Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 221055 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 655 AM EDT Thu Sep 22 2016 .SYNOPSIS... One more day of above normal temperatures is expected across northern New York and Vermont as high pressure gradually moves east of the area. Clouds will be on the increase this afternoon and tonight ahead of a cold front moving down from Canada. This feature will increase precipitation chances after midnight tonight through much of Friday. The front moves south of the area Friday night and behind it colder air will move in for the weekend. && .NEAR TERM /THROUGH FRIDAY/...
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As of 655 AM EDT Thursday...Other than a band of mid clouds over parts of northern New York and Vermont this morning...overall forecast in good shape. Have adjusted the sky grids to account for these clouds to persist over the next few hours before eroding. More mid and high level moisture will eventually move into the region later today on westerly flow aloft. Warm 925 mb temperatures remain in place across the area and this will give us another day of above normal temperatures with highs in the mid 70s to lower 80s. Cold front north of the border tonight will not move down into our area until after midnight and looks to exit the area during the afternoon hours. Most of the precipitation is along and behind the surface front...thus will not bring the bulk of the precipitation into the area until after midnight. Highest probabilities should be between 09z and 18z with total amounts ranging from a tenth to a half inch by late in the day on Friday. With the clouds and precipitation on Friday...high temperatures will generally be in the 60s...but around 70 over southern Vermont with the later timing of the cold frontal passage. Gusty north winds are also expected behind the front which will be the start of noticeable cold air advection for the weekend.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 423 AM EDT Thursday...Post frontal conditions in the short term period, with northerly flow, cold air advection, and drying in the mid and upper levels. 500 mb flow is a nearly blocked Omega pattern. A sharp ridge along the Mississippi River separates a closed low over the Canadian maritimes from a low lifting northeast through the intermountain west. Low to east and ridge to west will keep northerly flow over the forecast area, although ridge will slowly build east and relax the pressure gradient by the end of the period. Moisture trapped below frontal inversion Friday night will dry out through Saturday night with a decreasing trend in cloud cover. Temperatures to drop a few degrees below normal Friday night, and 5- 10 degrees by Saturday night. Lows Friday night in the 30s to low 40s except upper 40s near Lake Champlain where water temp remains around 70. Some wind Friday night will keep frost formation at bay. Odds are better for frost Saturday night as pressure gradient slackens and drier air allows temperatures to radiate down to solidly in the 30s. Have patchy frost Saturday night in the Adirondacks and Northeast Kingdom. 850 mb temps around 0 to +1 Saturday support max temps in the 50s to near 60 in the Champlain Valley. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 423 AM EDT Thursday...Model differences become apparent in the latter part of the extended period and reduced confidence in Tuesday and Wednesday forecasts. 00z ECMWF has completely flipped from previous run. Prior 12z run had slower moving ridge with cutoff low over the southern plains, and resembled the GFS. The latest 00z ECMWF run is much more progressive, and the ECMWF brings in rain as early as Monday night to a previously dry forecast. GFS is more consistent, although GFS ensemble mean is a little more progressive but not to the degree the ECMWF is. For now will go with a persistence forecast until model difference resolve themselves. This means a dry forecast until Wednesday/Wednesday night when the slow moving upper low moves out of the Great Lakes and into the northeast US. Patchy frost Sunday night, then a warming trend back to near normal temperatures in this period with the ridge shifting east and southerly return flow. Highs generally in the 60s and lows in the 40s. && .AVIATION /12Z Thursday THROUGH Monday/... Through 06Z Friday...VFR conditions are expected through the period. Expecting only mid and high level clouds to move into the region through 00z before clouds slowly begin to lower...but still remain above 5000 feet. Dry conditions are expected for much of the period...but as a cold front begins to move down from Canada...the threat for showers will increase at KMSS after 04z. The bulk of precipitation will not move into the entire area until after 06z. Light winds this morning will increase from the south and southwest by midday and persist through the period...but speeds will generally be under 15 knots. Outlook 06Z Friday through Monday... 06z Fri to 00z Sat: MVFR with scattered showers associated with a cold front. 00z Sat through 00z Tue: Mainly VFR as a ridge of high pressure builds into the region. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Evenson NEAR TERM...Evenson SHORT TERM...Hanson LONG TERM...Hanson AVIATION...Evenson/WGH is the U.S. government's official web portal to all federal, state and local government web resources and services.