Today and Tonight

Sunday, February 22, 9AM

Light rain has commenced across the area with snow already mixing in along the MD/PA border. Regardless of whether your area changes to snow later this morning or afternoon, temperatures should remain above freezing in the metro areas, so travel today shouldn’t be a problem. The exception is northern MD and areas with elevation where temps will be slightly lower.

My expectations for this storm have been somewhat muted for our area as I felt that things would end up east of us, but the recent model runs, particularly the short-range models, have me pretty excited for tonight into early Monday morning. If central MD is going to get any decent accumulations, it won’t happen until late this afternoon and into the overnight hours when colder air is pulled into the system and we lose the sun. Along the 95 corridor, I think snow becomes an issue around 4PM north of Baltimore to 6PM down by DC. Total snow accumulations from around 3″ down towards DC, and increasing to up to 8″ just northeast of Baltimore are possible, with that 8″ amount spreading west along the northern tier. There’s also going to be a narrow band somewhere, oriented on a line from northwest to southeast, that is going to get dumped on and has the potential for up to 12″. That will be a now-casting issue as it’s impossible to know where it happens. If anyone is interested in what causes this phenomenon in these types of systems, google norlun trough. So, for central MD, let’s just with a general 4 – 8″ by Monday morning.

I don’t have a lot of confidence in the accumulations that I stated, but I’ll be watching this all day and will probably annoy you with updates as the coastal storm develops. On that topic, if anyone wants to check in occasionally on the coastal development, this is a nice radar site for it. Click on the link, uncheck the Weather Stations box, check the Radar box, and then zoom out to get a nice view of our area and the coastal areas from NC to NY. Hit the play button and increase the speed to 5x. More later.

Saturday Morning Update

Saturday, February 21, 9AM

I don’t envy anyone that has to make a forecast for this event across the area as it has so many moving parts that it will be difficult to pin down snow totals for a specific area. There’s still a full day of model runs before anything begins, but I can’t recall a storm in the past 20 years that was within 24 hours and had this much uncertainty. The difficulty is that there are several pieces of energy that are phasing into a coastal storm and the timing and location of that phase will ultimately determine the outcome for central MD. If you want to be assured of a snowstorm, the best local’ish place to be is probably Delaware as they are further east and north enough to catch the full brunt of all the model’s placement of the developing coastal storm. Most areas on the eastern shore will start as rain on Sunday, but by Sunday evening, the rain changes to heavy snow with extremely high winds. Blizzard Warnings are up for the coastal areas of Delaware, extending north to New York, and will likely be expanded into New England later today. If you’re on the coast, Sunday night is going to be the real deal for a winter storm. Heavy snow, high winds, and huge drifts.

For central Maryland, we have several issues to overcome to get accumulating snow. Marginal temperatures through the day on Sunday are likely a problem. I am confident that it’s going to snow tomorrow, but with temperatures in the mid 30’s and a late winter sun angle, it’s going to be difficult to get accumulations on anything other than grassy surfaces. The only thing that could make tomorrow impactful is heavy snow rates, and for that to happen, we need the phase to happen early and the low to form and hover close to the coast. The gfs has that, but the euro does not. My initial guess, which could be really wrong, is that tomorrow will be a pretty day of falling snow but with minimal impact. By tomorrow evening, the coastal storm really starts cranking and it will pull cold air down so that temperatures around sunset will fall below freezing. That’s when things could get interesting but again will be determined by the placement of the coastal storm. Too far east and it’s just light snow, but if it’s closer to the coast, we could have several hours of moderate snow that would accumulate quickly. I do think tomorrow night has the potential to be impactful for the area. The NWS has issued, and recently expanded, Winter Storm Watches for at least 5″ of snow for the entire area. This is only a watch and it means the potential is there, but it is not a forecast. Just my thoughts, but the areas most likely to exceed the warning criteria from the coastal storm are along the fall line just west of I-95 and then points east. I think these areas could end in the 4 – 6″ range with more possible close to the Bay, especially to the north. Later today the watches will either be upgraded to a warning or just an advisory, so keep an eye on the NWS site to get an idea of what they expect. If your county goes pink, they think you’re going to see 5″ or more of snow. If it goes purplish, that’s an advisory for less than that.

