Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 061406 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1006 AM EDT Tue Jun 6 2023 .SYNOPSIS... Shower activity will increase in coverage today, along with some improvement to smoky skies from the Quebec wildfires. A few rumbles of thunder cannot be ruled out this afternoon, but no organized storms are expected. Below normal temperatures continue for the remainder of the work week with a gradual warming trend into the weekend. Diurnally driven showers are possible on most days this week. && .NEAR TERM /THROUGH WEDNESDAY/...
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As of 955 AM EDT Tuesday...Forecast in on track for some isolated to scattered showers developing this morning, becoming more numerous this afternoon with increasing instability. WV satellite imagery showing shortwave pushing into our area from the north, which has allowed a few showers to blossom over northern NY this morning. Still haven`t had any reports of precipitation at the surface, so it`s likely that most or all of the precipitation from these showers is not making it to the surface at this point. However, as forcing increases throughout the day with additional shortwave energy moving into the area, do expect a few hundreths of an inch of QPF to make it to the surface within showers. Otherwise, smoke forecast looks on track and the Vermont Agency of Natural Resources has reissued the Air Quality Health Advisory for all of Vermont. Do still expect some improvement in smoke today for Vermont, but enough of a concern remains to continue the Advisory. Further west, the Air Quality Alert remains in effect for our NY counties through midnight. Previous discussion follows... According to the US EPA Air Now page, worst conditions smoke wise for the pre dawn into the morning hours will be across western St Lawrence Valley. Seeing some radar reflectivity returns across our western zones but no rain has been reported or observed by ASOS or on webcams. This could be the result of the Quebec wildfire smoke dampening the lapse rates and suppressing the QPF output. In fact, CAMs have been overly aggressive with what should have been a wetting rainfall for parts of the region so far. So continued to cap PoPs at slight chance or low chance (30 percent) for the remainder of overnight hours. In addition, there could be areas of localized fog across the Northeast Kingdom during the pre dawn hours where the dew point depressions are a couple of degrees or less along with near calm conditions. For today, the main weather concern remains areas of smoke from the Quebec wildfires. The good news is that as showers become more widespread during the course of the day, hi-res guidance is showing near-surface smoke diminishing from the northeast to the southwest. This coincides with improved dynamics for more widespread rainfall coverage due to the phasing of a shortwave trough energy from the northwest along with the vertically stacked low pressure system along coastal New England. So have PoPs increasing during the daytime hours. And as PoPs reach the likely to low-end categorical threshold, the mention of smoke in the weather grids also goes away. We shall see how that unfolds, since the smoke has helped suppress rainfall so far, presumably due to the dampening of the atmospheric lapse rates. It is worth noting that this is rather unchartered territory for many NWS forecasters across the Northeast WFOs having to deal with wildfire smoke for the first time in their forecasting career. In other words, we are learning and adapting as the event unfolds. Models do show some weak instability developing in response to height falls aloft and some decent lapse rates during the afternoons. This may yield a few rumbles of thunder but it seems more likely this instability will be more useful in increasing the coverage of showers across the region. Like today, we will have to watch how the smoke impacts the skies as it could be a wild card and limit some much needed rainfall. On and off diurnally driven showers continue into Wednesday thanks to anomalously cold temperatures aloft that are more typical for early April according to the SPC sounding climatology. Wednesday will be another unseasonably cool day with highs 10 to 15 degrees below normal. Thunder potential is non zero but confidence is too low to include in the forecast. As with cold core upper level low pressure regimes, there will be good low-level and mid-level lapse rates but little instability to tap into. A tenth to quarter inch of rainfall is possible, which together with the rainfall on Tuesday be the first widespread wetting rainfall since May 24th. Much of VT is currently under the D0 abnormally dry category according to the U.S. Drought Monitor so the rain will be welcome. It does make for a rather dreary day though with daytime highs only in the mid 50s to low 60s. For reference, typical highs this time of the year are in the low to mid 70s. Some of the deterministic guidance Wildfire smoke from Quebec may continue to impact the region on Wednesday but details will have to be fine tuned in the next 24 hours as it remains outside of the HRRR/RAP guidance at this time.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 335 AM EDT Tuesday...Persistence will be the forecast for the end of the work week as a deep, closed upper level low over eastern Maine and Nova Scotia Wednesday night will retrograde southwestward over central New England through the period. The result will be continued daily chances for showers, though with greater areal coverage compared to previous days in the afternoons due to the projected location of the low and steeper low level lapse rates owing to cold upper level temps around -20C at 500mb. Showers will generally wane each day after sunset, but overnight can`t be ruled out completely. Temperatures will remain seasonally cool with lows mainly in the 40s for and 60s for highs which is about 5-10 degrees below normal for mid June. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... As of 335 AM EDT Tuesday...Heading into the weekend, it appears we`ll have one more day under the influence of the aforementioned upper low with scattered showers continuing on Saturday, but by Saturday night signals continue to point towards upstream blocking briefly breaking down allowing the system to shear out and shift north of Newfoundland. Dry conditions should develop for Saturday night into Sunday, but unfortunately, ensemble mean NAO forecasts indicate the blocking redevelops and supports another upper low dropping through the Great Lakes and closing off over the mid-Atlantic and/or Northeast States heading into Sunday afternoon and early next week. Time will tell exactly where this system will set up shop which will play a large role in precip chances next week, but one thing is for sure, the potential for any severe weather is quite low through the period. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... Through 12z Wednesday...VFR conditions expected to prevail through the TAF period, with periods of MVFR and locally IFR due to wildfire smoke from Quebec especially for the St Lawrence valley terminals. More widespread showers arrive this afternoon, which should lead to some improvement to the smoky skies across the region. Light north to northwest winds become gusty at 15-20 kt this afternoon. Better chance for more widespread rain showers with 4-5 SM vsby and MVFR cigs arrive after Tuesday 22z. Outlook... Tuesday Night: Mainly VFR, with areas MVFR possible. Chance SHRA. Wednesday: Mainly MVFR, with areas VFR possible. Likely SHRA. Wednesday Night: Mainly MVFR, with areas VFR possible. Chance SHRA. Thursday: Mainly MVFR, with areas VFR possible. Chance SHRA. Thursday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Friday: Mainly MVFR, with areas IFR possible. Chance SHRA. Friday Night: Mainly MVFR, with areas VFR possible. NO SIG WX. Saturday: Mainly VFR, with local IFR possible. Slight chance SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Chai NEAR TERM...Chai/Duell SHORT TERM...Lahiff LONG TERM...Lahiff AVIATION...Chai is the U.S. government's official web portal to all federal, state and local government web resources and services.