Area Forecast Discussion
Issued by NWS Boston, MA

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221 FXUS61 KBOX 261437 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 1037 AM EDT Sun Mar 26 2017 .SYNOPSIS...
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A front will remain stalled to our south today, then push N as a warm front late tonight into Monday. Another low pressure will move across southern New England Tuesday, bringing some rain showers. High pressure brings dry but cooler weather Wednesday and Thursday. More precipitation possible late Friday into Saturday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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*/ Highlights... * SPECIAL WEATHER STATEMENT through noon for the possibility of spotty sleet or freezing rain. */ Discussion...updated 1030 am. Fair amount of cold air lingering across interior Southern New England beneath an overcast cloud deck. Certainly not warming as fast as it is over E/SE New England where mostly clear conditions prevail and temperatures are quickly warming up into the low 40s thanks to the late-March sun. We got our sunglasses on our here in good ol` Taunton Massachusetts, it`s so bright. With the colder air around freezing in place as a line of wet weather approaches from the SW associated with some mid level frontogenesis and weak ascent per leading H5-7 impulse upon decent H85-5 moisture, in other words the mid-level warm front on the nose of very mild air moving N/E from the Mid-Atlantic. You can clearly see the differences in airmass from the 12z soundings out of Upton New York and Chatham Massachusetts. Wow. We are staged within the battle ground certainly. Forecaster intuition, expect the NW-SE line of wet weather to approach but erode in doing so, retreating to the NW and thus have timed PoPs accordingly so. Temperatures will gradually warm, albeit slowly, with the daytime heating even with the overcast cloud deck. It`ll be slow, tough to time, more so with the funneling N flow from high pressure over the N (ageostrophic flow as noted by previous forecasters). Precipitation mainly in the form of a cold, dreary rain, however freezing rain is possible, more so over sleet, for those areas still at or below freezing at the surface. Just look at the 12z sounding out of Upton, that`s quite a pronounced warm nose up around H85. A freezing rain sounding with shallow cold air. The freezing rain threat diminishes into the afternoon and have gone with SPECIAL WEATHER STATEMENTs for now, but colder air will work back in with continued N flow as we go into the evening with the absence of daytime heating. Have gone ahead with the FREEZING RAIN ADVISORY starting it off earlier in time.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Tonight... The stronger low level south winds shift farther east Sunday evening and bring a greater potential for lift and precipitation production through the night, especially after midnight. Temperature profiles showing a strong warm nose aloft. North ageostropic winds continue near the ground, which will set the stage for freezing rain across the higher terrain of central and western MA. Some freezing rain possible across northernmost Connecticut. However, thinking coverage is too limited at this time to warrant an advisory. This could change with later forecasts. Monday... Warm front finally moves north into southern New England. This will end the threat of any freezing rain across our region. However, that will not end the possibility for rain as a low pressure moves through our region. this rain could be moderate to heavy at times. Temperatures should be near normal. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Highlights... * Showery weather ahead of approaching cold front on Tuesday * Cooler but dry weather for mid-week * Active weather returns late in the week into the weekend Pattern Overview... 00z models and ensembles show fairly good agreement on the maintenance of a longwave trough over the western states with flat flow to moderate mean riding prevailing downstream over the East. A separate northern stream progresses along either side of the Canadian border. Within this consensus mean pattern models and ensembles have been showing a lot of spread for some of the embedded features. This is noticed as early as the Day 3 forecast. Both the GFS and GEFS are more amplified compared to the rest of model suite. However still anticipate open wave interacts with the northern stream bringing a shot of precip on Tuesday. Upper level trough with surface high pressure for the mid-week as another upper level closed low diffuses towards the region late in the week. Details... Monday night into Tuesday...Low confidence. Weak ridging in the mid-levels will result in a break in the precip Monday night into Tuesday morning. Focus then turns to the next open wave and how it will interact with the northern stream. The GFS is more amplified compared to the progressive EC with the remaining guidance inbetween. Used a model blend for this portion of the forecast. First wave will move offshore and with weak ridging aloft, anticipate a drying trend in the forecast. Timing issues for the next shot of precip on Tuesday, but feel there is enough of a chance to keep pops in the forecast ahead of approaching cold front. Thermal ridge over southern New England may help increase temps near or above seasonable. In fact, depending on mixing and cloud cover, we could see temps warm into the 60s. Southerly flow will help increase low level moisture and with approaching front, could see iso thunder as guidance hints at elevated convection. Cold front will sweep through during the overnight hours ushering in dry air and northwest flow Tuesday night. Wednesday into Friday...High confidence. Trough overhead as upper level low deepens as it moves towards the Canadian Maritimes. This puts the region in northwest flow through the period resulting in dry but breezy conditions. There might be a few showers across the northeast on Wednesday in cyclonic flow. Despite cold advection, the environment should be well mixed, so max temperatures will be close to normal. Northwest flow continues on Thursday with an area of high pressure building in New England. Anticipate increasing sunshine and lighter winds. Dry and seasonable conditions should persist through Friday with high pressure in control. Friday night into the weekend...Low confidence. Split flow remains over the region with the next southern stream wave interacting with the northern stream. Large model spread for the Friday night into the weekend time frame leading to a low confidence forecast. The GFS suppresses the system well to our south, with a dry northern stream flow dominating. However, the ECMWF and CMC continues to indicate the low opening into a progressive trough and tracking across the region. Overall this portion of the forecast will depend on the strength and timing of the upper level wave and thus surface reflections. Because of the large spread in the guidance will continue with low confidence forecast. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/...
