I provide a weather email service for people in MD. I am a storm chaser & Skywarn spotter. For daily weather tidbits follow me on Twitter: @wxmanMD.
By: cws6196, 4:53 AM GMT on January 31, 2013
Wow! What a weather day for Maryland in January! It isn't unprecedented but doesn't happen often (I think the last time was in the 1970's). As I write this there are no reports of tornadoes (it was always a very slight risk) but many flooding reports. Unfortunately, in the South, there were confirmed tornadoes and at least 1 death.
But, now that the cold front is moving through the temps will be more seasonable and we are once again talking about snow. The two snow events are Friday morning and late Saturday into Sunday morning. At this time they do not look to be major events for us.
TIMING: Late Thursday evening through Friday morning. The same with the Saturday / Sunday event.
ACCUMULATION: For both events I am looking at a dusting to an inch. There is some wiggle room depending on the track of the Low and the moisture in the air, but an inch or less is on target.
Follow me daily on Twitter (@wxmanmd) for weather tidbits and info. I will have another update late Thursday if necessary.
By: cws6196, 5:04 AM GMT on January 30, 2013
A wild last week of January! The warm air will continue to impact us on Wednesday with a southerly flow of air and moisture. Fog may develop in the morning and the rest of the day will be somewhat cloudy. How much cloud cover versus the amount of sun breaking through will help to destabilize the atmosphere and assist with stronger storms. But, clouds or not, the potential for severe weather still exists due to the dynamic interaction of the warm air, approaching cold front and low level strong jet streams.
Here is how I see Wednesday:
TIMING: Late afternoon into the late evening. This is a fast moving system.
PRECIP: All rain, heavy at times with localized areas receiving close to 2 inches of rain.
THREATS: The main threat will be strong damaging winds arriving late evening. Localized flooding is a slight concern. Tornado formation is not likely, but be aware of your surroundings and have your weather radio active.
There is also a chance for snow once the cold front moves through. It is still a bit early for specifics, but here is how I see it:
TIMING: Late Thursday night into Friday morning; then again Saturday into Sunday. Maybe early next week ...... ??
ACCUMULATION: Not too sure just yet, but both of these snow chances are minimal accumulations with more snow for those west and north of Baltimore, although S MD could see some flakes and maybe a dusting.
I will have another update late Wednesday evening, but if watches/warnings are issued I will do my best to update you here and on Twitter (@wxmanmd) and my Weather Phone: 443-470-9804.
By: cws6196, 4:06 AM GMT on January 28, 2013
The Winter Weather Advisory issued due to the anticipated mixed frozen precip in the morning has been extended, starting earlier (3:00am) and ending later (12:00pm in central MD). A look at the radar shows the mixed precip moving in faster than the models showed. This could mean it will end sooner, although it also means there is the potential for more ice. The upper atmosphere is warming as the southerly flow and warm front advance, but the lower layers are still well below freezing as is the surface as a result of the days of freezing temps and snow cover. But, for those north and west of Baltimore you could see a dusting of snow before it turns to freezing rain. Those in S MD, looking at the precip to your west you will note it is all rain. But, as that precip moves east and saturates the dry air ahead of it, it will drop the temp of the dry air causing the precip to change over to freezing rain.
Many are concerned about how much ice will accumulate. While I understand the concern, mainly for tree damage and loss of power, but to be honest, any ice on the ground during the morning commute will be a safety hazard. While the main highways may be fine, walkways, bridges and secondary roads will not. The Federal Gov is telling their employees to stay off the roads until 10:00am; not a bad idea.
TIMING: The mixed frozen precip (snow, to sleet to freezing rain) will be around 2:00 - 3:00am ending around 10:00am or a bit sooner if the system continues to come in quicker.
If you are curious as to the difference between sleet and freezing rain it has everything to do with atmospheric layer temperatures. Sleet forms when the upper atmosphere is cold but the surface is warmer. The ice crystals form and fall, but as they get closer to the surface they begin to melt. Freezing rain is the opposite (like we will encounter Monday) wherein the upper atmosphere is warm and the surface is below freezing. The precip falls as rain, freezing as it nears the surface.
I am still watching the storm potential for Wednesday afternoon as well as the snow potential for Friday. Follow me on Twitter (@wxmanmd) for weather updates and tidbits.
