textproduct: Burlington

WHAT HAS CHANGED

As of 249 AM EDT Sunday...

No major changes to the forecast with this update.

KEY MESSAGES

As of 249 AM EDT Sunday...

1. Rounds of showers will continue today, bringing an additional 0.20-0.60 inches of rainfall, potentially more in heavier or repeated showers and storms.

2. A steadier soaking rain is expected to move from west to east through New England Monday into Monday night, mainly impacting our southern counties but with the potential to track further north.

3. Mostly dry conditions late Weds into Thurs, followed by more unsettled and active weather late week into next weekend.

DISCUSSION

As of 249 AM EDT Sunday...

KEY MESSAGE 1: A vertically stacked low pressure system is located over the Gulf of St. Lawrence and Newfoundland, Canada, this morning. It is currently swinging a shortwave through northern New York and Vermont, resulting in continued showers early this morning. In the last 24 hours, the Champlain Valley, Greens, and northwestern Vermont have reported between a quarter of an inch and an inch of rainfall with higher amounts just over the border in Quebec. Over the next 6 hours, we anticipate showers chances 15-55%, highest on northern and western slopes of the mountains. Precipitation chances then increase towards noon and the early afternoon today as instability increases and temperatures head towards the upper 60s and 70s. Shower and thunderstorm chances will be around 30-70% today, with highest confidence in the Champlain Valley and the Green Mountains. As previous forecaster stated, severe winds and hail are not expected with these storms, though briefly moderate to heavy rain is possible. Additional rainfall amounts of 0.20-0.60" are likely today into the evening, with potential for higher amounts in any heavier shower or thunderstorm as modeled precipitable water values run as high as 1.00-1.25". If these heavier storms occur over an area that already has saturated soils from previous rain, this could mean localized ponding or isolated flooding, especially if these areas get repeated showers or thunderstorms, but the potential for these issues is much lower today. At this point, no rivers are forecast to go into flood stage over the next few days, though this could change if precipitation amounts locally exceed our current forecast.

KEY MESSAGE 2: Upper level closed low pressure currently in western Ontario is expected to track eastward into Quebec on Monday while another low pressure system and open wave currently in the Rockies track through the Ohio Valley Monday, sending a wave of precipitation into the Northeast. Deterministic model spread seems to have only increased in the latest runs. The GFS has shifted its track more southward and lowered precipitation in our forecast area, while the Canadian has generally stayed the course but increased precipitation amounts (and sharpened the gradient of precip on the northern edge), and the NAM12 model has brought the track more northward and increased precipitation amounts. Most noticeable trend about the NAM3 is that is has largely slowed down arrival of precipitation to the area. Current thinking has up to a quarter inch of rain Burlington northwards and 0.25-1.00" of rain south of Burlington, with highest amounts in southern Vermont. These higher amounts could reach north of Burlington if the storm tracks farther north, resulting in higher amounts than forecast in southern Vermont. On the other hand, the areas south of Burlington could see lower amounts if the storm ends up tracking farther south, and areas along the international border could even see little to no rain. This more southern track is looking the least likely as the southernmost-leaning models seem to be holding steady from run to run. Most likely scenario sees some measurable precipitation in the Adirondacks, central Champlain Valley, Winooski River Valley, and southward, with more uncertainty along the international border. At least a half an inch of precipitation is likely in Rutland and Windsor counties of Vermont. Temperatures will trend back towards seasonal normals for the first half of the work week, with widespread highs in the 70s to lower 80s and lows in the upper 40s to around 60 F, and drier weather is anticipated to follow this Monday-Monday night system into the midweek.

KEY MESSAGE 3: Mid/upper lvl trof remains acrs the Great Lakes into the NE CONUS for days 4 thru 7 with minimal change in our thinking. Initially fast west to east zonal flow is evident in the upper air analysis for Weds into Thurs with some lingering mtn showers possible on Weds aftn. Weak 1016mb high pres should keep most of the area dry into Thursday. By Thurs into Friday our next s/w drop southward acrs the Great Lakes and mid/upper lvl trof amplification is progged. This wl help advect deeper moisture and some instability back into our region late Thurs into Friday with an increase in areal coverage of showers and thunderstorms expected. Initially pw values are near 1.0" ahead of weak sfc trof reflection, while deep layer moisture may limit sfc heating/instability and how robust convection can become on Friday. Also, mid/upper lvl flow remain progressive from the southwest, before shifting to the west by late Friday, should help to minimal any flood threat.

Meanwhile, latest progs for next weekend shows additional s/w energy with higher pw values surging toward the NE CONUS, as boundary is progged to be draped acrs our cwa. Pw values climb to near 1.5" with potential for a convective cluster of showers and storms to impact our region. Of course this far out, exact placement of heaviest qpf and track of system is impossible to fcst, but ingredients looks favorable for some areas of heavy rainfall possible. Progged 925mb btwn 15-17C support highs mid 70s to lower 80s for Thursday and Friday, with some slightly cooler readings possible by next weekend. Little change in lows with values mid 50s to mid 60s.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Through 12Z Monday...Any lingering IFR ceilings at SLK/MSS will lift in the next 1 to 2 hours per latest satellite trends and surface observations. Additional scattered showers with embedded rumbles of thunder are possible again today across our taf sites, with brief MVFR cigs/vis in the heavier activity. Greatest potential will be between now and 20z today and have utilized PROB30 groups to cover in tafs attm. Light terrain driven winds less than 5 knots become southwest to northwest at 4 to 8 knots by 15z, before becoming light and variable again around sunset. Sounding data suggest a little more clearing tonight with developing sharp/shallow inversion, which could result in fog/br development with IFR or lower conditions at EFK/SLK and MPV. Given low confidence and time frame have shown 3sm BR with BCFG SCT002 for now. As confidence increases or decreases in potential fog development, this can be adjusted in later packages.

Outlook...

Monday: VFR. Chance SHRA. Monday Night: Mainly VFR, with local IFR possible. Chance SHRA. Tuesday: Mainly VFR, with local MVFR possible. Slight chance SHRA. Tuesday Night: VFR. NO SIG WX. Wednesday: VFR. NO SIG WX. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. Chance SHRA, Slight chance TSRA.

BTV WATCHES/WARNINGS/ADVISORIES

VT...None. NY...None.