Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 250206 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 1006 PM EDT Sun Mar 24 2019 .SYNOPSIS... A cold front sweeps across the region tonight followed by cooler but dry weather Monday. Dry weather continues through the end of the week with chilly weather Tue gradually moderating as the week progresses. Mild weather next weekend but risk of showers increases Sunday as cold front approaches. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... No major changes to the forecast this evening. Mid and high level clouds will gradually increase across southern New England overnight, particularly along and south of the Mass Pike. Main changes this evening were to bring temperature back in line with observed trends. Large dewpoint depressions will continue near the ground, for several more hours anyway. Not expecting much precipitation to reach the ground, but cannot dismiss the possibility of a few light showers later tonight. Showers more likely toward the south coast of New England late tonight, where the low level humidity is higher, and a cold front approaches from the north. This cold front was across central VT and NH at 10 PM, so it will take just about all night to reach the coast. Will continue to monitor its progress. Previous Discussion... Mainly high clouds currently moving across SNE ahead of mid level shortwave. Cold front moving south from northern VT will take its time as it approaches SNE and cross SNE late tonight and Mon morning. Moisture is limited so expecting a mainly dry fropa. Best moisture stays to our south with marginally dry low levels over SNE so this shortwave passage isn`t expected to bring much more than increased cloud cover. If anything a few light spot showers may appear Monday morning, best chance over the Berkshires where orographics can help, and along the south coast where higher dewpoints located. Lows only drop into the 30s given the warm airmass ahead of the front. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Cold front moves off the south coast Monday morning ushering in a drier airmass and quickly clearing skies. Best chance of seeing some clouds is along the south coast, closest to better moisture and a passing system to our south. High pressure expanding over SNE should keep this system suppressed well to our south. CAA behind the front but the coldest air doesn`t make it over the region until Tuesday morning, so we`ll still see highs in the upper 40s. Monday night north winds bring the cold pool south with 850mb temps dropping from -5C to -12C between Monday and Tuesday mornings. This brings lows back into the 20s; teens in the higher terrain. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights... * Dry weather through much of the upcoming week * Chilly Tue, then warming trend with above normal temps by Fri * Mild and mainly dry Sat, then increasing risk of showers Sun Tuesday through Friday... Mainly dry weather through at least Thu and possibly into Fri as well, but shower risk will increase slightly Thu night/Fri. Coastal storm moves well out to sea Tue with high pres building into New Eng Tue night/Wed leading to mostly clear skies. Mid level trough over New Eng on Tue with 850 mb temps -10C will bring below normal temps, then moderating Wed as trough lifts out and heights rise. Warming trend will continue Thu and Fri as high pres moves offshore with SW flow developing. Temps should be near normal Thu and above normal Fri with some 60s possible across interior locations. Still dry Thu, then northern stream trough passes to the north as weak cold front approaches from northern New Eng. This may lead to a few showers Thu night/Fri, mainly across the interior, but dry weather most of the time. Saturday and Sunday... Forecast confidence decreases as models differ on how additional northern stream energy dropping into the Great Lakes and New Eng interacts with approaching Pacific shortwave. It looks like mostly dry weather may hold on for Sat as front stalls to the north and west with backing flow ahead of next shortwave. Just a low risk for a few showers in western MA at this time, but this is day 6 and if the trough and front speed up, the risk for showers will increase. If front does remain to the north, potential for temps well into the 60s to near 70 degrees in the interior Sat. Low confidence forecast for Sunday. GFS indicating more progressive northern stream with cold front sweeping through Sat night with a period of showers then cooler and drier Sun. ECMWF shows much more amplified northern stream trying to phase with Pacific energy. Result is much slower timing of front with mild weather lasting into Sun although shower threat would be increasing from the west as front approaches. 12z EPS shows considerable spread with location of the boundary but favor a compromise between deterministic ECMWF and GFS with fairly high probs of rainfall. As a result we will indicate chc showers for Sun. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/... Tonight... VFR and dry this evening with WSW winds. After 06Z, VFR cigs OVC100 with a spot shower or sprinkle possible. WSW winds shifting to NW. Monday ... Brief MVFR in the morning, mainly south coast with low risk of a spot shower/sprinkle, then trending VFR from north to south with dry conditions. North winds. Monday night... VFR. KBOS terminal...High confidence in TAF. KBDL terminal...High confidence in TAF Outlook /Tuesday through Friday/... Tuesday through Wednesday: VFR. Breezy. Wednesday Night through Thursday: VFR. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/... This evening, extended the Small Craft Advisory for most of the south coastal bays and sounds. Observations continue to indicate gusts up to 25 kt late this evening. Tonight ... Dry cold front moves across southern New England. WSW winds become NW toward daybreak as cold front moves toward the south coast. Monday ... WSW winds becoming NNW by midday as dry cold front moves offshore. Monday Night ... Light N/NE winds. Seas less than 3ft becoming 3-5 ft Outlook /Tuesday through Friday/... Tuesday through Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Wednesday Night: Winds less than 25 kt. Thursday: Winds less than 25 kt. Seas locally approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 1 AM EDT Monday for ANZ232>235-237. Small Craft Advisory until 6 AM EDT Monday for ANZ254>256. && $$ SYNOPSIS...KJC/BW NEAR TERM...Belk/KJC/BW SHORT TERM...BW LONG TERM...KJC AVIATION...KJC/BW MARINE...KJC/BW

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