Area Forecast Discussion
Issued by NWS Boston, MA

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534 FXUS61 KBOX 211922 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 222 PM EST Tue Feb 21 2017 .SYNOPSIS... A weak cold front dissipates as it crosses New England late tonight. A series of low pressure systems move through the Great Lakes Wednesday through Saturday maintaining unseasonably mild temperatures in New England, with near record warmth possible Thursday. A strong cold front will cross the region Saturday, likely bringing some rain, followed by blustery and more seasonable conditions Sunday and Monday. && .NEAR TERM /THROUGH TONIGHT/... High pres moves offshore tonight with weak warm advection developing along with weakening shortwave moving into New England. Forcing for ascent is limited but models indicating deep moisture plume moving across SNE 06-12z. A few showers possible mainly after midnight as this moisture plume and weak shortwave moves through but some areas may remain dry. Will maintain low chc pops for late tonight. The main issue is the potential for some light freezing rain across interior N MA as the precip moves in as temps will be near freezing here. Elsewhere, expect temps will be mostly above freezing. Since temps will be marginal and some areas may remain dry, no advisory will be issued but will address potential for some spotty icy spots in an SPS. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... Wednesday... Moisture axis will be oriented south of the Pike by 12z and moving south of the coast during the morning. Clouds and a few showers are possible in the morning across CT/RI and SE MA, otherwise mid level drying moving in from the north should allow ptsunny skies to develop late morning into the afternoon from north to south. SW flow will bring milder temps into SNE with highs likely reaching the low/mid 50s across most locations but cooler Cape/Islands and higher terrain. However, potential for upper 50s to near 60 in the coastal plain if there is sufficient sunshine. Cloud cover may limit full heating. Wednesday night... Mainly dry conditions and above normal temps with modest SW flow persisting. Patchy low clouds and fog may develop overnight. Lows will range through the 30s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Highlights... * Record warmth possible Thursday * Linger cold front on Friday make keeps temps cooler * Mild with widespread showers likely sometime Sat/Sat night * Blustery and cooler Sun/Mon Pattern Overview... 00z guidance is in general agreement synoptically, still have some mesoscale features to resolve. Overall, mean ridge to start the forecast period for southern New England as digging trough develops of the western CONUS. This trough will eject across the Plain and eventually move towards the Northeast by Saturday/Sunday. Before then, a weak northern stream wave will move through late Thursday into Friday which could sag a weak cold front through the region. After potent trough moves through the area pattern appears to turn more zonal resulting in several shortwaves moving through the flow for next week. High confidence in above average temperatures for Thursday and Saturday as well as precipitation on Saturday into Saturday night. Details... Wednesday night into Thursday... High pressure offshore on Wednesday night resulting in the return of southerly flow. Guidance keeps most of the day dry on Thursday, however have noticed and increase in low level moisture. BUFKIT soundings do show a saturated profile in the low levels with dry air aloft, so cannot rule out low level clouds and/or drizzle for the area. Best location will be across the south coast. These low clouds may limit the amount of heating during the day. But with the potential mixing up to 950mb could still see low to mid 60s. Right now trended towards the low 60s because of low level moisture. This will be close to records for a few sites in southern New England. Cannot rule out the potential for some wind gusts on Thursday as 925 mb LLJ increases to 30-40 kts. If we mix higher than 950 mb then we could see gusts close to 25-30 MPH. Friday... Again a good check of Friday appears to be dry, but low level moisture continues to increase which could keep the drizzle potential for the area. Guidance continues to show a back door cold front late Thursday into Friday which could limit high temperatures. Highest confidence in across Northeast MA but the front could sag a bit farther southward. Large temperatures spread is possible and high confidence in bust potential, will have a better handle with hi-res guidance. A warm front will push through the region late Friday keeping temperatures overnight well above average. Could see a few showers associated with this warm front. Saturday... Potent shortwave will move through the flow and approach southern New England on Saturday. This wave will drag a cold front across the region ending the chances for above average temperatures. Ahead of the front, anomalous southerly flow with LLJ increasing to 35-45 kts as 925 mb temps warm to 12C. This will result in above average temperatures for the region as well as gusty winds. PWAT values also increase near 3 STD above normal as southern stream moisture is fed into the system. Will have to watch for secondary surface low that may develop along the front, which could indicate heavy rain for the region. Low confidence on thunder potential as EC ensemble mean indicates some instability. FROPA will be quick as temperatures plummet behind the front. Could see some wet flakes on the backside depending on how much moisture is left as front moves through. Sunday into Tuesday... Chilly and blustery NW flow will take over the region by Sunday into Monday. Temperatures difference between Saturday and Sunday could be close to 20F. Wind gusts could also increase close to 30 MPH as the region mixes well above 850mb. A weak wave appears to move through the flow on Monday into Tuesday, which could result in some rain/snow showers for the region. Low confidence on timing, but it is moving quickly and bringing in another round of cold air. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday Night/... Through 00z... VFR with increasing high clouds. Coastal seabreezes developing. Tonight...Moderate confidence. VFR cigs, but areas of MVFR developing late tonight in western MA and portions of northern CT. A few showers possible mainly after midnight with low risk of patchy freezing rain in interior northern MA. Wednesday...Moderate confidence. Patchy MVFR cigs/vsbys in the morning, mainly from CT valley to the south coast, improving to VFR in the afternoon. Low risk of a morning shower near the south coast. Wednesday night...Moderate confidence. Areas of MVFR/IFR cigs may develop along with patchy fog. KBOS TAF...High confidence in TAF. KBDL TAF...High confidence in TAF. Outlook /Thursday through Sunday/... Thursday...Moderate confidence. Mainly VFR but low clouds could keep conditions MVFR. Friday...Low confidence. Potential for easterly flow and MVFR cigs if backdoor front slips to the south. However, VFR with SW winds if front remains to the north. Saturday...Moderate confidence. Potential for widespread MVFR/IFR conditions with rain overspreading the region. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday Night/...High confidence. Persistent SW flow through the period with windspeeds and seas remaining below SCA. However, may see a few gusts 20-25 kt late tonight into Wed morning across eastern MA waters. Outlook /Thursday through Sunday/... Thursday...High confidence. Mainly SW flow with gusts to 20 kt. A few gusts to 25 kt possible Thu afternoon. Friday...Low confidence. Winds will depend on location of a backdoor front. Easterly flow if the front moves to the south, but continued SW flow with gusts to 20 kts possible if front remains to the north. Saturday...Moderate confidence. Increasing southerly flow with SCA gusts likely. Waves will also increase in response. Vsbys reduced in developing rain and fog. && .CLIMATE... Record Highs for Thu Feb 23 BOS...65/1990 BDL...68/1990 PVD...60/1990 ORH...61/1990 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...KJC NEAR TERM...KJC SHORT TERM...KJC LONG TERM...Dunten AVIATION...KJC/Dunten MARINE...KJC/Dunten CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.