Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 240557 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 1257 AM EST Wed Jan 24 2018 .SYNOPSIS... Drier air works into the region behind a cold front overnight. Blustery, dry and colder weather follows Wednesday through Friday, then a warming trend next weekend. A cold front may bring showers next Sunday or Monday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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1 AM update... Secondary cold front and true post frontal airmass arrives 4 am - 7 am from west to east. This is when winds will shift to the WNW and become gusty. Until expect light WSW winds. Could see some patchy black ice overnight into predawn hours across the CT river valley and the Merrimack valley of northeast MA as winds become light and some radiational cooling takes place.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... Wednesday... A west northwest flow of more seasonable temperatures will be working back into the region on Wednesday. High temps will not recover too much...generally remaining in the 30s to near 40 across parts of the coastal plain. Should be at least partial sunshine...but do expect some strato-cumulus clouds that will be focused across the interior. West to northwest winds will gust to between 25 and 30 mph at times. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Highlights... * Dry but cooler weather for the rest of the work week * Above average temperatures for Saturday and Sunday * Next shot of wet weather will be around Sun/Mon Overview... 12z guidance is in general agreement with the upcoming medium and long range. Progressive pattern over the region as ongoing upper level trough will push offshore as mid-level ridge builds into the area by the weekend. For the end of the period, still some uncertainty regarding the timing and amplitude of the upper level trough moving from the Northern Plains towards the East Coast Sun into Monday. GFS continues to be on the faster side of the envelope compared to the EC and UKMET. If the guidance continues to trend towards the slower envelope, than there is the potential for a more significant surface low to develop. This could result in warmer temps for the weekend, and heavier rainfall. If it is weaker, than cannot rule out some trapped cold air resulting in p-type issues. Still a lot of uncertainty and will trend towards a blend of the guidance until details can be sorted. Wednesday night into Friday...High confidence. Building high pressure across the southeast will build across the US East Coast resulting in dry weather through the period. Still some thermal gradients in the mid-levels as upper level shortwave passes through on Thursday. This will result in a breezy but chill day. Temperatures will still be in the 30s on Friday, but with less winds should make it feel warmer. Some mid-level moisture around 850-700mb will help bring in some clouds but overall a pleasant January day is on tap. Saturday into Monday...Moderate confidence. Subtropical ridge will build across the US East Coast over the weekend as northern stream system approaches the Northeast. All guidance as well as the ensembles are indicating precipitation for the area. Biggest uncertainty is the amount, exact timing and if all precip will be liquid. Current forecast is an ongoing blend of the guidance with a trend towards the UKMET and EC. Thus expect precipitation to move into the area on Sunday as mostly rain and temperatures will be well above average thanks to southerly LLJ. If precip lingers into Monday, CAA behind the system could switch any precip to snow, but overall confidence is low that this will occur. Will need better guidance to see this potential. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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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 Thursday/... 06z update... Thru 12z... VFR, dry runways and light winds. Could have some black ice at before winds pickup from the WNW 09z-12z. After 12z... Marginal MVFR with cigs BKN030 12z-17z then VFR this afternoon. Modest WNW winds 15-25G30kt. Tonight and Thursday... VFR, dry weather and modest NNW winds 15-25 kt few gusts up to 30 kt possible. KBOS Terminal...high confidence in TAF with wind shift to the WNW 15-25 kt beginning 11z-13z. KBDL Terminal...high confidence in TAF with wind shift to the WNW 15-30kt beginning 09z-11z. Outlook /Thursday Night through Sunday/... Thursday Night: VFR. Windy with local gusts to 30 kt. Friday: VFR. Breezy. Friday Night: VFR. Saturday: VFR. Windy with gusts to 30 kt. Saturday Night: Mainly MVFR, with areas VFR possible. Breezy. Chance RA. Sunday: Mainly MVFR, with areas IFR possible. Breezy. RA likely.
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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 Thursday/... Minor changes were made with this update to reflect the latest trends in observations and guidance. The forecast appears on track. Overnight...High confidence. Have converted the Gale Warnings to SCA with LLJ pushing east of the waters. May see a temporary lull in the winds...but they will pick back up after midnight with WSW gusts of 25 to 30 knots developing in the cold air advection pattern. Wednesday...High confidence. WNW wind gusts of 25 to 30 knots in the cold air advection pattern. SCA headlines will be needed for most waters. Outlook /Thursday Night through Sunday/... Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Chance of freezing spray. Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of freezing spray. Friday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas locally approaching 5 ft. Friday Night: Winds less than 25 kt. Saturday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Saturday Night: Winds less than 25 kt. Local rough seas. Chance of rain. Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain.
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&& .HYDROLOGY...
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A Flood Warning remains in effect for the CT River at Middle Haddam...but there are no other hydro concerns at this point. For details on specific area rivers, including observed and forecast river stages, please visit the Advanced Hydrologic Prediction Service (AHPS) graphs on our website.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ230>237-250-251-254>256.
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&& $$ SYNOPSIS...Frank/Dunten NEAR TERM...Frank/Nocera SHORT TERM...Frank LONG TERM...Dunten AVIATION...Frank/Nocera/Dunten MARINE...Frank/Dunten HYDROLOGY...staff

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