textproduct: Burlington

WHAT HAS CHANGED

As of 646 AM EDT Saturday...

Frost Advisories are expiring at 7 AM. Wind gusts have increased for Sunday morning, particularly in the western slopes of the Green Mountains and to a lesser degree in the Adirondacks.

KEY MESSAGES

As of 249 AM EDT Saturday...

1. Seasonably warm and dry conditions to start the holiday weekend will lead to cold water immersion safety concerns today.

2. Light rain and much cooler conditions are expected Sunday along with gusty southeasterly winds. Additional showers are possible on Memorial Day, especially during the morning.

3. Remaining unsettled through mid to late next week, likely trending cooler by next weekend.

DISCUSSION

As of 249 AM EDT Saturday...

KEY MESSAGE 1: A narrowing deep layer ridge will be centered directly over New England today, keeping us dry for one more day. High altitude clouds will gradually lower through tonight, but these clouds should allow enough sunlight to boost temperatures, especially as you go north and east within our region. Clouds will thicken enough to limit solar heating by late in the day, but by that point temperatures should have risen into the upper 60s to mid 70s. Given these temperatures, light winds, and much less desirable weather on Sunday, would expect a lot of activity on area lakes and rivers today. These water bodies remain dangerously cold, with risk of cold water shock and hypothermia if you are suddenly immersed in the water. Use caution if boating this weekend and take the necessary safe cold water boating practices such as wearing a life jacket and dry suit.

KEY MESSAGE 2: Rain is on track to overspread our region Sunday morning as a weak wave of low pressure passing to our west drags a warm front northeastward, resulting in substantial overrunning/rising motions in the mid levels. The most likely onset of rain remains similar to the previous forecast, soon after midnight in a swath across northern New York and far western Vermont stretching from northwest to southeast, gradually expanding eastward into the northern Champlain Valley and central Vermont near or soon after sunrise, and eventually reaching northeastern Vermont by late morning. Rain will then persist for much of the day, at times very light but occasionally steadier with pockets of hourly rainfall amounts likely near 0.1". Chances of rain diminish during the afternoon from the western Adirondacks and points west and in the evening as you go farther east. Total rainfall amounts through the day continue to look lightest in much of northern Vermont in the range of 0.1" to 0.25", trending a little heavier in western and southern portions of the state where they will tend to be in the 0.25" to 0.5" range. Highest amounts are favored in northern New York where low level convergence will be greatest, with amounts averaging in 0.3" to 0.75".

Wind gusts were further increased with this forecast given model trends in the magnitude of winds near the top of the low level inversion. 925 millibar winds are progged to reach 50 to 55 knots for a short period Sunday morning along the western slopes of the Green Mountains. Especially if these winds materialize ahead of rain falling, gusts approaching Advisory level become more likely, such as in the typical trouble spots such as Bolton and Lincoln. The consensus of guidance suggests winds will remain shy of criteria, but we'll re-evaluate as the latest data comes in.

The next round of rain on Memorial Day still looks primarily to pass through during the morning as low pressure and attendant weak front move through. Briefly moderate rain is possible with this system. Then much drier air aloft will enter the region coincident with a surface wind shift to west/northwest winds. Therefore, chances of rain during the afternoon currently look minimal and with decreasing cloud cover, it could be a very nice afternoon. Think forecast temperatures might be a bit too warm, especially if cloudy skies linger; confidence in high temperatures are a little higher in areas such as the St. Lawrence Valley than across eastern Vermont. Regardless, it should be much milder than Sunday. Highs Sunday will mainly be in the upper 40s to low 50s and on Monday are more likely to reach the mid 60s to low 70s.

KEY MESSAGE 3: Warmer and drier conditions look to return on Tuesday as weak high pressure builds into the Northeast. This will be short lived, however; although exact details differ widely from model to model and run to run, especially beyond Wednesday, confidence in a deep upper low developing over eastern Canada continues to increase. Shortwave troughs and associated surface systems will rotate around this upper low, bringing rounds of showers and cooler weather for much of next week. The first batch of precipitation arrives Tuesday night into Wednesday with a cold frontal passage. This front sets the stage for cooler temperatures; after highs in the mid 70s to low 80s Tuesday and Wednesday, the end of the week is looking quite a bit colder, and expect diurnal showers to develop on Thursday due to cooling aloft. There's a lot of model spread thereafter, but overall consensus is a robust upper shortwave, perhaps even a cutoff low, will cross overhead sometime in the Friday/Saturday timeframe. This would bring better chances for widespread precipitation and daytime highs potentially only in the 50s (or even 40s). Have stayed with WPC/NBM forecast with this package given the uncertainty, but we may need to start adjusting temperatures down and PoPs up for late next week if these trends hold true.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Through 12Z Sunday...VFR conditions will prevail through the most of the TAF period. Skies early generally BKN-OVC 250 this morning, but clouds will continue to thicken and lower through the day. Ceilings generally remaining AOA 10 kft through 00z Sun, and above 3500 ft overnight at all terminals except KMSS and possibly KSLK and KRUT, where MVFR conditions are possible after 08z. Steady light rain will start to spread into the region from SW to NE after 08z as well, with visibility 5-6SM. Light and variable winds this morning will become S/SE 6-12 kt after 15z today and remain so through the remainder of the TAF period, becoming locally gusty toward 10z. LLWS is expected at most sites after 06z Sun as well.

Outlook...

Sunday: MVFR. Windy with gusts to 30 kt. Chance RA. Sunday Night: Mainly MVFR, with local IFR possible. Chance RA, Chance SHRA. Memorial Day: Mainly MVFR, with local IFR possible. Chance SHRA. Monday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. Chance SHRA, Slight chance TSRA. Wednesday: VFR. Chance SHRA.

BTV WATCHES/WARNINGS/ADVISORIES

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