textproduct: Burlington

WHAT HAS CHANGED

As of 237 PM EDT Saturday...

No significant changes from the previous forecast.

KEY MESSAGES

As of 237 PM EDT Saturday...

1. Following a seasonable weekend, conditions will trend warmer Monday and then hot and humid on Tuesday.

2. A sharp cold front passing Tuesday night into Wednesday possibly bringing some thunderstorms followed by a cooling trend back to around seasonal averages.

DISCUSSION

As of 237 PM EDT Saturday...

KEY MESSAGE 1: Beautiful weather will continue through the weekend. Relatively cool low level temperatures in the 60s Monday morning while winds turn southerly could result in enhanced winds on Lake Champlain's broad waters (possibly in the 15-20 knot range) and a relative burst of breezy conditions will be noted in the mountain ridges as well, where 20-30 MPH winds will be possible following light winds on Sunday. These breezes will be more noticeable the following night into Tuesday morning and help advect in warmer and more humid air.

Tuesday continues to look like an interesting weather day. Heat will be the main story, with Heat Advisory issuance anticipated for at least parts of the region. An advective heat will continue with seasonally strong southwesterly flow transporting hotter low level temperatures through the day; it would be a good idea to do outdoor activities during the morning or early afternoon with this pattern. Forecast soundings show high instability (CAPE of roughly 2000 J/kg) developing by late afternoon amidst both hot and humid low level profiles and steep mid level lapse rates, but also pronounced CIN with a capping inversion or at least neutral stability above the boundary layer. Lack of a trigger and very dry air aloft will result in "wasted CAPE", consistent with a mainly sunny and dry. Uncomfortable conditions will linger through the evening with lack of precipitation/cloud cover, along with breezy southwest winds keeping the air well mixed.

Have continued to stay closer to the raw model guidance as opposed to the NBM for temperatures, which have largely remained the same as previous forecast cycles. This results in conservative heat index values similar to the most likely maximums, remaining in the 95-100 range in the Champlain Valley and 90-95 range in other valley locations. The heat index in the St. Lawrence Valley has the largest range of possibilities at this time, with potential for hotter conditions than currently indicated. There's some uncertainty in the dewpoints, which may trend a little higher than forecast given some of the latest guidance and moisture advection from the Great Lakes. Have also noted that the Extreme Forecast Index is consistent with the RRFS in showing the hottest/most unusual heat is favored for the southern portions of the eastern Champlain Valley, centered over western Addison County; this could be in part due to enhanced subsidence in the west-southwesterly flow downslope of the eastern Adirondacks and relatively small lake influence upwind. High temperatures here are most favored to reach at least 95 degrees with the heat index at or above this value.

KEY MESSAGE 2: Model consensus continues to promote the potential for the passage of a sharp cold front Tuesday night. Given the antecedent heat and amount of forcing projected along the boundary, some nocturnal thunderstorms are possible. Most likely areas for convection remain towards the Canadian border, but timing of the front could dampen impacts. Should the passage shift more overnight and away from the late evening time frame, then some low level stability would limit instability and strength of storms. Conversely, an earlier timing could allow for enhanced convection. Those with camping plans may want to keep a closer eye of the forecast as it evolves over the next couple of days.

Behind the front, temperatures trend cooler from Tuesday's unseasonably hot conditions. Wednesday will likely remain higher than averages, but the downward trend will continue with northwesterly flow through Friday where high temperatures are favored to range in the upper 70s to low/mid 80s. Successive waves could produce some showers late Thursday and again heading into the weekend.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through 18Z Sunday...Dry and VFR conditions will persist for most terminals through this forecast period with the exceptions of SLK/MPV where some IFR or lower CIG/VIS is most likely. Given dry conditions this afternoon, crossover temperatures will be difficult to achieve even at SLK/MPV, but a shorter duration of fog/mist cannot be ruled out 06-12Z. Otherwise, northerly winds for most terminals continue today with PBG responding to lake breeze. Could see a brief switch at BTV from 300 degrees 20-23Z.

Outlook...

Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. Monday Night: VFR. Slight chance SHRA. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. Slight chance SHRA, Slight chance TSRA. Wednesday: VFR. NO SIG WX. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. NO SIG WX.

CLIMATE

High temperatures on Tuesday will be hot, but we are at the climatological warmest part of the year. Therefore, it is far from a certainty that any records will occur. At this time, PBG, MPV, and MSS are the more likely long-term climate sites to set a record. See below for current records:

Max Temp Records Date BTV MPV MSS PBG SLK 07-14 100|1995 94|1952 92|2012 95|1952 95|1934

BTV WATCHES/WARNINGS/ADVISORIES

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