textproduct: Burlington

WHAT HAS CHANGED

As of 131 PM EST Saturday...

Confidence has increased in widespread river rises due to snowmelt this upcoming week.

KEY MESSAGES

As of 131 PM EST Saturday...

1. Warm, windy and wet weather through tonight. However, no significant impacts expected.

2. Unseasonable warmth will continue early next week, especially on Monday and Tuesday. Little to no snow will be left at elevations below 1000 feet.

3. Confidence in widespread river rises due to snowmelt has increased, particularly for early to the middle part of next week. Rivers will need to be monitored closely for river ice movement and potential ice jams and associated flooding.

4. After a stretch of spring-like weather, more widespread precipitation is expected to arrive for the middle of next week.

DISCUSSION

As of 131 PM EST Saturday...

KEY MESSAGE 1: A surge of unusually warm and moist air is making its way northward across much of the eastern US today ahead of a high amplitude trough. At the surface, a warm front is expected to stay hung up just to our southwest today as surface temperatures, especially in central and eastern Vermont, are relatively slow to rise. Also, localized colder spots near Lake Champlain In contrast, much of northern New York is seeing temperatures early this afternoon well into the 50s and even low 60s with dewpoints climbing into the upper 40s and low 50s. Eventually, extreme warmth will be seen across our region by this evening as we mix out a stubborn surface inversion with increasing south-southwesterly flow ahead of a slow moving cold front. Surface temperatures upstream ahead of this front in western New York have risen into the upper 60s and low 70s with dew points approaching 60. The warmth is impressive, particularly in the 850-700 millibar layer. Temperatures at 850 millibars, indicative of our higher mountain summit weather, will likely be as high as 13 degrees Celsius (55 F) later today into this evening. Note the observed upper air data (radiosonde) from Albany, NY at 7 AM today shows this extreme warm layer with exactly 13 degrees at 850 millibars, which appears to be a record through this point in the calendar year (back to 1948).

With regards to precipitation, the GOES-16 water vapor channels show a messy scenario. Widely scattered showers are present out ahead of batch of somewhat organized showers and thunderstorms over southern Ontario and western New York, where clusters of colder cloud tops can be seen within the warm sector of the frontal system. While ample warmth and humidity will be present, it is questionable if elevated instability will be sufficient for thunder in northern New York and Vermont. Consistent with the Storm Prediction Center analysis, risk of thunder generally is higher as you go west. Signals for whether any of this upstream convection, particularly thunderstorms, survive into our relatively cool/stable air mass are a bit mixed. Progged MUCAPE (Most Unstable CAPE) will possibly surge to near 100-200 J/kg as mid-levels saturate in the St. Lawrence Valley and western Adirondacks. These areas remain most likely to see heavier rainfall amounts than areas to the east given richer low level moisture and convergence. However, while PWAT (Precipitable Water) will be anomalously high, lack of instability, fast cell motions, and modest warm cloud depths reduce risk of heavy rainfall. Most likely amounts through tonight will be about a third to three quarters of an inch, with very localized spots possibly near 1", tapering off to a tenth to a third of an inch in much of Vermont, again with localized higher amounts exceeding a half inch especially in northeastern areas and high terrain.

Most CAMs (Convective Allowing Models) and time of arrival tools suggest these showers will begin after 5 PM with coverage increasing from 6 to 9 PM across the region. They will make it into Vermont relatively slowly given deep layer southwest flow close to parallel with the front. The actual cold front will lag behind this area of showers, so moist and mild southerly flow will persist for much of the night. A final round of scattered showers just ahead of the cold front will likely move across the area in the early morning hours, with precipitation chances rapidly decreasing from west to east towards daybreak as drier air filters in. Unseasonably warm and breezy conditions tonight will support rapid snowmelt (more on this in Key Message 3) and ripening of higher elevation snow. Typically this could be a foggy over snow scenario with high dewpoints in the 40s and even low 50s, but think there may be enough wind to reduce prevalence of fog tonight; this may need to be re-evaluated this evening. While the southerly channeled flow in the northern Champlain Valley will be relaxing tonight, a belt of 50 to 60 knot west-southwesterly flow in the 700 to 850 millibar layer will be coincident with the showers overnight. Stability should keep these strong winds from mixing effectively. However, towards daybreak as flow becomes westerly behind the front, some localized downslope winds will develop resulting in possible 45 to 50 MPH gusts. These will initially be east of the Adirondack high peaks and then expand into the eastern slopes of the Green Mountains, especially favoring western Windsor County with expected magnitude and orientation of the low level jet.

KEY MESSAGE 2: Large scale west-southwesterly flow and a storm track well to our north will keep us in a warm and dry weather pattern. Temperatures tomorrow behind tonight's cold front will still be rather mild in the 40s in most locations, and then as winds turn southerly again tomorrow night into Monday, we'll see warm air advection support temperatures surging into the mid and upper 50s in most locations. Despite some modest southerly winds with gusts of 15 to 25 MPH, ample sunshine alongside these temperatures should make this a really pleasant day for outdoor activities such as corn snow skiing and walking with a single layer of clothing.

Tuesday will be subtly different as a backdoor cold front may settle far enough south to flip winds to northerly during the afternoon in our northernmost areas while southern areas see further warming of the air mass to support highs in the low to mid 60s. Therefore, the forecast for Monday is a bit more certain than Tuesday with regards to high temperatures, especially in the Champlain Valley and northern counties in Vermont. The St. Lawrence Valley more definitely looks to see somewhat cooler conditions on Tuesday than Monday. As of now, across southern counties of northern New York and Vermont, Tuesday will be another warm and sunny day, while increasing clouds and slightly cooler weather is possible farther north.

