Isolated Severe Storms Possible This Afternoon (7-5-2020)
A conditional, but perhaps very locally higher-end severe threat could evolve across eastern New England later today. A surface moist axis characterized by mid-upper 60s surface dew points extends from near KOKX to KLON to KBOS, with drying occurring to the west of a surface boundary from near Newark, to Windsor Locks, to just east of Jaffrey, to west and north of Concord, NH. To the east of the boundary, low level stratus has largely cleared (except for along the immediate coast from Gloucester north into coastal Maine) allowing the boundary layer to warm into the 80s and destabilize.
Aloft, a shortwave rippling through the mid-level flow is approaching from the northwest. In advance of this shortwave, forcing should be strongest across northern New England, where a few updrafts area already noted on radar across northern Maine, but some upper level support will likely extend southward and overlap with the more unstable environment across the coastal plain. Strengthening mid-and-upper level north-westerlies will result in shear magnitudes of 30-35kt across the moist sector, supportive of organized convection.
Towards evening, there is some indication in the guidance that low-level shear will increase, with 0-3km SRH potentially >150m2/s2. Relatively straight hodographs would favor a multicellular storm mode, but any mesoscale augmentation of the low-level shear profile (boundaries, right moving cells, etc.) may locally increase the potential for rotating updrafts.
Given dry mid-levels and just glancing forcing, storm coverage is expected to be quite low. In fact, some CAMs don't develop storms at all outside of northern Maine. I do expect at least one or two storms to form further south, and given the environment previously described, any cell that manages to sustain itself could become severe. The most likely hazards appear to be large hail (perhaps 1-1.5" in diameter), strong winds, and the outside chance of a brief tornado.
More Forecasts
A Tornado Outbreak is Possible on Monday in Oklahoma & Kansas
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As of this evening, a broad corridor of conditional significant severe weather potential appears likely to evolve across Kansas, Oklahoma, and perhaps extreme northern Texas tomorrow afternoon and evening. If storms are able to form along the dry line between 3pm and 8pm, the ambient environment will be supportive of strong tornadoes, giant hail, and eventually upscale growth with an attendant damaging wind threat.
People in areas at risk for severe weather should monitor trusted sources tomorrow for additional information.
Synoptic Storm Expected Early Next Week (12-18-23)
Synopsis: A large low pressure system will bring active weather to much of the eastern seaboard, with a focus in New England, late this weekend into early next week. As the low moves northward from its current position in the northern Gulf of Mexico, a favorable upper-level pattern evolution should allow the system to deepen rapidly to near 980mb at 40°N. Rapid pressure falls should result in a large mass response/impressive low-level jet evolution, increasing the risk for damaging wind gusts and drawing a large plume of moisture northward. Near the surface low, a 10-18 hour period of steady to heavy rain can be expected, with a shorter window of potentially damaging winds along the NewEngland coast during the day on Monday.
Severe Storms in New England Thursday (7/27)
Thunderstorms are expected to develop across southern New Hampshire, the Hudson Valley, and perhaps northeast Pennsylvania, and move southeast with time through a favorable environment. Damaging winds, flash flooding, and tornadoes will all be possible with the most intense storms. A particularly favorable environment for tornadoes could evolve across northern MA/southern NH during the afternoon, where strong low-level shear will be co-located with substantial instability.
Strong Storms & Flooding Possible Friday (7-14)
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In a deeply moist and unstable airmass, subtle disturbances aloft should trigger waves of thunderstorms across New England and New York on Friday. A focused corridor of severe thunderstorm potential could emerge across portions of downstate NY and southern New England.