textproduct: Burlington

WHAT HAS CHANGED

As of 238 PM EDT Tuesday...

The Winter Weather Advisory has been cancelled. While a light glaze of freezing rain is still possible this evening and tonight, significant effects on travel are not expected.

KEY MESSAGES

As of 238 PM EDT Tuesday...

1. Periods of rain continue through tonight with localized light freezing rain possible.

2. Rain showers and patchy freezing rain possible Thursday into Friday.

3. River rises expected with local lowland field flooding possible into Wednesday.

4. Warm and gusty conditions likely Friday through Sunday with unsettled weather to end the weekend.

DISCUSSION

As of 238 PM EDT Tuesday...

KEY MESSAGE 1: The first round of rain moved through this morning and has exited. Overall, between 0.25 to 0.75 inches has generally fallen with some smaller totals toward the north and east. Now, the region is almost entirely in a break and that will continue for much of the afternoon, before the showers over the Great Lakes Region move in this evening and tonight. Before then, areas of mist and drizzle will continue to occur, especially across northern areas with northerly flow and a sharp inversion. Some elevated instability will be present this evening, especially in areas farther south. This will likely lead to a few rumbles of thunder, though the storms will likely weaken from what they are now over the Great Lakes. Overall, another 0.25 to 0.5 inches of rain is expected, though there will be some locally higher amounts over central and southern Vermont that see more of the elevated convection. High pressure will gradually build down from the north and drop temperatures in northern areas close to or slightly below freezing this evening and tonight. This will cause any rain to change to freezing rain and a light glaze is possible, particularly over far northern New York. However, the precipitation is expected to exit much sooner than before, and temperatures will be slightly warmer than forecast yesterday. Therefore, by the time the temperatures drop below freezing, most of the precipitation will be gone. A few areas dropped to 31 and 32 degrees this morning and likely saw some very light freezing rain, but the temperatures have since risen a couple degrees.

KEY MESSAGE 2: A storm system tracks well to the north and west of the region Thursday night into Friday. It will push a warm front across the region from south to north during the day Thursday. Precipitation continues to trend lighter with a farther west storm track. The current forecast of 0.1 to 0.25 inches of rain is likely still on the higher side. Temperatures in the colder hollows east of the Greens and in southern Essex County New York look to drop below freezing Thursday night. Therefore, any lingering showers there could fall as freezing rain. However, with marginal temperatures around freezing and low liquid totals, amounts should at most be a light glaze.

KEY MESSAGE 3: Despite a continued southward shift in the heaviest precipitation, river rises will continue to occur into Wednesday, and lowland field type flooding remains possible. Overall, the expected 0.5 to 1.5 inch totals over 36 hours would not cause much of a threat by themselves, but some elevated instability and associated rainfall enhancement will lead to locally higher totals in southern areas. The heaviest rainfall axis looks to set up over central and southern areas, where local amounts up to around two inches are possible. However, there will be some notable factors limiting the flood threat. The first is that the rain is coming through in two mostly separate rounds, with almost twelve hours in between, giving time for rivers to take up the water. The second is that the cool surface temperatures and dew points will continue, especially where the snowpack remains at the higher elevations. Dew points only look to reach the upper 30s and low 40s, with maximum temperatures not much higher. A gradually cooling trend should allow snowmelt to decline further going into tonight. With that being said, several rivers look to approach Action Stage and minor flooding cannot be ruled out in a reasonable worst case scenario. The river forecast to minor for the East Branch of the Ausable River in Ausable Forks is on the very high side, with ensemble guidance averaging below that and shadowing effects limiting precipitation as well.

KEY MESSAGE 4: Trends with the late week system have trended a bit north as strong southerly winds and a 50-60kt 850mb low-level jet will help to usher in abnormally warm southerly air. This warmup should scour out any lingering cold air east of the Greens Friday morning with surging surface temperatures into the 60s areawide. The ECMWF Extreme Forecast Index remains high on high temperatures being high Friday afternoon, particularly in the Champlain Valley and St. Lawrence Valley. Temperatures could easily reach the low 70s in the deeper valleys as southerly flow in the morning helps to mix and dry out the surface, which from recent trends, can lead to underestimating the high temperature by several degrees. Aiding this increased temperature forecast is the northward trend of the Thursday night system which will help draw more waa. The warmup will be accompanied by a strong 50-60kt LLJ at 850mb which should lead to gusty conditions. Again, recent trends have shown winds are underdone in setups like these, and have blended in NBM90th guidance with south wind gusts in the Champlain Valley 30-35 MPH, and as winds turn more westerly throughout the day, 30-35 MPH in the St. Lawrence Valley Friday afternoon. Have subsequently lowered PoPs during the day Friday, though some diurnally driven convective showers may be possible in the higher terrain.

Into the weekend, breezy conditions will remain as a weak cold front Friday night, will lift back north leading to further warm temperatures near 60 on Saturday. A more organized system with good moisture connection to the Gulf will move into the area late Saturday into Sunday. Shower chances increase as a cold front pass through the region. An isolated rumble of thunder may be possible with some elevated instability in the St. Lawrence Valley, but cloud cover and the forcing timing should keep thunder chances low. Shower chance persist through the day Sunday as the boundary slows, but should taper off by Monday morning. The front does not seem to have a strong thermal gradient behind as temperatures still warm into the low 50s Sunday, but winds will switch to the northwest late Sunday night which will be the signal for cooling temperatures back to near normal heading into next week. Winds will remain gusty behind the front Sunday into Monday.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Through 00Z Thursday...A wide range of conditions across the terminals at the start of the TAF period, ranging from LIFR at KMSS/KPBG to VFR at KRUT. Widespread shower activity, mist/drizzle, and low ceilings are responsible for these conditions, and expect we'll continue to see rounds of showers and low ceilings through 08z-10z. During this time, ceilings of 500-1500 ft will be most likely, with visibility 3-5SM. Visibility improves after 10z as showers end, but ceilings will likely remain IFR for a few more hours before gradually lifting through MVFR to near VFR by the end of the TAF period. Winds generally light and variable overnight, with a strong LLJ creating LLWS through 08z. After 12z Wed, expect N/NW winds 5-10 kt through the remainder of the day.

Outlook...

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