By: cws6196, 4:04 PM GMT on January 27, 2013
Seat belts on ... here we go ... this week will be a wild one weather wise. I will have a detailed update late today when I learn more from the data, but for now here is how it looks:
MONDAY: Accumulating ice from freezing rain (some snow along the MD/PA line) during the morning commute from around 5:00am - 9:00am or so. The rest of the day will turn to rain.
WEDNESDAY: Ready for this? Possibility of strong thunderstorms with associated damaging winds.
FRIDAY: Snow possible (too far out for details).
So, hang on, this will get bumpy. I will have another update late today. Follow me daily on Twitter (@wxmanmd) for weather updates and tidbits.
By: cws6196, 12:22 AM GMT on January 26, 2013
Well, once again we are hit by dry slotting. Looking at the radar the snow has left the area with the exception of S MD (again). In my post I talked about my concerns with dry slotting and energy being taken by the 2 Low pressure systems; darn, I was right. So, as I forecast, those along the PA line and S MD won this one. But, I do love snow and I got snow; I'm happy.
Next week will be a brief warm up before we return to the cold temps. Snow is "possible" next weekend.
Follow me daily on Twitter (@wxmanmd) for weather info and tidbits.
By: cws6196, 3:33 PM GMT on January 25, 2013
Looking at the radar and other data it appears the clipper is moving faster and producing more snow than the models previously indicated. I did mention in my last post that this system may over-perform. I am not yet saying we will get more snow than the average 3" I previously mentioned, but the potential exists. What I am saying though is the snow may start falling a bit earlier than originally thought. I mentioned the snow starting around 3:00, but we might start seeing some snow closer to 1:00 or so.
All else stays the same from my previous forecast. Follow me on Twitter (@wxmanmd) for updates and weather info.
By: cws6196, 3:54 AM GMT on January 25, 2013
The big question - what will happen Friday? This winter thus far has been a challenge to forecast, and I am not yet sure why. Part of the blame goes to the models, but I also see patterns forming this winter I had not seen in previous winters. Something for me to research come spring. I will leave the discussion to the end. Here is how I see it:
TIMING: The snow should start after noon, most likely 3'ish or so. The heaviest precip probably after 6:00pm. The storm should end around midnight.
PRECIP: All snow.
ACCUMULATION: Let me put it this way. On average most of us in central MD should see about 2" while those closer to the PA line and in S MD could see a couple inches more. These numbers are dependent upon my concerns listed below. Localized heavier snow bands possible.
CONCERNS: The bulk of this storm will occur around the evening rush hour. During the day the streets will warm enough that the first snow flakes will melt on contact. That water will then freeze as the snow piles on and the temp cools. Thus the bottom layer of snow on the road will be a thin sheet of ice.
WHAT CAN GO WRONG? In summary, here is what is happening. There are 2 Low pressure systems moving into the area. The air is relatively dry, although it will moisten. The southern Low comes in well before the northern Low. For snow lovers, we would want both of those to merge, or phase, and become one very strong Low with the potential to dump a lot of snow. But alas, it won't happen. Two major concerns of mine: too much dry air which will evaporate the snow as it falls (virga) and the creation of a dry slot between the 2 Lows as their energies are pulled apart from each other. Both of these scenarios contributed to the last 2 storm busts.
BUT ... Given the cold temps in place, moisture on the way, and recent history of these clipper systems over performing (stronger and more snow than indicated by the models), I am feeling confident that we can expect a couple inches of snow from this system. Thursday morning showed the over-performance, and this system is similar. So, I think 2" is conservative with those N and S of Baltimore receiving more. If the dry slot happens then we could see no snow. If the southern Low re-forms over the Atlantic in good timing and position we would see more snow. Both of those factors cannot easily be forecast.
I expect the NWS to issue a winter weather advisory for Friday, but thus far none have been issued. Follow me daily on Twitter (@wxmanmd) for weather updates and info. I will have another update as needed on Friday.
By: cws6196, 5:32 AM GMT on January 24, 2013
First, the snow happening now through Thursday morning should only be a dusting to an inch in central and N MD while S MD could see a couple inches. As the evening is progressing I am noticing that the dew points, moisture in the air, are increasing and the snow is filling in nicely. That pattern should help us for Friday.
