Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 281948 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 348 PM EDT SAT MAY 28 2016 .SYNOPSIS...
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The Memorial Day weekend will continue to see well above normal temperatures with daytime max temps between 10 to 20 degrees above normal. Increasing low level moisture will allow for higher relative humidities and an increasing chance for widespread showers with scattered thunderstorms possible on Sunday and Memorial Day.
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&& .NEAR TERM /THROUGH SUNDAY/...
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As of 344 PM EDT Saturday... With the 2pm observation in Burlington we reached 90 degrees for the second day in a row putting us two thirds of a way to a local heat wave. Expect warm and muggy (relative to normal for the North Country) conditions through the rest of the afternoon and early evening. The scattered cumulus field has continued to develop across both northern New York and Vermont, however the lack of any significant forcing has prevented any showers from developing as of this discussion. The lake breeze on the western edge of Lake Champlain may end up being the trigger for some late afternoon early evening convection depending on how inland it moves. Additionally, the western edge of the Champlain Valley has been considerable cooler with light to moderate onshore flow from the much colder lake water temps. With the area somewhat unstable 150-200 J/kg of MUCAPE any showers that do develop will have the potential to cause an isolated lightning strike or two. As the upper level ridge continues to build this evening expect another evening with some potential for patchy fog development. The best chance will be over northern New York where we are still drying out from the light rain that fell overnight Thursday. Across Vermont where we`ve gone with consecutive drys days we may not have enough boundary layer moisture to see widespread fog. Tomorrow, as mentioned by the midnight crew, becomes quite the active period. The upper level ridge overnight gives way to an advancing upper level trough. There will be a large influx of precipitable water with values rising to 1.6-1.8 by location. 925mb temps are elevated again Sunday and the 21-23C 925mb temps will support max temps tomorrow once again in the upper 80s to low 90s. Currently the forecast for Burlington reaches heat wave criteria with a max temps of 90 expected. Unlike today however there will be a few piece of shortwave energy the ride along the longwave trough providing the necessary trigger for convection to occur. So I`ve continue to offer high chance to likely pops for most of the forecast area. MUCAPE values are expected to exceed 500-1000 J/kg and K-index values also are indicated of thunderstormdevelopment. With the chance for thunderstorm development, slow storm motions, and abnormally high pwat, I continued to mention the chance for heavy rain in any thunderstorms that develop. We should be safe with regards to flash flooding due to how dry we`ve been in May but caution should be taken with any shower producing heavy rainfall.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/... As of 333 AM EDT Saturday...Most active period then takes shape by later Sunday into Sunday night with the approach of a longwave trough and its interaction with deep tropospheric moisture. The first half of the day should be more of the same with partly sunny, warm and modestly humid conditions with widely scattered terrain-driven showers/isolated storms. A few record high temperatures may again be threatened (see climate section at bottom). As mid level heights begin to fall by later in the day and toward evening expect a broader coverage of showers/storms to develop and continue into Sunday night as upper trough approaches. Anomalously high pwats in excess of 1.5 to 2.0 inches combined with a deep moist-neutral airmass to near 30 kft all spell at least the potential of locally heavy rainfall across the area, especially from the Adirondacks eastward where some interaction with the moisture plume from TD #2 may occur Sunday night. Will thus introduce this idea along with other surrounding NWS offices per intra-site coordination this morning. While antecedent dry conditions should preclude a widespread flood threat, localized hydrological concerns will be a possibility during this period. As we progress into Monday the upper trough pulls east with a drier, more stable airmass filtering into the region over time and precipitation chances lowering accordingly. In regard to temperatures I leaned close to blended MOS-based and bias- corrected data offering highs on Sunday in the 80s to locally near 90F in the Champlain/St Lawrence Valleys, then somewhat cooler from the upper 70s to lower 80s by Monday with more tolerable humidity levels. Overnight lows Sunday night mainly in the 58 to 66 range. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... As of 333 AM EDT Saturday...The period from Monday night onward through Thursday of next week will be dominated by surface high pressure with generally fair weather, light winds and tolerable humidity levels. Temperatures will remain several degrees above normal, continuing the present trend that`s been established over the past week or so. Highs should mainly range from the mid 70s to lower 80s each afternoon with overnight lows generally in the 50s to around 60. By late week, a slightly more vigorous northern stream trough and attendant surface front will make a run into the northeastern third of the nation. As this feature approaches expect a renewed threat of showers from Friday into next Saturday. && .AVIATION /20Z Saturday THROUGH Thursday/... Through 12z Sunday...Generally VFR conditions through the TAF period...with SCT mid-upper level clouds. Light fair weather cumulus has begun to pop up over the adirondacks with an isolated showers or thunderstorm possible. Areal coverage is minimal so I`ve only included vcsh for PBG which has the best chance to see a shower in the vicinity this afternoon. Generally calm to light and variable winds will continue this afternoon before going calm overnight and then southerly tomorrow morning. Outlook 12z Sunday through Wednesday... Mainly VFR with a daily chances for showers and thunderstorms each afternoon and evening. Greatest coverage/threat appears to occur in the Sunday and Monday time frame. Best chance for a dry day will be Wednesday. && .CLIMATE... Record maximum temperatures for Saturday 5/28 and Sunday 5/29 are as follows: 5/28 5/29 BTV - Burlington 92 in 1978 89 in 1978 MPV - Montpelier 88 in 1978 87 in 1978 MSS - Massena 89 in 1978 90 in 1978 St Johnsbury 93 in 1978 92 in 1978 Mt Mansfield 77 in 1978 77 in 1978 && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Deal NEAR TERM...Deal SHORT TERM...JMG LONG TERM...JMG AVIATION...Deal CLIMATE...BTV

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