textproduct: Burlington

WHAT HAS CHANGED

As of 224 PM EDT Sunday...

Have increased PoPs Monday morning as confidence grows in some scattered showers ahead of a warm front. Unseasonably hot temperatures are on track for the first half of the week while lake and river water temperatures remain dangerously cold.

KEY MESSAGES

As of 224 PM EDT Sunday...

1. Unseasonably warm temperatures continue this afternoon and trend well above seasonal averages with highs in the mid 70s to near 90 F through Wednesday. Meanwhile, lake and river water temperatures remain dangerously cold across the region, and breezes on Lake Champlain may result in rough lake conditions.

2. Shower and thunderstorm chances increase Tuesday through Wednesday ahead of and along a cold front.

3. Major shift to below normal temperatures on Thursday and continuing through the weekend. Rain to return next weekend.

DISCUSSION

As of 224 PM EDT Sunday...

KEY MESSAGE 1: A cold front is crossing the forecast area this afternoon, triggering a few showers in northern New York and southern Vermont. Otherwise, the afternoon is shaping up to be quite warm and quiet weather-wise, with widespread temperatures in the 70s. Winds are a touch breezy out of the northwest with gusts 15-30 knots, highest on mountaintops. With wind direction out of the north/northwest, we could see some additional channeling of winds in the Champlain Valley into the evening, producing rougher conditions on Lake Champlain. Water temperatures in bodies of water across the region, including Lake Champlain, remain in the 40s, so we urge anyone looking to recreate on waterways to use extreme caution and always wear a life jacket.

Multi-level high pressure and ridging will build into the forecast area from the Atlantic Ocean tonight through the mid week, resulting in southerly to southwesterly flow and 925 mb temperatures around 20 to 26 C each day. The upper ridge crests over northern New York and Vermont Monday as a surface warm front crosses with highs in the upper 70s to mid 80s. There is the potential for some clouds and showers Monday morning (20-50% chance of measurable precip) on the leading edge of the warm front, which could locally limit temperatures from reaching their full potential, but conditions are expected to largely clear by peak heating in the afternoon. Gusty winds once again look to channel through the Champlain Valley on Monday afternoon, resulting in potentially rough conditions on Lake Champlain in 25-30 knot winds. Though it will be a weekday, due to hot air temperatures, gusty winds, and local graduations drawing out of state travelers, we continue to draw attention to how cold the water temperatures remain this week and urge any recreators to use extreme caution on bodies of water.

On Tuesday, flow turns more southwesterly as a low level jet strengthens overhead, with highs forecast in the 80s to near 90 F, making this the likely hottest day of the week. Warmest locations may be east of terrain as flow aloft turns more southwesterly resulting in some compressional warming downslope off of terrain. Thunderstorms and rain showers Tuesday afternoon ahead of a cold front may blunt highs for locations that receive showers. Dew points also look highest on Tuesday afternoon in the lower 60s for most, making the heat feel a bit more sticky this day. These conditions will be the warmest of the year so far. It is important to remember to stay safe in warmer temperatures by staying hydrated and take frequent breaks if working outside, especially after we had such a cool start to the month. A cold front is expected to cross the region on Wednesday, which will impact how warm we can get that day. At the moment, highs in the upper 60s to mid 80s look likely, with central and southern Vermont getting the warmest before the cold front and associated precipitation arrive. In addition to warmth during the days, our lows likely won't fall below the upper 50s and 60s until the cold front arrives, providing only some relief from heat overnight.

KEY MESSAGE 2: All of the heat and humidity discussed in Key Message 1 will aid in destabilizing the atmosphere over the region on Tuesday, with high resolution models suggesting surface CAPE values around 400-1200 J/kg, highest in southern and central Vermont, even reaching into the Champlain Valley with widespread dew points in the lower 60s forecast and high temperatures in the 80s to near 90 F. Effective Bulk Wind Shear values range around 35-45 knots Tuesday evening, indicating that strong to severe storms are not out of the question. Forcing will be mainly from an upper level weak wave and its potential interactions with topography, while surface forcing looks minimal Tuesday afternoon into the overnight period, and mid level lapse rates don't look overly impressive. Most likely precipitation will be in the mountains and Northeast Kingdom on Tuesday. As things look now, we could see a series of weaker fronts early Wednesday morning before the main cold front drops through during the day Wednesday, which would allow some of Vermont to destabilize again before surface forcing arrives, resulting in highest chances of precipitation in Vermont on Wednesday. As we get closer to the event, the timing of the cold front or fronts should become more set. Should the front be delayed, the potential for stronger storms would increase during the day on Wednesday with more time to destabilize.

KEY MESSAGE 3: Following the frontal passage on Wednesday afternoon, a major pattern shift is expected to unfold across the region. High temperatures on Thursday will struggle to warm into the mid 50s to lower 60s in response to significant cold air advection in the wake of the cold front. The good news, however, is that we are expecting plentiful sunshine on both Thursday and Friday as high pressure becomes well entrenched across the region with subsidence keeping moisture noticeably lacking. Next weekend isn't looking as nice as it appears moisture along the northern edge of the subtropical high will advect northward and bring the return of cloud cover. A series of shortwaves associated with a trough to our west will likely be the focus for showers through the weekend. Model soundings show the potential for some heavier rain showers with PWATs hovering around 1.5" so it'll be something to keep an eye on. The timing of these showers will take a few days to resolve as these low amplitude features are not well forecast by low-resolution global guidance.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Through 18Z Monday...We are looking at VFR conditions prevailing through the forecast period with some mid to high level clouds expected to traverse the region. Current cloud bases range from 5000 to 12,000 ft and we really shouldn't see ceilings any lower given plentiful dry air in the lower levels. There are a few showers across southern Vermont which may come close to the KRUT terminal so we have included a PROB30 group through 21Z for very brief reduction in visibilities due to falling rain. Otherwise, we are mainly looking at gusty west to northwest winds this afternoon with light winds expected overnight. Winds will switch to the south after 12z on Monday and become gusty in the Champlain Valley by 16Z.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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