Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 261912 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 312 PM EDT Mon Sep 26 2016 .SYNOPSIS... Nearly stationary upper level low pressure just north of Lake Superior this afternoon will push and occluded front through the North Country tonight, accompanied by some light rain showers. Tuesday and Wednesday will be mainly dry behind the front with temperatures warming to above seasonal normals. Greater chances for rain return Thursday and into the weekend as the upper low moves into the Ohio River Valley and Northeast. && .NEAR TERM /THROUGH TUESDAY/... As of 224 PM EDT Monday...It`s a fantastic early fall day across the North Country as we remain under the influence of high pressure anchored just off the New England coast. Temperatures have rebounded nicely from this mornings chilly start, and are on track to top out in the low 60s east to near 70 west under partial sunshine from an increasing high deck. Moving on into this evening and the overnight hours, mid/high clouds will continue to increase as an occluded front associated with a deep vertically stacked and nearly stationary upper low just north of Lake Superior approaches. Associated rain showers are already moving into far western New York and should shift into the BTV CWA shortly after 00z, and east of the Connecticut River by sunrise Tuesday. Currently showers are very scattered in nature along the boundary, and expect much of the same as it moves through the North Country. Some local enhancement is expected on southern and southwestern facing slopes due to a developing 40kt jet at 925mb, while this feature will in turn limit QPF in the St. Lawrence and Champlain Valleys. Overall not a big QPF event though, with only a tenth to perhaps 2 tenths of rain expected. With increasing winds and southerly flow, lows tonight will be much milder than the past 2 nights, and generally range from the mid/upper 40s across eastern Vermont and the Northern Adirondacks, to low/mid 50s in the deeper Champlain and St. Lawrence Valleys. Behind the front, a strong mid-level dry slot builds over the area for Tuesday so after showers exit during the morning hours across eastern Vermont, we should be looking at a generally dry day. South/southwesterly flow persists behind the boundary, keeping temperatures above seasonal normals and with 925mb temps averaging around +13-15C we should see highs in the mid 60s to low 70s under partly sunny skies. There remains though the outside chance for some lake effect rain showers downwind from Lakes Ontario/Erie tomorrow afternoon, but confidence is fairly low at this time and latest hi-res guidance isn`t all that bullish either so I`ve painted in just some low chance PoP`s during the afternoon up the St. Lawrence River. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
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As of 312 PM EDT Monday...Dry slot moves into the North Country behind the cold front, bringing an end to rain showers through the early half of Wednesday night. Meanwhile, large closed 500mb low sinks south and east into the Ohio river valley. Associated surface low will be slow to align with upper low. Broad surface low develops around the Carolinas with inverted trough extending toward the 500mb low still over the Ohio Valley. At the surface, east to NE flow will affect the North Country with drier and cooler air. Expect Tuesday night and Wednesday night temperatures in the 40s to around 50. Wednesday daytime temps look to reach the 60s to around 70.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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As of 312 PM EDT Monday...Much uncertainty continues in the long term as the 500mb closed low resides over the central/southern Appalachians before gaining momentum northward late in the week. Canadian surface ridge over Quebec, but secondary to the amplified flow over the plains states, looks to impeded northern progression of precip associated with the closed 500mb low. ECMWF and GFS show mid-level ridge over the Atlantic blocks eastward progression of the 500mb low, therefore the low eventually moves northward into the eastern Great Lakes bringing showers to the North Country late in the period. With such a meridional flow across North America, expect high uncertainty in the details of the forecast to continue.
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&& .AVIATION /19Z Monday THROUGH Saturday/... Through 18Z Tuesday...VFR conditions this afternoon and evening will trend towards MVFR in rain showers as an occluded front traverses the area after 00z. Mid/high cirrus deck will gradually lower through time, remaining VFR through about midnight across northern New York, and 2-4AM across Vermont before lowering to MVFR. Vsby remains largely VFR in the showers, with periods of lowering to MVFR. After 12z, front exits the region to our east with conditions gradually improving back to VFR by 18z. Winds generally not an issue, less than 10kts, but a few gusts towards 18-22kts from the south will persist at KBTV and KPBG this afternoon and evening. Outlook 18z Tuesday through Saturday... 18z Tue - 00z Thu: Generally VFR, though an MVFR marine layer may intrude from the east late Tuesday night through mid-day Wednesday. 00z Thu - 00z Sun: Mainly VFR with MVFR in rain showers possible, especially on Saturday. && .MARINE... Funneling south winds ahead of approaching front will bring 15 to 25 knots and possibly higher gusts to Lake Champlain tonight...already 20 knots at times this afternoon. After front passes Tuesday morning, winds should begin to diminish. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Lahiff SHORT TERM...KGM LONG TERM...KGM AVIATION...Lahiff MARINE...slw

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