textproduct: Burlington

WHAT HAS CHANGED

As of 247 PM EDT Wednesday...

No major changes, widespread wetting rain is still on track for tonight. Patchy Frost was added to the Champlain Valley Friday night.

KEY MESSAGES

As of 247 PM EDT Wednesday...

1. Following near critical fire weather conditions this afternoon, widespread rainfall is expected this evening into tomorrow.

2. Unsettled and cool conditions will follow a cold front heading into Friday and Saturday.

3. Areas of frost expected over the weekend and early next week.

DISCUSSION

As of 247 PM EDT Wednesday...

KEY MESSAGE 1: A Special weather statement remains this afternoon until 8 PM for all of Vermont and eastern Clinton and eastern Essex County in New York for near critical fire weather conditions. Relative humidities as low as 30 to 35 percent, with brisk south southeast winds 5 to 15 MPH with gusts up to 25 MPH will continue this afternoon into this evening, and with very receptive fuels, and fires that are ignited, could quickly get out of control. While not as extreme conditions as yesterday, anyone planning to burn, should check with their local fire officials before setting any fires.

Moisture advection will return to the region beginning tonight ahead of a surface low that will track through the St. Lawrence Valley tonight into tomorrow. Good southwest moisture advection along a cold front extending along the St. Lawrence Valley into the deep south, with an area of high pressure off the coast of the Mid- Atlantic, will help to increase dewpoints and precipitable water areawide as Pwats increase to near 1 inch. Showers are already across the Finger Lakes region of New York and are expected to move north into northern New York by late this afternoon. An isolated rumble of thunder in the southwestern St. Lawrence County is possible with some meager elevated instability with MLCAPE values between 100-200J/kg on the latest HRRR soundings. Furthermore, there has been some observed lightning over Ithaca, NY as well as some showers further upstream into central Pennsylvania. Showers tonight will persist along an axis from Malone, NY to Wanakena, NY with moderate rain at times. Total precipitation could reach 1 inch in places along the St. Lawrence River, with the HREF showing a 70% chance of 1 inch in portions of St. Lawrence County. Some isolated convective elements embedded in the showers may locally push some locations to an inch and a quarter of rainfall through tomorrow morning. No flooding concerns are expected as this region is abnormally dry from a lack of rain over the last week, however, some river rises are expected due to the added rainfall into the basins, particularly in northern New York. Showers will move into Vermont closer to tomorrow morning with dry air firmly in place today which will be harder to overcome. However, widespread rainfall around half an inch is expected for much of Vermont. Rain in Vermont will mainly be of a lighter nature rather than the moderate rain rates that are expected across northern New York. The bulk of the rain will exit the region by late morning into early afternoon tomorrow, with just some lingering light showers in its wake.

KEY MESSAGE 2: Behind the aforementioned frontal system, the remainder of the work week into the weekend will trend cooler with some lingering chances of light showers. Cyclonic flow associated with a dominating upper level low behind the frontal system will keep shower chances through the day Thursday into Friday. These showers will be isolated to scattered and mainly confined to the Northeast Kingdom and northern Adirondacks as low level lapse rates will steepen under cooling northwest flow aloft. Surface highs Friday and Saturday will be similar with highs in the mid to upper 40s in the higher terrain and near 50 degrees in the wider valleys. With the cooling temperatures, especially overnight, some showers may fall as snow in the higher terrain above 2000 ft, though accumulations will little if any at all, as temperatures rise into the 40s during the day.

One thing to note is that the climatological start to the growing season in the Champlain Valley begins May 1st (this Friday) when we expect overnight lows to be near Frost Advisory criteria (32-36F) both Friday night. Cloud cover may limit the overall cooling that takes place, but conditions still look favorable for patchy frost development. Have introduced patchy frost into the forecast for the Champlain Valley Friday night as confidence in cooling temperatures, calming winds, and better confidence in some cloud clearing has increased.

KEY MESSAGE 3: The chilly overnights will continue Saturday night and Sunday night. Forecast lows these nights range from the mid 20s to the mid 30s, and a frost to local hard freeze is possible both Sunday and Monday mornings. Anyone with vulnerable plants outside should take precautions to protect them over the weekend. The frost/freeze program will have officially started in the Champlain Valley on May 1st, so that area may see Headlines if conditions continue to look favorable for frost. However, we still have a few days to evaluate just how cold temperatures will get as well as how the cloud cover and winds will evolve. Temperatures will warm back up to near normal by Monday night/Tuesday morning and additional frost beyond Sunday night/Monday morning is not anticipated.

Outside of frost potential, the weather will remain generally unsettled to start the next week. Progressive upper-level flow will become established through mid-week, allowing multiple low-amplitude disturbances to move through. Expect multiple chances for showers, but no hazardous conditions are expected at this time.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Through 18Z Thursday...TAFs are starting off predominantly VFR, however ceilings will lower towards widespread MVFR with areas of IFR after 06Z. A frontal boundary will move through slowly overnight from west to east, bringing a period of light to moderate intensity steady rain between 00Z and 18Z. The best chances of IFR ceilings will be between 09Z and 15Z, especially at KMSS, KSLK, and KMPV. Other sites may see brief reductions towards IFR ceilings, but should remain predominantly MVFR. Visibilities will fall to 3-6SM as rain develops, with some brief reductions to below 3SM possible within areas of moderate intensity rain. There is a small chance of some thunderstorms near KMSS between 20Z and 00Z, however chances are too low to include mention in the TAF. Ceilings and visibilities will improve after 15Z as the front departs to the east and precipitation ends. Winds will be generally from the south/southeast at 5-15 knots, with some sporadic gusts to 20 knots through this evening/early tonight. Given the weakening of low-level lapse rates as the front approaches, expect gusts to slacken and redevelop at times, then come to an end all together as the steady precipitation arrives overnight.

Outlook...

Thursday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Friday: VFR. Slight chance SHRA. Friday Night: VFR. NO SIG WX. Saturday: VFR. Slight chance SHRA. Saturday Night: VFR. NO SIG WX. Sunday: VFR. Slight chance SHRA. Sunday Night: VFR. Slight chance SHRA. Monday: VFR. Chance SHRA.

BTV WATCHES/WARNINGS/ADVISORIES

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