textproduct: Burlington

WHAT HAS CHANGED

As of 221 AM EDT Saturday...

Wind Advisory was slightly expanded slightly in area to include eastern Chittenden and eastern Franklin counties in Vermont, and magnitude of highest wind gusts were increased to near 55 MPH in localized areas in northern New York and in the vicinity of Lake Champlain.

KEY MESSAGES

As of 311 AM EDT Saturday...

1. Strong south to southeast winds will likely produce localized power outages late tonight ahead of a cold front. Widespread rain will occur Sunday morning with additional gusty westerly winds behind the front.

2. A late season light snowfall is likely for much of the region along with unseasonable cold. Greatest coverage of snow and snow showers is favored for late Monday night into Tuesday.

3. High pressure brings dry weather for mid week, but precipitation chances increase by the weekend. Temperatures remain seasonable through the latter half of the week.

DISCUSSION

As of 311 AM EDT Saturday...

KEY MESSAGE 1: Following a brief quiet and seasonable period today, another large and well-defined frontal system to our west will lift northeastward tonight. There are some similarities and key differences to the event we just had Thursday night into Friday.

Starting with the winds: a Wind Advisory remains in effect, with particular attention to the northern foothills of the Adirondacks and vicinity of Lake Champlain. It was expanded to the western foothills of the northernmost Green Mountains with hi-res model guidance showing strong near-surface southeasterly flow, including 950 millibar winds near to just above 50 MPH. The southeasterly flow looks lighter in central and southern portions of the Green Mountains reducing risk of impactful winds in those western slopes. The slight easterly component to the wind also seems to be why strongest winds in the Champlain Valley show a preference for northwestern portions of the valley towards Rouses Point and Chazy. Have bumped up peak wind gusts there into the range of 50-55 MPH, with similar magnitudes near the NY-Route 11B corridor in Franklin County. Like today, winds areawide will also be gusty behind the cold front but for a longer duration as cold air advection will persist into Sunday night and Monday morning on westerly winds.

As for precipitation: there again will be scattered to numerous showers developing associated with the system's mid-level warm front. As it moves northeastward through the area we also will have some elevated instability. However, the progged MUCAPE is less than last night, which should reduce potential for thunderstorms associated with development of CAPE in the hail growth region of the cloud. Greatest risk for thunder and heavier rain showers appears to remain in the immediate St. Lawrence Valley and during the first portion of the night. Cold air damming in eastern Vermont will again develop with some sub-freezing temperatures supporting freezing rain. Comparing forecast soundings shows similar inversion level and magnitude of the warm nose aloft, but the shallow cold air looks slightly less cold, which should limit coverage of wintry weather compared to last night. Pockets of freezing rain/snow/sleet certainly still could occur, but the threat looks low. The bulk of the rain will pass through the region in an organized west- to-east fashion over the course of about 4 to 6 hours centered during the mid morning hours, with most rain east of Vermont by noon. Brief moderate rainfall rates will occur with total rainfall only 0.2" to 0.5" for most locations in addition to the scattered showers that occurred during the night.

KEY MESSAGE 2: Unseasonably cold air, with 925 millibar temperatures dipping to near the 10th percentile by Tuesday morning, will enter northern New York and New England early next week. A north to south gradient in this cold air and upper level waves dropping southward around the base of the upper level trough will set the stage for widespread snow shower activity at times Monday through Tuesday. Consensus location of most precipitation, and potential for light snowfall, is currently across southern areas of the forecast area. Various positive snow depth change model output is consistent with forecast soundings showing impressively cold air aloft, steep low level lapse rates, and high relative humidity in the snow growth zone, that could support measurable snow of up to a few inches across our region. Greatest risk of slippery travel appears to be in higher terrain and where more persistent snow showers develop. For now, we show up to an inch of snow throughout the Adirondack region and central and southern Greens. Note also on the initial push of colder air early Monday some upslope snow showers will be possible that would provide our northern mountains with some minor accumulations, as well.

KEY MESSAGE 3: High pressure will drift across New York and New England Wednesday and Wednesday night, before moving off shore Thursday and Friday. We'll see a couple of dry days as a result. Wednesday will see temperatures return to seasonal normal, followed by a warming trend through the remainder of the week. Highs will be in the 50s and 60s Thursday and Friday. Things become more uncertain thereafter, as a low pressure will move by well to our north, dragging a cold front along in its wake. There are a wide variety of solutions amongst both the deterministic and ensemble guidance on this frontal boundary, whether it sinks southward through our region on Friday with showers and perhaps thunderstorms, or if it hangs up along the international border, keeping us mostly dry heading into the weekend. Given the uncertainty, have not made any adjustments away from WPC's forecast for the latter half of the week.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Through 12Z Sunday...Currently a mix of MVFR and VFR conditions across the region this morning, with impacts mostly from ceilings. The exception is KEFK, which is reporting 3-5SM in drizzle/mist, but expect this to dissipate by mid morning. Otherwise, lower ceilings will lift and give way to a period of VFR conditions at all terminals through much of the daylight hours. However, we will once again see conditions lower to MVFR this evening and overnight as showers spread across the region. Ceilings will drop to 1500-2500 ft, with localized IFR possible, mainly at KSLK/KMPV. Visibility generally 4-6SM in showers. Some pockets of freezing rain are possible in eastern VT, but expect these will be isolated.

The other threat is gusty winds. Generally N/NE 6-10 kt this morning, becoming variable as they turn toward the S/SE by evening. Gusts will intensify to 25 to 35 kt by 00z or shortly thereafter, especially at KBTV/KMSS due to channeling. LLWS is also expected after 00z as a 60+ kt LLJ works across the region.

Outlook...

Sunday: Mainly VFR, with local IFR possible. Windy with gusts to 35 kt. Definite SHRA. Sunday Night: Mainly VFR, with local MVFR possible. Slight chance SHSN. Monday: Mainly VFR, with local MVFR possible. NO SIG WX. Monday Night: Mainly VFR, with local MVFR possible. Slight chance SHSN. Tuesday: Mainly VFR, with areas MVFR possible. Chance SHSN. Tuesday Night: VFR. NO SIG WX. Wednesday: VFR. NO SIG WX.

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...Wind Advisory from 8 PM this evening to 8 AM EDT Sunday for VTZ001-002-005-016-017. NY...Wind Advisory from 8 PM this evening to 8 AM EDT Sunday for NYZ026>031-035-087.