textproduct: Burlington

WHAT HAS CHANGED

As of 227 PM EDT Wednesday...

No significant changes made to the forecast this cycle.

KEY MESSAGES

As of 227 PM EDT Wednesday...

1. Cool and quiet weather will continue through Thursday night.

2. A dynamic system will bring rain, gusty winds, and some higher elevation snow on the backside.

3. Temperatures trending above normal with mostly dry conditions prevailing Sunday through Tuesday of the extended forecast.

DISCUSSION

As of 227 PM EDT Wednesday...

KEY MESSAGE 1: One round of light shower activity has exited east of Vermont, and there are some additional light radar returns upstream in Canada. Steady, breezy conditions are expected today as northwest winds begin to increase overnight. This should allow for some continued rounds of light, orographically enhanced showers into. Northwesterly flow will result in somewhat cooler air filtering in, but the nighttime lows are relatively close to seasonal lows around the 30s to lower 40s. Conditions may still be brisk early tomorrow morning, but winds show be subsiding by Thursday morning with a cool day on tap where we struggle to get much above the 50s beneath gradually increasing cloud cover during the afternoon as the next system approaches.

KEY MESSAGE 2: For the rain component - Another solid soaker is expected for Friday. A digging upper trough and closed mid-level cyclone will result in efficient transport of more tropical Pacific air. PWATs will surge to around 250-275 percent of normal as a warm front begins to approach. Initially, surface conditions will be rather dry Thursday night. Still, increasing south flow will result in temperatures leveling off after a rather fast initial drop to the 30s to lower 40s. Confluent low-level flow will bring in some low level moisture off the Atlantic. By dawn on Friday, an 850mb jet around 45 knots will result in efficient isentropic lift along the warm front which will get hung up near or just north of the international border. Most likely, precipitation will fall as rain, but wet-bulb zero heights are flirting quite close to the ground in the Northeast Kingdom with a substantial warm nose overhead. NBM probabilities depict 2% snow, but realistically, that would be the chance for some wintry mix. Then by afternoon, surface low pressure will track through the St. Lawrence Valley. Guidance has the surface low track almost overhead, with little time spent in the warm sector. We will see temperatures climb into the mid 50s to near 60, but that could be a little optimistic. The surface low will shift east by Friday night, and then cooler air will quickly filter in behind it as a strong 1035mb surface high builds to our west.

For the wind component - The wind forecast is somewhat challenging. On one hand, the low-level jet is strong, but it appears most likely to be raining when it peaks, and forecast soundings depict the jet above the bottom of the inversion layer. It seems most likely that the strongest winds will come from channeled flow with the highest gusts of 30-40 mph in and around Lake Champlain for Friday morning. Winds will briefly dip as surface low pressure tracks over the region during the day, and then wind speeds will ramp up due to the increasing pressure gradient from the strong 1035mb surface high. Widespread 25 to 35 mph gusts will persist Friday night into early Saturday as temperatures cool. This will make for a chilly night as temperatures fall into the mid 20s to mid 30s. Apparent temps/wind chills will reach the teens in higher elevations and lower 20s in the broader valleys for Saturday morning.

For the snow shower component - With temperatures falling into the mid 20s to mid 30s range, that means we get to talk snow. Low-level moisture is expected to linger into midday Saturday. With the persistent northwest flow, orographic lift is expected for our northwest facing mountains. Snow levels appear like they could make it near the valley floors, but high froude values and incoming dry air will generally favor accumulations above 1500 ft agl. So even as far down as Burlington could feasibly observe snow, but it's more likely to be just a quick dusting for the Adirondacks, Northeast Kingdom, and summits of the Green Mountains. Snowfall amounts for these areas will be generally 1" or less, but 2" could feasibly occur atop mountain peaks above 3000 ft.

