Hello everyone!
Remember yesterday? That’s happening again today minus maybe 5 or 10mph on the wind. Look for highs in the 10’s and 20’s with NW winds gusting in the 20-30mph range. Not quite the 30-40mph of past days but still enough to make it feel nice and chilly. Welcome back to winter!
-Jack
Hello everyone!
Remember yesterday? Yeah, that’s what to expect today with just a hint less wind. NW winds will still be gusting over 30mph, actual temps will hover in the 20’s with wind chills not far removed from zero, and blowing/drifting snow will continue to cause sporadic slick spots/low visibility. Just another day in Maine.
-Jack
Hello everyone!
Today will feature mainly sunny skies though winds will be blowing and temps will be dropping. Look for temps right around 20 at the coast and in the low to mid 10’s north. Winds could gust over 35mph thus bringing wind chills below zero for many. Here in Yarmouth we’ve picked up 9″ of fluff this weekend (5″ Saturday, 4″ yesterday) and by the looks of it most areas saw at least 6″ of fluff over the weekend as well. This snow will take to the skies today with all the wind and blowing/drifting snow could cause issues in terms of reduced visibility and possibly some slick spots as well if the snow happens to drift into the roads. Use caution if out and about today. In the mountains, a very favorable upslope pattern is setting up and 4-8″ of upslope snow is likely in the favored areas. Watch for that if you’re heading north.
You may’ve heard about a storm this weekend. As of now, monitor for details as they become available tonight and especially tomorrow but it looks like we just get a glancing blow as the storm slides south. Many solutions are still on the table so continue to monitor the forecast over the next few days.
-Jack
Hello everyone!
The forecast for snow today remains on track and light snow will continue to fall through the day as the Norlun trough meanders over the region. Accumulations will be light for most with a general coating-2″ expected. More is possible in southern NH. Temps will be in the 10’s north and 20’s south.
-Jack
Hello everyone!
A tricky forecast is lined up for tomorrow as a Norlun trough develops over the area. The players remain largely the same as when I wrote yesterday’s post so please check that out for an explaination of the situation. These are tricky to forecast so anyone in SW ME, southern NH, and NE MA should be prepared for a coating-4″. Again, please check out last night’s post for details on the setup. I’ll repost last night’s snow map below as I see no reason to change it. The only thing different from last night’s post is that it appears unlikely any mesolow feature would form in time to provide meaningful impacts but if you want to learn how they work, that’s an interesting read.
-Jack
Hello everyone!
Today will feature high pressure briefly nosing in from the north as yesterday’s storm departs and tomorrow’s storm approaches from the south. Look for highs in the 20’s north and low 30’s south. Another storm will pass well SE of the area tonight into tomorrow but indications are a Norlun trough will develop on the back side leading to locally moderate snow somewhere along the coast. I’ll be back this evening to talk about the details.
-Jack
Hello everyone!
After a nice little storm today, we turn sunnier and cooler tomorrow as low pressure moves east. Another low is already developing in the Gulf of Mexico and will be moving offshore well to our SE Monday. Normally, this would be a slam dunk miss but a strong upper low will be driving SE and there’s a lot of energy on the leading edge. Surface low pressure will develop over the Great Lakes in response to the upper low and a surface trough will develop between the Great Lakes low and the offshore low. This sets up a tricky forecast for Monday as this trough could take on some Norlun traits leading to narrow and possibly heavy snow bands.
Looking at the 500mb setup, there are a lot of things going for a Norlun event. A strong upper low is moving in from the NW and on the leading edge, a strong peice of energy is moving right over us. Also, being ahead of the upper low, the flow aloft is divergent. To put this in simpler terms, the air at 20,000 feet is spreading out. This leaves a void that air from below must rise to fill. Think of what happens when you pull your hands apart on the surface of a lake or bath. Water rises to replace the water you pushed to the side. This rising motion helps generate precip. This is how everyone will see a coating to an inch or two of snow tomorrow night into Monday morning. The real fun is along the southern coast with a Norlun trough.
At the surface a storm will blast by well SE tomorrow. Another weak wave will develop over the great lakes. The link between the two will manifest itself in the form of a Norlun trough extending NW-SE across the area. Everyone sees light snow from synoptic (large) scale divergence aloft but any moderate snow amounts will be dominated by a mesoscale (small) norlun trough. These troughs generate narrow, heavy snow bands (think lake effect type) that can drop moderate to heavy accumulations in one town while the next town over sees some flurries and maybe a coating. My point here is that uncertainty is quite high.
Another thing to watch out for with Norlun type events is the threat for a mesolow to develop. Mesolows are caused by rising air along and near the trough and also westerly winds accelerating and veering as they move from a high friction environment (over land) into a low friction environment (over water). Imagine the right front tire of your car running into a patch of ice. As that tire moves from a high friction environment (pavement) into a low friction environment (ice) it accelerates while the left front tire is stuck on the high friction pavement and can’t move as fast. The result is your car spinning out. The same thing happens with air moving from over land to over water. Above I’ve drawn up a quick graphic showing how west winds and a cold airmass emerging over water can generate a low. The divergence aloft and strong upper energy aids in this process. This doesn’t happen behind every cold front because often the air is and sinking. The air monday will be rising due to the approaching upper low/divergence which will help with the development of the low.
