Marine Weather and Tide Forecast for Mariaville Lake, NY

NEAR TERM /THROUGH SUNDAY/
Key Messages:

- Lake-effect snows continue into this afternoon primarily for the southwestern Adirondacks and Mohawk Valley, bringing an additional 1-3 inches. Winter Weather Advisories remain in effect in Herkimer and Fulton Counties until 4 PM today.

- A clipper system will bring widespread light to moderate and elevation-dependent, locally-heavy snowfall late this afternoon through Sunday. Confidence is medium to high (60-90%) in snow accumulations of 4 or more inches in the highest elevations of the southwestern Adirondacks and southern Greens. Additional winter headlines will likely be necessary in these areas. A Winter Weather Advisory may also be necessary into the northern Berkshires where confidence is low to medium (30-60%) in accumulations of 3-4 inches.

Discussion:

A single, ragged lake-effect band off Lake Ontario continues this morning beneath zonal mid-level flow. Transient streamers have reached as far east as the Capital District and Berkshires, but more persistent snows and therefore accumulations are still limited to the western/central Mohawk Valley and southern slopes of the Adirondacks. Increased shearing will see the band broaden and ultimately weaken into this afternoon, with a few additional inches of snow expected within the Winter Weather Advisory through then. As the band dissipates, expect headlines to be cancelled or expired by early this afternoon.

Elsewhere, cold temperatures in the 20s to low 30s and dry weather aside from a few flurries continue beneath mostly cloudy skies. A northern-stream shortwave and associated clipper low will approach into this evening, with steady light to moderate snow arriving from the west beginning late this afternoon. Accumulating snowfall through tonight is most likely north of Interstates 88 and 90, while there is lower confidence to the south, where any accumulations will remain light, generally an inch or less. Brief periods of heavier snow rates of around 1 inch per hour are possible overnight, particularly where upslope flow reinforces large-scale isentropic ascent.
Snowfall of generally 2-6 inches is expected, with potentially higher amounts in the western Adirondacks and southern Greens, and lighter totals along the Hudson and Champlain Valleys.

Given current Winter Weather Advisories in effect over western areas for lake-effect snow, no headlines have yet been issued for snows associated with this clipper low in order to maintain straightforward messaging. Additional headlines are likely in aforementioned areas as confidence remains medium to high in sufficient snowfall accumulations beginning this evening and continuing into Sunday morning. Elsewhere, there remains low to medium confidence in accumulations which may merit Advisory issuances. Interested parties should stay tuned to forecast updates through today as changes to headlines are expected.

Overnight lows largely in the 20s will see light snowfall continue into Sunday morning, before the progressive clipper low exits eastward by the afternoon. Some lake-enhanced and upslope rain and snow showers may continue in western areas, with a dry break expected elsewhere through Sunday afternoon. Southwesterly flow behind the departing low will push temperatures back up toward seasonal norms, with afternoon highs reaching the upper 20s to mid 30s in high terrain and upper 30s to low 40s at lower elevations. Partly to mostly cloudy skies will persist through the period, with the highest sky cover in areas of upslope flow.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/
Key Message:

- Additional rain/snow or wintry mix expected Monday afternoon, transitioning to rain by Monday night in all but the highest elevations.

Discussion:

Dry conditions are anticipated Sunday afternoon through Monday morning as shortwave ridging builds into the region from the west. Low temperatures Sunday night will fall largely to the 20s as the cold front associated with the clipper low slowly sinks south through the region before becoming washed out by Monday morning.

Additional precipitation is anticipated Monday afternoon as a southern-stream shortwave tracks north and east into the Ohio Valley. Latest guidance continues to trend cooler, making for a challenging precipitation type forecast for the onset of precipitation Monday afternoon. This element of the forecast will be highly dependent on timing. If precipitation begins earlier, before temperatures rise above freezing, precipitation type could be sleet in the Eastern Catskills where forecast soundings indicate a shallow warm nose. However, if onset it later, primarily rain will be the onset type. But precipitation type is a challenge throughout the day Monday especially at higher elevations of the Southwest Adirondacks and Southern Greens. With a retreating surface high parked to our north- northeast, cold air could become dammed up against the higher terrain, allowing mixed precipitation to be observed at the surface. At this time, sleet looks to be a larger possibility than freezing rain, given the shallow nature of the warm nose, but this is definitely something to watch moving forward as run-to-run solutions have shown discrepancies over the past several days. However, confidence is high in rain occurring at least from the Capital District south and west for much of the day Monday as high temperatures reach the upper 30s to low 40s in these areas. Elsewhere, expect low/mid 30s similarly to Sunday.

