Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 270824 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 424 AM EDT Thu Apr 27 2017 .SYNOPSIS...
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A ridge of high pressure aloft will be over the North country today and early tonight, with high temperatures today in the 70s to around 80 from western Vermont to northern New York. High temperatures will be mainly in the 60s to lower 70s over eastern and northeast Vermont today. A frontal system will move into the region after midnight tonight bringing a a chance of rain showers to the region and a slight chance of thunderstorms. There will be a chance of showers Friday morning, but skies will become mostly sunny by Friday afternoon.
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&& .NEAR TERM /THROUGH FRIDAY/...
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As of 424 AM EDT Thursday...An upper ridge will be over the region today, with skies becoming partly to mostly sunny. However, a low level temperature inversion over eastern and northeast Vermont will keep low clouds in there through this morning before skies become partly sunny this afternoon. Areas of fog over the Adirondacks and the Saint Lawrence valley early this morning will burn off later this morning, with skies becoming partly to mostly sunny with highs in the 70s to lower 80s expected from the Champlain valley westward to the Saint Lawrence valley. Clouds east of the western slopes of the Green mountains will keep temperatures cooler there today with highs mainly in the 60s to lower 70s. Tonight, a weakening frontal system will approach the region from the eastern Great Lakes and will bring rain showers to the North country after midnight tonight. Have also continued to mentioned a slight chance of thunderstorms late tonight, as Showalter indexes slightly negative, suggesting some elevated convection possible. Lows will be mainly in the 50s tonight. Showers to linger into early Friday morning, with skies becoming mostly sunny by Friday afternoon. High on Friday will be in the upper 60s to mid 70s.
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&& .SHORT TERM /FRIDAY NIGHT/... 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. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... 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 underestimate 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 troughiness 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. && .AVIATION /08Z THURSDAY THROUGH MONDAY/...
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Through 06Z Friday...A ridge of high pressure will be over the region through the period. However, rather widespread MVFR ceilings across eastern and northeastern Vermont as of 06Z Thursday, as moisture is trapped below a low level temperature inversion. Expecting MVFR ceilings in these locations til 18Z Thursday, and then becoming VFR. Also, widespread IFR/LIFR in ceilings and fog across the Adirondacks and Saint Lawrence valley in northern New York at this time. Expecting conditions to become VFR in these locations by 15Z Thursday. Rain showers associated with an approaching frontal system should remain west of the region through 06Z Friday. Outlook... Friday: VFR. Breezy. NO SIG WX. 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. Breezy. Chance SHRA...TSRA.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...WGH NEAR TERM...WGH SHORT TERM...Nash LONG TERM...Nash AVIATION...WGH/Taber

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