Area Forecast Discussion
Issued by NWS Boston, MA

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102 FXUS61 KBOX 161915 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 315 PM EDT Fri Mar 16 2018 .SYNOPSIS... Mainly dry but unseasonably cold weather will continue this weekend into at least Monday. The potential continues for a Noreaster sometime between next Tuesday into Thursday...but confidence on if/how we are impacted remains highly uncertain. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 200 PM Update... Did a quick forecast update to include isolated rain/snow showers. Been on radar for a while, but have received only a few reports of snow actually reaching the ground probably due to high temp/dewpoint spreads (on order of 15-20 degrees). With the radar coverage, could see some brief, spotty snow showers, possibly mixed with rain across SE coastal areas, through the remainder of the day. Winds remain blustery across the region thanks to the weak trough moving across the region. Noting gusts up to 30-40 mph at many locations, with the 40 mph gust at KBOS at 18Z. Still noting excellent mixing with passing 30-35 kt low level jet from H925 through H9, but should weaken somewhat across inland areas toward sunset as lapse rates decrease. Temps topped off only in the mid-upper 30s across central and northern Mass at 18Z, with some readings touching 40 along the S coast. However, with the gusty winds, it feels much colder. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... Overnight... A bit of a meteorological squeeze play as secondary robust shortwave/H5 cutoff approaches from the N while slight low-mid lvl warm advection occurs to the S. This results in mid lvl confluence and a slight rise in heights. However, it also increases the pres gradient. This will enhance near sfc cold advection. In spite of the clearing implied by the slight rise in heights, these winds should allow min temps to drop into the upper teens to mid 20s, one of the colder nights of this week. Sat... The robust H5 shortwave rotates S, but given the rising heights to the S the core should remain to the N during the daylight hours as it rotates toward the Maritimes. Still, weak low-mid lvl cold front should pass across the region early. While these feature, like the many before it s moisture starved, lift is a bit stronger thanks to enhanced baroclinicity already in place. Also, noting a well mixed BL to nearly H7, with a pool of moisture around the top of the mixed layer. Lapse rates from the sfc to the top of the mixed layer are also quite high, nearly 7C/km. Therefore, could see some flurries/sprinkles develop through the morning as this wave makes its closes pass. Expect little if any accumulation. Otherwise, with the core of the cold associated with the cutoff approaching H85 temps drop as low as -15C by afternoon. However as mentioned above mixing should exceed this. Therefore, expecting highs similar to Fri, low to upper 30s. Winds continue, but more northwesterly, expecting gusts 25-35 mph. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Highlights... * Dry but unseasonably cold Sun/Mon * Potential Noreaster sometime next Tue into Thu but low confidence on if/how we are impacted Details... Sunday and Monday... Northwest flow aloft and at the surface will result in dry but unseasonably cold weather for this time of year. Low temperatures will mainly be in the teens to lower 20s. Highs mainly in the 30s...but some lower elevations may reach 40 on Monday. Tuesday through Thursday... We continue to watch the potential for a Noreaster to impact the region sometime in the Tuesday through Thursday time frame. Confidence though remains low as this is a very complex situation. Numerous pieces of shortwave energy are involved and their specific timing/strength and location will determine if/how our region is impacted. The models are also struggling with timing of the event as they appear unsure which piece of energy they want to amplify. Overall...there is not much more we can do at this point than indicate the potential for a Noreaster and run with chance pops over this time frame. We also need to keep all options on the table from a miss, to a wintry mix, or a significant snowstorm. Given this will likely be a few more days until we get a better handle on this situation. Needless to say though it does bear watching. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday Night/...High confidence. Through 00Z... VFR. Areas of BKN clouds at around 5-6kft. Brief isold -SHRA/-SHSN will diminish toward sunset. NW winds continue with gusts 25-35 kt, highest along the coast and higher terrain. Tonight... VFR. W wind gusts up to 25-35 kt will linger across higher terrain and along the coast through most of the night, but will diminish this evening elsewhere. Saturday... VFR. W-NW winds gusting up to 25-30 kt, highest along coast and higher terrain. Band of BKN clouds around 4-5kft move across with another weak trough. Isold to SCT -SHSN possible from mid morning through the afternoon. Saturday night... VFR. Becoming CLR by midnight. W-NW wind gusts up to 25 kt diminishes in the evening. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Sunday through Wednesday/... Sunday through Monday Night: High confidence in VFR conditions. Tuesday: Low confidence. VFR conditions may deteriorate to MVFR-IFR thresholds late depending on the timing/track of a coastal storm which is highly uncertain. Chance SN, chance RA. Tuesday Night and Wednesday: Low confidence. MVFR/IFR conditions possible depending on the timing/track of a coastal storm. Windy with gusts to 30 to 40 kt possible along the coastal plain. Chance SN, chance RA. These conditions are highly uncertain and dependent on strength/timing of coastal low pressure. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday Night/...High confidence. Through Tonight... W-NW wind gusts will gradually increase across the waters through the day. Peaking first on the S waters late this afternoon and evening with gusts around 35 kt on the open ocean waters. The E waters then follow, with gusts also around 35 kt. Near shore waters will be slightly weaker, therefore Gale Warnings will be issued late this afternoon/evening for the outer waters with Small Craft Advisories mostly close to shore. Seas peak early Sat AM around 10-12 ft on the outer waters. Sat... NW Gales continue mainly across the E waters with Small Craft Conditions lingering across the S waters. The Gales drop off by afternoon, with Small Craft Advisories following all waters thanks to both gusts/seas. Outlook /Sunday through Wednesday/... Sunday: Moderate to high confidence. Small Craft Advisory winds possible with gusts up to 30 kt. Areas of seas approaching 5 ft. Sunday Night: Moderate to high confidence. Small Craft Advisory winds possible with gusts up to 30 kt. Local rough seas. Monday through Monday Night: Moderate to high confidence.Winds less than 25 kt. Seas locally approaching 5 ft. Tuesday: Low to moderate confidence depending on track/timing of a coastal storm. Winds less than 25 kt. Chance of snow, chance of rain. Visibility 1 to 3 nm. Tuesday Night and Wednesday: Low confidence. Potential for gale force winds with gusts between 35 and 45 kt. Rough seas up to 15 ft. Chance of rain, chance of snow. Visibility 1 to 3 nm. These potential conditions are highly uncertain and hinge on the track and strength of a potential coastal storm. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT Saturday for ANZ230-232. Small Craft Advisory until 5 PM EDT Saturday for ANZ233>237. Gale Warning until 2 AM EDT Saturday for ANZ231-255-256. Gale Warning until 2 PM EDT Saturday for ANZ250-254. Gale Warning from 8 PM this evening to 2 PM EDT Saturday for ANZ251. && $$ SYNOPSIS...Frank NEAR TERM...EVT SHORT TERM...Doody LONG TERM...Frank AVIATION...EVT/Frank MARINE...EVT/Frank is the U.S. government's official web portal to all federal, state and local government web resources and services.