The 12Z CMC shows this potential well. Should this occur, most of the coast could see a moderate snowfall and amounts would be slightly less dependant on the fickle Norlun. While most models don’t show this, based on warm waters (still over 40 degrees!), rising air ahead of the upper low, the strong energy aloft, and the movement of the surface airmass, I think there is a good chance some sort of mesolow develops and strengthens tomorrow afternoon.
Here are my thoughts for snow. This is tentative as Norlun troughs are notoriously fickle. I’ll have another update tomorrow morning.
-Jack
Hello everyone!
Today will feature mainly awful weather conditions with a mix of snow, sleet, and freezing rain with a hint of normal rain along the immediate coast. Temps are already beginning to crash as winds are turning northerly and moving cold air in. Expect to change over to snow in the next couple hours even at the coast. Heavier bands are moving in from the ocean but I have questions as to how far they make it. I expect snow totals to come in on the lower side today for most especially inland. The trend overnight has been towards slightly less total precip. Not a complete forecast bust but don’t be surprised to see a tad less than expected. Freezing rain will be another threat along the coast as temps at the surface remain steadfastly below freezing while temps aloft still have a bit of cooling to do. We already have a solid glaze at the coast and as snow falls on top of a layer of ice on top of ice leftover from our last storm, expect extremely slippery roads and sidewalks. Temps will be falling through the 20’s today as cold air moves in.
-Jack
Hello everyone!
We’re still on track to receive a sizeable storm tomorrow as low pressure moves up the coast. The trends this afternoon have been towards low pressure being slightly farther east which would mean slightly cooler temps along with slightly less total precip. Overall, this leads to little shift in terms of how I think things play out but there are a few important differences. These differences mainly revolve around how things play out at the coast and just inland.
Looking at observations this evening, the forecast mainly looks good. A coastal front is forming across York County and will continue to sharpen up as low pressure develops offshore. The GFS shows this well. Keep in mind, models have had a very difficult time with this storm so don’t take any of the model graphics I post verbatim. They’re just to illustrate an idea not an exact figure or forecast.
Temps on the warm side of the coastal front are already above freezing over Coastal York county. Winds are off the water there and thus temps will continue to rise through the evening. Wherever that sets up, look for rain on the SE side and snow/freezing rain on the NW side. As always, snow amounts could be bumped up a few miles NW of the front as clashing warm and cold air will increase lift/forcing.
While dynamics don’t look crazy for this event, there is modest forcing for heavy precip tomorrow morning through midday. As this map shows, bands are likely to extend well into the mountains. Don’t worry at the coast, precip will be moderate to heavy there too but driven by different factors. The heavy precip will assist in dynamic cooling which will further assist cold air in moving southward tomorrow midday. I think everyone sees accumulating snow tomorrow afternoon/evening even areas that see rain for most of the event.
I’m sticking with my snow map for now as I don’t have the flexibility for adjustments and it still looks good. The jackpot will fall in the southern mountains and northern foothills with lesser amounts north and south. The one area to watch for higher amounts will be the southern end of things towards the coast. There is more liquid available at the coast but less cold air. If the cold air can show up, that extra QPF (Quantitative Precipitation Forecast) could allow for bust potential.
I’ll have updates when I can this evening on Twitter and another blog update will arrive tomorrow morning.
-Jack
Hello everyone!
It looks like we’re heading into a more active period of weather and our next storm is lined up for Saturday. While this one does look to pass well offshore, that doesn’t mean we’re out of the woods for mixed precip. Let’s break it down.
Setup
As with most winter forecasts, there are factors for and against snow. There are some indications that some weak Cold Air Damming could form but there is no big high pressure to the north. The stronger low will rapidly intensify to our east but it takes a while for the western low to decay. Before it does, it will try really hard to pull warm marine air northward. By default, it takes a heck of a lot to drag a warm airmass inland very far inland over cold air with a fresh coat of snow. Right now, I doubt rain moves much farther inland than I-95/I-295. It will take a bit more to convince me a weakening low over southern Ontario can accomplish significant warming.
Snow/Rain
Precip arrives tomorrow night first in the form of light snow in the evening. Warm air will be moving in from offshore and will rise up and over the existing cold air. Snow remains mainly light until Saturday morning when the low gets closer. At this time, it looks like most areas see snow with the coast at risk of rain. At this time, it looks like some low level warmth makes it a few miles inland just above the surface where Cold Air Damming has less of an effect. Should this occur, sleet and or freezing rain could present issues mainly in the area outlined in Purple. Keep in mind, areas south of the current heavy snow area have a legitimate shot at seeing more snow. Experience has taught me never to underestimate cold air in Maine in January. Looking for proof? Remember Tuesday night.
Everyone changes back to snow Saturday evening as cold air blasts south behind the developing storm. Cold air follows for Sunday before more snow arrives Monday. It looks like this could be a Norlun type setup so details will have to wait until Sunday.
I’ll do my very best to get an update up tomorrow afternoon but my school obligations are stacked against me. I’ll be at the indoor track meet at USM for most of the later evening following a team dinner earlier in the evening.
Regardless, I’ll have updated details tomorrow morning and Saturday morning.
-Jack
Forecasterjack 