The final complicating piece to all of this is a trailing upper lever low that will cross the area Sunday night. Models have been pointing to a relatively narrow band of nearly stationary heavy snow developing somewhere west of I-95 that could dump a lot of snow in a very short time. That location is very difficult for anyone to pin down and will probably be a nowcasting situation. So, to reiterate the difficulty in making a forecast, it’s entirely possible that areas near the Bay end up with 8″ of snow from the coastal storm, and somewhere west of 95 ends up with 8″ of snow from the upper level low, and some areas in-between end up screaming at the sky. I’m going wait to see what the midday model runs say and then update.

Saturday Morning Update

Saturday, January 24, 10AM

The arctic airmass has obviously arrived, and global models have come to some agreement, but the mesoscale models, which should be in range at this point, are concerning. They drive the primary low into the arctic mass to the west of us which brings a relatively warm layer aloft. So, although at the surface it’s well below freezing, snow falls from high altitudes, passes through a warm layer, melts to rain (or least no longer snow), then after passing through the warm layer, hits cold air and refreezes. If the cold layer at the surface is deep, the rain refreezes before hitting the ground as sleet. If the surface layer is shallow, the rain hits surfaces as a liquid and refreezes (freezing rain). Freezing rain is the most dangerous because it coats everything, including trees and power lines, with a heavy coating of ice. Sleet is terrible for roads and walkways, but it doesn’t stick to surfaces. Think ball-bearing ice pellets. It still is going to snow, but if the short range models are right, then the snow totals will be on the lighter end of the totals I’ve said the past couple of days. I’d be only guessing as to which scenario is correct, but the end result will still be extremely impactful.

In summary, snow develops around midnight, becoming heavy by morning with significant accumulations. I’m sticking with the totals from the past couple of days, but it depends on when the changeover occurs. After the change, there will be significant accumulation of sleet. In some areas it is going be really impressive. Hopefully we don’t get any freezing rain or drizzle because that would just make the glacier worse. I’ll update this evening with more details.

Finally, a reader asked a couple of questions and wanted my thoughts. First, they wanted to my opinion on when to start clearing a messy system like this. It’s a great question. Just my opinion, but for a storm like this, I would say to wait for all precipitation to end to start shoveling and clearing vehicles. Yes, it’s going to be much heavier, but getting under the fluffy snow is much easier than trying to get under ice. If it was going to be an all snow event, then I would say try to keep up, but with possibility of freezing rain, I am waiting. Also, we always read stories about heart attacks from shoveling, so go slow, and take breaks. You’re in no hurry as we are likely not going anywhere tomorrow or Monday.

The second question was about phone weather apps and why they show ridiculous snow totals. I never look at my iPhone app, but I just did and even now it say’s 20″ for tomorrow. That’s comical. I don’t know the algorithm that they use, but I suspect it is AI and obviously has no human input. I googled “why my phone app says high snow totals” and ironically, the AI response is pretty good, though there are a lot of human articles too. But here’s what AI wrote (the highlighting is not mine):

“Your phone’s weather app is likely showing high snow totals because

it is pulling raw, automated data from a single computer model—often the American GFS model—without any human meteorologist to interpret or adjust the numbers. These models often over-calculate, particularly when they cannot accurately differentiate between heavy snow, rain, or a wintry mix.

