March is known to feature some crazy and surprising weather and the 1958 blizzard that occurred in the Mid-Atlantic region between March 18th and 23rd was indeed rather unexpected. In general, forecasts on the morning of March 18th had no mention of snow. This was in an era when computer forecast models were just in their infancy and it was even before satellite imagery existed which could aid in the forecast. By afternoon on that particular day, the light rain had changed into huge, wet snowflakes and - for the next few days - history was being made.
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If you had a chance to bet on the over/under for the number of nor’easters this month, I hope you took the over. There have been three nor’easters in the past ten days or so and there is the threat for another one around Tuesday of next week. In fact, as we approach the middle of March, it is hard to find any sign of sustained spring-like weather for the Mid-Atlantic/Northeast US and the colder-than-normal temperature pattern is looking like it will go right into early April. In addition, instability in the upper-atmosphere will bring much of the region snow showers this afternoon with isolated snow squalls and perhaps a repeat tomorrow afternoon.
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Strong low pressure will head towards the Mid-Atlantic coastline on Monday and it could result in accumulating snowfall for the DC-to-Philly-to-NYC corridor. In addition to the persistent high-latitude blocking to our north, two key players in the upcoming storm threat will be separate waves of energy in the northern and southern branches of the jet stream. These waves will ultimately consolidate into one deep upper-level trough and if the phasing takes place quick enough then a strong storm would indeed impact the DC-to-Philly-to-NYC corridor.
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There have been two major coastal storms in the Mid-Atlantic/Northeast US during the past several days and there is the chance for another significant one early next week. After a couple of relatively quiet days, multiple short-waves of upper-level energy will slide towards the Tennessee Valley by Sunday and begin to consolidate resulting in the formation of surface low pressure in the Southeast US early next week. This storm will then intensify as it begins to head towards the Mid-Atlantic coastline. It is a bit too early to tell exactly how far up the coast this system will travel, but the overall weather pattern certainly allows for an impact on the DC-to-Philly-to-NYC corridor in the late Sunday night/Monday time period.
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There have been two major coastal storms in the Mid-Atlantic region and Northeast US during the past six days and there is the chance for another one early next week. After a few relatively quiet days, a couple of waves of upper-level energy will slide towards the Tennessee Valley and Southeast US by the latter part of the weekend. This combination of energy will help to set off the formation of a strong surface storm near the Carolina coastline by late Sunday night or early Monday morning. At this time, the storm will then begin a turn up the east coast; however, it is just a little early to say how far north it will go. Many computer forecast models tend to push the system to the south and east of the DC-to-Philly-to-NYC corridor, but the overall weather pattern and teleconnections (e.g., -NAO) certainly warrants the close monitoring of this system over the next few days.
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A major storm will throw just about everything imaginable to the Mid-Atlantic region and Northeast US on Friday and Friday night with the potential for flooding rains, heavy wet wind-whipped snow, sleet and damaging wind gusts. The threat for widespread power outages exists on Friday and Friday night throughout the DC, Philly and NYC metro regions with 60+ mph wind gusts quite possible. This storm will have an impact on the I-95 corridor for an extended period of time due to very strong high-latitude blocking that has set up to our north. As a result, the storm will run into an “atmospheric brick wall” near Cape Cod, MA and rather than taking the usual track for a nor’easter off to the east of Maine, it will be forced to the south and, in turn, impact the weather around here all the way from later today into early Saturday.
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The overall weather pattern across North America will soon feature strong high-latitude blocking over Greenland and northern Canada and this transition period in the atmosphere will result in a slow-moving and powerful storm over the western Atlantic Ocean by the end of the week. Strong low pressure will head towards the Ohio Valley on Thursday, but then it will become overshadowed by intensifying low pressure over the western Atlantic Ocean and it is this system which will run into a brick wall in the atmosphere as it tries to push to the north. As a result of the blocking pattern setting up in the atmosphere to our north, this strong ocean storm will be forced to the southeast - perhaps in a "looping" fashion - and this will prolong impacts from the immediate I-95 corridor to the coastline. Rain and wind will increase from later Thursday into Thursday night and, as colder air wraps into the system on Friday, there is the chance that some areas generally to the north of the PA/MD border see a mixing with or changeover to ice and/or snow before the precipitation winds down.
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High-latitude blocking refers to an atmospheric pattern in which higher heights (and pressure) compared to normal sets up in high latitude regions such as Greenland or northern Canada and it can remain in place for an extended period of time leading to a large-scale obstruction of surface weather systems. High-latitude blocking tends to be more likely during periods of low solar activity and that is certainly the case now as (weak) solar cycle 24 heads towards the next solar minimum. During the latter stages of winter, this type of setup can result in a persistent colder-than-normal weather pattern for the central and eastern US and perhaps stormy conditions as well. All signs point to a strong high-latitude blocking pattern to develop later this week across the North America side of the North Pole and this virtually ensures winter will not go down without a fight in March in the central and eastern US. This change in the overall pattern will also likely result in the generation of a powerful ocean storm late this week just off the Mid-Atlantic coastline and it will likely be a slow mover.
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There has been a major stratospheric warming event over the past couple of weeks with a displacement of the polar vortex to lower latitudes and over the next several days a significant high-latitude blocking event will unfold leading to way above normal heights over places like Greenland and northeastern Canada. These large-scale atmospheric events are having an impact on weather patterns all across the Northern Hemisphere. They will be contributing factors to the extreme cold that is about to invade Europe from the east (Siberia) and to a cold pattern that looks like it will develop across much of the US during March which may feature a nor'easter during the transition period late next week.
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Record-warmth has been swept away from the Mid-Atlantic region by an overnight passage of a cold frontal system and the next couple of days will stay on the chilly side with occasional rain or drizzle. The weekend will feature milder conditions although still on the wet side and then much of next week looks relatively mild for this time of year. By the end of next week; however, important changes will be taking place to the overall upper-level pattern across North America. A deep upper-level trough of low pressure will begin to retrograde (i.e., move from east-to-west) to the east coast at the same time strong high-latitude blocking forms over northeastern Canada and Greenland. The ultimate result is likely to be a strong storm near the east coast at the end of next week and with colder air potentially wrapping into the system, accumulating snow may very well become a real threat in parts of the Mid-Atlantic region and Northeast US by the first weekend of March.
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