textproduct: Burlington

WHAT HAS CHANGED

As of 232 AM EDT Thursday...

No significant changes have been made to the forecast. Additional showers and possibly a few thunderstorms will continue today but the threat for flooding will remain low today.

KEY MESSAGES

As of 232 AM EDT Thursday...

1. Unsettled weather to continue today with quieter weather expected Friday and Saturday.

2. Widespread rainfall expected on Sunday. Isolated flooding possible.

3. Cold frontal passage brings lingering rainfall Sunday night, followed by clearing and warming conditions for early to mid next week.

DISCUSSION

As of 232 AM EDT Thursday...

KEY MESSAGE 1: The negatively tilted upper level trough will be in no hurry to exit the region today with the surface low pressure system expected to slowly slide offshore around daybreak. We will remain under the influence of cyclonic flow and plentiful deep layer moisture with PWAT values remaining in the 1.3 to 1.6 inch range. Cooler temperatures today will limit daytime heating and instability but it's plausible that we see a few breaks throughout the day, especially across eastern Vermont. These breaks could yield 500 J/kg of CAPE which would be sufficient to produce a few thunderstorms. The main focus on heavier precipitation today will be across the Connecticut River Valley which is an area that was not hit hard over the past 48 hours. While we remain in a marginal risk for flash flooding throughout the day, it's unlikely we will see the rainfall rates needed to yield flash flooding. Still, the slow motion of the storms will be concerning and will bear watching this afternoon and evening.

After days of rainfall, high pressure will settle into the region Friday and Saturday with drier weather expected during this timeframe. Temperatures will warm closer to seasonal normals as we start to see some sunshine while dewpoints will remain in the mid 50s to lower 60s. It's likely that we see some patchy dense fog Friday and Saturday mornings given a subsidence inversion and saturated soils from recent rainfall.

KEY MESSAGE 2: A slow moving upper level trough will move over New England on Sunday and is expected to take on a neutral so slightly negative tilt. Both the ECMWF and GFS have this transition to a slower moving system Sunday afternoon into the early Monday timeframe with the Canadian model showing a more southerly track and less phasing of the subtropical jet. There should be sufficient frontal dynamics ahead of an approaching cold front coupled with decent mid-level jet dynamics. In addition, deterministic guidance shows impressive PWAT values in the 1.7 to 1.9 inch range which is in the 90th + percentile. The slow moving front may yield another round of slow moving convection across the North Country and northern New York with rainfall totals in the 0.75 to 1.5 inch range very much in play. Depending on the motion of the storms, WPC believes we could see some localized 3+ inches of rainfall and have placed us in a marginal risk for flash flooding on Sunday. This system has some similarities to what we just saw across the Capital Region of New York and is something to watch closely for the second half of the upcoming weekend.

KEY MESSAGE 3: Cold front and attendant mid-level trough should be progressing across the North Country from west to east Sunday night per consensus of 00Z NWP guidance suite. May see a few embedded thunderstorms with brief heavy rainfall with convective activity along the front. However, the good news is that this system appears to be relatively progressive, with the highest PoPs before midnight (70-80% across VT) and then exiting eastward toward daybreak on Monday. Depending on translation speed of the front and overall timing, would generally expect 0.5 to 1.0 inch rainfall most areas Sunday night. A clearing, drying, and warming trend is expected thereafter for the Monday through Wednesday time frame. Valley highs on Monday generally reach the lower 80s with dewpoints in the lower 60s. Will see a gradual increase in temperatures and humidity levels thereafter with highs back in the mid 80s on Tuesday and in the upper 80s to near 90F for next Wednesday.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Through 12Z Friday...Closed/weakening 500mb low centered across CT at 1130Z will maintain mainly VFR ceilings and areas of light to moderate rain across the North Country TAF sites this morning. Vsby will generally remain 6SM or higher, though brief MVFR or even IFR conditions can't be ruled out in slow moving areas of moderate rainfall.

With daytime heating, scattered convective showers will develop during the afternoon hours with just a slight chance of thunder. Generally handled afternoon shower and isold tstm threat with PROB30 groups. As low shifts to the east, winds will generally go from light and variable to N/NE at 5-8kts for the balance of the daylight hours. Better potential for partial clearing Thursday night may lead to isold FG/BR potential 06-12Z Friday, especially at EFK/MPV/SLK.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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