Here is a breakdown of why your app is showing high, and potentially inaccurate, snow totals:

Raw Model Output (No Human Touch): Apps often take direct, unedited output from computer simulations. Human meteorologists analyze multiple models and local factors to filter out these “fluke” high numbers, but apps generally just display the automated result.
The “10:1 Ratio” Fallacy: Many apps calculate snow by assuming 1 inch of rain equals 10 inches of snow. However, if the atmosphere is warmer or the snow is lighter, the ratio changes, and the app will significantly overestimate the total.
Wintry Mix Miscalculations: If the storm includes sleet, freezing rain, or rain, the computer model may mistakenly interpret this as heavy snow, leading to massive, inaccurate, and “eye-popping” numbers.
Model “Flip-Flopping”: Computer models often produce wildly different totals with every update (every 6 hours). The app may be showing a maximum potential model run rather than a likely scenario.
Timing of the Forecast: If the high number is for a storm several days away, it is highly likely to change as the storm gets closer and forecasters get more precise data.

What to do instead:
For more accurate, localized, and context-driven forecasts, it is highly recommended to check with your local TV meteorologists or the National Weather Service. “

Friday Update

Friday, January 23, 12:30 PM

The global models have stopped the north bleeding since I last posted yesterday, and if anything, they are trending slightly south and with a colder profile. We are still too far out to rely heavily on the mesoscale (short range) models, and until the globals come to a consensus, I don’t see any reason to change much from yesterday’s post. In summary, the NWS has issued Winter Storm Warnings early this morning for all of MD west of the bay for Saturday night into Monday morning. Arctic air is arriving today and there are also Cold Weather Advisories for dangerous wind chills tonight through early next week. Regarding the storm, and this is still preliminary, but snow will develop from southwest to northeast across MD from 10PM to 1AM tomorrow night. The snow will initially be light but will pick up in intensity and be moderate to heavy by sunrise. Heavy snow will continue during the morning, but a warm layer will begin working in from the south and east, and snow will transition to a mix of snow and sleet, and even all sleet in many areas. It’s too early to know when that happens, but I still feel that 6-9″ of snow accumulation for areas along the bay to just west of I-95 respectively, before the changeover. For the normally colder western and northern counties west of Route 32 and north of I-70, 8 – 14″ of snow before any changeover, if at all. By Sunday evening, colder air will begin wrapping into the system’s higher levels and we will have to see if there is a changeover back to snow with additional accumulations. The accumulations that I stated are initial thoughts for what I think that accumulate before the changeover. We can save any talk about any possible additional snow accumulations Sunday night until tomorrow. Also, although the NWS defines sleet as snowfall, I am talking about just snow. Some areas are going to be measuring sleet in inches, so regardless of whether your area changes to sleet, this is going to be a very impactful storm well beyond Sunday. Sleet over snow with the frigid temperatures is going to make for a glacier. The good news is that right now freezing rain does not appear to be a major concern for most of central MD as the depth of the cold should be able to overcome a narrow warm layer. The exception is for readers in south and east areas including lower AA, Calvert, and especially St. Mary’s counties as icing could be substantial in some of those areas.

I’ll update later today if there are any substantial changes. If not, assume no changes, and I’ll send out something tomorrow morning. And finally, never trust snow accumulations on a phone’s weather app.

Weekend Update

Wednesday, January 21, 11AM

Yesterday at this time we were hoping that the storm wouldn’t be suppressed south, but model trends through yesterday afternoon and overnight has a lot of people wondering if this is going to end up too far north. I’m in the camp that we are going to see some big adjustments as the players come onto the playing field. The NWS stated in their discussion this morning that they will be sending recon flights over the Pacific where our southern energy is currently located, and that data from those missions will be ingested into tonight’s 0z model runs (midnight, our time). Additionally, the northern stream energy, specifically the arctic high that will be moving across the northern US during the event, is currently located in an area where data sampling is sparse. With that in mind, this will probably not be settled until late tomorrow or even Friday. But, we can still discuss what the models see at this point, but know that we are still early so expect changes.

