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Area Forecast Discussion
Issued by NWS Boston, MA
Issued by NWS Boston, MA
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610 FXUS61 KBOX 271726 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 1226 PM EST Thu Feb 27 2025 .SYNOPSIS... A frontal system brings periods of rain today, with snow changing to rain in northern MA this morning. Dry blustery and cooler conditions follow behind this system on Friday. A quick moving clipper tracking to the north will bring another period of snow to northern MA Friday night, with a few showers and milder temperatures Saturday ahead of a cold front. Blustery and cold weather follows behind the front for Sunday and Monday. Milder air returns by the middle of next week along with another chance of rain. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 10AM update... Mainly all rain across the region, a small pocket of -SN in northwest Franklin County and perhaps pockets of -FZRA in northern Worcester County. As temperatures continue to warm above freezing, opt`d to not extend the SPS. Snowfall reports have been limited to northern Mass of 1-2 inches of snow. Forecast on track. Previous discussion... Key Messages: * Minor travel impacts in northern MA for the morning commute with snow and pockets of freezing rain changing to rain * Gusty SW winds developing across portions of RI, SE MA and Cape/Islands Light precip on radar moving into SNE with steadier precip at the nose of the low level jet approaching from the west. The steadier precip will move across SNE through daybreak with focus across northern MA. Ptype will be mostly rain south of the MA Pike, but soundings support snow or a snow-rain mix to the north before the column warms with snow transitioning to rain between 6 and 9 am in northern MA. Snow accum will generally be a coating to an inch north of the MA Pike, but up to 2 inches over the Berkshires. Still have to watch for the potential for some freezing rain during the ptype transition. Soundings not especially supportive for ice with near isothermal profiles as the column is warning. However, low level cold air will be slow to erode so there may be pockets of freezing rain for a few hours over the higher elevations in the Berkshires and northern Worcester Hills before temps rise above freezing. Just minor impacts to the morning commute are expected, mainly over higher elevations. Will issue a SPS to address the minor travel impacts. Model guidance is focusing the steady precip across northern MA this morning into early afternoon within the mid level jet axis and proximity to the mid level shortwave. Closer to the south coast, any rain is expected to be spotty with dry periods, then band of showers ahead of an approaching cold front will move eastward across SNE this afternoon reaching the Cape/Islands late today and early evening. There may even be a rumble of thunder over the Cape/Islands as soundings indicate marginal instability above the frontal inversion. Fairly impressive 925 mb jet 60-70 kt develops to the south and lifts across the Cape/Islands this afternoon. The jet is above a strong low level inversion so will not mix these winds down to the surface. General rule of thumb for potential gusts with strong inversions is to take 50 percent of the low level jet which translates to 30-40 mph gusts for the Cape/Islands. Temps: Warm front lifts northward across SNE which will allow temps to rise into the 50s this afternoon across RI and SE MA with mid- upper 40s in the interior, but cooler NW MA. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Tonight... Focus for scattered showers this evening will be across the Cape/Islands as the front moves through, otherwise excellent drying moves in behind the front as PWATs drop sharply. Expect clearing skies overnight, but upslope clouds may spill into the Berkshires and can`t rule out a few flurries here as mid level trough axis and cold pool approaches. Lows will be in the low- mid 30s, with upper 20s over higher elevations. Friday... Weak shortwave ridging and subsidence moves into the region behind the departing mid level trough. Expect lots of sunshine mixed with developing CU and mid-high clouds will be moving in from the west late in the day ahead of the next system. It will be somewhat breezy as well mixed boundary layer supports W-NW gusts to 20-30 mph. Near seasonable temps with highs upper 30s to mid 40s, but lower 30s Berkshires. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Key Messages: * Another round of snow changing to rain expected Friday night into Saturday * Cold and blustery conditions settle in behind a cold front Saturday night, and continue into early next week * Above normal temperatures towards mid week * Another rain storm expected to approach Wednesday Latest guidance suite continued the trend of rather good agreement with the overall synoptic picture. Still some timing and intensity differences, but these appeared to be minor. Still have above average confidence for this portion of the forecast. Another low pressure should pass over northern New England Saturday. Have greater confidence in showers across northern MA that towards the south coast. Should be mostly a rain event, with the possibility of some light snowfall towards the end sometime Saturday afternoon into Saturday night. Not a lot of moisture to work with here, so any precipitation is expected to be light. High pressure then expected to return drier and colder conditions Sunday into Monday. Still dry but likely warmer Tuesday. Anticipating temperatures to not be as much above normal Friday, before a brief surge of warmth Saturday. A large high pressure moving southeast from central Canada trends temperatures below normal Sunday into Monday. Thinking it will be a little warmer Tuesday as this high pressure moves offshore. The timing for another low pressure towards mid week is not as certain. Could see a risk for some rainfall as early as late Tuesday night. However, it is more likely that heavier rainfall holds off until later in the day Wednesday. && .AVIATION /18Z THURSDAY THROUGH MONDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18z TAF update... Moderate confidence, mainly due to timing of changing conditions. Mixture of MVFR and low-end VFR with period of -RA through this afternoon/early evening ahead of the cold front. Improvement to VFR from W to E 00-06z, but a few hours later Cape/Islands. VFR Friday. Winds are S/SW and increase this afternoon with 25-35 kt gusts towards the coast. LLWS expected near coast as well with 020 winds S/SW 50-60kt, strongest near Cape Cod. W-NW wind gusts 20-25 kt Fri. KBOS TAF...High confidence in TAF trends. Lower confidence in timing and specific details. KBDL TAF...High confidence in TAF trends. Lower confidence in timing and specific details. Outlook /Friday Night through Monday/... Friday Night: Mainly VFR, with local IFR possible. Breezy. Chance SN, chance RA. Saturday: Mainly VFR, with local MVFR possible. Breezy. Chance RA. Saturday Night: VFR. Breezy. Slight chance RA, slight chance SN. Sunday through Monday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Today...High confidence. Increasing S winds today turning SW this afternoon with gusts 25-30 kt developing. A few gale force gusts to 35 kt possible this afternoon over the waters adjacent to Cape Cod. Seas build to 7-10 kt over outer waters. Scattered showers with perhaps an isolated t-storm late today over waters around Cape Cod and Islands. Tonight and Friday...High confidence. Winds shift to W tonight with diminishing speeds below 20 kt, then ramp up again from the W-NW Fri with gusts 20-30 kt. Outlook /Friday Night through Monday/... Friday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain. Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Chance of rain. Saturday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Slight chance of rain. Sunday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Chance of freezing spray. Sunday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of freezing spray. Monday: Winds less than 25 kt. Seas locally approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ230. Small Craft Advisory until 10 PM EST this evening for ANZ231- 236-251. Small Craft Advisory until 7 AM EST Friday for ANZ232>235-237- 250-254>256. && $$ SYNOPSIS...Belk/KJC NEAR TERM...KJC/Dooley SHORT TERM...KJC LONG TERM...Belk AVIATION...Belk/KJC/Dooley MARINE...Belk/KJC