Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 180530 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 130 AM EDT Sun Mar 18 2018 .SYNOPSIS... Dry but unseasonably cold weather will continue into early next week. A multi-part storm system moves to the Mid Atlantic states midweek. This system may affect parts of Southern New England Wed and Thu, but it is also possible the storm stays to our south with little impact. However uncertainty remains high on the evolution of this storm especially its eventual track. High pressure builds with drier weather Friday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 10pm update... With SKC conditions across all of SNE, the first in several nights, along with a slackening pres gradient, we have seen pretty good decoupling already so far this evening. This is likely helped by an established snowpack. 2m raw temps a little better than MOS, but will still leave some weight on the coolest MOS with this update as well. Otherwise forecast on track, the primary update will be on colder temps/dwpts. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... Sunday... Cold and dry NW flow continues with more sunshine than clouds. However a chilly day with highs only 30-35 with upper 20s across the high terrain. These temps are about 10-15 colder than normal. The only good news is fairly light winds will not contribute to much of wind chill. Sunday night... Another cold night with 1034 mb high pres over Ontario building southeast into New England, decoupling winds away from the urban areas and high terrain. Another round of mins in the teens. Monday... Dry but cold NW flow continues. Not as cold with highs in the mid to upper 30s, low 30s high terrain. Fairly light winds and more sunshine than clouds will make the cold conditions a bit more tolerable. Monday night... Potentially good radiational cooling with ridge of high pres cresting over the area combined with mostly clear skies, light winds and a very dry airmass. Mins in the teens once again outside of the urban areas. && .LONG TERM /TUESDAY THROUGH SATURDAY/... */ Highlights... - Tuesday into Wednesday, keep it cold and dry, N winds - Wednesday night into Thursday, monitoring potential storm - Friday into Weekend, keep cool, dry pattern for now */ Overview and discussion... Evaluating potential storm development. At set, SE Canadian gyre as Pacific energy train continues. La Nina tendencies still at play, N- Pacific H5 ridge re-emerges poleward. N-stream energy dislodged, the trof-ridge-trof pattern amplifies downstream thru the week ... but where exactly? NE CONUS perspective, progged upstream energy, even NW CONUS, bowls within a preferred H5 trof. Yet downstream pattern becomes lax, opens, suppressive wave presently slips E, NAO forecast positive. This as a mild Pacific C CONUS punch emerges. A wave-train nudge E allowing cyclonic trof digging further offshore? Or can N- stream energy, colder air cut S faster, sharper-amplified baroclinic setup closer coastal, less flat, more pronounced, per enhanced H5 C CONUS ridging? Lot of moving parts, chaotic, expect adjustments in later forecasts. Focus late Wednesday into Thursday when suppressive, confluent flow can eject E as N-stream cyclonically digs through preferred H5 trof pattern, creating a favorable environment towards storm development near NE CONUS. Believe any activity prior will be suppressed S, off- shore, beneath confluent flow aloft, only maintaining cold air. Only certainty, looks chilly through the end of the month. Threats, impacts, precipitation amounts? Way too early to say with any specificity. Proximity of any storm, thermal fields, intensity, time of day, etc., etc., all fairly unknown for now. Best advice, stay informed, keep tuned to later forecasts. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/...High confidence. Through this evening... VFR. FEW-SCT CU mainly 040-060 across SW MA/CT this evening. Winds mainly N-NW gusts to around 20 kt occasionally this afternoon. Tonight into Mon... VFR. NW winds generally lighter than previous days, mainly around 10 kt. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Tuesday through Thursday/... Tuesday: VFR. Breezy. Tuesday Night: Windy with areas gusts to 30 kt. Slight chance SN. Wednesday through Wednesday Night: Windy with gusts to 35 kt. Slight chance SN. Thursday: Windy with gusts to 35 kt. && .MARINE... Short Term /through Monday Night/...High confidence. Tonight... Gales concluded. Small crafts in effect. NW winds continue behind a dry Arctic front as high pressure settles in N/W. Low risk of areas of light freezing spray across the eastern MA waters. Sunday thru Monday night... Modest NNW winds with possible areas of light freezing spray eastern MA waters at night, then diminishing Mon night as ridge of high pres builds across the waters. Outlook /Tuesday through Thursday/... Tuesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Slight chance of snow. Tuesday Night: Low risk for gale force winds with gusts up to 35 kt. Local rough seas. Slight chance of rain, slight chance of snow. Wednesday: Moderate risk for gale force winds with gusts up to 35 kt. Rough seas up to 10 ft. Chance of snow, chance of rain. Wednesday Night: Moderate risk for gale force winds with gusts up to 40 kt. Rough seas up to 11 ft. Chance of snow. Thursday: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 11 ft. Slight chance of snow. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 2 AM EDT early this morning for ANZ230>234-250-251-256. Small Craft Advisory until 6 AM EDT early this morning for ANZ254-255. && $$ SYNOPSIS...Nocera/Sipprell NEAR TERM...Doody SHORT TERM...Nocera LONG TERM...Sipprell AVIATION...Doody/Sipprell MARINE...Nocera/Sipprell is the U.S. government's official web portal to all federal, state and local government web resources and services.