Just about every model shows snow moving into the area Saturday night and continuing Sunday. The snow is moderate to heavy at times and they all show at least 8″ along the 95 corridor into early afternoon Sunday. They also show that surface temperatures stay well below freezing for all of central MD throughout the event. Where they differ is how much warm air is pulled in at the higher levels that could change the snow to sleet or possibly freezing rain. That is dependent upon how far north the primary low goes to our west as the storm transfers its energy to a coastal storm. The more north, the greater the chance of mixing. I am only guessing but the arctic high pressure to the north should be very strong so I don’t see it getting bullied as much as some models have shown. Not to mention, this is still a La Niña and the phasing and amplifying that we’re seeing right now on the models could be overdone. One other thing that is certain is that whatever falls, it won’t be going anywhere for awhile as temperatures next week look to be frigid for the duration.

I don’t like investing in any one model this far out, but I’m waiting for the midday GFS to run before posting, so for fun, here is what the morning AI EURO (6z) showed. Snow beginning around midnight Saturday/Sunday with a total of 10 – 12″ with temperatures never exceeding the mid 20’s. Some mixing in the afternoon on Sunday, but mainly south and east of 95. I only chose the AI Euro because it’s been fairly consistent from run to run so far.

Anyway the 12z GFS is done and it stopped the north bleeding and has snow starting late Saturday evening and going into Monday morning. Verbatim, there is no mixing issues for areas west of the bay, temperatures never get above about 20 degrees for duration and total accumulations are similar at 10 – 12″.

My takeaway from the runs this morning is that a major winter storm is likely across the mid-Atlantic on Sunday, but there are a lot of details to iron out. If the midday Euro and AIEuro show any drastic changes, I’ll do a brief update, otherwise I will probably wait until after the later evening model runs.

Early Thoughts for the Weekend

Tuesday, January 20, 10AM

There’s a long way to go, but every model is in agreement that a significant storm will traverse the southern US and impact the mid-Atlantic region some time this weekend. Obviously, the exact track will determine the amount and type of precipitation we see, and over the next several days you might hear some newer terms that forecasters will use in explaining the possibilities. I’ll try to briefly explain those terms below so we all know what the heck they’re talking about.

Frequent readers know that I often refer to the GFS, NAM, and EURO weather models. The GFS and NAM are American models and, as you likely surmised, the EURO is a European model. There are others of course, including Canadian, German, and British models, but most forecasters rely on the American and European models. Recently, however, there have been AI additions to these models. I don’t completely understand how they work, but the traditional models are physics based and use complicated equations to make forecasts. The new AI models use historical data and pattern recognition to make their forecasts. Again, I may sound like I know what I’m talking about, but saying it doesn’t mean I understand it. Regardless, it is a new tool to use in forecasting, especially because they have shown some surprising accuracy, especially the aieuro inside 4 or 5 days. Additionally, the sometimes crazy nam is due for retirement in March of this year and is being replaced by the Rapid Refresh Forecasting System (RRFS), which is already available to the public.

So, as we track this storm over the next 5 days, I’ll refer to the traditional GFS and EURO, but also the AIGFS and AIEURO. As we get closer to the event (hopefully), I’ll also refer to the short range or mesoscale models like the NAM and the new RRFS.

With all that being said, where do we presently stand for the weekend? As I said in a recent WM post, there is an abundance of cold air available and over the next few days, temperatures will modify a bit until a strong surge of arctic air comes in later in the work week. Initially, most models showed the cold air keeping the weekend storm suppressed to the south, which is still a possibility, but recent trends have brought the storm more north so that every model now has central MD getting into at least some of the action. The GFS has been the most south, but the early morning run has become more in line with its AI brother and brings about 4-6″ of cold powder late Saturday and Sunday. The axis of heaviest precipitation in both models is along the VA and NC border. Looking at the European suite, both EURO models also have the axis of heaviest precipitation to the south, but both bring more overall precip to our area. The EURO and AIEURO are slightly different in how the storm plays out, but in the end, they both say anywhere from 8 – 12″ of snow in central MD. How this eventually plays out is impossible to predict, but the overall trend has been coming north so although suppression is still a possibility, it is becoming less likely.

Frankly, I like where we stand right now. At four or five days out, I much prefer the storm being to our south than on top or north of us. There are still a lot of uncertainties but hopefully we can reel this in and get a much needed region-wide snow event. Finally, and not to get ahead of ourselves, but the pattern looks to continue into the foreseeable future.