Friday does not look to be the major storm I once thought it had the potential to be. But true to form with the storms this winter; the models in the long-range show nice storms, only to take them away in the short-term. I don't yet have a 100% forecast for Friday, but here is how I see it shaping up.
TIMING: Late afternoon into the evening. Some flakes could be seen earlier, but honestly, the greatest snow impact could be around the evening commute.
PRECIP TYPE: All snow. The snow should be fluffy and so power outages and tree damage is unlikely.
ACCUMULATION: This is still not 100%, but realistically we could see around 2 - 4 inches in most areas. Slightly higher in S MD. Some localized areas could see a burst of snow.
CONCERNS: It does appear, similar to this evening, that the dry air I am concerned about can be overcome. If that is the case accumulation rates will be higher. Another factor is the slight chance for a re-formation of the Low near the coast. If that happens than areas south of Baltimore could see an increase in accumulation.
All in all this is not a big storm, but given the cold air it will be nice to have snow to go along with it.
I will have another update later Thursday. Follow me on Twitter (@wxmanmd) for frequent weather updates and tidbits.
By: cws6196, 4:03 AM GMT on January 23, 2013
Sorry to say, but at this time Friday still remains a mystery. I know you want me to tell you how much snow to expect, but I just can't yet do that for you. I will say that most of us in Maryland will experience snow, but how much is still the question.
WEDNESDAY EVENING / THURSDAY MORNING
A weak clipper system moves through the area late Wednesday bringing with it the chance for snow. This is nothing major and should only be a dusting to an inch in isolated locales. This is true for central and S MD.
Moving from S MD up to central MD, the precip should begin later in the morning to early evening, respectively. I won't yet say how much accumulation, but I am confident in saying the precip will be snow with a chance of sleet in S MD mixed with the snow. The atmosphere will be too cold for rain or freezing rain. Although, the local NWS is still forecasting freezing rain and rain for Friday. It appears they believe that as the Low approaches it will bring in warmer southern air over top of the cold air. That set up will produce sleet, but I just don't see that much warm air making it into the atmosphere. All other local NWS in the region are forecasting all snow. I agree.
But, I do have a concern with this system. As I mentioned yesterday, cold is not the issue, and the position of the Low is obvious in regards to its impact on our accumulation, but I think the greater concern for us will be dry air. In the past couple storms it was the dry air that stopped our snow accumulation. I think that is a concern for Friday as well. The cold air today is quite dry, and the system moving in Friday is not an overly strong one, therefore, a lack of moist air. I'm not saying it won't snow Friday, but we might not see large accumulations.
WHY THE DELAY?
So, given all of our technology, model data, and experience, why don't we yet know what will happen 3 days from now? First,the storm which will impact us on Friday is currently over the Pacific Ocean! It isn't even in the US yet! The other issue is with the models. Very briefly, model data works by inputting weather observations into a computer programmed to analyse the data based on a pre-programmed equation and historical outcomes in similar situations. This is one of the reasons why the models do better as the storm nears since the model is being fed more current and regional data. In this case, the data being entered is from sources over the Pacific. Once the storm comes on land we will have more observation points, and the models will have more historical data to compute. Within a day or so of a storm I start to compare acutal radar images along with satellite imagery to where the models said the events would happen. This tells me how well the models are doing with the data. In this sorm's case I need to see some consistency in the models, but that won't happen until more data points can be entered (please note that the above explanation is greatly condensed).
I will have another update later Wednesday, and will hopefully have more details by then. Follow me daily on Twitter (@wxmanmd) for weather info and tidbits.
By: cws6196, 5:05 AM GMT on January 22, 2013
Many are wondering what is happening this coming Friday. Personally, I hope more happens this coming Friday than did last Friday (weather-wise). But to be honest, it is too far out to really know with any degree of confidence what will happen. I know that is not the answer you all want to hear, but it is the best answer as of this moment. Reviewing the model data these last few runs does not show me any consistency. Minus consistency I truthfully can't say what exactly will happen. But, since people want to know, here are a couple scenarios that I feel are the most reasonable. Bear in mind that this is not my forecast.
1. An all snow event beginning after midnight Friday lasting most of the day. Some indications hint at 5+ inches.
2. An all ice storm event with sleet and freezing rain for most of Friday. Some estimates are as high as 0.5 inches of ice (again, not a forecast).
