Area Forecast Discussion
Issued by NWS Burlington, VT

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155 FXUS61 KBTV 261912 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 312 PM EDT Wed Apr 26 2017 .SYNOPSIS... A low pressure area at the surface and aloft along the mid Atlantic coast will drift slowly northeast today and be near Cape Cod tonight. A ridge of high pressure will build northward from the mid Atlantic states northward into northern New York this afternoon. Expecting rain showers this morning to begin to taper off by this afternoon, with mostly cloudy skies expected. A ridge of high pressure will be over the North Country on Thursday, with highs in the 70s to the lower 80s. && .NEAR TERM /THROUGH THURSDAY/... As of 1136 AM EDT Wednesday...Updated forecast to integrate latest trends into the grids and associated forecast. Water vapor continues to show cyclonic flow with low level upslope southeast flow impacting our central/eastern vt cwa...while some drying aloft is occurring across northern NY. We are in the squeeze play today between drier air associated with building ridge aloft and subsidence and low level moisture with low pres along the coast. Thinking some breaks in the overcast develop this afternoon along and west of the cpv with mostly cloudy continues prevailing across central/eastern VT. Clouds will have a big impact on temps with cool maritime airmass in eastern sections with highs only in the 50s to near 60f...while upper 60s to lower 70s are possible over the SLV. Have trimmed back the pops as most of the area should remain dry...besides some light sprinkles/drizzle in the mountains of VT. Rest of fcst in good shape. Previous discussion from 416 AM EDT Wednesday...Radar loop showing scattered rain shower activity around the region this morning. Expecting the showers to taper off this afternoon as a ridge of high pressure aloft builds northward into northern New York this afternoon. Expecting skies to be mostly cloudy today and tonight. Highs today will be in the 60s. Lows tonight will be mainly in the 40s to lower 50s. A ridge of high pressure will be over the region on Thursday with highs mainly in the 70s to lower 80s. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
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As of 310 PM EDT Wednesday...Models have come much more into agreement with timing of a cold front Thursday night. Have used a blend of hi-res models for better defining the hourly progression of the front and associated precipitation. Models do have a minimal amount of instability ahead of the front, however dynamics are in short supply and with the overnight timing, we don`t have daytime heating. Thus expect a broken line of showers to trek eastward fairly quickly. Thinking late evening in the St Lawrence Valley to about daybreak in the Champlain Valley then by mid-morning exiting Vermont. Coverage and intensity of precipitation will be diminishing as the front moves east, so overall QPF will be less than 1/4". Given the instability signals, can`t rule out a rumble of thunder, so have maintained "slight chance" levels of thunder. All the clouds will keep it very mild. Lots of 50s overnight, perhaps staying above 60F in the Champlain Valley. Friday isn`t looking all that bad. Westerly flow develops, with drier air moving in. 925mb temperatures are still relatively mild, ranging from about 18C far west to 23C or so far southeast. This will support above normal highs from the mid/upper 60s west to upper 70s across the lower CT River Valley in southeast Vermont. Friday night, pretty quiet, though clouds will start increasing ahead of the next cold front, though lows will still be a good 10F degrees above normal.
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As of 310 PM EDT Wednesday...Fairly changeable weather through the period, however the longer term models are in pretty darn good agreement. That raises the overall confidence of what is expected. Taking it day by day... Saturday: Cold front will be moving across the region during the day. Not a lot of moisture or instability or dynamics with it, but enough for a few spotty rain showers. We should still see above normal temperatures despite the clouds and showers. Looks like warmest temperatures will be south and east. Clears out for Saturday night as a weak ridge of high pressure tries to build in as the front stalls just to our south. Lows will be near normal, and probably patchy frost around given clear skies and relatively light winds. Sunday: Seasonable temperatures, and dry for at least the first part of the day. Clouds will increase during the afternoon with initial push of warm air advection aloft associated with a pretty big low well to the west. Can`t rule out a few spotty light showers across western sections of northern NY during the afternoon. Monday/Tuesday: Looks like southerly flow will strengthen and push a warm front through and north of the region Monday, putting us into a mild warm sector. It`s possible we`ll get into a solid dry slot for Monday afternoon, and if that happens we could have enough sun to push temperatures well into the 70s. Not confident enough about that right now, so stuck to model blend for highs (still mid-upper 60s). Decent southerly jet with 40-45kt at 850mb that develops. Should be breezy in the Champlain Valley at least. Tried to increase wind gusts a little from raw model output (which tends to way underdo wind gusts). Perhaps 25-35mph gusts. A front comes through Monday night into early Tuesday. Models indicate some weak instability, so went ahead and tossed in mention of slight chance of thunderstorms. Should be a widespread rain event, perhaps 1/2" to 1" of rain, which should not cause any significant hydro problems on rivers. Residual clouds/showers around on Tuesday in a breezy westerly flow, though not terribly cold as this storm system originated in the southern Plains and isn`t really tapping into any very cold air. Wednesday: Still weak troffiness around along with plenty of low level moisture, so chance level PoPs and at least partly cloudy skies look good. Flow aloft turns more northwest and does start to bring in cooler temperatures from Canada, so at this point it looks like highs will be a few degrees below normal and primarily in the 50s.
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&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... Through 18Z Thursday...Very challenging aviation forecast with low confidence in overall flight categories and potential impacts on TAFS overnight. Current obs show a wide range of conditions from ifr at mpv in low clouds to vfr at btv/pbg/slk. Thinking mainly mvfr/vfr this afternoon with another hour or two of ifr at mpv. Winds generally light and variable...except northeast at mss btwn 5 and 10 knots. Tonight...lots of low level moisture is lingering with surface dwpts in the low to mid 50s...57 currently at slk...thinking with some clearing over the SLV/northern NY areas...temps will drop below cross over values with areas of fog/br possible after 04z. Have mention ifr prevailing with lifr tempo btwn 07-11z at mss/slk. Meanwhile...thinking southeast flow of low level moisture will help advect ifr cigs back into MPV by midnight or so. Rest of taf sites will remain between vfr/mvfr overnight. Winds shift to the south/southeast on Friday with mvfr trending to vfr at all sites by 15z. Outlook... Thursday Night: VFR. Chance SHRA. Friday: VFR. Chance SHRA. Friday Night: VFR. Slight Chance SHRA. Saturday: VFR. Chance SHRA. Saturday Night: VFR. NO SIG WX. Sunday: VFR. Slight Chance SHRA. Sunday Night: VFR. Chance SHRA. Monday: VFR. Chance SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...WGH NEAR TERM...Taber SHORT TERM...Nash LONG TERM...Nash AVIATION...Taber is the U.S. government's official web portal to all federal, state and local government web resources and services.