Plaincast
What the forecast actually says — NWS Area Forecast Discussions, decoded into plain English.
Revised in 3 passages since the 3:16 AM discussion. See every revision.
Plenty of sunshine with comfortable humidity today & Sat and highs in the 70s. Lows tonight in the 40s & 50s.
Showers and possibly a few thunderstorms with brief torrential rainfall possible late Sat night into the first half of Sun. Low probability for localized flash flooding.
Dry and seasonable Mon-Tue but a brief bout of summer warmth and humidity possible Wed and/or Thu ahead of a cold front.
KEY MESSAGE 1. Plenty of sunshine with comfortable humidity today & Sat and highs in the 70s. Lows tonight in the 40s & 50s.
Large high pressure builds over the region today into Sat. This will result in plenty of sunshine and very pleasant September weather with comfortable humidity. Highs today and Sat will be well into the 70s with much less wind than yesterday. Mainly clear skies, light winds, and a dry airmass in place will result in ideal radiational cooling conditions tonight. Low temperatures tonight will bottom out in the 40s to the lower 50s. But middle to upper 50s in the urban centers of downtown Boston/Providence.
KEY MESSAGE 2. Showers and possibly a few thunderstorms with brief torrential rainfall possible late Sat night into the first half of Sun. Low probability for localized flash flooding.
High pressure moves off the coast for the second half of the weekend. At the same time. a shortwave and an associated warm front will approach from the southwest. This will result in quite the mid level instability burst. Showalter indices drop nearly 20 units to near or below zero inside about 12 hours. That rapid change in stability supports the development of a complex of showers and perhaps a few thunderstorms. This coupled with Pwats rising to around 2 inches support the potential for pockets of torrential rainfall. This will be dependent on where a meso-surface low tracks and sets up a boundary for enhanced convergence. This will of course be a nowcast/mesoscale type of forecast. but given the Pwat plume/low level boundary there is a low probability for localized flash flooding. Usually for this to occur. several things need to happen on the mesoscale but it is something we need to watch with the main concern near and south of I-90.
The timing still needs to be refined. but favoring late Saturday night into Sunday morning as to when the bulk of the rainfall occurs. Rainfall amounts are highly uncertain and potentially extremely variable. Perhaps just a tenth to half inch in many locations. but the potential exists for a very localized narrow band of 2-3"+ of rainfall in a short amount of time. The models that indicate this risk have it in a different locations too. And even if this occurs it may not end up in our forecast area. Nonetheless. it is something we certainly need to watch. It will be also become quite muggy by Sunday afternoon with highs in the 70s.
KEY MESSAGE 3. Dry and seasonable Mon-Tue but a brief bout of summer warmth and humidity possible Wed and/or Thu ahead of a cold front.
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Data from the National Weather Service. Translated by Claude. About · For developers & agents · Subscribe: RSS feed for this office · Source on GitHub