KEY MESSAGE 3: With a prolonged period of above freezing temperatures expected through the first half of next week, river response is likely areawide due to runoff from snowmelt. This weekend's warmer weather is a preview of what's to come, and will likely serve as a primer for more river rises later in the week.

Snowmelt is just starting in earnest this afternoon as temperatures have warmed well into the 40s and even 50s from the Champlain Valley westward. In addition, note dew points have likewise risen above freezing (or will by later today in the case of eastern VT). Add in gusty south/southwest winds, and it's the perfect recipe for snowmelt. While rivers haven't show a whole lot of response just yet, we do anticipate waterways will start to rise this evening and continue overnight. The latest river forecasts from the Northeast RFC do show a few of our river gages (Ausable R near Ausable Forks, Otter Creek near Center Rutland, and Mad River near Moretown) approaching or just exceeding action stage at some point Sunday. There could be some nuisance-type flooding of low-lying areas along these waterways, but no significant impacts are expected.

Our bigger concern is heading forward toward the middle of next week. This weekend's snowmelt should slow or even stop Sunday night as temperatures drop back close to or below freezing, allowing rivers to recede a bit. However, this will be short lived as we'll warm well into the 50s and even 60s Monday, Tuesday, and Wednesday. Like today, we'll see warming dew points as well, along with periods of gusty winds. Overnight temperatures are expected to mainly stay near or above freezing, so there won't be a whole lot of recovery between peak snowmelt times. The snowpack will likely take a pretty good hit; note that the latest NOHRSC analysis shows everything melted out below 1000 ft or so by early Tuesday morning. Higher elevations will also see substantial loss of the pack, though how much exactly is still hard to determine at this point. Looking at the latest GEFS/NAEFS ensemble runs, a general 2-4 inches of SWE loss seems reasonable through Thursday. While rainfall isn't expected to be overly heavy during this time frame, it will be enough to add to the runoff. Given the prolonged period of mild temperatures, we're growing more confident that there will be ice movement on area rivers next week, particularly on southern waterways that have a better chance of seeing persistent mild conditions. Of course, river ice break up and resultant ice jams and any flooding are fairly unpredictable, especially this far out in time. With that in mind, we urge anyone with interests along area waterways to monitor future forecasts closely. As far as open water flooding, it really takes both snowmelt and heavy rainfall to create significant problems, but some ensemble guidance shows rivers such as the Mad River, Ausable, and Otter Creek potentially exceeding minor flood stage. And at the least, waterways will be running high, even smaller tributaries and streams.

KEY MESSAGE 4: A low pressure system centered over the Great Lakes will track northeastward towards the middle of next week, bringing widespread precipitation chances to the region Wednesday into Thursday. There is still a lot of uncertainty in regards to precipitation type at this point, both due to temperatures and low track. The current forecast supports mostly rain, with a brief transition to snow during the day Thursday as a cold front pushes across the region, although there is some guidance that supports the possibility of a wintry mix and some freezing rain. At this point is is still too tricky to tell for sure, as small differences in thermal profiles and surface temperature can play a large role in the precipitation type, but is something to monitor over the next few days as we get closer. After the cold front Thursday, temperatures for the end of the week look to trend closer to seasonal normals for early March, with highs in the mid 30s to low 40s.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Through 00Z Monday...Outside strong winds near 20 knots sustained with gusts 32-38 knots at KBTV, most areas are seeing winds subside towards 5-10 knots with occasional gusts to 20 knots. Rain running out ahead of a cold front is present over northern New York, and will reach Vermont in the 30-60 minutes. Activity is disorganized, with relatively little impacts to visibility being noted, though KOGS did reach 2 1/2SM very briefly. Given the disorganized nature, outside areas where it is raining now, mainly utilized TEMPOs and PROB30s to note 3-6SM visibility restrictions in rain. Low-level wind shear remains prevalent as winds at 2000 ft agl range between 45-55 knots out of the southwest. Some additional precipitation will develop along the St. Lawrence River Valley, with the potential for a couple rounds of rain. Ceilings will lower, though, and KSLK could observe some 700-1000 ft agl cloud bases ahead of the incoming front. The main axis of the front will shift east about 10z-16z. It will correspond with a trend to southwest winds, a decrease in LLWS, and one last round of light rain showers. However, after 16z, improving conditions are expected for all terminals. Winds will remain elevated, towards 7-13 knots sustained with gusts 16-21 knots, locally increasing towards 30 knots at KMSS about 22z Sunday.

Outlook...

Sunday Night: VFR. NO SIG WX. Monday: VFR. Windy with gusts to 30 kt. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. NO SIG WX. Tuesday Night: Mainly VFR, with areas MVFR possible. Chance RA. Wednesday: Mainly MVFR, with areas IFR possible. Definite RA. Wednesday Night: Mainly MVFR, with areas IFR possible. Definite RA. Thursday: Mainly MVFR, with areas IFR possible. Likely RA, Chance SN.

CLIMATE

Temperatures today have become quite warm, particularly in northern New York. Possible daily records for 3/7 include:

Massena (MSS) Record High: 60|1973

Saranac Lake (SLK) Record High: 58|1946

EQUIPMENT

The KBTV ASOS has suffered a communications failure. The issue has been diagnosed, but there is currently no estimated time of return to service. The affected communications line is not serviced by the NWS. Terminal Aerodrome Forecasts will continue, but regular observations may not be available.

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.