Area Forecast Discussion
Issued by NWS Boston, MA

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046 FXUS61 KBOX 301543 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 1143 AM EDT MON MAY 30 2016 .SYNOPSIS... Lingering showers over RI and Eastern MA will trend offshore during early afternoon. A few thunderstorms may develop this afternoon across Eastern NY and move into Western MA/Northern CT late afternoon/early evening. Mainly dry weather is then expected tonight except for another batch of showers that may graze the south coast and Islands. Dry conditions with warm afternoons follow Tuesday into Wednesday. Unsettled weather may return by the end of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... The flow of tropical air into New England is shifting east. Showers and the deep high moisture air is shifting with it. Extrapolation of the showers would take most of them offshore early afternoon. Showers located south of Long Island are moving almost parallel to the upper flow toward Cape Cod/Islands and will continue to affect that area through roughly 3-4 pm. Satellite images show a clearing trend west of the Hudson River that will be moving east this afternoon and should allow some breakage of the sky cover over western MA and NW CT. Fair amount of instability over Eastern NY which with the solar heating should allow showers/scattered tstms to develop during the afternoon. The partial clearing in the CT Valley region should generate enough instability for this convection to reach the valley, and possibly enough to reach the Central Hills as well. Still patches of dense fog lingering off the south coast, although the only land station showing this was Chatham at 1/2 mile vsby. While fog may linger in spots, we expect the trend to higher vsbys to continue through the afternoon. No change to expected temps at this time. Where there is enough sun in the west, temps should have a shot at 80. Farther east, 70s looks more reasonable. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/... ***Patchy dense fog may develop late tonight*** Tonight... If a few thunderstorms are able to develop across interior southern New England, they will weaken this evening with the loss of instability. Otherwise, much of the night will be dry but can not rule out a few brief showers as the actual cold front crosses the region. The one exception to this is along the south coast and particularly Martha`s Vineyard/Nantucket, where a weak surface trough will combined with still relatively high PWATs. This will likely result in another period of rain showers overnight. Low temperatures tonight will mainly be in the upper 50s to the lower 60s. Breaks in the clouds overnight may allow for some patchy dense fog to develop given the wet ground, so something will have to watch closely. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights... * Mainly dry with above normal temperatures Tue/Wed * Unsettled weather may return toward next weekend Medium range models are in good agreement on the overall synoptic pattern. A mid-level ridge will move over southern New England Tuesday and then move offshore Wednesday. Mid-level troughing then moves into Quebec towards the end of the work week and starts influencing our weather with several shortwaves working around the base of the trough. This will result in more unsettled weather towards the end of the week. Tuesday and Wednesday...Mid-level ridge moves over southern New England. This will bring dry weather to much of the area. A dry cold front will move through southern New England Tuesday, resulting in a wind shift to the north. This is followed by another back door cold front on Wednesday. Temperatures will be above normal through both days, especially across the western zones. Onshore flow will result in more seasonable temperatures along the east coast. Thursday through Sunday...Mid-level trough moves into Quebec allowing several shortwaves rotating through the base of the trough to move through southern New England. This will result in periods of showers, particularly Friday and Saturday. Due to the difficulty in pinpointing when and where these showers will occur, have kept chance PoPs in the forecast for much of this period. However, not expecting rain to be widespread, nor for the entire period. Temperatures will be around normal for much of the time. && .AVIATION /16Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tonight/... Today...Moderate confidence. Lingering low ceilings across the region late morning. Cigs of 500-1000 feet should continue through early afternoon. A clearing trend in Eastern NY suggests some drying in the lower layers which may allow ceilings to lift this afternoon. Low confidence as to the mid-late afternoon heights. These could be as low as 1500 feet or as high as 4000 feet depending on how this drying takes shape. Fog and showers will hang tough along the South Coast and Islands. This may hold down cigs/vsbys in this ares through mid afternoon. Meanwhile there is potential for a few thunderstorms developing in Eastern NY and moving into Western MA/Northwest CT with timing after 19Z / 3 PM. These may reach Worcester and the Central Hills late afternoon/evening. Tonight...Moderate confidence. Mainly MVFR to even VFR conditions this evening, except the Cape and Islands where IFR conditions persist. Localized IFR to even LIFR conditions may develop late across other areas in patchy dense ground fog. KBOS TAF...Moderate confidence in TAF. KBDL TAF...Moderate confidence in TAF. Outlook /Tuesday through Friday/... Tuesday and Wednesday...Moderate confidence. VFR. Thursday...Moderate confidence. Mainly VFR conditions expected. Increasing clouds with diminishing conditions through the night, particularly along the south coast. Friday...Moderate confidence. Mainly VFR conditions expected. Brief MVFR conditions are possible in SCT -SHRA at times. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tonight/...High confidence. Patches of dense fog lingered late morning over Nantucket Sound and Buzzards Bay. But the overall trend has been for improving vsbys and so we expect this trend to continue across the waters. A period of southwest wind gusts in the lower 20 knots may affect the near shore waters of the south coast this afternoon, but kept them just below small craft advisory thresholds. Some very marginal 5 foot swell may arrive into our extreme southern outer- waters overnight, but they look to cover such small area will let the next shift assess. Outlook /Tuesday through Friday/... Tuesday...Moderate confidence. Some uncertainty on wave heights with swell from Tropical Depression Bonnie potentially moving up into the coastal waters. At this point there is potential for 5 foot seas, especially on the outer waters. Southwesterly winds remain below 20 kts, shifting to the north Tuesday night. Wednesday...Moderate confidence. Northeasterly winds and seas will remain below Small Craft Advisory criteria. Thursday...Moderate confidence. Easterly winds and seas increase. Seas may rise above 5 feet, especially on the outer waters. Friday...Moderate confidence. Easterly winds are expected to remain below 15 kts. Seas decrease through the period. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Frank/RLG NEAR TERM...WTB/Frank/RLG SHORT TERM...Frank LONG TERM...RLG AVIATION...Frank/RLG MARINE...Frank/RLG

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