3. A mixture of #1 and #2. The total snow amount would be cut down, but ice would be in the mix.
A lack of cold air is not necessarily the question in this forecast, rather, the issue is the placement of the Low which is coming from the mid-west. Why is the location of the Low so important? A Low pressure system spins counter-clockwise. If you image an analog clock face moving from the Midwest toward MD, imagine as it is moves east it is simultaneously spinning counter-clockwise. Where you are located relative to the spin of the Low will dictate the air flow in the atmosphere. If the Low is over us or to our north, the flow will bring in moisture from the Atlantic as well as warmer southern air. If the Low is to our south it will bring in moisture from the Atlantic and colder northern air. Therefore, the position and travel direction of the Low impacts the precip type as either snow, ice or a mixture. As of this writing, one of the models has shifted the Low further south, and if that pattern continues than we are looking at a more snowy storm.
I will keep you posted this week. Follow me daily on Twitter (@wxmanmd) for weather info and tidbits.
By: cws6196, 4:57 PM GMT on January 20, 2013
Winter is still with us, even after the other day. For those who feel our winter is over should understand that we typically see our heaviest snows from the end of January through the beginning of March. Plus, those in central MD saw snow on Christmas Eve, a first in 10 years! We currently have 2 snow events on the horizon and a very cold air mass mid week. It wouldn't surprise me to see wind chill products issued by the NWS this week. The first snow event is Monday and the second event Friday/Saturday.
This is not a major event, but still snow. As a cold front and the arctic air moves toward the region we will see winds coming from the east, picking up Atlantic moisture. This low level moisture, combined with a higher elevation cold air mass, together will produce snow flurries. Not a steady snow, rather bursts of snow squalls. Accumulation across the area should be less than an inch. S MD up through the MD/PA line should see these squalls. Timing of the snow is later in the afternoon lasting into the evening.
Since this is a number of days away, and given the history of the models not handling snow storms well this year, I don't want to say too much just yet. But be aware that there is a concern for snow the end of week. Right now it appears to be under 6 inches of accumulation across S MD and Central MD, but things could change. The difference with this storm system from the last one is that we won't have the problematic warm layer to deal with. By the end of the week the atmosphere will be sufficiently cold to support snow. The main issue with this next storm is the exact path of the Low. I will keep monitoring this and will have updates as I begin to see some consistency in the data.
Follow me daily on Twitter (@wxmanmd) for weather info and tidbits. I can also be found on Google+ by searching "weather man maryland"
By: cws6196, 11:30 PM GMT on January 19, 2013
So, the main weather models are showing a strong winter storm in the mid-Atlantic end of next week. Too early for me to comment on, but if there is consistency for the next few days I might find it interesting. Thoughts?
By: cws6196, 10:10 PM GMT on January 18, 2013
Ok, let me start by saying that yes, my forecast for yesterday went bust. I won't make excuses, but I do want to explain what happened and what could have been done to foresee what happened. As I have reviewed the data and tracked the storm yesterday, a few items of interest began to appear. But, keep in mind that in my post prior to the event I did detail my concerns for the event producing as forecast. Unfortunately, those concerns, and then some, came to fruition. This was always meant to be a southern storm. And if you recall in my first post about this storm I stated that I had not mentioned anything about this to you sooner because I didnt see it as an issue, and I felt it was going to stay south of MD. That is what ultimately happened, but I changed my forcast when I saw solid data indicating the storm would move further north. And in actuality, the storm did just that! Here's my take:
1. If you looked at the radar yesterday you would have seen that the precip was all over MD. Actually, the precip field extended into New England. I would say that it drifted further north..... Also, last evening, looking at the radar it was showing that it was snowing throughout S MD, yet that didnt happen. What was happening is called "virga". This is when the precip doesnt make it to the ground. The radar beam looks into the upper atmosphere, and there the precip and snow was, but it was evaporating as it neared the ground. Those in central and N MD didnt see anything because of that. There was a dry layer of air just below the layer of precip. The precip couldn't saturate that lower layer.
2. In S MD there was a lot of rain! The issue here was not virga, but a warm surface layer. This was due partly as a result of a warmer Bay water temp and warmer, wet ground (both of which I listed as my concerns in my previous post).
