough cold air to be around to give us some winter precipitation.  Too early to talk of type or how much, but Saturday afternoon and Sunday could be sloppy.  Regardless of what happens with that storm, behind it will bring the coldest air of the season Sunday night and Monday.

We officially have a winner for the second one inch snowfall of the season!  BWI recorded its first inch of snow for this event at 11PM on January 12th, and we had a tight finish between Patricia Bramson, Ryan Enck and Stacy Cashmark.   Although no one picked the 12th, all three prognosticators were within a day of the storm, but Stacy was the closest with a 10AM guess on the 13th compared to Ryan’s 8PM guess, and Patricia was closest on the other side with a guess of January 11th at 3AM.  Congratulations Stacy!  Hopefully our next big snow falls during a Caps game and after I shovel your driveway, we can watch and celebrate a Caps win while the school closings scroll across the bottom of the television screen.

So yesterday’s storm delivered in a big way, but not entirely in the way I expected.  The warm air advection portion of the storm was well-forecasted and delivered a general 4 – 5″ across the region Saturday night.  On Sunday morning, I expected that the coastal development would provide additional snowfall but that never really developed.  However, the upper level low that moved across the area in the evening was incredible, but only for areas from I 70 south.  Just north of 70 there were total accumulations from 3 – 6″, while just 10 miles to the south, there were over 1 foot totals reported in Howard and Montgomery counties.  Even Reagan airport, notoriously known for low snow totals, finished with over 10″ while BWI reported around 7″.  In any case, it was a great storm and one that will have lasting impacts for several days, especially on morning commutes with daytime melting and overnight refreezing.

Looking ahead, the pattern change that was being advertised on the long-range models a couple of weeks ago is occurring and that means more winter weather for our area.  For at least the next two weeks we can expect more storms and more arctic air intrusions.  That doesn’t always translate to snow for us but our chances for more accumulating snow events is higher than normal for the foreseeable future.  The first opportunity is this Thursday night into Friday morning, and then a more significant storm is possible over the weekend.  Models are all over the place right now, so I’ll wait a day or two before delving into details.

What a great storm so far!  I have to give props to Cam Rahnama because he called this storm on Thursday.  I didn’t think there was much of a chance for the coastal low to impact us, but I was (gladly) wrong.

Anyway, as of 7AM, about 4 – 6″ of snow has fallen across central MD and more is on the way.  There will be two periods to monitor today that will determine how much more snow we get.  First is the developing coastal low, and presently there are healthy radar returns to the southwest of our area that will likely impact the 95 corridor during the morning and early afternoon.  Depending on your location, snow could become moderate to heavy at times this morning, especially south of I 70 and east of 270, with an additional 2 – 4″.  After that round of snow, there may be a period of light snow or even a lull into the early evening, but then another round of snow is possible as the upper level low that is off to our west now moves across the area.  That may drop a relatively quick inch or so after sunset.  Snow should taper to light snow and eventually end overnight.

I’ll be around throughout the day and if I see anything unexpected develop, I’ll post an update.  Enjoy the snow!