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Showers Return for Northern New England Wednesday; Everyone for Thursday

On Wednesday, a trough digs into the Great Lakes region with a cutoff low very stubbornly hanging around the Canadian maritimes. Weak high pressure sinks farther south of New England during the day. This will increase the southerly flow, allowing for moisture levels to creep upward. While high pressure will generally keep southern New England dry (for one more day), forcing will be stronger for showers and storms across northern New England.


Showers and storms will likely begin to develop throughout the afternoon across the northern tier of New England in the afternoon and continue into the evening. There remains some discrepancy on just how widespread (or isolated) the coverage will be as forces will be working both for and against development. Storms will be most likely across the Green and White mountains.


GFS showing potential weather around mid-afternoon Wednesday:


While thunderstorm development is possible, the threat for severe storms remains low. While plenty of moisture will be present, along with instability (CAPE values will be in the order of around 1,000), lift and shear will be overall lacking. The main threat from any storm that develops will be the chance to produce torrential downpours as moisture will be elevated.



On top of this, showers and storms will be slow moving as flow over New England remains weak. Storms are being highlighted to be able to produce one inch an hour rainfall rates at times. With dry conditions in place after minimal rainfall recently, the flash flood threat is low and any issues with that should remain isolated at worst to non-existent at best. The threshold for flash flooding to occur in areas where storms are possible has been pushed to around 1.5-3 inches of rain in an hour, which is unlikely for most at this point.



With that said, if storms stall in one place, or if multiple rounds move over a single area, some minor issues may arise. The Weather Prediction Center does have central and northern Vermont and New Hampshire, as well as western Maine in the "marginal" category (level 1 of 4) for excessive rainfall. Again, the recent dry spell will help greatly in keeping the threat minimal and isolated.


After Wednesday, all of New England will be in the running for wet weather as the very slow moving system over the Great Lakes region sends its fronts (and a surface low) through New England. This will provide the focus for a more widespread, steady rain to move through the region.




Most of New England will likely see a quarter of an inch to an inch of rain (depending on where any heavier downpours set up) through Thursday. Eastern Maine will remain the driest in New England as they will be furthest removed from the system as a whole. The steadiest rain appears to be in the morning for most, but unsettled weather will persist all day.


While the front and surface low will be rather progressive and move through New England by Friday, the trough and cutoff low to the northwest of New England will remain in place. This will allow the unsettled weather to persist through at least early next week. After Thursday, the chances for any day to be a washout drop, but persistent mostly cloudy skies will persist with daily scattered shower chances.


CMC showing potential weather from Thursday morning through next Monday (June 10). You can see periodic rounds of showers cycling around the upper low:


Despite the unsettled weather, temperatures during this time are looking to run seasonable to slightly below average with 70s dominating. With that said, full summer heat is not in the picture right now for New England (after a quick hit of warmth on Wednesday).



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