Clouds are overspreading the area ahead of our next storm this afternoon. Today’s cold weather was brought to you by a sprawling high pressure system moving in from the west. This high will set up shop to our north and become locked in providing a plentiful supply of cold air. A low pressure system is moving up the Ohio valley into the Great Lakes region this evening as well. A long fetch of moisture is setting up beginning in the Gulf of Mexico and dumping out just to our west. Overnight, the moisture feed will move east, overhead, and snow will begin from west to east. By dawn, everyone will have snow falling with an inch or two on the ground. Snow will become moderate to heavy through the morning hours at which point sleet looks to mix in for southern areas. Lets break it all down.
Initial Snow: Tonight Through Mid Morning Tomorrow
Snow will arrive from west to east tonight and will be light to moderate through dawn. Moderate to heavy snow will arrive after dawn in time for the morning commute. This period of time is when the accumulating snow will fall for SW areas and at the immediate coast. Falling snow will cause visibility problems in addition to slippery roads due to the accumulating snow. All and all, a pretty messy morning commute is expected.
Heavy Snow To Mix: Mid Morning Through Early Afternoon
The NAM sounding for Portland tells us a lot about this phase of the storm. Snow will fall into a warm layer right around 10,000 feet. The snow will then melt, falling as rain. However, we’re not at 10,000 feet here in Maine. The cold air from today will remain locked in at the surface. The rain will then re-freeze into sleet and that’s what many in southern areas are likely to see. Farther north up into the mountains, the precip type is likely to remain all or mostly snow. The image is showing what the temperature would be like if you traveled straight up in the atmosphere from Portland.
Lingering Light Snow/Mix: Mid Afternoon-Late Evening
After the main push of precip comes to an end tomorrow afternoon, some moisture will continue to linger in the lower levels even as the mid/upper levels dry out. This will result in a period of light precip that will continue through late tomorrow evening. Across the south, this will be a mix of snow, sleet, and freezing rain. Across the north, more snow is likely. While accumulations will likely be limited from this phase of the storm, the big thing will be that it will continue to keep roads very slippery especially across the south where sleet and freezing rain is most likely. Even after the heavy precip has stopped, roads will continue to be very slippery so continue to use caution through tomorrow night.
Final Snow/Ice Totals
Overall, not a huge storm by New England standards but given what we’ve had to deal with so far this season, it will be reasonably impactful. Warm air could creep in along the east side of a coastal front Tuesday afternoon but Coastal York county south is where impacts should be confined to.
Given the plethora of precip types incoming with this storm, tomorrow would be a great time to give the mPING app a workout! Over the past few days you’ve seen how hard it is to forecast multiple precip types. Here’s a chance for you to help forecasters out! Simply download the free app and take a look outside! Send in your report of snow, sleet, freezing rain, or rain and you can help forecasters like me with forecasting multiple precip type events! The data is sent to the National Severe Storms Laboratory to help with radar development which gives models better data which improves forecasts. Read all about it over on the NSSL webpage. Also through that website, you can view your report and everyone else’s reports to track the rain/snow/sleet line in real-time! Happy reporting!
I’ll have another update tomorrow morning and will be on twitter for most of the day tomorrow with more frequent updates @JackSillin.