Area Forecast Discussion
Issued by NWS Boston, MA

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964 FXUS61 KBOX 180707 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 307 AM EDT Wed Oct 18 2017 .SYNOPSIS... High pressure will maintain dry weather and warmer than normal temperatures through the weekend. && .NEAR TERM /THROUGH TODAY/...
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Starting to see wide range in temperatures this morning, with 30s showing up where winds have gone calm and 40s where light SW winds prevail. Expect to see some fluctuations through sunrise but frost threat will be very limited. High pressure builds south of New England today, resulting in plenty of sunshine and milder W/SW flow with highs in the 60s and lower 70s. Once again today there is possibility of weak sea breeze along eastern MA coast later this afternoon, mainly from 3-6 pm as gradient weakens for a time. Forecast soundings show winds slackening through lowest 2kft and heating over land should create enough land/sea differential for sea breeze development.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/...
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Tonight starts off clear but model cross sections show potential for some low clouds to develop across NE CT, RI, and SE MA due to persistent SW flow and increasing low level moisture. Not entirely confident this will occur, as high-res models can overdo cloud cover in these situations, so for now we simply trended forecast to indicate some cloudiness in these areas. Any low clouds should burn off quickly Thu morning, followed by plenty of sunshine and increasing SW winds. Highs should end up a few degrees warmer than today, mainly in low to mid 70s, except 60s near south coast, Cape Cod, and Islands. This will fall a bit short of tomorrow`s record highs which are in the low to mid 80s (BOS 84 in 1945, PVD 83 in 2016, BDL 82 in 1963, ORH 81 in 1963).
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Highlights... * Above average temps and dry conditions lasting into the weekend * Next shot for precip appears to be around Tuesday Pattern Overview/Confidence... 12z guidance is in good agreement for the long term. Upper level shortwave will move through the flow on Thursday. Behind this wave, anomalous ridging will develop across the East Coast. Heights and temperatures will rise to 2-3 STD above normal. This strong ridge will last into early next week before a pattern change appears to take hold of the area. This switch will be associated with the digging trough across the eastern half of the CONUS by the Tuesday timeframe. Details... Temperature Forecast... Overall trend in the forecast is for above average temperatures through the period. Thursday`s breezy southwest flow combined with 850 mb temps near 10-12C will result in highs in the low to mid 70s. Cool front will sweep through the region Thursday night leading to a cooler day on Friday. Anomalous ridge will begin to build for the weekend into Monday resulting in high temps into the mid 70s. Tuesday`s temperature forecast is a bit trickier as it is dependent on the timing of the front. Thus will trend towards a model consensus until guidance gets a better handling on the FROPA. Precipitation Forecast... Frontal system on Thursday will pass through, but lack of moisture with the front will lead a dry passage. High pressure will take over the area on Friday through Monday leading to dry weather. Next chance or precipitation will be around the Tuesday timeframe when a potent trough will dig into the Ohio Valley and towards the East Coast. Several waves of low pressure will ride along this through resulting in a more unsettled weather pattern Tuesday and beyond. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Thursday/...High confidence. VFR. Exception is across NE CT, RI, and SE MA late tonight into Thu morning where we may see IFR ceilings develop, including KPVD. SW flow expected today through Thu, though weak sea breeze is once again possible along E MA coast for a few hours later this afternoon. If it occurs, it would be roughly from 19z to 22z. KBOS Terminal...High confidence in TAF. Low chance of weak sea breeze 19z-22z but am more confident in S/SW winds during that time. KBDL Terminal...High confidence in TAF. Outlook /Thursday Night through Sunday/... High Confidence. VFR. && .MARINE...
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Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Thursday/...High confidence. Maintaining SCA for outer waters from Stellwagen Bank to east of Cape Cod, due to lingering 25kt winds and 5-6 ft seas this morning. Otherwise high pressure building south of New England will result in SW flow through Thursday, which should build seas on south coastal waters to 5-6 ft during afternoon. May need to issue another round of SCA if it becomes more likely. Outlook /Thursday Night through Sunday/...High confidence. High pressure prevails through the upcoming weekend with sub SCA conditions. The only exception is that SCA conditions may be approached Thursday night ahead of a passing front as SW winds could gust up to 25 kts.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 11 AM EDT this morning for ANZ250- 254.
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&& $$ SYNOPSIS...Belk/JWD NEAR TERM...JWD SHORT TERM...JWD LONG TERM...Belk AVIATION...Belk/JWD MARINE...Belk/JWD

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