textproduct: Burlington

WHAT HAS CHANGED

As of 650 PM EDT Wednesday...

Have updated hourly temperatures and dew points using latest model guidance to better capture the slower cooling occurring across the region this evening.

KEY MESSAGES

As of 257 PM EDT Wednesday...

1. Near critical fire weather conditions expected for parts of the area on Thursday due to gusty winds and low humidities.

2. Seasonable and mostly dry conditions are expected for the weekend. Additional chances for rainfall are expected through early next week with unseasonably warm temperatures.

DISCUSSION

As of 257 PM EDT Wednesday...

KEY MESSAGE 1: The combination of low humidity, gusty winds, and warm temperatures, along with areas of receptive fuels has increased our fire weather concerns for Thursday. A Special Weather Statement has been issued for near critical fire weather conditions expected, after coordination with partners on fuel conditions.

Mid/upper lvl ridge and associated 1036mb sfc high pres wl shift off the New England Coast by 12z Thurs, as northern stream trof and weak boundary approaches our western cwa on Thurs aftn. The pres difference btwn 1004mb low pres and departing 1036mb high pres wl strengthen the southerly winds acrs our region late tonight into Thursday. Progged 925mb winds are in the 35 to 45 knot range with strongest values over the SLV, while 850mb winds are slightly stronger at 40 to 50 knots. As sfc heating occurs mixing heights increase, allowing for better momentum transfer to the sfc, resulting in localized gusts 25 to 35 mph, except near 40 mph northern CPV and northern Dacks. Lighter winds are expected over protected valleys of central/eastern VT, including parts of the NEK. Meanwhile, sounding data shows extremely dry air near ridgetop with progged dwpts well below 0C, mixing toward the sfc. This wl result in critically dry humidity values in the 20 to 28% range on Thursday, with driest conditions over the CPV/CT River Valley and parts of northern NY. If more mixing occurs than expected humidities could drop into the mid/upper teens in localized areas. Progged 925mb temps btwn 7-10C, support highs well into the 50s to mid 60s in favorable south/southwest downslope areas.

Tonight is interesting with mid/upper lvl thermal belt with poor rh recoveries possible in the 2500-4500 foot level. Sounding data shows very dry air in this layer, with some increasing south/southwest winds aloft, while valley locations decouple. This scenario is nearly impossible to highlight in our grid world, but potential for wide spread ranges in temps/humidity values are likely overnight depending upon elevation/location. Lows range from near 10F NEK to near 30F with some warming toward sunrise in the CPV and SLV.

First in a series of boundaries approach our region on Thurs night, but given deep dry layer in place, feel most precip falls as virga, especially with dampening s/w energy and dissipating 850 to 500mb rh fields. Have chance pops mostly confined to northern NY and northern VT mtns attm. Stronger boundary with much sharp thermal gradient develops on Friday with deeper moisture advection progged acrs our region. The probability of at least a wetting rainfall is btwn 70 and 90% per NBM on DESI. Have bumped pops accordingly into the 60- 80% range for now. Otherwise, with more clouds/precip temps wl be cooler, except lower CT River Valley near VSF.

KEY MESSAGE 2: Behind a frontal system on Friday, more seasonable temperatures will follow this system for the weekend with more dry and seasonable conditions. Daytime highs will be in the mid to upper 40s with overnight lows in the 30s as high pressure builds in Saturday. Saturday night will be the cooler of the two days as an area of high pressure crests over the region. Saturday may be a bit breezy, particularly in the eastern slopes of the Greens, as a LLJ slides east with northwest flow. 925-850mb winds between 25-30 mph could lead to some surface gusts up to 20-25 mph during the day Saturday, but should quickly weaken into Saturday night with calming winds and high pressure.

Temperatures will begin a warming trend heading into next week as our flow becomes south dominant with our high sliding east. 925mb temps will warm to 15-17C Monday and Tuesday, peaking Tuesday afternoon. These warm upper air temperatures will support surface highs in the mid to upper 60s, and perhaps near 70 degrees to start next week. These warm temperatures will be accompanied by breezy to gusty afternoon winds and shower chances as a boundary will be draped across the northwest portions of the forecast area. Shortwaves will ride along a positively-tilted long wave trough across the Great Lakes leading to rounds of shower chances, mainly across northern New York and extreme northwestern Vermont which could inhibit the max heating during the afternoon hours. The boundary in the recent model trends has shifted eastward denoting a setup around the St. Lawrence Valley. Where this boundary sets up and where the precipitation corridor is will have a large impact on daytime temperatures both Monday and Tuesday. Locations across the northern St. Lawrence Valley may only warm to the low to mid 60s, with low to mid 70s in southern Vermont Monday, and perhaps nearing 80 across southern Vermont Tuesday with a closer boundary setup and stronger waa. We will keep an eye on the trends in the days to come. In addition to the temperatures and precipitation, a low level 850mb jet between 50-60 MPH will also lead to breezy to gusty winds in the south to north oriented valleys which typically accompanies these seasonal warmups.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Through 00Z Friday...Gusty winds and dry conditions are anticipated over the next 24 hours, with high confidence of VFR flight rules. Current southwesterly to southerly winds as of 23Z Wednesday are running 3-9 knots, though exact wind direction is highly variable and dependent on location. Throughout the overnight period and into Thursday, we anticipate winds to increase out of the south with widespread sustained winds 10+ knots by 09Z-15Z. Gusts are likely to exceed 20 knots everywhere by around 12Z-15Z Thursday, increasing further to 30-40 knots at BTV, SLK, PBG, and MSS by roughly 15Z-18Z, enhanced by channeling in the Champlain and St. Lawrence valleys. BTV will likely be the first site to see winds heighten in this way due to this channeling. It's not out of the question for gusts at PBG to exceed 40 knots around 16Z-20Z Thursday in peak valley channeling and atmospheric mixing, but at this time, confidence is not high enough to include that in the TAF. Some localized low-level wind shear will develop at MSS over the next few hours with a 30-40 knot southwesterly jet moving overhead. This will also spread to SLK and EFK around 15Z-18Z as the jet shifts northeastward and strengthens to 40-45 knots.

Outlook...

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

EQUIPMENT

The Colchester Reef meteorological station is out of service. This site is not serviced by the NWS. An estimated return to service is May 1st. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

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