A relatively quick prospectus tonight to outline what's developing this week.
The longwave pattern features our stalled upper level low south of New England that will weaken gradually, producing showers of a more scattered nature as it fills, then finally being swept northeast as rising heights move across the Northeast. This allows for a long-range pattern that will feature much higher average 500 mb heights across the Northeastern United States, indicating the average temperature will be noteably higher for the start of July, though it's interesting to note that the mean trough position remains over Eastern Canada, the Eastern Great Lakes and New England, varying in longitude from time to time, but producing a pattern that should bring thunderstorms every few days, and the potential for shots of cooler Canadian air behind each cold front, though not as cool as the recent spade of chilly weather, with average high temperatures near or slightly above normal over the period from late this week through the first week of July, with above normal temperatures likely during the first half of that timeframe.
In the shorter range, the most immediate effect on our weather is clearly the storm center stalled to our south. Surface and low-level convergence bands have been focusing ocean moisture to produce bands of steady rain that have been migratory in the northeast flow across Eastern New England. Even mesoscale models have great difficulty nailing the location of these convergent bands and that's likely to continue to be the case in the coming days, but the general agreement among guidance is to carry steady and at times heavy rain that's been offshore of the Cape onto Cape Cod late Sunday night into Monday morning, with another batch of steady and heavy rain possibly rotating onshore to the Midcoast of Maine late Monday/Monday evening. Northeast winds will continue gusting to 40 and perhaps 45 mph on Monday based upon mixing to 925 mb, though worth noting the NMM wind gust algorithm indicates perhaps 40-42 knot gusts on Cape Cod late Monday.
Of course, this continuing northeast wind will force water up against the coastline, and as mentioned in NWS products, coastal flooding on northeast facing shorelines will continue to be a possibility through Tuesday high tide cycles with new moon on Tuesday and though the tide is not astronomically all that high midday Monday, the midnight Monday night high tide is quite high and should pose problems for many communities.
Each day on Tuesday and Wednesday, bands of rainfall will become less impressive, more breaks of sun will emerge in Northern and Western New England, but moisture will hold tough for lots of clouds on Tuesday, then on Wednesday any breaks are likely to fill back in as diurnal heating fills low level stratocu back in again. Thursday brings a westerly wind or even a northwesterly wind and this dries us out effectively with downsloping, and warm advection keeps coming from the west, very quickly moderating the atmosphere. Upstream highs in this airmass have been in the 80s, and we should make that jump for the end of the week. Of course, as mentioned in the longwave pattern synopsis, shortwaves will continue traversing New England in the upper level flow, and this will breed periodic scattered thunderstorms that will be largely diurnally driven.
That's all for tonight - see you on TV in a few hours!
Matt
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