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.

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.

Sunday

Preface

If after reading the update, you feel like you haven’t learned anything, it’s deliberate because confidence is low on specifics. My official first forecast for tomorrow is that it’s a good day to get any errands or activities wrapped up by late morning and then hover around a fire for the remainder of the day.

Saturday, January 18, 9AM

Hopefully we all got a chance to enjoy the relatively milder temperatures because the bottom is about to fall out. During the day tomorrow arctic air will begin spilling into the area and for the MLK holiday and well into the shortened work week, temperatures will struggle to reach even 20 degrees for highs, and some areas will likely fall below zero for the first time in years. I’ve been a pretty quiet regarding tomorrow because the snow portion is a tricky forecast, but the coming cold air is guaranteed. The difficulty in the forecast for Sunday for the majority of the area is the timing of the arrival of the cold air, so I’m going to keep this short and worry about details in later updates as the models come in during the day today.

Precipitation will arrive tomorrow morning from southwest to northeast across the area from 7 – 9AM. If it starts as snow, you’re locked in to 4 – 6″. If it’s raining, obviously the amount of snow will be determined by when the colder air arrives. I think areas west of 95 changeover by noon and east of 95 to the bay between noon and 2PM. Regardless, by about noon until about 5PM, the precip could become moderate to heavy. It’s a quick moving system, but I think all areas west of the bay across central MD get 2 – 4″ by the time things wrap up, and areas that are currently under a Winter Storm Warning (Frederick, Carroll, and northern Baltimore counties) end up in the 4 – 6″ range.

I’ll send out an update this evening between the upset in Kansas City and the taming of the Lions.

We Reeled One In!

Friday, Jan 19, 430AM

By the time most will be reading this, they may have surmised that the models are playing catch up with this system. The short term mesoscale model runs this morning were a thing of beauty and enough for the NWS to hoist Winter Storm Warnings across central MD including Montgomery, Howard, and all the MD/PA border counties from Frederick east including Baltimore. We can now expect 4 – 5″ of snow in those areas, and possibly more. Models suggest that a heavy band of snow will set up somewhere across central MD and if so, those areas could do even better.

At 4AM, light snow has commenced for most and it will become steadier and heavier through the morning commute. I’m secretly thinking we might even do a little better than what the models are suggesting now, but I could be just getting greedy. Regardless, I am delighted to see two things as a result of this storm. First and foremost, that it can and will still snow here. The past two years have been brutal for people that enjoy winter, so this past week has been pretty good, and frankly, therapeutic. Secondly, I really enjoy that in spite of all the advances and technology in data gathering and modeling, snow can still sneak up on us. It’s nice to recognize that we can’t control everything even if it’s just snow.

Anyway, after today’s storm, a fresh blast of cold air for the weekend and then a January thaw looks to commence. Hopefully the pattern reloads in early February and we can do another week or two of real winter. If anything changes today, I’ll update.

Mostly Wet but a Pasting for Western Areas

Friday, Jan 5, 3PM

I’m hoping that the models are wrong and things will be colder than expected, but for areas along and east of 95, this should be a little wintry mix followed by a bunch of rain. Of course, the usual rule of heading further north and west, the better the chances for snow. Regardless, precipitation arrives around noon tomorrow probably in the form of snow for most, then transitions quickly to rain for eastern areas. For the 95 corridor, there may be a quick coating on grassy surfaces but the snow should change to rain in the early afternoon. The rain/snow line should continue working north and west through the afternoon as warmer air moves in from the east, but areas along the PA line and west of Frederick may stay all snow throughout the day. Winter Storm Warnings are posted for those areas for up to 5″ of snow and maybe ice, and the lesser Winter Weather Advisories are posted for the peripheral areas to the east, including Howard.

Not to get anyone’s hopes up, but if the precipitation comes in heavy enough, there might be a few surprises even along 95. Heavier precipitation can mix the atmosphere and drag enough cold air down to overcome some warming. I’m not expecting that but it is a possibility. If that were to happen, we might be able to get a little snow thump before the transition to rain in the metro corridor.

I’ll send an update early Saturday morning for those that might have travel plans.