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Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday/...Moderate confidence. 14z update... Today... Mostly VFR. Believe MVFR-IFR mix will come in late across W MA and W CT, 0z Monday. Continued N slowly turning E along the coast. Spotty FZRA possible across N CT / W and Central MA thru roughly 16z. Tonight... MVFR lowering to IFR-LIFR. N winds still turning E except within the CT River Valley where they remain light N. RA / FZRA coverage increasing across the terminals. FZRA more likely for interior areas (E Central MA across to W MA, NW RI, N CT) with the highest risk across the high terrain of the Berkshires and Worcester Hills. Mainly trace accumulations but as high as a tenth of an inch. Main impacts after midnight into Monday morning, FZRA threat eroding to the N as well towards Monday morning. Monday... FZRA risk persists during the morning hours across N/W MA especially the high terrain. Otherwise RA with MVFR-LIFR cigs with light E winds initially turning SE and increasing. KBOS TAF...Not expecting any FZRA impacts at the terminal with E onshore flow. Lowering MVFR down to LIFR after midnight Monday into Monday morning. KBDL TAF...Low risk FZRA through noon as temperatures have already warmed above freezing as of 14z. Greater threat around midnight Monday with the possibility of spotty impacts. Not expecting any ice accretion, at most a trace. Outlook /Monday Night through Thursday/... Monday night...Moderate confidence. Improving conditions to VFR. Tuesday...High confidence. MVFR conditions within any passing rain showers with improving cigs to VFR. Low risk for thunder. Wednesday into Thursday...High confidence. Gusty N/W winds Wednesday with VFR conditions into Thursday.
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&& .MARINE...
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Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday/... 1030 am update...No major changes to the forecast. Today...High confidence. E winds less than 20 knots. Seas less than 5 feet. Tonight...High confidence. Approaching low pressure from the west will spread rain across the waters from west to east. Winds will remain below 20 knots and seas below 5 feet through the period. Monday...Moderate confidence. Warm front with weak low pressure along it may kick up southeast to south winds to near 25 kt gusts and seas could build to 5-6 ft over the outer waters. Small Craft Advisories are likely for some of the outer waters. Outlook /Monday Night through Thursday/... Tuesday...Moderate confidence. Frontal system will pass over the waters increasing them to above 5 feet. SCA may be needed. Wednesday into Thursday...High confidence. Gusty NW winds near gales on Wednesday will help increase seas. SCA will be needed at the very least. High pressure nosing in on Thursday will slowly relax seas.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...Freezing Rain Advisory from 8 PM this evening to 8 AM EDT Monday for MAZ002>004-008-009-012-026. RI...None. MARINE...Small Craft Advisory from 5 PM this afternoon to 8 AM EDT Monday for ANZ256.
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&& $$ SYNOPSIS...Belk/Dunten NEAR TERM...Belk/Dunten/Sipprell SHORT TERM...Belk LONG TERM...Dunten AVIATION...Belk/Dunten/Sipprell MARINE...Belk/Dunten/Sipprell

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