New England Weather This Week: Water-Logged

Spring often has two sides in New England. One side features the return of warm, sunny weather. The other side features prolonged periods of cooler and unsettled weather as blocking patterns take hold. Take a guess at which side we'll see this week.

MONDAY-WEDNESDAY

For the first half of this week, New England (and the United States as a whole) will be entrenched within an Omega Blocking pattern.  This will be a strong and classic Omega Block, which involves a large ridge of high pressure flanked by the two cutoff low pressure systems on either side of it. This can shape the jet stream to appear as the Greek letter Omega. Dry and mild weather is often observed under the ridge with unsettled and cooler weather in the troughs, and New England will be within the eastern trough.

Below: 500mb flow pattern Monday afternoon, showing a pretty clear Omega Block situation:

While the cutoff low continues to spin to New England's west and very slowly move eastward, a frontal boundary associated with it will remain stalled over New England. This will provide the basis for multiple rounds of showers over the next few days. Monday afternoon will likely see lighter and more scattered showers, with the most activity centered over Connecticut and western Massachusetts.

Below: WRF-ARW showing potential weather this afternoon:

Tuesday continues to look like the wettest day, where showers will be the most widespread and heaviest. The main batch of rain looks to move into southern New England through Tuesday morning before lifting north and east into Maine through the afternoon. Rounds of lighter and more scattered showers will continue through Wednesday.

Below: WRF-ARW showing potential weather late-morning Tuesday (1st image) and late-afternoon Tuesday (2nd image):

By Thursday morning, a widespread 1-3 inches of rain will likely have fallen across southern New England and much of New Hampshire. Lesser amounts remain likely across Vermont and northern Maine as they will be further removed from the best forcing for showers, resulting in more limited activity. There remains a chance for areas to see upwards to 3-5 inches across interior southern New England due to upslope enhancement in the Berkshires, Litchfield Hills and maybe Worcester Hills.

This will be a beneficial rainfall in the end as much of southern and central New England continues to make up for the massive rainfall deficit from last fall. With that said, the ingredients will be in place for heavy downpours Monday and Tuesday. A modest low-level jet coming out of the southeast will transport a plume of high moisture into New England.

The frontal boundary over New England will provide ample forcing for downpours to develop within this moisture-rich environment. This could result in some isolated flash flooding issues, mainly over interior southern New England. The exact threat level on Tuesday will be dictated by how much rain falls over the next 12-18 hours. Areas that see more rain today and tonight will have a higher threat on Tuesday.

The persistent clouds and showers will combine with an onshore flow to keep chilly temperatures around through Tuesday. A more southerly flow that turns offshore should help boost temperatures a couple notches on Wednesday.

THURSDAY

The cutoff low to our west will finally push to our east by Thursday. This will result in a much drier day across New England. The best chance for showers will be over eastern Maine, closer to the low. Elsewhere, plenty of clouds and spot showers will likely be around, but coverage should be much less than Monday to Wednesday. A cold front will dive into northern New England, resulting in a cooler day compared to Wednesday. For central and southern New England, temperatures will likely hang around levels seen on Wednesday.

Below: AIFS showing temperature departure from average Thursday afternoon:

FRIDAY

By Friday, the cutoff low responsible for the Omega Block will have moved away from New England. This will likely be replaced with expansive ridging over the western and northern United States. Another trough will likely undercut the ridge over the northeast and cutoff.

Basically, another cutoff low will be replacing the current one here at the beginning of the week.

Below: Height anomaly late next week showing the expansive ridging building over the west with a potential trough undercutting it across the south and northeast:

All of this will result in another day that will likely be filled with showers. The exact coverage and intensity of these showers is very difficult to say at this point as cutoff lows are notoriously difficult to forecast. It could range from just a few showers to a near-washout. The trends will b e watched through the week. What's much more certain is that Friday will be a chilly and raw day.

WEEKEND

This cutoff low will likely hang around Saturday, continuing the theme of plenty of clouds and showers. Overall, Saturday is highly uncertain as the weather will come down to the track and timing of the cutoff low developing at the end of the week along with an approaching cold front. These two features will determine both coverage and intensity for Saturday.

Below: Current weather map for Saturday morning (May 10):

As of now, this trough looks to clear out in time for Mother's Day, resulting in a drier and possibly warmer Sunday. With that said, guidance also has a tendency to struggle with blocking patterns and often shows them breaking down quicker than they actually do. With that said, Sunday could absolutely trend cloudier, wetter and cooler throughout the week.