Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 241959 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 359 PM EDT Wed Aug 24 2016 .SYNOPSIS... High pressure will provide another nice evening across the region with mainly clear skies and seasonal temperatures. An approaching surface trough will bring increasing clouds and the threat of showers across northern counties by Thursday morning, and a few thundestorms across the entire area by Thursday afternoon into Friday morning. Behind the front a return to seasonably mild and dry weather is expected for the upcoming weekend. && .NEAR TERM /THROUGH THURSDAY/... As of 300 PM EDT Wednesday...Another quiet evening is expected across the area as high pressure progresses offshore while a few high clouds filter in from the north and west. Dry weather is expected as temperatures fall into the 70s, bottoming out in the 60s to around 70 by morning as clouds slowly increase north and west with the approach of a weak surface trough. Latest CAM output suggests at least a nominal threat of a few light showers or sprinkles far west toward morning, but most areas should remain dry under continued light southerly flow. By Thursday we continue to advertise an increasing threat of scattered showers and a few thunderstorms as weak surface trough will interact with mid-level energy and nominal instability. Height falls remain negligible and given rather meager mid level lapse rates severe weather is not expected. However, latest AMSU/SSM-I PWAT analysis does show the northern periphery of a very moist airmass currently residing across the Upper Ohio Valley and Great Lakes (1.6 to 2.0 inches). It is this airmass that will advect east- northeast and reside across our area during the day, so the idea of brief tropical-like downpours in scattered convective cores still appears reasonable at this point. Mid-level flow looks strong enough to keep activity moving however, so from a hydrological standpoint I`m not overly concerned. With higher coverage of clouds I did trend maximum temperatures downward just a tad and in closer agreement with blended bias-corrected output offering readings in the 78 to 84 range. Dewpoints will be rather high though (65 to 72F) so it will feel rather muggy. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
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As of 350 PM EDT Wednesday...more consensus with the hi-res, and even global models regarding thursday night into friday morning. Deep west-southwest flow with moist airmass (precipitable water values around 2.0") will be in place. Models all pretty consistent that a little ripple in the flow will spark a round of precipitation overnight. Elevated instability remains in place all night, so can`t rule out isolated t-storm at any point. Based on latest model guidance, it looks like the better chances for these showers will be 05-09z across northern New York, and 09-14z across Vermont. Though the atmosphere will be moist, the showers/t-storms will move along rapidly enough that we aren`t concerned for any flooding issues. However when it rains, the downpours will be heavy albeit brief. High dewpoints (upper 60s to lower 70s) Thursday night will mean it will be a tough sleeping night. Showers quickly push off to the east by late morning Friday, with quickly clearing skies. 925mb temperatures will range from around 19C in the north to 22C in the south. That suggests it will be a warm day, with highs in the 80s areawide -- with some southern valleys pushing into the upper 80s. Decent boundary layer mixing should result in some afternoon wind gusts of 15-20 mph or so. Friday night, quiet and drier and cooler (at least compared to Thursday night) with lows in the 50s to lower 60s.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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As of 350 PM EDT Wednesday...in general, the forecast period is rather quiet, with only 1 weather system to bring any precipitation. 12z GFS and ECMWF are in okay agreement, but do have some differences with their 00z counterparts (especially with the ECMWF). Stuck pretty close with the model blend for the forecast, and thus the forecast doesn`t offer too much change to the previous version. Daily details: Saturday: sunny and dry. 925mb temperatures range from 14C (north) to almost 20C (south). So look for 70s north to lower 80s in the south (perhaps approach the mid 80s in southern valleys). Sunday: starts dry, but upper level trough and associated front will be approaching the region by late in the day. Looks like the system will be moving across overnight. Models do indicate minimal instability, so can`t rule out isolated t-storms embedded within a band of showers that should move eastward across the area. Ahead of the system, temperatures aloft warm a couple of degrees, so Sunday will be a couple of degrees warmer than Saturday in most places. Should be a good outdoor activity for most of us as the precip mostly holds off until late. Monday: 12z suite of guidance does indicate Monday will be mostly dry as the upper trough and surface front pushes east of the region by morning. However, previous model runs were a little bit slower, so as a result have maintained some small PoPs for Monday. Given all the tropical activity well to our south, the models will struggle with the overall large scale synoptics as well. Cooler airmass (compared to Sunday) should come in on Monday, however it will still be a couple of degrees above normal. Primarily 70s for highs, with lower 80s in southern valleys. Tuesday & Wednesday: High pressure should be in control. So high and dry. Continues to stay above normal on the temperatures, looking at 70s to lower 80s each day. However confidence isn`t all that high, given that there could be some sort of tropical activity well to our south that could have some sort of feedback into the placement of mid-latitude troughs and ridges.
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&& .AVIATION /19Z Wednesday THROUGH Monday/... Through 18Z Thursday...VFR under light to moderate southerly flow and SKC-SCT250 through 06Z Thursday. After 06Z thickening cloud cover to BKN/OVC 060-150 AGL with scattered showers/isolated thunderstorms arriving from the west with approach of cold front. Activity should be scattered with highest coverage generally toward the end of the TAF forecast cycle at northern/western terminals. NOTE: Rutland AWOS (RUT) is not operating. Because of the lack of disseminated observations, we continue our suspension of amendments for the RUT TAF. Once the communication problem has been resolved, and we again get routine observations automatically transmitted, we will lift that restriction. Outlook 18Z Thursday through Monday... 18Z Thursday through 18Z Friday...VFR with scattered MVFR/brief IFR in scattered showers/thunderstorms. Brief heavy downpours with reduced visibility and turbulence in stronger convective cores. 18Z Friday through 00Z Monday...VFR/high pressure. 00Z Monday onward...VFR with scattered showers/MVFR possible. && .EQUIPMENT... As of 118 PM EDT Wednesday...The AWOS (automated weather observing system) at the Rutland-Southern Vermont Regional Airport (KRUT) remains out of service at this time. The FAA has advised us that a new computer is on order to fix the problem at the KRUT AWOS. There remains no estimated return to service at this time. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...JMG NEAR TERM...JMG SHORT TERM...Nash LONG TERM...Nash AVIATION...JMG EQUIPMENT...WFO BTV

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