Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 180657 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 157 AM EST Sat Feb 18 2017 .SYNOPSIS...
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After a chilly start this morning mild temperatures overspread southern New England this afternoon through Sunday. Dry weather prevails this weekend as well. A dry cold front swings through Southern New England Sunday night, bringing a return to chilly weather into Tuesday. Milder weather returns the middle of next week however another cold front maybe accompanied by some precipitation Wednesday.
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&& .NEAR TERM /THROUGH TODAY/...
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2 AM Update... WAA pattern overspreading the area early this morning in the form of mid/high clouds. These clouds will move offshore this afternoon with increasing sunshine. This WAA pattern will be accompanied by a strengthening low level SSW jet. This will result in breezy to windy conditions this afternoon with strongest winds across RI and eastern MA where model soundings support gusts up to 30-35 mph this afternoon. This low level warming will yield highs this afternoon in the upper 40s and low 50s, well above normal with climo being about 40 for a high temp this time of year. Leaned toward the warmer MOS temps for today`s high temps.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM SUNDAY/...
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2 AM update... Tonight... Not as cold as previous nights with WAA pattern yielding 925 mb temps of +6C to +10C across southern New England! Low pres tracking across northern New England will support a modest westerly surface winds, precluding decoupling from occurring. This will result in most locations remaining above freezing all night! Dry weather prevails. Sunday... A dry cold front moves across the region during the afternoon. Given a mild start to the day with morning temps only in the 30s combined with partly to mostly sunny conditions and CAA holding off until after 18z...highs will likely climb into the low to mid 50s (except upper 40s high terrain), well above the normal high of 40 degs! Model soundings support breezy conditions developing by late morning and into the afternoon with WNW gusting up to 30 mph.
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&& .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Big Picture... Pattern shows northern and southern jet streams for the weekend. This breaks down a little in the Plains early next week with more of a meridional pattern which shifts into the Eastern USA midweek. As long as there is a distinct southern jet intercepting Gulf moisture our likely weather is moisture-starved. When this weakens midweek we see a brief window for measurable pcpn. Otherwise a dry period. Longwave pattern shows building ridge over the Eastern USA and digging trough over the West. Heights over New England show above normal values through the period, which suggests warmer than normal temps. One northern stream shortwave sweeps through late Sunday- Monday bringing crashing heights and brief colder temps. Ridge and building heights return Tuesday. So a brief cool-down expected early week followed by a return trend to above normal during midweek. Model mass fields are similar through Tuesday but then diverge. Differences are mostly in details rather than the general pattern. Confidence for the long term is moderate to high, with highest confidence Sunday and diminishing confidence with time. Details... For the most part, a quiet period for weather. Sunday through Tuesday... Dry weather Sunday as low pressure passes north of New England. Temps at 925 mb cool a degree or two, but nothing fantastic. Mixing to 925 mb would support max temps 40-45, mixing to 900 mb would support 45-52. Shortwave from the Canadian Prairies moves east and connects with a closed low over Newfoundland. This connection then sweeps the shortwave southeast over New England Sunday night and Monday morning. Limited low level moisture with the shortwave may bring a few clouds. High pressure builds in later Monday and moves overhead Tuesday. Winds become light and variable Tuesday, possibly some southerly flow Tuesday afternoon. Temps moderate a few degrees each day. Temps 20 to around 32 Sunday night and 15 to 25 with radiational cooling Monday night. Clouds and a southerly flow suggest milder temps Tuesday night. Wednesday... Cold front over the Great Lakes moves across New England. Not a lot of moisture available, but enough to mention a low probability of showers during the day. A southerly flow and temps at 950 mb suggest mild temps in the 40s. If the sun Thursday-Friday... High pressure builds surface and aloft Thursday bringing dry weather. Temps at 950 mb and 925 mb suggest max sfc temps in the low to mid 50s. Weather system that reaches the West Coast midweek races east across the country. Models show differences in timing with the GFS fastest, but all show a low level southwest jet ahead of the system overrunning a southeast surface flow over New England either Friday or Friday night. The uncertainty is whether this overrunning takes place over Southern New England or Northern New England. Expect dry warm sector weather if the latter. We will show slight chance pops in our eastern zones and low-end chance pops in the East Slope and CT Valley zones. Better chance of showers with the main weather system after Friday night. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
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Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 2 AM update... High confidence thru Sunday. Today... VFR and dry weather. Only issue today will be strengthening SSW surface winds up to 30 kt this afternoon across RI and eastern MA. Tonight... VFR and dry weather continue along with decreasing surface winds. However winds remain strong aloft yielding LLWS. Sunday... VFR and dry weather with modest WNW winds. KBOS TAF...High confidence in TAF. KBDL TAF...High confidence in TAF. Outlook /Sunday Night through Wednesday/...Moderate confidence. Sunday night through Tuesday... Generally VFR. A cold front moving through Sunday night could bring brief MVFR cigs. West winds ahead of the cold front turn from the North overnight and Monday with gusts to 30 knots possible. Winds diminish Monday night and Tuesday as high pressure moves overhead. Wednesday... Cold front sweeps through with Southwest winds leading the front, then shifting from the West after passage. CIGs and Vsbys lower to MVFR in showers, then improve to VFR after the front moves through.
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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 Range /through Sunday/...High confidence. 2 AM update... Today... SSW winds increase today to around 30 kt near shore this afternoon, 20-25 kt offshore. Dry weather and good vsby. Tonight... SSW winds not as strong and become westerly late. Dry weather and good vsby continue. Sunday... west winds become NW late in the day as a dry cold front sweeps across the region. WNW winds will likely gusts up to 25 kt or so. Dry weather and good vsby continue. Outlook /Sunday Night through Wednesday/... Moderate confidence. Monday-Tuesday... North winds gust 25 to 30 knots Monday, diminishing Monday night and Tuesday as high pressure builds overhead. Seas east of Cape Cod and Nantucket start Monday at 5-6 feet, but diminish Monday night and Tuesday. Seas on the remaining waters should be less than 5 feet. Small Craft Advisory may be needed Monday. Wednesday... A cold front will cross the waters later Wednesday. Increasing south-southwest winds ahead of the front. Winds then shift from the west after the cold front goes through. Winds should remain at 20 knots or less, and seas less than 5 feet.
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&& .EQUIPMENT...
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2 AM update...KBOX radar is off-line again. Technicians will be in the morning. We apologize for any inconvenience.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 11 AM this morning to 7 PM EST this evening for ANZ230>237-250-251-254>256.
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&& $$ SYNOPSIS...Nocera NEAR TERM...Nocera SHORT TERM...Nocera LONG TERM...WTB AVIATION...WTB/Nocera MARINE...WTB/Nocera EQUIPMENT...Nocera

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