textproduct: Burlington

WHAT HAS CHANGED

As of 254 PM EDT Friday...

Rainfall amounts on Sunday have increased slightly with most locations seeing between a quarter to half of an inch of rain with closer to a tenth of an inch of rain near the Canadian Border.

KEY MESSAGES

As of 254 PM EDT Friday...

1. Showers end this afternoon with drier weather expected through Sunday afternoon. Rainfall associated with the remnants of Hurricane Isaias will impact the region Sunday evening and overnight but not flooding is expected.

2. Widespread showers are expected on Tuesday ahead of a seasonably strong frontal system, leading to sharply cooler and drier weather for Wednesday into Thursday.

DISCUSSION

As of 254 PM EDT Friday...

KEY MESSAGE 1: We continue to be under the influence of an upper level trough with a pocket of cold air aloft. This has lead to convective showers once again which should taper off this evening with the loss of daytime heating and building mid-level heights and increasing subsidence. Deep layer ridging will then begin to build into the region overnight with Saturday looking to be a beautiful but chilly day with plenty of sunshine, light winds, and highs in the mid 50s. This ridge will remain entrenched across the North Country through Sunday morning before the remnants of Hurricane Isaias will shunt the ridge eastward. Widespread rainfall will hold off until after sunset on Sunday for most locations with a quarter to half of an inch of rain expected for many locations. Areas near the Canadian Border will likely see the least rainfall with amounts closer to a tenth of an inch. The RRFS and NAM are hinting at a pocket of frontogenetic forcing in the northwest sector of the remnants Sunday night and are beginning to show a pocket of enhanced rain totals nearing 1.5 inches. This will likely change run to run and with the lack of mesoscale models having the temporal resolution to analyze this feature, we won't know about placement of this possible banded precipitation until tomorrow afternoon most likely. Nevertheless, the rainfall seen Sunday night, even if it's in the 1-1.5 inch rain locally, will be highly beneficial with no flood concerns anticipated at this time. A strengthening mid-level jet Sunday night will act to quickly shift these remnants eastward with dry conditions expected by daybreak on Monday.

KEY MESSAGE 2: Following the rain on Sunday night, another high probability rainfall event (about 100% chance of rain) is setting up for Tuesday. It appears moisture from the remnants of Tropical Storm Rachel in the eastern Pacific gets pushed into a strengthening front approaching from the north. An associated jet streak situated to our northeast will help increase large scale lift such that rain becomes widespread ahead of the boundary beginning early Tuesday morning. Would expect numerous showers and even a chance of thunder (around 10% is too low to mention in the forecast) with some elevated instability likely. The temperature forecast for Tuesday given the position of the thermally strong cold front is rather uncertain. However, very moist low level air will limit temperatures even in the warm side of the boundary. Meanwhile, shallow cold air advection is noted in forecast soundings, such that areas such as the northern St. Lawrence Valley could see temperatures fall into the 40s during the day.

Currently, probabilities of rainfall in excess of 1" during this event are mainly 20-45% and trend a bit higher towards northernmost New York and Vermont. For 0.5" these probabilities are about 40-70%. The evolution of this system Tuesday afternoon/evening is actually fairly uncertain, with one cluster of guidance favoring a faster exit and others keeping rain in the area through Tuesday night. It appears the front will finally clear the region as low pressure deepens to our east by Wednesday morning, in what could be a long duration rainfall event. Perhaps there will be enough moisture for some early season upslope mountain snow showers Tuesday night/early Wednesday if the cold air advection is sufficiently strong. Otherwise, while there is some spread in the upper air pattern for the remainder of next week, overall the consensus right now is for seasonably cool and breezy conditions on Wednesday ahead of a ridge of high pressure that preserves dry weather through at least Thursday.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Through 18Z Saturday...A large cluster of showers in eastern Ontario is moving towards the airspace, with high probabilities of producing rain over the course of about 30 to 90 minutes at most terminals. Within those showers, there will likely be some MVFR intervals due to visibility primarily, and have used TEMPO groups at terminals where chances are greatest. Most of this activity will move through in the 20Z to 00Z timeframe, peaking in the 21-23Z range based on radar trends. Westerly winds in and outside of showers could occasionally gust in the 15 to 25 knot range through the next six hours, trending northwesterly. Winds after 00Z will become lighter, and possibly calm especially in New York sites as high pressure builds in from the west. Think MSS may see fog development with combination of recent rain and light flow, with greater confidence in the 09Z to 11Z period. There are some hints at fog at SLK as well and have mention of BR after 08Z for now, but could see some fog earlier especially with more evening rainfall. Otherwise, mainly VFR conditions are expected.

Outlook...

Saturday Night: VFR. NO SIG WX. Sunday: VFR. Slight chance SHRA. Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHRA. Columbus Day: Mainly MVFR, with local IFR possible. NO SIG WX. Monday Night: Mainly VFR, with areas MVFR possible. Likely SHRA. Tuesday: Mainly MVFR, with local IFR possible. Likely SHRA. Tuesday Night: Mainly MVFR, with areas IFR possible. Chance SHRA. Wednesday: Mainly MVFR, with local VFR possible. NO SIG WX.

BTV WATCHES/WARNINGS/ADVISORIES

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