690 FXUS61 KBTV 011449 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1049 AM EDT Mon May 1 2023 .SYNOPSIS... Cool and showery conditions will persist through much of the upcoming work week, as upper low pressure meanders between the Great Lakes and New England. The low will finally move east of the area on Friday, leading to drier and warmer weather heading into next weekend. && .NEAR TERM /THROUGH TUESDAY/... As of 1041 AM EDT Monday...Main concern has been to follow hydrologic trends on area rivers this morning. The Au Sable River has risen above flood stage, but is NOT expected to rise to moderate flood stage levels as hydrographs show rates of rises decreasing. There is a break in rain currently over the rivers basin which will help with draining. However, another pulse moving down basin is expected with an additional line moving into the Adirondacks this afternoon. The North Branch of the Black River is also spilling over its banks near Amsden, Vermont. These waters are expected to recede below minor flood levels over the next couple of hours. Bottom line is that rivers are running fast and should be avoided today; if flooding is occurring, do not drive through the water - you cannot see the condition of the road which may have washed out. Some modest adjustments were made to precipitation timing based on radar imagery and most recent CAMs. Steadier rain is shifting into northern Vermont and southern Canada with a bit of a break in activity. Another line of showers outlining the upper trough is apparent moving into the Adirondacks and southern Vermont. This band will swing through over the afternoon hours with another break expected later this evening. Otherwise, forecast is on track with no real changes to the general idea of periods of rain through the next 24 hrs. Previous Discussion...No significant changes were needed with this update. Still seeing a swath of showers lifting northward across the region, with the steadiest activity across northern New York. Rivers continue to show rises, especially the East Branch of the Ausable which is currently forecasted to go above minor flood stage. We will continue to monitor the hydro situation through the day. Have made some tweaks to PoPs to match the latest radar trends, but overall the forecast remains in good shape. Previous discussion...Widespread rain continues across much of the North Country this morning as moisture streams northwestward around low pressure currently centered near Long Island/southern New England. This feature will gradually lift northward into our area this morning, along with its attendant frontal boundary. This will bring the rain to an end for a short time toward mid morning. In the meantime, moderate to briefly heavy rain will be possible, along with sharp river rises. See the hydro section below for details. Locally gusty winds will continue through early this morning as a strong 850 mb jet also lifts north. Southeast winds are gusting 30 to 40 mph across some of the western slopes in the Northeast Kingdom and northern Greens, and isolated gusts to 50 mph will still be possible through about daybreak, when the core of the jet will exit to our north. Once the front lifts north of the international border, we'll start to see lapse rates steepen as cooling occurs aloft. This combined with a shortwave trough rotating around the parent upper low spinning over the Great Lakes will allow additional showers to develop this afternoon, especially across northern NY. Instability will be pretty meager, but can't totally rule out a rumble of thunder or two with any of the more robust activity. The showers will wane this evening as the sun sets and we lose daytime heating. Highs today will mainly be in the 50s, and tonight's lows in the upper 30s to mid 40s. The aforementioned upper low will spin even closer to our area on Tuesday, centering itself just west of the St Lawrence Valley. As such, widespread showers will once again develop and persist through the day. Most spots should top out in the lower to mid 50s tomorrow, but a few locations in the Northeast Kingdom and Adirondacks will likely struggle to get out of the 40s. Temperatures at summit level should remain in the 30s, so some snow will be possible, mainly above 3000 ft. