I appreciate you checking in on this Memorial Day - a beautiful summer-like day for most of New England. The weather map shows a double barreled high pressure off the Eastern Seaboard - one center just southeast of the Cape, and another just southeast of Cape Hatteras, NC. To the west of New England, an area of low pressure is moving east from the Upper Peninsula of Michigan. The pressure gradient is creating a large swath of gusty winds, with gusts as high as 35 to perhaps even 45 mph by day's end, especially along the South Coast. This wind churns the seas and is the reason for small craft advisories, and is the reason I wouldn't encourage new boaters or small pleasure craft boaters to venture too far outside the bays, harbors, sounds and inlets today. The wind has been a strong crosswind for the return leg of the Figawi race from Nantucket to Hyannis Port. Inland, the active wind coupled with low relative humidity is the cause for the Red Flag Warning for explosive fire conditions from the NWS - largely because of the ventilation the active wind provides.
Showers and clouds near a warm front will continue to migrate across the far North Country. A shortwave slated for overnight tonight was gaining big billing in the 00Z model suite but has lost some of its definition in successive runs, perhaps somewhat a result of convective feedback initially, plus a flatter ejection in a slightly more pronounced shortwave ridge ahead of an impressive vorticity maximum slated for passage on Tuesday into Tuesday night. The result for Monday night should be some showers for much of Central and Northern New England as convection that will develop in the Ohio Valley and Great Lakes Monday afternoon will weaken while moving east. Of course, the cold front associated with the area of low pressure moving east out of the Upper Great Lakes will draw closer, not making passage across New England until later Tuesday. A stiff southwest wind will continue in advance of the front and though lots of clouds seem likely with mid-level debris from leftover/decayed convection, there should also be plenty of breaks of sunshine to get temps around 80 and this will boost instability and convective parameters. The result will be a developing and intensifying line of thunderstorms across especially Central and Southern New England later Tuesday as impressive surface convergence coordinates with dynamic lift in the cyclonic vorticity advection ahead of the approaching strong vorticity maximum. Though that energy center eventually passes across Northern New England, and not until Tuesday night, the vorticity advection combined with a ripe pre-frontal low level environment will be sufficient for convective initiation. Winds are mostly unidirectional but increase with height - from 25-35 kts at 850 mb to 35-55 kts at 700 mb and 50-65+ kts at 500 mb! LI (lifted index) will be -2 to -4 and surface based CAPE runs 1000+ J/kg, all of which indicates sufficient updrafts to carry this wind to the surface, so a late afternoon/evening severe thunderstorm event seems to be in the cards with at least line segments if not a bona fide squall line developing out of initiating clusters. Some clusters are likely to remain ahead of the line, but helicity values are somewhat limited, so I don't think we're looking at a real supercell threat the way I see it now - more dry intrusion downburst type convection. Hail only in the strongest cores given the extremely warm boundary layer, but torrential rain likely in most cells along with frequent cloud to ground lightning.
Though rain may linger the first part of Tuesday night in far Southern New England, the front keeps moving, and from there on out the rest of the week is pretty quiet with one shot of Canadian cool on Wednesday, then another temperature rebound Thursday before perhaps some cool advection on Friday behind a shortwave of little impact.
Have a good Memorial Day.
Matt
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