Before we begin, we just want to shamelessly plug our upcoming 2018-2019 Winter Weather Outlook. We’ll be publishing this in our weekly Sunday Storm this Sunday (11/4). Be sure to check it out, it covers a lot!
The severe weather threat has shifted to the East today, covering the entire eastern seaboard. Rainfall associated with this system, and the one trailing behind it, could cause flooding in some parts of the Northeast. Meanwhile, the Northwest is also experiencing a large system today, with heavy rain and possible snow in the Northern Rockies.
Welcome to the Friday edition of your Morning Briefing. Let’s dive right in.
Severe Weather Threat Up and Down the East Coast:
- A cold front that is currently draped up and down the country, from Lake Erie to the FL Panhandle, will swing northeastward today. Rising motion ahead of this cold front will likely cause rain and storms for most of the East coast, with a marginal chance for severe weather to develop.
- Cloud cover today will most likely hinder a lot of destabilization, but plumes of instability could allow smaller cells to develop.
- Further south, especially in the Carolinas and VA, strong low-level winds have a small chance to promote tornado and hail development within any severe storms.
The surface low that developed yesterday near the Gulf coast has made its way into the Northeast this morning. As with most mature low pressure centers, this cyclone displays a beautiful frontal setup, with the classic warm, cold, and occluded fronts all in place. The cold front has the most active frontal boundary, and the circulation ahead of the front is what causes the rain and storms we generally experience with their passage. This morning, this cold front is draped from north to south across the country, from Lake Erie to the FL Panhandle. It’s this cold front that will be the cause of the risk for severe weather up and down the East coast today. As this front passes, rising motion at the leading edge of the frontal circulation will cause rain and thunderstorm development. The risk for severe weather remains so widespread today because destabilization is uncertain, and as this cyclone continues to deepen into this evening, a little destabilization could go a long way. Within the same area that contains marginal risk for severe storm development, the possibility for tornado formation and high winds also exist. Strong low-level winds developing along the coast could promote the development of storms strong enough to form tornadoes or hail, especially in VA and the Carolinas. While this chance remains low at about 2%, it is still a distinct possibility.
Rainy Weekend for the Northeast:
- The first surface low will pass our area later tonight, bringing rainfall totals of 1-2 inches across the Northeast overnight.
- The second system will trail right behind the first, delivering rain tomorrow morning and midday, with totals of only around 1 inch for most of the region.
- Locally higher rainfall is possible in any developing storm cells. Flooding is also possible along rivers and low-lying, flood prone areas.
Aloft over the eastern half of the US today and Saturday is a shortwave trough. This trough will continue to propagate eastward throughout the weekend, deepening today and ultimately lifting into the Northeast late this evening. As this trough deepens, so will its associated surface low, which will bring rain and possibly severe weather into the region today. The first wave of heavier rains won’t pass until tonight, bringing 1-2 inches to the Northeast. Locally higher rainfall amounts are possible if storms develop, increasing likely local totals closer to 3 inches. With this particular shortwave trough aloft, we will see another surface low develop from it. This pair will drop rain in two parts, the first late tonight and the second midday tomorrow. Severe risk tomorrow will remain confined to MA, RI, and parts of NY, where lift will be greatest. However, rainfall totals from this storm will be much less, only near an inch. Again, locally higher amounts are possible within developing storms. Along rivers and low-lying areas, flooding is possible, even with only a few inches of rain. After these two bouts of rain, we should see clearer skies for the rest of the weekend and early next week.
Unsettled Weather Today for the Northwest:
- Another shortwave trough will move into the Northwest this weekend from Canada, bringing a low pressure center at the surface that will cause precipitation with its developing frontal system.
- Precipitation ahead of this developing front will likely not be heavy, but will be widespread, dropping some form of precipitation on almost 12 states before Sunday.
- Snow is expected in higher elevations in the northern Rockies and parts of MT and ND. Winter weather advisories have been issued in MT and ND, despite relatively light snow, due to higher wind gusts.
As a weak shortwave trough moves into the Northwest from Canada, its associated low pressure system at the surface will cause trouble for that region of the country as well. It has been an active last half of the week for most of the country, and the Northwest is no exception. The frontal boundary associated with this low pressure center will cause light to moderate precip for most of the Northwest today, before moving southeast and delivering more rain to the lower Mississippi Valley tomorrow. Higher elevations in the Northern Rockies and parts of MT and ND will see a bit of snow with this system’s passage, with light accumulation expected. Winter weather advisories have been issued for parts of MT and ND, with snow and high winds creating possibly hazardous conditions for some areas. In general, rain with this system will not be heavy, but it will be widespread, delivering rain to likely 10 states before strengthening near the central Midwest Sunday afternoon and moving back north into Canada.
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Also (as mentioned before), be sure to check out this week’s special edition of The Sunday Storm, where we’ll be giving you our Winter Weather Outlook for 2018-2019, as well as Five Things to Watch This Week next Monday.