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... As of 328 AM EDT Monday...An upper level low pressure system overhead will be centered around the eastern Great Lakes and shifting southeastward into northern Pennsylvania throughout Tuesday night. Surface low pressure and an associated occluded frontal boundary will provide forcing for continued shower activity and plentiful clouds in such a moisture- rich environment. Highest PoPs early in the night up to 90% in the northern Adirondacks and central VT, but generally decreasing to around 60-80% PoPs widespread throughout the night. QPF coming out to about 0.05-0.20" total for the night. Some of the higher peaks of the Adirondacks could even have up to around an inch of snow if showers occur there. Cool air advection could allow for seasonable lows in the upper 30s and lower 40s with light easterly surface flow. Wednesday will be another rainy and cloudy one as the upper low hangs around northeastern Pennsylvania, pumping more moisture and showers into the forecast area and turning wind direction slightly more northeasterly. Pops highest outside the Northeast Kingdom around 70-90% with an additional 0.10-0.30" of precipitation and snow showers continuing at the highest points of the Adacks. With a cold pool of air now overhead, highs will be a bit cooler in the mid-50s for the Champlain Valley and upper 40s/lower 50s elsewhere, which will be around 10 degrees below average for early May. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 328 AM EDT Monday...The cloudy and wet pattern should continue into Thursday as the upper level low mentioned above slowly exits the region into the Atlantic Ocean. Showers should gradually become more sparse the further out in the week we get, and cloud cover could become more scattered areas or periods of gray skies. By the end of the week, the upper low will likely wave goodbye due to a break down in blocking, and we'll finally usher into a period of drier weather. PoPs Wednesday night up to 50-70% fall to 00-20% Thursday night. Highs Thursday in the lower to mid-50s will become highs Friday in the mid- to upper 50s, then into the 60s and even near 70 for the weekend. It's important to note that it's still a bit early to determine exact timing of the amplified blocking breakdown, but at this time it looks to occur in this way with drier and even some clearer/sunnier conditions starting around Friday and a northerly to northwesterly wind over the weekend. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... Through 12Z Tuesday...A mix of MVFR/VFR conditions across the region this morning as an area of showers shifts northward. Steadiest rain ends by 15z, with visibility 4-6SM and ceilings generally 1500-3500 ft, though clouds may dip below 1000 ft briefly at KMSS and KSLK. Ceilings will gradually lift after 15z, but scattered showers will redevelop this afternoon, and MVFR visibility and ceilings will be possible should any of these showers drift over a terminal. Showers wind down after 21z with all sites VFR, but another round of precipitation will start to bring ceilings back down after 06z Tuesday. A 50-80kt southeasterly jet will continue to move from south to north across the region through 15Z resulting in LLWS and moderate to severe turbulence, mainly at KBTV and especially KEFK. At the surface, winds generally south to southwest around 10 kt with gusts to 20 kt through 21z, then subsiding to around 5 kt. Outlook... Tuesday: Mainly VFR, with areas MVFR possible. Definite SHRA. Tuesday Night: Mainly MVFR, with local IFR possible. Likely SHRA. Wednesday: MVFR. Definite SHRA. Wednesday Night: Mainly MVFR, with local IFR possible. Chance SHRA. Thursday: Mainly MVFR, with local IFR possible. Chance SHRA. Thursday Night: Mainly MVFR, with areas VFR possible. NO SIG WX. Friday: Mainly VFR, with areas MVFR possible. Slight chance SHRA. && .HYDROLOGY... As of 330 AM EDT Monday...Steady rainfall has been occurring across our region for the past several hours, with the highest amounts so far in the favored eastern slopes of the Adirondacks and central/southern Greens. In these locations, 1 to 2 inches of rain has fallen, and up to another half inch will be possible through daybreak, especially in the Adirondacks. Rivers have started to show rises as a result, especially some smaller waterways such as Ayers Brook in Randolph, Ranch Brook in Stowe, the East Orange Branch in East Orange, and the Dog River in Northfield Falls. Mainstem rivers have been a bit slower to respond but hydrographs are starting to trend upward. With steady rain now to focus in mainly northern sections of the forecast area through the remainder of this morning, our focus continues to be the East Branch of the Ausable River. Otter Creek will also need to be watched as the headwaters have received upwards of 1.75 inches of rain over the past 12 hours. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Hastings NEAR TERM...Boyd/Hastings SHORT TERM...Storm LONG TERM...Storm AVIATION...Hastings HYDROLOGY...WFO BTV