Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 191850 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 250 PM EDT Fri May 19 2017 .SYNOPSIS...
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A cold front moving over Southern New England will move offshore this evening. High pressure from Canada will build south over our region tonight and remain in place for much of the weekend. More seasonable weather is expected for the weekend into early next week. Dry initially then turning wet Monday ahead of a sweeping cold front. A brief reprieve Tuesday prior to more rain expected mid to late week along with continued near-seasonable conditions.
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&& .NEAR TERM /THROUGH TONIGHT/...
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This evening... Still watching convective potential for the late afternoon and evening hours. Drier air has moved into areas north of the Mass Pike with dew points in the 50s. Higher values remain to the south. One shower fired near White Plains NY early afternoon. The HRRR forecasts scattered convection to fire over parts of CT- RI and SE Mass until 00Z. The instability is in place with CAPE forecast near 1500 J/Kg over those areas. Certainly warm enough with sfc temps reaching 88-91. Moisture remains limited, but could be just enough for widely scattered showers/t-storms to form. We will continue our POPs from the earlier forecast, generally slight chance or low-end chance over RI and SE Mass. Tonight... High pressure builds south from Canada tonight. clearing skies and drier air will overspread all of Southern New England. Dew points will fall back into the 40s and eventually the 30s. This will make room for temperatures to fall back into the 40s inland and low 50s near the shore.
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&& .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
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Saturday... Fair weather day with high pressure build in. Some high clouds may linger to the south and southwest, but otherwise a sunny day. Mixing should again reach at least 850 mb, where temperatures will be 4-6C. That would support max temps in the mid and upper 60s. If we mix higher, which is very possible in the interior, temps would reach the lower 70s. Winds will turn northeast in eastern Mass and RI in response to the position of the high center. There could also be a sea breeze component along the immediate coast. Either way, temps in eastern Mass should be cooler than farther west. We will go with a range of 60s east to lower 70s west. Saturday night... Fair skies and light wind. Dew points in the mid 30s to low 40s. Expect min temps in the upper 30s to mid 40s.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/... */ Highlights... - Seasonable and dry for Sunday - Rain with embedded heavier showers for Monday - Dry on Tuesday - Wet for the mid to late week period, remaining near-seasonable */ Overview and Discussion... Not much change in the long-term forecast. While unclear as to the circumstances leading up to, enhanced H5 ridging over the NE Pacific gradually transitioning E into the W CONUS promotes downstream gyre across the Central and E CONUS through which individual disturbances rotate. Averaged out and generally speaking, an active weather setup with periods of wet-weather while being near-seasonable throughout. Pretty decent consensus we`ll salvage the weekend, comfortable and dry. Yet beginning Monday morning we`ll see a pattern of successive areas of low pressure and accompanying periods of rain through the remainder of the week inbetween which there will be lulls of drier weather and likely sunshine. Only main concern is how efficiently each individual disturbance is able to capture sub-tropical air and drag it N into S New England, as to whether there is the chance for thunderstorms and/or effective warm-rain processes. In addition the magnitude of the S draw and both the depth and richness of moisture involved. Some anomalous signals per SREF/GEFS on the order of +1-2 standard deviation with S low-level inflow and precipitable waters. Could be contending with both low cloud and/or fog issues as well as blustery S winds. Perhaps Monday and then again on Thursday. High chance to likely PoPs with a slight chance mention of thunder. Some stronger gusts and a hint of fog. All in all, seasonable conditions throughout for late May with highs in the upper 60s to low 70s and lows down into the upper 40s to low 50s. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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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 Saturday Night/... This evening... Moderate confidence. VFR. Widely scattered showers/t-storms over RI and SE Mass, especially along the south coast. This activity diminishes by 8 pm. Tonight...High Confidence. VFR. Mostly clear. Northwest winds turning from the north. Saturday...High confidence. VFR. Onshore wind expected along east coastal MA. North winds continue in the interior. Saturday night...High confidence. VFR. Mostly clear skies, light wind. KBOS TAF...High confidence. VFR expected through the period. Note wind shifts to be from the east on Saturday afternoon. KBDL TAF...High confidence. VFR expected through the period. Outlook /Sunday through Tuesday/... Sunday through Sunday night... S winds into Sunday as CIGs lower and thicken. A mix of MVFR-IFR into Monday morning W to E with onset of -RA/RA. Monday into Monday night... MVFR-LIFR. Lowest conditions likely for the S-coast with potential fog impacts. Increasing S winds ahead of a line of widespread -RA with embedded RA/+RA late and into evening. Gusts up to 25 kts. Low risk TSRA. Possible LLWS impacts with S/SW winds 2 kft AGL 40-50 kts. Tuesday into Tuesday night... VFR. Clearing. Possible SKC if not SCT-BKN low-end VFR CIGs and possible mid-level CIGs late. NW winds initially turning S. May be light enough to allow onshore sea-breezes.
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&& .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 Saturday Night/...High confidence. Lingering 5 foot seas on the southern and southeast outer waters this evening, but this should diminish this evening. A cold front moves across the waters early tonight. Winds then turn from the northwest and eventually from the north. Winds will be less than 25 knots and seas less than 5 feet through the night. High pressure builds over the waters Saturday and Saturday night. Winds turn from the northeast Saturday and then become light variable Saturday night. Seas will remain less than 5 feet. Outlook /Sunday through Tuesday/... Great boating weather continues into Sunday with light S winds and waves 1-2 feet. Going into Monday, S winds on the increase with gusts up to 25 kts ahead of a cold front along with a widespread line of rain with embedded heavier showers beginning Monday morning and dissipating late afternoon into evening. A low risk of thunderstorms. Clearing out after midnight into Tuesday morning though waves build 5 to 6 feet and are slow to diminish under NW winds. Winds are light through Tuesday turning S so this should allow seas to subside.
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&& .CLIMATE...
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High temperatures through 2 pm... BOS 88 90 (1986) PVD 90 New record, old record 89 (1906) BDL 90 94 (1962) ORH NA 92 (1962) Lost in the talk of high temperatures... all four climate sites broke their high minimum temperatures on Thursday. BOS 71 Old record 63 (1896) PVD 70 Old record 62 (1943) BDL 67 Old record 64 (1906) ORH 69 Old record 63 (1943)
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ235- 254>256. && $$ SYNOPSIS...WTB/Sipprell NEAR TERM...WTB SHORT TERM...WTB LONG TERM...Sipprell AVIATION...WTB/Sipprell MARINE...WTB/Sipprell CLIMATE...

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