Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
045 FXUS61 KBOX 300728 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 328 AM EDT SAT JUL 30 2016 .SYNOPSIS... Most of today will be dry across the area with increasing clouds west to east during the afternoon. A series of weak low pressure areas will bring periods of showers across southern New England tonight into the first part of next week especially across western and northern sections. Scattered showers may linger into early Tuesday, especially in western sections. Low pressure will move out to sea Tuesday. High pressure returns with dry and seasonable conditions for the middle and latter portion of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Believe nearly entire forecast area will remain dry through the daylight hours today, although clouds will be on the increase from west to east during the afternoon. Slight chance of showers developing along and west of the CT river valley during the late afternoon. Max temperatures under partial sunshine will likely reach near to slightly above normal. Have gone with a model blend for the dewpoint, which lowers values about 5 to 8 degrees from Friday across most of the region outside the south coast zones where dewpoints may only drop one or two degrees. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... What looks to be a series of short wave trofs moving about a slowly progressive long wave upper trof will initiate a series of weak waves along the front stalled south of the area for tonight through Sunday. The pattern looks conducive to at least modest overrunning in an environment depicted with deep moisture from Bufkit soundings and precipitable waters around 1.5 inches. Due to at least some of the area in a drought, we are taking a conservative approach on both POPs and QPF forecasts. Also, models appear to be influenced by some convective feedback. The focus for showers is expected to be across the western half of the area tonight. For Sunday, have the POPs highest north and west where the models suggest the better forcing. With K indices in the lower 30s, cannot rule out isolated thunder this evening and again Sunday late afternoon and evening. Clouds will keep temperatures elevated some tonight with lows in themid to upper 60s across most of the region. The combination of clouds and generally onshore flow is expected to keep temperatures in the mid to upper 70s on Sunday. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Highlights... * Unsetlled Sunday through early Tuesday with scattered showers, mainly in western sections. * Mainly dry and seasonable weather Tuesday afternoon through Friday, with a warming trend. Overview and model preferences... Models in reasonably good agreement through the period. An upper level trough moves from the eastern Great Lakes Sunday across New England early Tuesday, then out to sea. A ridge of high pressure builds aloft across the northeast states, cresting over the region on Friday. At the surface, a warm front will develop to our south Sunday. Several waves of weak low pressure are forecast to move along the front, but remaining to our south. The low finally consolidates then moves out over Georges Bank by Tuesday. High pressure settles over New England Tuesday afternoon through Friday. A cold front is then poised to move through the area next Saturday. Used a consensus blend of available model and ensemble guidance for this portion of the forecast. Details... Sunday through early Tuesday... Expect waves of low pressure to move slowly along a stalled front just south of New England, keeping low and mid level moisture in place with a light east-southeast flow gradually becoming northeast. On Sunday afternoon and evening, models have been consistently showing instability over the Hudson Valley in southeast NY. With upslope flow, our best chances of showers will be in the higher terrain of western MA and perhaps also in the Worcester hills. The ECMWF is an outlier in showing heavy convection/thunderstorms moving eastward from the Hudson Valley into CT and then into southern RI, as it travels along and just north of the warm front. For now have 50-60 percent probabilities in western MA and northwest Hartford County, with lesser chances as one heads east. Generally the same reasoning continues Sunday night through early Tuesday. During this time, low pressure consolidates and moves out sea, southeast of Cape Cod/Islands. There could be scattered showers at any time, with the best chances in the western hills. But most of the time it will be rain-free. Temperatures will run slightly below seasonal normals with highs Sunday in the 70s and mainly 75-80 Monday. Tuesday afternoon through Friday... A high amplitude 500 mb ridge moves east from the eastern Great Lakes and crests over New England on Friday. By Wednesday, our winds will shift to a southwesterly direction and the gradual warming trend will begin. Maximum temperatures will rise a few degrees each day, reaching the mid and upper 80s Thursday and upper 80s to lower 90s on Friday. No precipitation is forecast, although we cannot rule out an isolated shower or thunderstorm in far northwestern sections late Friday afternoon. A cold front is then expected to move through the area next Saturday with a chance of showers or thunderstorms, but that`s beyond our current forecast period. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday/... Today...High confidence. The combinaton of a high summer sun angle and intrusion of modestly drier air should help burn off areas of fog by mid morning and resulting in widespread VFR conditions. Increasing mid to high clouds is expected west to east during the afternoon but remaining vfr. Tonight...Moderate confidence. VFR ceilings are expected to prevail with areas of MVFR visibility and ceilings in vicinity of some showers tonight. More widespread MVFR conditions expected in areas of fog along southeast coastal areas. Light winds with sea breezes developing along both the south and east coasts by afternoon. Sunday...Moderate confidence. Becoming mostly VFR ceilings with some MVFR ceilings in vicinity of showers. Pockets of IFR ceilings and visibilities due to morning fog acros southeast coastal sections. KBOS TAF...High confidence. Generally VFR conditions expected through the period, although occasional MVFR ceilings possible in vicinity of showers and fog late tonight/early Sunday. KBDL TAF...High confidence. VFR conditions expected through the period except patchy fog may develop late tonight. Outlook /Sunday Night through Wednesday/... Sunday night through early Tuesday...Moderate confidence. Mainly VFR conditions. However, there will be scattered showers at any time. Cannot rule out a heavier shower or thunderstorm, especially in the slopes of the Berkshires and in northern CT on Sunday. Brief MVFR/IFR conditions are possible in the heavier showers. Patchy late night/early morning fog is possible, especially along the south coast, closer to the warm front. IFR conditions are likely in any areas of fog. Tuesday afternoon through Wednesday...High confidence. VFR. Just a few areas of MVFR possible in patchy late night/early morning valley fog and in the usual fog-prone places. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday/...High confidence. Winds and seas are expected to remain below Small Craft Advisory thresholds through Sunday. Areas of visibilities 1 to 3 nm in areas of late night/early morning fog are expected. Outlook /Sunday Night through Wednesday/...High confidence. Expect easterly winds (southeast through northeast) and seas below small craft criteria through the period. Seas may build to 4 ft Monday into Tuesday as low pressure passes through the region and out to sea around Georges Bank. Northeast winds may gust up to 20 kt mainly over the eastern outer waters Monday night and Tuesday. Locally reduced visibilities in scattered showers or an isolated thunderstorm through early Tuesday morning. Patchy late night/early morning fog through the period. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...GAF/Thompson NEAR TERM...Thompson SHORT TERM...Thompson LONG TERM...GAF AVIATION...GAF/Thompson MARINE...GAF/Thompson is the U.S. government's official web portal to all federal, state and local government web resources and services.