textproduct: Burlington

WHAT HAS CHANGED

As of 247 PM EDT Monday...

The forecast for the mid-week rain and flood threat remains about the same.

KEY MESSAGES

As of 247 PM EDT Monday...

1. Widespread showers and thunderstorms will occur Tuesday through Thursday as a slow-moving system tracks through, bringing the potential for localized flash flooding.

2. Unsettled weather continues into the weekend with the approach of another developing mid to upper level trough.

DISCUSSION

As of 247 PM EDT Monday...

KEY MESSAGE 1: An upper-level low builds into the region tomorrow and remains over the area into Thursday. An associated surface low will form over the Great Lakes and occlude as it moves into New York and New England, bringing consistent showers. The showers enter northern New York tomorrow morning and enter Vermont tomorrow afternoon as a south to north oriented line. There will be some convective enhancement on the frontside, due to surface CAPE reaching up to around 1,000 J. A lack of deep-layer is expected to prevent any severe threat. These storms will likely have the highest rainfall rates of the entire event, but dry antecedent conditions and some south to north storm motion should keep the flood threat relatively low for the day on Tuesday. The axis of rain looks to become more sse-nnw oriented heading into Tuesday evening and night, and east to southeast flow will develop. While the precipitation should trend toward more stratiform as the night goes on, some convective enhancement will still be likely, especially in southern Vermont where the highest totals are expected. This Tuesday night into Wednesday morning would likely have the highest concern for any flash flooding as the axis of rain looks to stay relatively stationary. Heading through Wednesday, the dynamics weaken and the axis of rain looks to become more broken and lighter. Periods of showers will continue Wednesday night through Thursday, but they will become much lighter and gradually less widespread as the surface low weakens and pushes east. The area of highest concern is the eastern slopes and spine of the southern Green Mountains where the best dynamics will combine with upsloping. The east slopes of the Adirondacks will likely be the second area of focus due to the upsloping. Still, in the more favored areas, only isolated flash flooding looks to be possible. The Champlain Valley and Northeast Kingdom will likely receive some locally lower totals due to downsloping.

KEY MESSAGE 2: An unsettled weather pattern will continue into the weekend as our approaching system slowly departs Friday with an additional system possibly arriving sometime late into the weekend. There is still a large spread in timing of the departure of our approaching system and the weekend system, but trends have moved towards lingering showers and embedded thunderstorms Friday, with a more delayed trend in the weekend activity, perhaps closer towards Monday next week. Models denote cyclonic circulation lingering to our south and east Friday with continued wrap around moisture in portions of eastern Vermont. With easterly flow blocked against the Greens, a differential heating boundary between the cooler eastern Vermont and warmer Champlain Valley and northern New York may set up. This will lead to areas of shower development along the convergence boundary Friday afternoon potentially.

Weak ridging tries to build into our cwa for Saturday, before another shortwave, associated with a 700-500mb trof approaches from the Great Lakes. Model ensembles in the GEFS and GEPS denote a more delayed system evolution closer to Sunday or Monday, with more isolated to scattered terrain showers Saturday afternoon. This is line with abundance of subsidence that may be across the area as our current system occludes and subsides over southern New England late this week. Latest guidances shows Saturday highest potential over northern NY, while Sunday activity wl be more widespread impacting both VT and NY. Limited run to run continuity and large spread in potential solutions results in low forecaster confidence and associated predictability on probability and timing of precip, especially Sunday into early next week. Temps will be driven by clouds/precip, but mostly above normal values anticipated, especially at night with lows in the upper 50s to upper 60s, while highs range from the mid 70s to mid 80s. Some levels of humidity are expected, but the probability of much above normal temps or significant heat is low given the anticipated pattern.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

Through 00Z Wednesday...A few showers and thunderstorms continue to periodically develop along the Adirondacks and Northeast Kingdom of Vermont. Pulsing convection will drift east over the next few hours and dissipate by about 02-03z. Some fog is possible overnight, but some flow will remain at 500-1000 ft at 10-15 knots which should result in some mixing. These winds appears strongest across northern New York. KEFK was directly under a downpour, but most other terminals have received little rain. So focused on climo favored spots with the most pessimistic outlook for KEFK. 1SM is forecast at KMPV and KEFK about 07z-11z, but may fall lower depending on how winds just off the surface impact fog development. Fog will dissipate after 11z-12z with southeast winds 5 knots becoming 7-10 knots around 16-18z. Showers and thunderstorms will begin developing after 16-17z, generally moving south to north followed by a batch rain 21z-01z Wednesday. Convection could be widespread, and so PROB30s are noted for most terminals as activity lifts north, but there's some uncertainty to the timing and focus of heaviest rainfall. So we'll tack down those details as we draw nearer. Winds after 22z, trend back towards 4-8 knots and ceilings will also be falling towards 3000-7000 ft agl.

Outlook...

Tuesday Night: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance TSRA. Wednesday: Mainly MVFR, with areas VFR possible. Windy with gusts to 30 kt. Likely SHRA, Slight chance TSRA. Wednesday Night: Mainly MVFR, with local IFR possible. Likely SHRA. Thursday: Mainly VFR, with local IFR possible. Likely SHRA, Slight chance TSRA. Thursday Night: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance TSRA. Friday: Mainly VFR, with local IFR possible. Chance SHRA, Chance TSRA. Friday Night: VFR. NO SIG WX. Saturday: VFR. Slight chance SHRA, Slight chance TSRA.

BTV WATCHES/WARNINGS/ADVISORIES

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