textproduct: Burlington

WHAT HAS CHANGED

As of 203 PM EST Saturday...

Snowfall amounts continue to increase for southern and central Vermont for Sunday night into Monday.

KEY MESSAGES

As of 203 PM EST Saturday...

1. Snow showers continue to taper off this afternoon but linger over northern New York.

2. Continued northwestward trend in the nor'easter sunday night into Monday.

3. Cold midweek, then another round of widespread precipitation is possible over the latter half of the week.

DISCUSSION

As of 203 PM EST Saturday...

KEY MESSAGE 1: A backdoor cold front is slowly progressing down from the northeast. There is much drier air behind it with the snow stopping and the sun coming out. It should push through northern Vermont by this evening and the rest of Vermont and parts of Clinton County by tomorrow morning. While the sunshine will likely be reserved to the Northeast Kingdom and adjacent areas, the snow showers should end in the rest of the places after its passage. A few snow showers will linger across parts of northern New York through much of tomorrow.

KEY MESSAGE 2: A powerful nor'easter develops off the Mid- Atlantic Coast on Sunday and its center tracks southeast of Cape Cod and the islands Sunday night into Monday. It is increasingly looking like an ideal storm track for southern New England, while Vermont and northern New York will be on the northern fringe. As typical for these events, there looks to be sharp gradient on the northern edge. Probabilities of 4 or more inches for Rutland and Windsor counties remain around 25-40 percent, but there is some old guidance going into those so they will likely rise a bit due to the westward shift. There is also the potential for a mesoband to reach southern Vermont and locally increase snowfall amounts there. Northern areas are only likely to see an inch or two at most, barring an unexpected major change in the storm track. The surface pressure of the low is expected to drop below 980 mb and potentially below 970 mb as it passes by, creating a significant pressure gradient. A strong easterly low level jet looks to develop across southern Vermont, with 40-60 KTs looking increasing likely at 4,000 feet. This is thankfully higher and weaker than in many high wind events, but gusts in the 30-40 mph range look increasingly likely in southern Vermont. Downsloping will likely reduce snow amounts in the areas around Rutland and south along the Route 7 corridor. Channeled northerly flow also looks likely in the Champlain Valley later Monday, with gusts in the 25 to 35 mph range possible. Overall, there has been an impressive westward shift in guidance relatively close to the event. Back on Thursday, it was just the GFS and a couple GEFS/CAN ensembles bringing any notable snow to southern New England, and now they are expecting blizzard conditions and several inches are increasingly likely across southern Vermont.

KEY MESSAGE 3: Cold air advection behind a departing coastal storm will push us about 10-15 degrees below normal in the mid teens and 20s Tuesday afternoon. Portions of northern New York could see wind chills Tuesday morning and early afternoon approaching 15 below. Tuesday night into Wednesday morning will feature min temperatures in the -5 to 5 F range. Our next chance for precipitation will be on Wednesday when a shortwave slides through the region and a surface low pressure moving across the Great Lakes and New York/Vermont international border. With low pressure to our west, we anticipate some warm air advection across northern New York and Vermont on Wednesday. Wednesday night, the surface low looks to ride along the international border before speeding north and east early Thursday morning. The Canadian model and ECMWF both seem to try and keep this system separated into two upper shortwaves. A greater gap between the two means snow for the onset Wednesday into Wednesday night, but southwest return flow is allowed to take place and warm us above freezing with a wintry mix or rain, particularly Wednesday night into Thursday night and mainly in the valleys. For the ECMWF and Canadian, having not combined the waves for the Wednesday system, that secondary wave rides through quickly behind on Thursday, though placement and speed of cold frontal boundaries still create discrepancies between the two models. The GFS, however, combines the two waves into one and includes some upslope precipitation behind it on Thursday. Where the systems are more closely entwined like in the GFS solution, there's less warm advection that takes place and more snow. The GFS brings another wave through Thursday night and Friday. This differs from the other two models, which keep us mostly dry by Friday. With both scenarios, precipitation is likely, but the nature of how and when this plays out between Wednesday afternoon and Friday is uncertain.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Through 00Z Monday...Primarily a mix of MVFR/VFR this evening, with KSLK the lone exception due to IFR ceilings. Clear skies dominate northeastern VT, with a blanket of MVFR clouds covering much of the region and a majority of our TAF sites. This will be the trend this evening and into the overnight. KMSS/KSLK/KRUT/KBTV have the best chances of remaining MVFR with ceilings 1200-2800 ft. KPBG and KMPV will be on the edge of the cloud deck and could have periods of VFR with SCT clouds. Guidance continues to indicate some mist/fog at KEFK late tonight into early Sunday morning as moisture gets trapped under a strong inversion. Have stuck with 5SM and SCT003 05z-13z due to uncertainty, but IFR is a possibility. KRUT will have periods of IFR through 04z with light snow and occasional lowering of ceilings below 1000 ft. Otherwise, the only other terminal with visibility restrictions will be KMSS, where light snow is expected 10z-15z Sun. Visibility mainly 3-5SM in snow. Some improvement is expected during the day Sunday as ceilings lift, but overall still anticipate VFR/MVFR. Winds light and variable overnight, trending toward the S/SE at KBTV/KRUT and E/NE at KMSS after sunrise Sunday.

Outlook...

Sunday Night: VFR. Slight chance SN. Monday: VFR. Chance SN. Monday Night: Mainly VFR, with areas MVFR possible. Slight chance SN. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. NO SIG WX. Wednesday: Mainly MVFR, with local VFR possible. Chance SN. Wednesday Night: MVFR. Chance SN. Thursday: Mainly MVFR, with areas IFR possible. Chance SN, Chance RA.

EQUIPMENT

The KMPV ASOS has suffered a communications failure. The issue has been diagnosed, but there is currently no estimated time of return to service. Terminal Aerodrome Forecasts will continue, but amendments to those forecasts will be suspended.

NOAA Weather Radio station WXM-44, transmitting from Mt. Ascutney, Vermont, on frequency 162.475 MHz is non- operational at this time. NWS technicians have diagnosed the problem, but repairs will likely not be able to occur for quite some time due to circumstances beyond our control. Therefore, the time of return to service is currently unknown. The following NOAA Weather Radio transmitters may be able to provide service during this outage: WWG 50 from Burke Mtn, VT at 162.425 MHz and WNG 546 from Hanover, NH at 162.525 MHz.

The Colchester Reef meteorological station is out of service. This site is not serviced by the NWS and there isn't an estimated return to service at present. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

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