Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 211536 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 1136 AM EDT Thu Jun 21 2018 .SYNOPSIS... Low pressure near the New Jersey coast early this morning will bring an area of showers across southern areas, which should push offshore by midday. Another weak weather system may bring some spotty showers across central and eastern areas this afternoon. High pressure will bring dry conditions but a bit cooler temperatures on Friday. Unsettled conditions Saturday, continuing through early Monday with the chance of showers and thunderstorms. Dry weather expected Tuesday and Wednesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 10 am Update... Forecast is in good shape. Last of showers exiting South Coast, which will be followed by clearing early this afternoon. Still expecting scattered showers this afternoon as short wave rotates through SNE and combines with sufficient moisture and some instability (CAPE around 100-300 J/kg). Continuing with 30-40% PoPs which is in line with high-res guidance. Bumped up temperatures a few degrees based upon latest observations. Many interior spots should reach lower 80s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Tonight... Expect conditions to be mostly clear away from coastal areas tonight. E-NE winds will continue with the high to the N, so low level moisture will remain. Brought in low clouds and fog especially along the coast, but could push further inland as well. Should see lower conditions along the immediate coast. Temps will fall back through the 50s, though may hold on close to 60 in the urban centers. Friday... Any coastal fog should dissipate by mid morning or so. Otherwise, high pressure remains in control with mostly clear conditions. It will remain cool especially along the coast with continued onshore winds. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... */ Highlights... - Saturday perhaps not a washout, skirting rains S/E - Showers / t`storms N/W Sunday, sweeping SE into Monday morning - Prolonged dry conditions during the week - Watching weeks-end for additional wet-weather disturbances */ Overview... Pattern this weekend should feature above normal precipitable water. Precipitable water values drop off to near to below normal levels early next week. Temperatures on the other hand should remain near normal, except for Saturday, and perhaps Monday. Split mid level flow regime should merge into a more unified flow across much of the towards Monday. It appears likely the pattern will transition from a potent mid level low over northern Quebec with a weaker cutoff over Indiana to start this weekend, to one which features a more amplified mid level trough by Monday. This trough should move over the North Atlantic towards the middle of next week. At the surface, this should mean a low pressure moving through the Great Lakes towards northern New England this weekend. While not a total washout, we will have at least a chance for showers this weekend. A secondary cold front, along with a mid level shortwave, should be enough to cause showers to linger into Monday. This timing may change with later forecasts. Instability is enough to warrant a mention of at least a few thunderstorms at times this weekend. High pressure with drier weather Tuesday into Wednesday. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. * Updated 1135 AM * Short Term /through Friday/...High confidence. Amended ACK for impending IFR ceilings which arrive early this afternoon and persist into Friday morning. IFR or even LIFR conditions should affect much of South Coast, Cape Cod, MVY, and BID as well, especially later this afternoon. Otherwise VFR through afternoon as showers depart South Coast and scattered showers develop across interior SNE. Winds gradually shift to E/NE at 10kt or less. Tonight... Mainly VFR. MVFR CIGS along SE coastal areas with the E-NE winds in place. Patchy fog with areas of MVFR VSBYS move onshore mainly across E Mass into RI. Friday... Mainly VFR, but with E winds lingering, may see lower clouds linger across E coastal areas with local MVFR conditions possible. KBOS Terminal...High confidence in TAF. VFR through the evening push, then some MVFR CIGS/VSBYS may work in after 03Z-04Z Fri. KBDL Terminal...High confidence in TAF. Showers and lower clouds/patchy fog pass S of the terminal. VFR conditions. Outlook /Friday Night through Monday/...Moderate confidence. Friday: VFR. Friday Night: VFR. Breezy. Chance SHRA. Saturday: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA, isolated TSRA. Saturday Night: MVFR/IFR conditions possible. SHRA likely, slight chance TSRA. Sunday: Mainly VFR, with local IFR possible. Chance SHRA, isolated TSRA. Sunday Night: Mainly VFR, with local MVFR possible. Chance SHRA, isolated TSRA. Monday: VFR. Breezy. Chance SHRA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday/...High confidence. Today...Low pressure will pass across the southern outer waters with showers and patchy fog that will reduce visibility to 1-3 nm at times through midday or early this afternoon. Seas 3 ft or less. Light W winds will shift to E-NE with gusts briefly up to 20 kt. Tonight and Friday...High pressure will build N of the waters, keeping a E-NE wind flow in place through most of this timeframe. May see occasional gusts to 20 kt at times. Seas up to 3 ft, though may approach 4 ft at times across the southern waters Fri. Areas of fog will reduce visibility tonight into Friday morning. Outlook /Friday Night through Monday/...Moderate confidence. Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Friday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Saturday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, isolated thunderstorms. Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain showers likely, slight chance of thunderstorms. Sunday through Sunday Night: Winds less than 25 kt. Local rough seas. Slight chance of rain showers, isolated thunderstorms. Monday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Belk/EVT NEAR TERM...JWD SHORT TERM...EVT LONG TERM...Belk AVIATION...JWD MARINE...Belk/EVT is the U.S. government's official web portal to all federal, state and local government web resources and services.