textproduct: Burlington

WHAT HAS CHANGED

As of 241 AM EDT Saturday...

No significant changes.

KEY MESSAGES

As of 241 AM EDT Saturday...

1. Two rounds of showers this weekend and some flakes in the mountains.

2. Patchy frost possible Saturday night.

3. Mainly tranquil weather mid-late week.

DISCUSSION

As of 241 AM EDT Saturday...

KEY MESSAGE 1: Round one of the showers is currently passing through the region. Rainfall totals have reached the 0.75 -1.5 range across much of Vermont, and the 0.1-0.3 range in northern New York with a sharp gradient between them in the Champlain Valley. Localized totals up to 1.75 inches have been observed across parts of the Northeast Kingdom. Overall, rainfall rates are expected to decline during the next few hours with up to an additional half inch expected. The notable feature with this one is the cold temperatures aloft. This has caused freezing levels to drop below summit levels. Based on observed temperatures and radar correlation coefficient, snow levels are likely between 2,500 and 3,500 feet. Above that level, 1-3 inches are expected. In that range, a slushy coating is likely. Lower temperatures aloft will be present farther east, and a few flakes could drop down to 2,000-2500 feet across eastern Vermont, though accumulations are not expected that low. A few flakes will mix in the higher elevations in the Northeast Kingdom, and could also occur in the higher elevations south through Groton and into Orange County. The rain showers will exit early this morning and some clearing should occur by afternoon, so today should overall be a decent day with highs in the 50s to low 60s. The second round of showers arrives Sunday afternoon and continues Sunday night, though the dynamics will be weaker with this one. Temperatures aloft will also be warmer, so snow levels should be mostly above summit levels, though a few flakes cannot be completely ruled out at the summits of the High Peaks. The highest rainfall totals will again be across the Northeast Kingdom, but at most a couple tenths of an inch are currently expected.

KEY MESSAGE 2: An unseasonably cool airmass will be present tonight and daytime clouds for part of the day today should limit diurnal heating a bit. Skies will gradually clear as the day goes on, though, and by sunset they should be mostly clear. Boundary layer flow will significantly weaken by sunset, and while some light winds will likely continue during the night in exposed areas, the protected hollows should have no trouble decoupling. These factors will lead to relatively favorable radiational cooling conditions. High clouds should gradually infiltrate the region as the night goes on, but not before temperatures will be able to drop significantly and the clouds could be too thin to have much of an effect on the radiational cooling. Overall, temperatures in the 30-38 degree range are expected across parts of the Adirondacks while temperatures between 35-40 are expected in the Northeast Kingdom. Due to some uncertainty with clouds and boundary layer winds, no frost headlines were issued, but a Frost Advisory may be needed for the Adirondacks if confidence increases in ideal radiational cooling conditions.

KEY MESSAGE 3: Current indications are that a narrow deep-layer ridge will be our controlling weather feature for the Wednesday through Friday period. This feature should bring light wind conditions along with partly to mostly sunny daytime conditions. With moderating 850mb temperatures, expecting maximum temperatures to moderate from the low-mid 70s on Wednesday, to the low-mid 80s for Thursday and Friday. Humidity levels should remain modest with sfc dewpoints remaining in the 50s. Consensus of 00Z Canadian/ECMWF/GFS and associated model ensembles is for a frontal system to approach from the Great Lakes/Ontario sometime Friday night into Saturday, June 6th. System is relatively quick moving when it eventually arrives, but timing varies across the 00Z NWP suite. Currently forecasting 40- 50% PoPs for rain showers during the Friday night and Saturday period, with timing representing the greatest uncertainty. If deep- layer ridge axis holds, there's a reasonable chance that frontal rain showers would be delayed into the latter half of the weekend.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Through 12Z Sunday...Strong mid-level low pressure system is migrating south of the area this morning. Will see rain ending at MPV, SLK, and RUT by 14Z, with MVFR ceilings improving back to VFR areawide by late morning. There is a band of LLWS which will impact KMPV and KRUT through 13Z before exiting to our south. Moderately strong N-NE winds will help bring clearing during the late morning hours as low departs. N-NE winds will remain moderately strong and gusty thru the daylight hours, locally 20G30KT at BTV/MSS/PBG during the late morning through afternoon period before subsiding toward sunset. Light and variable wind conditions are expected during Saturday night with generally VFR conditions continuing. Will need to monitor for an outside chance of patchy fog 06-12Z Sunday, especially given saturated ground conditions.

Outlook...

Sunday: VFR. Chance SHRA, Slight chance TSRA. Sunday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Monday: Mainly VFR, with local MVFR possible. Chance SHRA. Monday Night: VFR. NO SIG WX. Tuesday: VFR. Slight chance SHRA. Tuesday Night: VFR. NO SIG WX. Wednesday: VFR. NO SIG WX.

MARINE

Winds have been increasing in the last few hours as they have shifted towards northwesterly, and they are expected to continue to increase in the next couple hours as they become northerly. By sunrise, sustained winds should be in the 20-25 KT range with gusts up to 30 KT. Winds stay elevated this morning but they should drop quickly heading through the afternoon. They are expected to be below 10 KT by evening. Waves of 1-2 feet will increase towards 2-4 feet, especially when more sustained flow is established this morning. Wave heights drop below 1 foot by evening.

BTV WATCHES/WARNINGS/ADVISORIES

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