Area forecast discussion National Weather Service Buffalo New York 133 am EDT Sat may 25 2013 Synopsis... Canadian high pressure building across the Great Lakes will bring mainly dry and cool conditions this weekend. Temperatures will rebound back to above average next week. && Near term /through today/... as of 130 am...regional radars show the back edge of the coastal low/S precipitation shield lingering near the Lewis County border...with patchy light rain/scattered light showers extending back to the Interstate 81 corridor in central New York. With the position of the coastal low changing little overnight...will keep a chance of rain showers in place across Lewis County...along with continued mostly cloudy skies across the north country. Further to the west...skies have been slowly clearing...with lingering clouds south of Lake Ontario. With 850 mb temperatures of -2c and lake surface temperatures in the middle 40s to lower 50s...suspect a modest contribution from lake moisture is likely helping clouds to linger south of Lake Ontario in combination with the upper low. A persistent flow of drier air upstream...and the eastward track of the upper low should eventually dry things out...with a gradual clearing trend through the early morning hours. With the clearing skies and chilly airmass that is in place... temperatures will be a concern overnight...particularly across interior sections of the southern tier that only have a short ways to go before reaching the freezing mark...and where the current freeze warning still looks plausible. Meanwhile further to the north...some spots cloud see temperatures as low as the middle 30s...however feel there will be enough of a gradient and/or lingering cloud cover to prevent much in the way of a frost threat. Saturday...models in closer agreement with the slow progression of the upper low. Associated precipitation looks to back in from the east and may impact areas east of Lake Ontario. Bulk of the area will see plenty of sunshine. With cold air mass centered over the area we will only see highs in the middle 50s to lower 60s...although cool will be an improvement over todays readings in the 30s and 40s. && Short term /tonight through Monday night/... Saturday night a closed upper level low will be sitting over New England...with a cold northwest flow across the eastern Great Lakes. Moisture and precipitation around this area of low pressure will largely be confined to areas just to our east...though a few light showers may brush by our north country. By Sunday morning cold air under this area of low pressure will back slightly westward such that -2c air at 850 hpa will be found across the western foot hills of the Adirondacks and would not be surprised if a few snow flurries mixed in with the light rain showers. Away from the north country mainly clear skies will be found and cold with a northwest wind. The gradient between high pressure nosing southward over the central Great Lakes and the closed low over New England will be about the same Saturday night as Friday night. Current thinking is that freezing temperatures will be a concern again across the southern tier...and that the light winds will limit the frost formation. Closer to the lakes is where the warmest overnight lows will be found with upper 30s to around 40 for nighttime lows. There will be a little improvement Sunday as the closed low slowly lifts through northern New England. This movement should be enough to keep our area dry with lingering clouds brushing by the eastern portions of the north country. Elsewhere plenty of sunshine will again be found across areas south of Lake Ontario and with 850 hpa ranging from +2 to +4 our highs will be a couple degrees warmer than Saturday...with highs in the low 60s. A light northwest wind will again be found across the County Warning Area. Sunday night will be dry and winds backing to more of a southwesterly flow. While freezing temperatures will be very spotty across the southern tier and inland north country the lighter winds and relaxed pressure gradient will allow for some patchy frost. On Monday surface high pressure will slide into the region. Subsidence with this feature will bring a dry Memorial Day and abundant sunshine across the region. Though a Blue Sky temperatures will still fall shy of normal with afternoon highs in the middle to upper 60s. Dewpoints will also be low...in the middle to upper 30s which will bring low relative humidity values. Dry conditions will continue through the night Monday with lows dropping back into the 40s. && Long term /Tuesday through Friday/... this time period will be mainly dry...with building heat and humidity. There is still a bit of uncertainty as to when a warm front lifting northeastward will cross the eastern Great Lakes region. The 12z GFS/12z Canadian operational model runs are a little faster than the 12z European model (ecmwf)...with a passage Tuesday...while the European model focuses more upon Wednesday. Will bring low chance probability of precipitation for showers and thunderstorms across the region Tuesday night-Wednesday night. Before the frontal passage it will be comfortable with low dewpoints and seasonable late may temperatures. After the warm front passes humidity will begin to build while temperatures each day will likely be a degree or so warmer. By Friday afternoon highs will be well into the 80s across the region. The building ridge over the region Thursday and Friday will likely cap any afternoon showers and thunderstorm development...and thus we will maintain a dry forecast for now. && Aviation /06z Saturday through Wednesday/... low pressure will close off in the upper levels across New England...with our region on the western periphery of this system. Expect a general clearing trend through 12z or so at most taf sites...with any lingering clouds VFR in the 5-6k feet range. After this expect mostly clear skies today at buf/iag/roc/jhw. Clouds should linger longer at Art...closest to the low...with possibly a sprinkle middle-day today as moisture pivots around the low. Outlook... tonight through Wednesday...VFR. && Marine... unseasonable conditions are in place over the lower lakes region due to the presence of a deep upper trough and plenty of associated cold air aloft...with a persistent northwesterly low level flow sustaining low end advisory level conditions. These will persist into the overnight hours on Lake Erie and the western end of Lake Ontario...before winds begin to diminish. This said...small craft conditions may redevelop on Lake Erie Saturday afternoon. Further east...the modest northwesterly flow will persist into Saturday on the eastern end of Lake Ontario...which will maintain low end small advisory-level conditions there. Conditions will improve Sunday and Monday as high pressure moves overhead...with no issues foreseen for the latter portions of the Holiday weekend. && Buf watches/warnings/advisories... New York...freeze warning until 7 am EDT this morning for nyz019>021. Marine...Small Craft Advisory until 4 am EDT early this morning for lez040-041. Small Craft Advisory until 2 PM EDT this afternoon for loz043>045. Small Craft Advisory until 4 am EDT early this morning for loz042. && $$ Synopsis...tma near term...apffel/jjr/tma short term...Thomas long term...Thomas aviation...apffel marine...jjr/tma