Low temperatures Monday night will fall widely to the 30s with upper 20s in the Southern Adirondacks and Southern Greens.
Precipitation will continue throughout much of the night as the aforementioned disturbance continues to track north and east through the region. While precipitation type remains a challenge during the overnight period Monday, at this time, guidance points to rain and snow or a mix thereof.

LONG TERM /TUESDAY THROUGH FRIDAY/
Key Message:

- Moderate confidence for a heavy precipitation event Tuesday night into Thursday with 1-2 inches of precipitation possible.

Discussion:

The extended forecast period remains active across eastern NY and western New England into the mid week. A mid and upper level trough will be situated over the central CONUS on TUE and become fully amplified near the MS River Valley and upper Great Lakes Region by WED morning. Clouds will thicken and lower ahead of a warm front with a wave of low pressure over southeast Ontario and the northern Great Lakes Region. Some light rain will develop with a mix of light rain/snow over the mtns. Temps will be above normal with mid and upper 40s in the valleys and mid 30s to lower 40s over the higher terrain. The full latitude mid and upper level trough moves over the eastern CONUS with moisture being entrained from the Gulf of Mexico, as a wave of low pressure and a cold front moves east of the Appalachians Tue night into Wed. Periods of rain develop on the east side of the upper trough as the wave tracks to west of the Hudson River Valley on several ensembles and the majority of the medium range guidance. PWATS rise 1 to 3 STDEVS above normal on the latest NAEFS. Lows will be in the 30s to around 40F Tue night with a widespread rainfall developing with favorable upper dynamics. Some wet snow may mix in over the southern Dacks briefly.

The latest NBM probabilities of >1" of QPF are in the 60-90% range 12Z WED - 12Z THU are across most of the forecast area. Mild air breaks into most of the forecast area on Wed with highs in the mid 40s to mid 50s from the Capital Region south and east, but as a wave of low pressure approaches, colder air will begin to collapse in from the northwest in the late afternoon and early evening. As the cyclone moves to the east of the region the pcpn transitions to snow Wed night into Thu. It is a tricky forecast with the thermal profiles. The higher terrain and west of the Hudson River Valley stands the best chance for accumulating snowfall by Wed night into Thu morning, but even some of the valley areas could receive some snow. A lot of uncertainty exists on the snow transition timing and amounts. We have at least a few inches across the forecast area especially the higher terrain at this point. We will continue to monitor if moderate to locally heavy amounts look more certain for some areas. Lows fall into the teens and 20s.

A much colder air mass builds into the forecast area in the wake of the front for Thursday. Isolated to scattered lake effect snow showers are possible across the western Adirondacks, western Mohawk valley and northern Catskills. Temps will fall below normal in the 20s to lower to mid 30s on Thu. High pressure builds in with cold and mainly dry weather to close the work and school week with temps continuing to run below seasonal normals.

AVIATION /15Z SATURDAY THROUGH WEDNESDAY/
Through 12Z Sunday, a mixture of MVFR/VFR conditions will continue impact the TAF sites this morning with some fragmented lake effect snow showers may reaching KPSF/KALB. Vsbys have briefly gone IFR at KPSF but remain VFR at KALB. The cigs are MVFR at KPSF in the 2-3.0 kft AGL and will continue the next few hours. Overall, an improvement is expected to VFR at all the TAF sites into the afternoon. KGFL may have MVFR cigs with the lake activity lifting northward toward noon. Mid level clouds will increase in the afternoon with the approaching clipper. Clouds will thicken and lower during the afternoon/early evening with low VFR/MVFR cigs forming from KALB-KPSF northward. Some light snow will move into the TAF sites 23Z/Sat-03Z/SUN and we used PROB30s or started the snow with MVFR cigs 1.5-3.0 kft AGL with vsbys IFR/MVFR. The snow will last until 09Z-12Z/SUN. Some improvement to MVFR/VFR levels is expected thereafter.

Winds will be southeast to southwest at 4-8 KT this morning.
The winds will be south to southwest at less 10 KT during the afternoon, but will increase from the south at 7-12 KT after 00Z/SUN. LLWS may become an issue Sat night and may need to be added to some sites with later TAF issuances if confidence increases.

Outlook...

Sunday Night: No Operational Impact. NO SIG WX.
Monday: High Operational Impact
Definite RA
SN.
Monday Night: High Operational Impact
Likely RA
SN.
Tuesday: Moderate Operational Impact. Chance of RA.
Tuesday Night: High Operational Impact. Definite RA.
Wednesday: High Operational Impact. Definite RA.
Wednesday Night: High Operational Impact
Likely RA
SN.
Thursday: Low Operational Impact. Breezy. Slight Chance of SHSN.

ALY WATCHES/WARNINGS/ADVISORIES
CT...None.
NY...Winter Weather Advisory until 4 PM EST this afternoon for NYZ032-038-039-082.
MA...None.
VT...None.