3. Actually, the forecast was "right" when it came to accumulated snow - had that rain in S MD actually changed to snow. If you recall my previous post I explained how snow accumulation is calculated. In S MD I recorded 0.68 inches of rain yesterday. Converted to snow that would have equaled around 5-6 inches of snow. The NWS forecast was for up to 8" and I surmised around 5". Had the warm layer not been present the forecast for S MD would have been on target.
4. So, why wasnt virga and the warm layer taken into account in my forecast? Not to make excuses, but variables such as those are rarely able to be identified prior to the event. What happened yesterday to allow the dry and warm air layers to exist was not simply one factor out of place. What we saw was that the secondary Low that was to form and move off the Carolina coast early in the day, bringing in colder, moist air, failed to form until later in the day. When it did form it was weaker than expected and further SW than predicted. Also, the high to our north ended up being weaker than expected. Combine those factors and the air flow around the High and Low were not srong enough nor positioned properly to bring in the cold, moist air. Instead we had a layer of dry and warm air. Could that have been accounted for? Possibly, but not likely. Especially not prior to the event. As the day progressed I started to see what was happening and began to realize that central MD wouldn't see anything and I cut down my totals for S MD. But, I still held out that the Low, even though weaker, would eventually position itself to bring snow. It never did, allowing for the warm air to stay in place and so deliver rain.
I hope this summary helps. I do not write it as an excuse, but in the hope you will better understand the complexities of forecasting. I also write this to help me learn from the event.
Follow me daily on Twitter (@wxmanmd) for weather updates and tidbits.
By: cws6196, 9:23 PM GMT on January 17, 2013
Those in Baltimore and north of the city can ignore this as the snow chance is all but gone. That was always the idea, but the hope for a dusting or so lingered.
Those in S MD, all I can say is patience. The snow is coming and we should see about 3 or more inches. In my detailed post last night I talked about my concerns, and the fact that the warmer air staying longer causing more rain to fall was one of them. But what is really happening is a timing issue. Please please understand that Moter Nature does not live by our clocks. One of the dynamics needed to bring us the snow was the forming of a low in the Carolina's. The energy from that low was to help bring in the colder air and moisture. Unfortunately that low is only now forming, hours late by our calculations. This is one of the reasons the rain has persisted in S MD. Now it will get interesting as the energy from the primary low (in GA) is transferred to this new low, especially now that the sun is setting.
Bottom line, this was always a southern storm, and soon we will see the snow falling in S MD. I do believe 3-4 inches in St. Mary's Co is reasonable, with lower amounts as you move north.
Follow me on Twitter (@wxmanmd) for updates and weather tidbits.
By: cws6196, 6:50 PM GMT on January 17, 2013
The winter storm warning remains in effect for S MD until 1:00am Friday. The rain has been steady in S MD and will begin changing to sleet than snow in another couple hours. The system is still on track, but a bit delayed. It also looks more likely, as I previously stated, that Baltimore and north will not see much of anything. The cold dry air to the north is keeping the moisture further south.
My only tweak is to lower the snow accumulations north of the City down to a dusting or an inch near the City. Closer to PA there will be nothing.
I will have another update as needed. Follow me daily on Twitter (@wxmanmd) for weather updates and tidbits.
By: cws6196, 12:51 AM GMT on January 17, 2013
Ok, so what's going on here. Well, as I mentioned this morning, I had noticed this potential for snow a couple days ago, but most of the data was keeping the system to our south and so no real threat. Now the data is moving the system further north. Why do I believe this data over the previous data Looking at the current radar and satellite images I can see the movement of the storm is to the north, and the surface temps in our area have been trending colder than forecasted. Historically, this season we have seen our winter weather trend further north than actually depicted in the data. Therefore it appears that this new data is accurate based on current observation. Here's the deal:
TIMING: The storm in coming from the south, so those in S MD will see precip prior to central MD, but most will see precip around noon Thursday lasting through midnight or a bit longer. Friday should be dry.
PRECIP TYPE: Mainly snow except for those in S MD where the precip should start as rain and gradually change to snow. Once it changes it will remain as snow. The change over from rain to snow should not last long.
ACCUMULATION: This is the tough part, which I will explain below. Those south of Baltimore will see the bulk of the snow, around 4" or so. But the further south you go into S MD those totals could add up to 5+ inches, maybe 8 in localized areas. North of Baltimore could see 1 - 2 inches, if you are lucky. I am thinking more like 1 inch or less, but 2 isn't out of the question.
