Monday, April 4, 2011

Spring Makes its Long-Awaited Arrival with a Multi-Hazard Storm System to impact the Northeast

It took its sweet time, but it looks like it's finally safe to say that Spring is here in the Northeast. Yes, technically it's been here since March 21, but you wouldn't have known it based on the downright wintry weather and cold we've had over the past two weeks. Temperatures that had been running anywhere between 10 and 20 degrees below normal are returning to the values they should be at during this time of the year. For us here in Upstate New York and Western New England, that means highs in the upper 40s and low 50s!

Also with Spring’s arrival, comes the threat for those powerful Springtime storm systems that barrel across the country every year at this time. They bring everything from snow and icy precipitation, to heavy rains, severe thunderstorms, and tornado outbreaks. We had a brush one of the first of these Spring storm systems about two weeks ago when we just missed getting snowed on as a storm passed by to our south. Spring lovers rejoiced, hardened snow lovers grimaced, and us forecasters pounded our fists on the desks when the dry air ate away nearly all of the snow we were calling for.

Then of course, we have the infamous Spring Nor’easters. These storms are notorious for taking towns from the nice, warm comfort of a sunny Spring day, and burying them under several inches of snow the next. They also bring the battering winds and flooding rains that can swell and overflow rivers for days or even weeks. Thankfully, this is yet another storm we manage to dodge early in this Spring season. The potential was there for Upstate NY and Western New England to see another big snowfall on the order of a foot or more in some areas; particularly over the Green Mountains and the Berkshires. In a seemingly unprecedented turn of events, the major forecast models, that for nearly a week had disagreed on everything from the time of the storm’s arrival to the intensity and type of precipitation came into almost complete agreement. Everything pointed to a significant April Fool’s Day snowfall in our area, and across much of the Northeast. Then at the last possible model run before the storm’s arrival, the disagreement was back. Only now, it was getting into the “now-casting” phase of the storm. The storm formed farther east into the Atlantic Ocean and took a track that kept it far enough out to bring only a few inches of snow at best to our area, which then changed to a nasty, cold rain. So on April Fool’s Day, the joke was on us as forecasters. Although the storm almost seemed to poke fun at as by hooking just a bit West and hugging the New England coast, as if to say “Ooh, you were so close!” So Winter seemed to score one more victory by teasing us into going for a big snowfall, and then leaving us eating humble pie and hitting our heads against the wall. But when all’s said and done, Spring is a fun and challenging season to forecast in. So now that it seems to be settling in for the long haul here in the Northeast, we find ourselves staring at a multi-hazard storm system that has us square in its sights.

While much of what we see here in Upstate NY and Western New England will be rain, this storm will be bringing a multitude of weather to the Eastern United States. The warm front reaches us first during the early morning hours on Monday April 4. Initially, the air mass overhead should be cold enough to support some snow in the high elevations of the Catskills, Adirondacks, Greens, and Berkshires. Valley locations may see a brief period of a rain/sleet mix, but this will all change to rain once the warm front lifts off to the northeast. Temperatures will quickly rise into the 40s, and should peak in the low or middle 50s. Monday’s highs could very well occur at the very end of the day, since warm air is expected to continue to pour into the region well into Tuesday morning. The main threat for us on Monday will be the rain, which could be quite heavy at times. This presents a problem for areas in the Adirondacks and western Mohawk Valley where there is still snow on the ground. The warm air and rainfall will accelerate snowmelt, so flooding around creeks and low-lying areas could be a big problem. Flood Watches are posted until Tuesday afternoon, for several counties north and west of Albany so be extra careful on the roadways.


Here are the counties under Flood Watches as of 10:48 PM Sunday, 4/3.

But remember, this is a multi-hazard storm. While we will be dealing with some brief snow or mixed precip and then ultimately rain, parts of the Midwest and the Southeast could be looking at another outbreak of severe weather.


Above is the severe weather outlook for Monday 4/4, showing the greatest risk over parts of Missouri and Kansas. A slight risk exists over a large swath of territory from Michigan into northeastern Texas. The outer (gold) swath indicates an extremely slight risk, including parts of our area.



Taking a closer look, here’s the outlook for hail on Monday. This also appears to be the main threat as far as severe weather is concerned with this system. There is a slight risk of tornadoes with this system on Monday, but a very slight risk.

Then we get to Tuesday, and the storm gets a bit more interesting for us. The cold front responsible for all of this weather arrives in our area early Tuesday morning, and could jolt you out of a sound sleep with a rumble of thunder or two. While I don’t anticipate any severe weather in our next of the woods, the storms early Tuesday could produce some very heavy downpours gusty winds, and of course, some cloud-to-ground lightning. This doesn’t mean that a severe thunderstorm warning or two is completely out of the question, though. The tricky forecasting part for Tuesday morning will be the day’s high temperature. Model data points to the chance that temperatures could soar to the middle and upper 60s, but I’m reluctant to shoot that high given the fact that it will be raining, which tends to cool the air. Nonetheless, temperatures stand a good chance of spiking to 60 or so briefly Tuesday morning with the frontal passage. Temperatures will then drop through the remainder of Tuesday as we start to clear out behind the front.




This is the GFS forecast for 06Z (2 AM) Tuesday morning 4/5, around the time that the cold front will be moving into the region. It indicates a sharp spike in the temperatures at the 850 mb level in the atmosphere, which will translate into a spike in temperatures here at the surface. So, while I don’t want to jump quite to the extreme that the models are indicating, it also is not a foregone conclusion that we could reach above 60 degrees.

It looks to be an interesting storm, with a wide range of weather. Looking to the end of the week, it seems we will be getting our fair share of April showers.

Until next time!