KEY MESSAGE 3: Mid/upper trof wl be replaced by zonal flow with some potential for developing southeast CONUS ridge to expand into the Mid Atlantic/NE CONUS by early next week. This large scale synoptic pattern supports temps trending above normal levels by early next week with mostly dry conditions prevailing. We can never completely rule out a weak embedded short wave in the fast zonal flow aloft, producing a low probability (<20%) of precip. However, pw values are mostly in the 0.40 to 0.65" range or a STD below normal for most of the upcoming week. The 925mb to 850mb waa on Sunday into Monday is supported by moderately strong llvl jet of 30 to 40 knots as gradient btwn 1032mb high pres over southern New England and weak 1010mb low pres over Hudson Bay strengthens. The wind gusts provided by WPC look too low, especially summits on Sunday night into Monday, where gusts of 30 to 40 mph wl be likely based on wind fields and sounding profiles. This broad southwest flow wl help to advect much warmer 925mb to 850mb thermal profiles into our cwa starting Sunday and prevailing into Monday and Tuesday of next week. Some hints at a potential cooling trend toward midweek as 1032mb high pres from central Canada noses toward our cwa. Still a rather large spread in potential timing and magnitude of caa, along with any impacts.

Sunday morning could be the coldest of the fall season with lows ranging from near 20F SLK/NEK to l/m 30s near Lake Champlain, but still some question with regards to wind profiles and lingering clouds in the nw flow aloft. Temps rebound into the mid 40s NEK to mid 50s SLV on Sunday under developing southerly flow. Another cool night is anticipated Sunday night into Monday, especially east of the Green, where bl wind may decouple in the deeper/protected valleys. Lows generally mid 20s eastern/central VT to mid/upper 30s Lake Champlain. Warming trend continues on Monday and Tuesday with highs mid 50s to l/m 60s with mostly sunny skies expected.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Through 18Z Thursday...While there will be some variability in flight conditions this evening through tonight, the majority of TAF sites will remain MVFR through around sunrise Thursday morning, then improve to VFR later Thursday morning.

More specifically, highest probabilities of low stratus with IFR ceilings will remain over higher elevations of the northern Adirondacks, especially over KSLK, through 07Z. Meanwhile, TAF sites over the broader valleys, including KMSS, KBTV, KPBG, and KRUT, will see ceilings generally between 2000 and 4000 ft AGL through the evening. Have included some TEMPO groups to account for ceilings varying between MVFR and VFR levels at these sites. After 00Z, expect MVFR ceilings to settle at these sites for the remainder of the night.

Winds will be from the west/northwest, with some localized gusts up to 20 knots overnight.

Outlook...

Thursday Night: VFR. Definite SHRA. Friday: Mainly MVFR, with areas IFR possible. Definite SHRA. Friday Night: Mainly MVFR, with local IFR possible. Windy with gusts to 30 kt. Likely SHRA, Chance SHSN. Saturday: Mainly VFR, with local MVFR possible. Windy with gusts to 30 kt. Chance SHSN. Saturday Night: VFR. Slight chance SHSN. Sunday: Mainly VFR, with local MVFR possible. NO SIG WX. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX.

MARINE

North to northwest winds are expected to briefly ramp up across Lake Champlain overnight, especially in the broad and southern waters. Winds will increase to 15 to 25 knots from about midnight through 7am tomorrow before gradually subsiding. In this span of time, the southern half of Lake Champlain could see wave heights build to 2 to 4 feet.

CLIMATE

On Saturday, daily low maximum temperatures are likely. Current records are indicated below at some climate sites in our region:

Record Low Maximum Temperatures:

October 17: KBTV: 42/1970 KPBG: 44/2015 KSLK: 36/1970

EQUIPMENT

The NOAA Weather Radio transmitter located at Mt. Ascutney has been damaged due to the storms from yesterday. Technicians are heading over to determine repair needs. Alternative transmitters that users may be able to connect to are Burke Mountain WWG50 at 162.425 MHz or Hanover WNG545 at 162.525 MHz.

BTV WATCHES/WARNINGS/ADVISORIES

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