NEXT ISSUE: I am still looking at the possibility of snow this Monday / Tuesday. Stay tuned.
CONCERNS: The totals I listed above are in line with the NWS, and in this case I agree with them, with caution. Snow accumulation totals are calculated on a formula taking into account the liquid present (as indicated by computer models) and the surface temps. Ratios are utilized based on the temps. For instance, if we say the ratio, based on temp, is 10:1, than for every one inch of liquid we would have 10 inches of snow. The numbers above are based on the ratios. But, what concerns me is a) warm Bay water temp keeping surface temps up a bit; b) warm and saturated ground will melt the first layers of snow, therefore just because the ratio signifies 6 inches, the actual accumulation on a warm saturated ground may be 4 inches. Given all the rainfall we have just had, coupled with mixed precip to start, the real accumulation numbers could be a few inches lower. If the snowfall rate at the beginning is heavy, than the amount of snow and the cooling effect will combine to keep the actual accumulation high.
I will have another update if conditions change. Otherwise this is my forecast. Follow me daily on Twitter (@wxmanmd) and on Google+ search for me "weather man maryland"
By: cws6196, 1:26 PM GMT on January 16, 2013
I will have more details later but it appears S MD could see 4-6 inches while those north of Baltimore on an inch. More to come.
This will be a quick note, just to say that yes, snow is quite possible tomorrow into Friday. This situation kind of just popped up, although I have been watching hints of it for a few days. We could see an inch or so. Also, I'm watching the potential for snow Monday into Tuesday, but we are too far to be sure.
I will have a detailed update later today.
Updated: 8:14 PM GMT on January 16, 2013
By: cws6196, 5:01 PM GMT on January 13, 2013
Enjoying this early taste of Spring? Actually, due to the fog these past couple days the temperature has stayed lower than predicted, although still above normal for this time period. But all that will soon change. If you look at current weather maps of the nation you will see very cold temps in the west and central US. Those temps will be moving our way, and the arctic air should be right behind it. Not to get too detailed (unless you want the details than let me know), but this coming week we will see a steady drop in temps as a cold front advances, yet the following week those temps should plummet and we will truly feel what Winter is about.
Will it snow? In the long term, yes, we will see snow this winter (as I have been saying since at least the end of November). In the short term we also may see some snow. No need for panicked trips to the grocery store though.
For the next couple days rain will be the predominant feature as the temps drop. But, Tuesday evening, those west and north of the about I-95 could see some snow or freezing rain. Those who do see snow will only see a dusting or so. Nothing major; but still snow. Those in S MD should stay all rain. But, there is a slight, small chance, that a coastal low would form. If that were to happen than there would be more snow in more areas. But honestly I don't yet see that scenario playing out. If I am wrong I will let you know ....
Follow me daily on Twitter (@wxmanmd) for weather updates & tidbits, and find me on Google+ by searching "weathermanmaryland".
By: cws6196, 4:52 PM GMT on January 05, 2013
Don't get too excited ... There is an Alberta Clipper moving near the area, and with today's high pressure system moving off the coast the return flow could draw moisture into the clipper adding to the snow chance. But, all I am talking about is a dusting at most. Even those in S MD could see snow flakes flying. Those across the MD/PA could see an inch of accumulation. The timing is around midnight tonight into early Sunday morning.
Those who want snow, do not yet despair. I hear many people comparing this winter to last year's lack of snow, yet that was not a normal winter for us. Nor was the 2009/2010 winter wherein we had back to back blizzards. It seems that particular winter has become the standard many people compare future winters against, but as with last year, that was an anomaly. The snow this past Christmas Eve central MD encountered was the first Christmas Eve snow in 10 years! Typically central and S MD doesn't see measurable snow until late January through the beginning of March. Any other snow is bonus. So, if you want snow, have faith.
Next week we will experience a warm up with some areas into the 60s degrees. The following week looks to be a cool down with the end of January a possibility for frozen precip, but way too far out to bank on anything just yet.
Follow me daily on Twitter (@wxmanmd) for weather updates and tidbits. I can also be found on Google+ by searching for "maryland weather man" and adding me to your circle.