I’ll update as needed.

An Unsettled Weekend

Friday, January 16, 9:30AM

A predominantly northwesterly flow of Canadian air is setting up shop for the foreseeable future across the eastern US, so oscillating temperatures from slightly below to well below normal should be the rule going into next week. Unfortunately, the southern jet isn’t cooperating (yet?), so it will also be relatively dry. The exception is a couple of northern vortices presently diving down out of Canada that may or may not bring some snow to areas on Saturday and/or Sunday. Models are vastly different in how the weekend plays out, but the euro is suggesting a coating to as much as an inch in some northern areas tomorrow, while the gfs is passing on tomorrow’s piece of energy and focussing on another behind it for Sunday. The gfs enhances the second piece of energy early Sunday, but too late to impact central MD, suggesting that the eastern shore may have snow on Sunday. The euro says the gfs should lay off the hooch as the Sunday system stays offshore. My best guess is to cover all the bases and say that central MD may see some snow tomorrow with marginal temperatures that may accumulate on grassy surfaces, and the eastern shore may see some snow on Sunday that could make for some icy spots for a few hours. How’s that for a big, ‘I have no idea.”?

All models agree that after the weekend, the northwesterly flow continues to ebb and flow bringing a mix of bone-chilling to slightly below normal temperatures. The models are also in loose agreement that the southern jet becomes more active late next week into early February. That always brings the chance of the dreaded “cold and dry followed by warm and wet, repeat,” but with so much cold, Canadian air over us or just to our north, it wouldn’t take much to luck into a more sizable snowstorm. I have my fingers crossed that things get much busier here by the end of next week.

Snow Contest & Tonight / Early Sunday

Saturday, December 13, 11AM

First things first, the winner of the Snow Contest this year is Mikaela Lidgard with her guess of December 4, at 8AM, and the actual first inch of snow at BWI was recorded on December 5, at noon. To be honest, I was caught off-guard because at my house well north of BWI, there was only a coating, so I was surprised to see that the airport did so much better. But, as has been the case the last few winters, the southern areas have done better than the north Baltimore metro area. I was also surprised that no one in the contest (125 entries) picked December 5th as the first snow as it has occurred three or four times since we started doing this some 17 years ago. Anyway, congratulations to Mikaela! Her coffee mug is being ordered and will be on the way soon (as is last year’s winner’s mug, Shelley Clemens!).

As far as tonight, believe it or not, I think it might actually snow! I will say that there is a significant bust possibility because of the type system that we are dealing with. A strong cold front is moving across the midwest today, and as it approaches the coast, a low will develop along the front. We’ve been burned pretty bad in the past by systems like this as it is difficult for models to pinpoint where and when the storm will form, but there is undoubtedly solid model agreement that it should happen far enough south and west for central MD to get 2 – 4″ of snow overnight. The area most likely to see accumulating snow is again from I-270/ MD Route 15 and east, with the possibility of heavy snow occurring along the 95 corridor for several hours overnight. There may be some scattered light rain or snow showers up until about 10 or 11PM, but around midnight, the precipitation should become steadier. The front associated with the system has plenty of cold air to work with, so any rain should change to snow quickly once the steady precipitation begins. By morning, all areas will be below freezing and will stay that way through the day as the very cold air is ushered in on strong northwest winds. Tomorrow is going to look very wintry wherever it snows tonight because of the cold temperatures, gusty winds, and blowing snow.

Today is pretty busy for me, but I’ll try to send an update early this evening if anything changes.

The 18th Annual Snow Contest

The Weather Mill is back for another year! It’s hard to believe that we’ve been doing this for over eighteen years, but here we are heading into another holiday season when snow optimism always seems to run high. The majority of forecasts that I have seen are bullish that central Maryland could see near average to even above average seasonal snowfall, but with the Pacific in a La Niña phase, I’ll believe it when I see it. Regardless, the Snow Contest is back! Anyone can enter, and to win, simply forecast the day and time when you think the first inch snowfall will occur. The closest guess is the winner. I’ll keep the contest open for guesses through Thanksgiving weekend.

