textproduct: Burlington

WHAT HAS CHANGED

As of 242 PM EDT Saturday...

Little to no changes with regards to a pattern shift towards more showers and thunderstorms next week.

KEY MESSAGES

As of 242 PM EDT Saturday...

1. Gradually increasing rain and storm chances for the new week.

2. Multiple rounds of rain mid-week.

DISCUSSION

As of 242 PM EDT Saturday...

KEY MESSAGE 1: Mostly dry conditions are expected today into tonight. Modest radiational cooling will be offset by incoming high clouds, overnight. Mid 50s to mid 60s are expected early tomorrow morning, with perhaps a few cool hollows in the upper 40s. On Sunday, surface high pressure that has locked our region beneath a dry, stable air mass will shift farther out to sea. High temperatures will rise into the upper 70s to mid 80s for Sunday. Increasing moisture is expected, mainly over northern New York while a subtle trough angles south of the Adirondacks. 250-750 J/kg of CAPE will develop with daytime heating with weak flow aloft. Isolated to scattered showers and thunderstorm will be possible across northern New York, while Vermont will remain mostly dry. Showers will likely favor terrain boundaries, drift off their point of initiation, and generally decay. With slow-movers, a few brief downpours could occur. With the loss of daylight, shower activity will decrease, though perhaps not entirely 0 percent. Mid 50s to mid 60s are expected still.

Monday will be a rinse-and-repeat, but everything will have shifted slightly east. With increasing surface dewpoints, we could eke out closer to 500-1000 J/kg of CAPE, but there will be little shear present. Northern New York will remain the primary focus for convection, with fewer cells across Vermont. Some surface confluence will be present, but there won't be any upper feature. Convection will remain garden variety with somewhat higher potential for localized downpours due to the greater extent of rain and slowly increasing PWATs.

Then Tuesday will also be largely the same. A stronger upper level vort will approach from the west, but its influence won't creep into the area until relatively late on Tuesday or even Tuesday night/Wednesday. Forecast scenarios diverge, with the main differences being the strength and intensity of the incoming surface low. Most guidance favors a deep, sub 1000mb surface low closing off near Lake Ontario with the occlusion process resulting in briefly erratic motions before it shuffles east. A minority favors a weaker system with a surface low not developing until the upper trough is moving offshore. All told, there will be chances for showers and thunderstorms with little change to shear or instability regardless of which forecast scenario you pick. Localized downpours will be possible, mainly wherever surface convergence aligns with increasing upper divergence in association with the developing upper low.

KEY MESSAGE 2: An upper level low builds into the region for middle and late week and brings periods of rain. It looks to move slowly from west to east Tuesday through Thursday, and the time of its exit is still very uncertain. A relatively potent surface low should form along it and bring an area of consistent rainfall, but its exact position is uncertain. The solution favored by most EPS members puts the bullseye over central/southern Vermont, where probabilities of 2, 3 and 4 inches of rain are 50-70, 20-50 and 10-20 percent respectively. This could lead to a flood threat that would need to be watched carefully. A saving grace is that the precipitation won't be as convective after Monday, something that would cut down on rainfall rates. PWATs look to be in the 1.3-1.5 inch range, sufficient for heavy rain but not overly high as the trough is northern stream. The GEFS/CMCE ensembles favor the track of the surface low over coastal New England and keep the probability of 3 inches under 10 percent, and the probability of 2 inches in the 10-40 percent range, something less concerning given the relatively long time of the precip and lower rates. The rain should become more scattered and diurnally driven late week and into the weekend, but isolated to scattered afternoon showers will still be possible.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Through 00Z Monday...Predominantly VFR conditions are expected for the next 24 hours. The only exception may be KMPV, where some valley fog could develop between 08Z and 11Z. Thinking with incoming mid-level clouds, any valley fog that does develop won't be dense or long-lived, thus have included a tempo group for briefly reduced visibilities in the KMPV TAF. Otherwise, fog at KSLK and KEFK is still possible but less likely, and have thus left mention out of those tafs. All other TAFs have high confidence in VFR conditions. Winds in general will be light and terrain driven.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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