Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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. --
131 FXUS61 KBOX 291941 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 341 PM EDT Thu Sep 29 2016 .SYNOPSIS...
-- Changed Discussion --
A wave of low pressure will pass south of the region, bringing cloudy, cool conditions with showers Friday through Saturday which may linger into Sunday. Low pressure lifts to the Great Lakes over the weekend and sweeps east across New England early next week. High pressure then brings dry weather midweek.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --
4 PM Update...Northeasterly winds will continue into tonight, gusting up to 25 to 30 mph, particularly along the east coast. Otherwise, clouds will build back in overnight as high pressure retreats back north and a weak wave of low pressure works its way up the coast. Much of the night should be dry, though cannot rule out a few showers starting on the south coast before daybreak. Low temperatures will fall back into the upper 40s to mid 50s.
-- End Changed Discussion --
&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
-- Changed Discussion --
Friday and Friday night...A strong pressure gradient between the high pressure to the north and a weak low pressure to the south will result in a strong low level jet and periods of showers. There will be plenty of moisture with a plume of higher PWAT (1.5-2 inches) air moving into the region at this same time. Periods of heavy rain are possible, particularly where collocated with the anomalous low level jet along the south coast. That said, the drought continues, with only up to around an inch of rain expected for most places. In addition, gusty northeasterly winds will continue. Expect similar temperatures to today with highs in the upper 50s to lower 60s and lows in the upper 40s to mid 50s.
-- End Changed Discussion --
&& .LONG TERM /SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
Big Picture... Longwave scale shows high pressure lingering over the West Atlantic through the period while a trough remains over the Western USA. Shortwave scale shows the Atlantic ridge shifting south a little during the weekend, making room for Midwest closed low to lift a little and then eject across New England early next week. High pressure then builds over the Northeast USA midweek. Operational GFS at long ranges is showing Matthew approaching up the coast for later Thursday. The track has again moved to a western/inland path. The ECMWF is much slower with Matthew over the Bahamas, a substantial blocking ridge over the Northeast, and no trough to guide the storm north. The lack of model-to-model and run- to-run consistency leads to no confidence in any forecast bringing rain to our area Thursday. This remains a storm to watch, but at this time expect a slower solution for us than what the GFS hints. Details... Saturday-Sunday... Closed upper low over the Midwest and upper ridge over the West Atlantic provide a south-southwest channel in the upper flow. A 100- knot jet in that flow moves toward New England with our area in the right entrance region, favoring upper venting and lift. Meanwhile the low-level easterly flow remains in place with 25-30 knot winds just off the deck. Expect the moist south flow to be lifted over the low level easterlies generating showers. PW values 1.5 to 1.75 inches, so any showers may have locally heavy downpours. Expect the low level east- northeast flow to maintain clouds and fog. Monday-Tuesday... Upper low and cold pool move overhead late Monday and Tuesday. This will bring instability with totals in the upper 40s, and should maintain partly to mostly cloudy skies each day with a chance of showers. Surface wind flow will maintain a northeast direction off the ocean. This buffers temps with max values in the 60s to around 70, warmest in the CT River Valley. Wednesday-Thursday... High pressure builds over the region with dry weather and partly sunny skies. Northeast flow continues. As noted above, GFS handling of Matthew is a fast outlier and so is discounted in favor of the slower solutions.
-- End Changed Discussion --
&& .AVIATION /20Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday Night/... Through 00Z...Moderate confidence. A mix of conditions will continue through the rest of the day with a mix of MVFR and low end VFR conditions across eastern MA and a mix of VFR to clear skies across the western zones. NE winds gusting to 25-30 kt across E MA/RI. Tonight...Moderate confidence. Mainly VFR tonight near and N of the Mass Pike. Low end VFR-MVFR CIGS move into southern areas. Gusty NE winds to 25-30 kt continue along the east coast. Friday and Friday night...Low confidence, mainly for timing. Will see MVFR- IFR CIGS and/or VSBYS as -SHRA and patchy fog move in from S-N during the day. NE wind gusts up to 25 kt continue along the coast. KBOS TAF...High confidence in trends, moderate confidence in timing. KBDL TAF...High confidence in trends, moderate confidence in timing. Outlook /Saturday through Tuesday/... Saturday-Sunday...Moderate confidence. MVFR/IFR cigs and vsbys in showers and fog. Northeast flow with gusts 20 to 30 knots Saturday, diminishing Sunday. Monday-Tuesday...Low confidence. VFR with areas of MVFR in scattered showers.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday Night/... High confidence. Small craft advisories and gale warnings continue on the waters for much of the period with gusty NE winds continuing through Friday night. These winds will allow seas to build as well. Therefore, added about 30 percent to the SWANNAM wave heights to bring the waves more in line with what we`re seeing now and what we`re expecting over the next 36 to 48 hours. Outlook /Saturday through Tuesday/... Saturday...Northeast winds gusting 25 to 30 knots. Rough seas with Eastern MA exposed waters reaching 7 to 10 feet and outer Southern waters around 5 feet. Poor vsbys in showers and fog. Small craft advisory will be needed. Sunday...Diminishing Northeast winds with gusts 20 knots or less. Seas 5 to 6 feet on the waters east of MA. A Small Craft Advisory may be needed on the eastern waters. Monday...Northeast winds less than 20 knots. Seas less than 5 feet. Tuesday...Northeast winds with gusts 20-25 knots on the outer waters. Seas build to 5-7 feet on the outer waters. Small Craft Advisory may be needed on those waters.
-- End Changed Discussion --
&& .BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None. MA...High Surf Advisory until 6 PM EDT this evening for MAZ007-022- 024. RI...None. MARINE...Small Craft Advisory until 8 AM EDT Saturday for ANZ231>236- 250-251-254-255. Small Craft Advisory until 6 PM EDT this evening for ANZ230. Gale Warning from 2 AM to 8 PM EDT Friday for ANZ237-256.
-- End Changed Discussion --
&& $$ SYNOPSIS...WTB/RLG NEAR TERM...RLG SHORT TERM...RLG LONG TERM...WTB AVIATION...WTB/RLG MARINE...WTB/RLG

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.