Area Forecast Discussion
Issued by NWS Burlington, VT

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162 FXUS61 KBTV 211139 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 739 AM EDT Tue Mar 21 2017 .SYNOPSIS... A weak upper level trough will move eastward across the North Country today, resulting in considerable cloudiness and a few rain or snow showers. An arctic front follows tonight, bringing a period of late evening snow showers or localized snow squalls, followed by gusty northwest winds and much colder temperatures. Highs on Wednesday will only reach the upper teens to lower 20s across northern New York and Vermont. A strong area of surface high pressure builds in for Thursday, with lighter winds and a moderating temperature trend. A warm front approaching from the southwest will bring a chance for mixed wintry precipitation on Friday. && .NEAR TERM /THROUGH WEDNESDAY/...
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As of 736 AM EDT Tuesday...Widespread cloud cover now in place across the North Country associated with weak/positive tilt 850-700mb trough crossing into nrn NY from sern Ontario. Getting some weak radar returns along the intl border at 1130z, and can`t rule out some very light precipitation in spots this morning. PBL temperatures are marginal for snow in the lower valleys (34-36F), so may see a rain/snow mix with anything that does fall during the late morning/afternoon. All in all, more of a nuisance and not anticipating any travel issues with trace to just a few hundreths of an inch of liquid equiv. possible. PoPs are only around 30%. It appears the shortwave trough passes to our east this afternoon, but weak low-level wind fields should allow areas of stratus to linger, per latest IR imagery. Went a bit cooler than MAV/MET MOS based on clouds, with highs generally in the upr 30s to lower 40s this aftn. Strong arctic frontal passage will occur tonight. It appears the front will race through KMSS at 02Z and through BTV by 04Z, before exiting south and east of VT around 06Z. Still seeing some indications of possible snow shower or snow squall activity associated with sharp low-level convergence along the frontal zone. Steep low-level lapse rates contribute to SBCAPE up to 100 j/kg per 00z NAM, and there is an axis of strong 925mb frontogenesis forcing along the boundary as well. SNSQ parameter values reach 3-6 units per 00Z NAM. PBL temps will likely be slightly above freezing as the front moves thru, at least in valley locations. So, anticipate potential for briefly moderate snowfall (vsby near 0.5sm) and some of that snow to initially melt on paved surfaces with road temps above freezing. However, the strong CAA that follows (lows single digits to lower teens) will result in some icy spots on the roadways with the temp drop, and will be something that we`ll need to closely monitor following FROPA from a travel perspective. Anything along the lines outlined above can be handled with a Special Weather Statement as conditions unfold, but will make brief mention in the Hazardous Weather Outlook as well. Wednesday will be a cold day with N-NW winds 15-25 mph and some gusts up to 35 mph with steep low-level lapse rates and 850mb temps falling to near -24C at 18Z/Wed. Highs on Wednesday will only range from the upr teens to lower 20s, with wind chill readings 5 to 15 below in the early morning, and 5 above to 5 below during the afternoon hrs. May continue to see some mountain snow flurries through the first half of the day.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 335 AM EDT Tuesday....Winter`s final charge should be in full force as an arctic airmass will be in place over the region on Wednesday night. Expect the coldest temperatures of the week to be Wednesday evening as the high pressure crests overhead. Excellent radiational cooling will see temps drop into the single digits over the North Country with the near lake areas a few degrees warmer in the low teens. High pressure continues during the day on Thursday with quiet weather conditions expected. The dry air aloft should mean that we should see some mostly clear to partly cloudy skies with below normal temps in the 20s. The cold air starts to exit the region Thursday night as the high pressure dives south towards the DelMarVa peninsula. We should see overnight lows in the single digits for Vermont while the warm air starts creeping back in over Northern New York. Lows across the Saint Lawrence should be in the lower 20s. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 335 AM EDT Tuesday...The models have come in slightly better agreement for a Friday solution. The departing high pressure dives south however the upper level ridge amplifies. The result is that the northern stream disturbance has weakened and a warm front never reaches the North Country. Two things here, one, that means we`d be looking at some sort of a mixed bag with regards to precip and two, as the ridge amplifies the whole system could end up south of the area and the northern tier of counties see little to no precip at all. Given its still 72 hours out I dont have great confidence in what situation plays out. So I`ve opted just continue the mention of rain changing over to snow at some point over the weekend. Coming out of the weekend, there will be another cutoff upper level system that could bring additional mixed precipitation type concerns as a warm nose creeps up the Saint Lawrence. Overall temperature trends are that the general source air becomes more Pacific than arctic and so temp should be on the rise back to near normal for late March. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
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Through 12Z Wednesday...Weak mid-level wave bringing BKN-OVC MVFR-VFR ceilings to the region today, with periods of MVFR already occurring at SLK and BTV, along with HIR TRRN OBSCD. May see a few flurries or sprinkles later this morning, and ceilings may briefly fall into the MVFR range at most TAF locations late this morning before improving some this afternoon. Arctic frontal passage occurs around 02Z/Wed at KMSS and 04Z/Wed at BTV. Should see a brief period of IFR conditions associated with snow showers and squalls along the front, with moderate snow possible for 15-30 minute period. May see a "flash freeze" situation with snow initially melting on warm surfaces, but quickly freezing as temps drop rapidly overnight Tuesday night. This may be an issue for airport ground ops. Winds light during the day, but becoming NW 15-20kt with gusts 25-28kt following frontal passage tonight. 12Z Wednesday through Saturday... Returning to VFR Wednesday with flurries confined to the mtns. VFR Thursday with strong high pres in place and lighter winds. Warm/stationary front brings possible MVFR conditions with mixed wintry precipitation possible Friday/Saturday.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos SHORT TERM...Deal LONG TERM...Deal AVIATION...Banacos

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