Presently, there are no storm systems on the horizon, but I have been reading some forecasts that suggest December could be a decent winter month for the eastern half of the country. Personally, I would prefer a cold and snowy December as it just seems to add to the spirit of the season, so I am picking December 13th, at 11PM. As always, don’t read anything into my pick because it really is just speculation. To enter the contest, just follow the link below and complete the form. Good luck!

Click here to enter the 2025-2026 Snow Contest

Here is the complete list of past winners:

2024 – 2025 Robb MacKie

2023 – 2024 Shelley Clemens

2022 – 2023 No winner due to lack of snow

2021 – 2022 Andrea Katkow and Alessandra Ciccone

2020 – 2021 Kristin Taylor

2019 – 2020 Matt Berkowitz, Tiffany Carmean, and Stacy Cashmark

2018 – 2019 Stacy Cashmark

2017 – 2018 Must have been rigged because I had the closest guess

2016 – 2017 Sue Carlson

2015 – 2016 Carol A. Collins

2014 – 2015 Zenon Fernandes and Martin Vandenberge

2013 – 2014 Margaret Hunt

2012 – 2013 Katie Lovell

2011 – 2012 Frank Eastham

2010 – 2011 Pat Pecor

2009 – 2010 Barb Gilmartin and Carrie Quintavalla

2008 – 2009 Carol A. Collins

2007 – 2008 Carla Stocksdale

Wave After Wave After Wave

Friday, February 7, 8AM

During the cold stretch in January, the jet stream looked like a roller coaster with a big northern arc (ridge) over the western US, and a big dip (trough) across the eastern US. This is important because the jet stream acts as a boundary between warm air and cold air. An oversimplified explanation is that if the jet stream is to your north, it’s generally warm, and if it’s positioned to your south, it’s cold. Since we were in a trough through most of January, and the jet stream was south of us, arctic air was plentiful. Since that pattern broke a couple of weeks ago, the jet stream has stretched out and is now more zonal (west to east) without a big ridge or trough. The chatter among weather enthusiasts was that this period would probably be a break from winter until around mid month when the pattern looks to change again with a more “buckled” jet stream (and the pattern does look really good for the second half of the month). What no one really expected was that this period of zonal flow would give us multiple waves of winter weather, but that’s exactly what is happening. Waves of low pressure are sliding along the boundary, and depending on what side of the boundary we are on for any specific wave, we could have rain, snow, or a mix. This looks to continue for the next week or so with precipitation possible every two or three days.

First up is the system for tomorrow. Like yesterday’s event, this will also be slopfest. Some form of precip develops across the area around 1 – 2PM and continues into the overnight hours. Temperatures look to be a little bit colder for most areas, so tomorrow afternoon could be sketchy if you’re planning to be out. The one thing going for us is that it will be during day light so that should mitigate a lot of icing on roads, but know that by about 5PM, if temperatures are still below freezing, things could deteriorate very quickly with the setting sun. Tomorrow is a good day to find something to do at home.

After tomorrow comes the system on Tuesday/Wednesday that already has everyone talking. Right now it looks like we will be on the cold side of the boundary, and cold enough for accumulating snow. Models are about the same with timing which is Tuesday afternoon into early Wednesday morning, but are not in agreement on the exact placement of the boundary or the amount of precipitation. For now, just know that winter weather is likely beginning after noon on Tuesday, and it could be in the form of moderate snow. Any accumulation numbers you’re reading or hearing now are just a guess, and I’d certainly be skeptical of the big numbers that the GFS is tossing out. Some GFS runs have produced pretty snow maps that are a lot of fun to look at, but it has not been consistent from run to run so don’t believe them. The Euro has been more consistent with a moderate event that frankly looks more convincing. I’ll update periodically over the weekend.