textproduct: Burlington

WHAT HAS CHANGED

As of 319 AM EDT Monday...

Added patchy freezing rain late Tues into Weds and mentioned a slight chance for thunder Tuesday afternoon into Tuesday night.

KEY MESSAGES

As of 319 AM EDT Monday...

1. A challenging temperature forecast and associated impacts on precipitation type is expected Tuesday into Wednesday.

2. A slight chance of thunderstorms with localized heavy downpours possible Tues aftn into Tuesday night, which could cause sharp rises on area streams and rivers.

3. Mixed precipitation possible Thursday night into Friday, with active weather continuing through the period.

DISCUSSION

As of 319 AM EDT Monday...

KEY MESSAGE 1: Sfc analysis places a warm frnt acrs our northern/central cwa this morning with some virga on radar, as crnt rh values in the CPV are in the 32% to 40%. A warm southwest flow is expected today with progged 925mb temps in the 7-10C range, which with some sunshine should support highs mid 50s to mid 60s acrs our region. A few localized locations in the lower CT River Valley could approach 70F. As sfc heating occur our mixing depths wl increase, resulting in localized wind gusts in the 18-25 knot range.

Tonight into Tues several embedded s/w's wl pass along near the International Border as arctic high pres near Hudson Bay tries to move southward. This wl quickly sharpen a low level thermal boundary acrs our region on Tuesday into Weds, as shallow cold air on northerly flow undercuts warming temps aloft. The sharpening inversion on soundings is extremely impressive with progged 850mb temps near 12C, while bl temps are in the mid 30s. This complex thermal setup makes for a very challenging temps/ptype fcst on Tues into Weds, as bl temps are progged to hover near 0C by late Tues into Weds acrs the northern CPV and SLV. Have utilized the high res NAM3KM with Reggie/HRRR to highlight cooler bl thermal profiles on Tues into Tues night, with cold air draining down the deeper valleys. On Tues night the higher trrn of the Dacks and central/southern Greens could see temps in the mid 40s to mid/upper 50s, while northern SLV and northern CPV is in the l/mid 30s with pockets of freezing rain. Given the warm ground temps, feel any ice accumulation wl be confined to mostly elevated sfcs with minimal impacts on roads, especially with marginal air temps near 0C. The greatest potential for a light glaze to a tenth of an inch or so of ice accumulation wl be northern SLV and northern CPV, especially northwest Clinton County.

KEY MESSAGE 2: Several ingredients are present to produce localized heavy rainfall acrs our region late Tuesday into Weds, where WPC continues to place our cwa in a marginal risk (5%) of exceeding flash flooding guidance. Given our recent dry spell and expected qpf values, think this is a little aggressive but there is a non zero threat. The ingredients available for producing localized heavy rainfall include a sharp boundary, pw values near 1.0" or 2 to 3 std above normal, and modest values of elevated instability. Areas of rain with embedded heavier downpours with a few rumbles of thunder are possible late Tues aftn into Tues night. Given the most unstable CAPE values of 300-700 J/kg, a few rumbles of thunder are possible, especially northern NY, which could result in localized heavy downpours. The storm vector analysis suggests some training/back building of precip, as flow aloft is paralleling the low level thermal boundary on Tues night. Its extremely difficult to pin point where the location of the heaviest rainfall wl occur, but greatest probability at this time would support central NY into the Dacks and acrs central/southern VT, but this is subject to change with movement of boundary. A wide range in highs and lows are expected on Tues and Tues night, with generally cooler weather for Weds. Additional mixed precip is expected on Weds night into Thurs as sharp llvl thermal boundary lifts back northward.

KEY MESSAGE 3: A low pressure system will track west of our region on Friday and bring mixed precipitation and then rain to the north country. With cold high pressure in place ahead of this system, biggest threat for some freezing rain will be areas east of the Greens where there will be some cold air damming on Thursday night into early Friday. Models continue to show some increased for freezing rain and ice accumulation east of the Greens. Changes in the storm track could greatly alter the precipitation type, and will continue to monitor this system as we get closer to the end of the week. Low pressure slides eastward Friday night and precipitation will end from west to east as the low moves away. Another low pressure system with a similar storm track is poised to impact our region Saturday night into Sunday with low passing to our north and west. The GFS and ECMWF are in decent agreement with track of this system, though GFS is faster than ECMWF at this time. Cold high pressure will ridge into the area out of Canada towards the beginning of next week.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Through 12Z Tuesday...Mid/high clouds moved in overnight. This SCT-BKN cloud cover will remain AOA 5000 ft through 18z Mon, then start to slowly lower thereafter as moisture increasing ahead of an approaching cold front. Ceilings should generally remain VFR until 00z, with KSLK the lone exception where some MVFR ceilings will creep in during the afternoon hours. A few showers are possible this afternoon, mainly over the higher terrain. Gusty conditions develop today. Gusts of 20-30 kt are expected, with the strongest gusts to occur in the St Lawrence and Champlain Valleys.

Outlook...

Tuesday: Mainly MVFR, with local IFR possible. Chance RA. Tuesday Night: Mainly IFR, with areas MVFR possible. Definite RA. Wednesday: Mainly MVFR, with local IFR possible. Chance RA. Wednesday Night: Mainly VFR, with local MVFR possible. Slight chance RA. Thursday: Mainly VFR, with areas MVFR possible. Chance RA, Chance SN. Thursday Night: MVFR and IFR. Likely RA, Likely SN. Friday: Mainly MVFR, with local VFR possible. Likely RA.

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.