AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 757 PM EDT Mon Apr 6 2026 .WHAT HAS CHANGED... Monitoring late tonight into early Tuesday for snow showers. Otherwise, dry weather with increasing southerly winds Wednesday and Thursday could lead to fire weather concerns. && .KEY MESSAGES... - Weak system moves through tonight into Tuesday bringing light rain/snow showers. No accumulation expected. - Gradual warming trend starts Wed and Thurs, although it will be quite dry to go along with increasing south winds on Thurs. - Mild and dry Friday heralds a cold frontal passage Sat but with limited rain chances. Onshore flow/possible backdoor frontal boundary then ushers in a cooldown for Sun. && .DISCUSSION... KEY MESSAGE 1...Weak system moves through tonight into Tuesday bringing light rain/snow showers. No accumulation expected. A deeper upper-level trough shifts across the region tonight and Tuesday. This trough brings along a cold pool aloft with 500mb temperatures around -30C and 925mb temperatures -3C to 1C. A shortwave trough moves through the flow aloft supporting some weak lift and marginal moisture and even a little instability to support scattered "popcorn" showers. Considering that we have such cool temperatures aloft, this should support light snow showers for the higher elevations and snow mixing in elsewhere. Given weak convective element, can`t rule out even a little graupel in any showers. High-resolution guidance is still lacking agreement on the finer details of the timing and shower coverage. Overall there is a signal for a few showers very early Tuesday AM. Probabilities increase (30-45%) for scattered showers closer to 7/8AM and after as the main surface low tracks across the region. Any snow/frozen precip accumulation would be very light and little impact. Worst case 1". Temperatures will be below normal in the 40s. KEY MESSAGE 2...Gradual warming trend starts Wed and Thurs, although it will be quite dry to go along with increasing south winds on Thurs. Rather strong 1038+ mb high pressure cell south of Nova Scotia early Wed will extend a surface ridge southwestward through the Southern New England coastline into the mid-Atlantic and central Appalachians, remaining more or less in place into Thurs. Warming 925 to 850 mb temps and full sunshine should permit a general warming trend thru Thurs with highs on Wed in the mid 40s to low 50s (low 40s near the coast) and into the 50s in most areas by Thurs. With a few days of generally dry weather early this week, fire weather concerns are possible on both days, as dewpoints drop into the teens to low 20s in the pre-greenup period allowing for minimum RH`s in the 20 to 25 percent range from the coast. Although southerly winds are on the light side Wed, they pick up a little more on Thurs with gusts around 20-25 mph, so Thurs probably offers the strongest chance for fire weather concerns. KEY MESSAGE 3...Mild and dry Friday heralds a cold frontal passage Sat but with limited rain chances. Onshore flow/possible backdoor frontal boundary then ushers in a cooldown for Sun. Looks like one final day of full sun and even milder temps back into the mid 60s Friday, so it looks like Fri ends up as the pick of the workweek. Sat starts off mostly sunny, but will have increasing cloud cover as a weakening frontal system moves through Southern New England during the afternoon to first part of the evening. This frontal boundary won`t have much moisture to work with, and it may just result in some enhanced cloudiness with limited prospects for rain showers. Looks like late Sat night or into Sunday, guidance continues to show presence of a NE onshore flow/possible backdoor front with cool 850 mb temps 0 to -2C. It`s still early but it doesn`t look like there is a signficant amount of RH and pressure gradient doesn`t look too strong, so this backdoor front doesn`t look to be as pronounced in terms of strong onshore winds and as overcast as e.g. this past Saturday`s backdoor front was. Regardless, expect a cooldown as we move into the latter part of the weekend, though temperatures start to modify once again as we move into early next week. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 00z TAF Update: Tonight: High confidence through midnight, then moderate toward morning. VFR through at least midnight, with decreasing WNW winds. After midnight, layer of OVC VFR decks works its way in, with winds becoming light ESE. Scattered snow/rain showers then begin to break out from SW to NE between 08-12z Tue with ceilings trend to MVFR; scattered nature of precip means visbys probably will fluctuate but should slot in the VFR-MVFR range. SE/E winds under 10 kt by morning. Tuesday: Moderate confidence. Continued mainly MVFR with VFR-MVFR visby scattered rain/snow showers thru 16-19z, with winds backing to E/ENE under 10 kt to northerly by afternoon. Accumulation if any probably is minimal given showery nature to precip. Showery precip during the first part of the day ends and ceilings could trend MVFR-VFR range. There are hints in the guidance around 19-23z of a pretty potent cold frontal passage with another period of scattered showers, some with either graupel or isolated squally activity. This front`s passage would bring a marked increase in NW winds, with speeds 10-15 kt with gusts 20-28 kt for a few hrs. Tuesday Night: High confidence. VFR. NW winds 10-15 kt with gusts upper 20s kt range early, but then settle to NW winds 5-10 kt late evening thru 12z Wed. KBOS Terminal...Moderate Confidence in TAF. VFR thru 08z, easing NW winds to trend light ESE. Conditions then trend MVFR with E winds and scattered -RASN around 11-13z. NE winds with continued scattered -RASN 15-19z before trending to BKN/OVC VFR. Possible second round of SHRA/possible graupel or squall 20-23z with brief gusty NW winds 10-14 kt gusts to 24-28 kt. KBDL Terminal...High Confidence in TAF. VFR thru 08z, easing NW winds to trend light ESE. Conditions then trend MVFR with ENE winds and scattered -RASN around 08-14z. NE winds with continued scattered -RASN 15-19z before trending to BKN/OVC VFR. Possible second round of SHRA/possible graupel or squall 19-22z with brief gusty NW winds 10-14 kt gusts to 24-28 kt. Outlook /Tuesday Night through Saturday/... Wednesday through Wednesday Night: VFR. Thursday through Thursday Night: VFR. Breezy. Friday: VFR. Friday Night: VFR. Slight chance SHRA. Saturday: VFR. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. High confidence. Gusty winds diminish this evening with seas 2-4 ft. This will allow the small craft advisories to be dropped this evening. Low pressure moves across region Tuesday with winds shifting through the day from SE,eventually around to the N/NW late afternoon-early evening. Northwesterly wind gusts may approach SCA levels Tuesday evening across the southern waters ahead of an approaching high pressure system. Outlook /Tuesday Night through Saturday/... Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Wednesday Night through Thursday Night: Winds less than 25 kt. Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Friday Night through Saturday: Winds less than 25 kt. Seas up to 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ254>256. && $$