Marine Weather and Tide Forecast for Poestenkill, NY

NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
As of 4:00 PM EDT...Currently, an upper low and occluded sfc low are pushing into the western Great Lakes region. Out ahead of this system, low-level warm and moist advection has allowed for temperatures to rise well into the 70s to low 80s, with upper 50s to mid 60s dewpoints. Skies have become partly to mostly clear, so the combination of sun and warmth/moisture have allowed for MLCAPE values to rise to 500-1000 J/kg, with a plume of higher CAPE values expected to push in from the west later this evening between now and sunset. However, current GOES 16 WV imagery shows a lot of mid-level dry air and subsidence behind an MCS that decayed as it tracked near our region earlier this morning. Model forecast soundings show a slight capping inversion that is likely inhibiting convective initiation.
There have been some isolated showers and thunderstorms across the ADKs and southern VT, but the rest of the region remains mostly dry at this time.

However, with heights falling aloft this evening there may be enough additional forcing to overcome any cap, especially with the strongest subsidence beginning to move to our east. So, we are still monitoring the potential for some additional showers and storms to develop this evening. Greatest chance appears to be along and north of I-90. Vertical shear isn't overly impressive at <25-30 kt so widespread/organized severe weather isn't expected, but with DCAPE values approaching 750-1000 J/kg a few storms could contain damaging winds. We still agree with the SPC marginal risk across the region. PWATs on the order of 1.25-1.45" could also lead to some locally heavy rainfall within thunderstorms, and storm motions won't be overly fast, so isolated hydro issues can't be ruled out this evening.

Tonight, lingering convection is possible for a couple hours after sunset, mainly south and east of the Capital District. The threat for any stronger storms should also diminish with the loss of daytime heating after sunset. Diffluent flow aloft and low-level warm advection will lead to plenty of clouds around tonight and a few lingering showers. A couple non-severe thunderstorms will also be possible overnight with some pockets of elevated instability. Lows will be quite mild, mainly in the 50s to 60s. Some patchy fog and low stratus are expected across the Mid Hudson Valley and southwestern New England due to light low-level S/SE flow, with some additional patchy fog for areas that receive rain this evening.

SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/
Key Message:

- There is a slight risk for severe thunderstorms Saturday from late morning through mid to late afternoon for much of eastern NY and western New England.

- The slight risk for severe weather has been shifted further north and east from the previous forecast.

Discussion:

Tomorrow, the upper low and occluded low track eastwards across the Great Lakes region. A weak warm frontal boundary lifts northwards late tonight/very early tomorrow morning, and there could be some lingering isolated showers/storms across northern areas tomorrow morning. However, additional showers and thunderstorms are expected to develop by mid to late morning as a pre-frontal trough tracks through the region. Some of these storms could become strong to severe (more below). There may be a brief lull in convective activity for a few hours in the mid to late afternoon, before another line of storms tracks from west to east across the region ahead of the system's actual cold front. Despite strong forcing for ascent, instability should diminish behind the first wave of convection, so the probability for severe weather with this second round of convection looks lower at this time. This is a change from the previous forecast, which messaged a greater severe potential with the second round of convection later in the day.

Regarding the severe threat, timing appears to be from roughly 10 AM to 4PM tomorrow. There is some uncertainty in how much instability develops, but the HRRR suggests that 1000-1500+ J/kg of SBCAPE is possible, with the greatest instability in the Hudson Valley from the Capital District northwards. This instability will overlap with 35-40+ kt of deep-layer wind shear. Damaging wind seems to be the primary threat with DCAPE values of 700-1000 J/kg, but large hail will also be possible with WBZ heights near 9.5 - 10.5 kft and mid-level lapse rates of 6.5-7C/km. There is also a chance for an isolated tornado or two tomorrow with some low-level curvature to the hodographs and low LCLs, although the fact that most of the wind shear is above the lowest 1 km makes this a lower-end threat. The threat appears greatest from roughly the Capital District north and east tomorrow, and given this we have collaborated with SPC and WFO BTV to have the slight risk moved into this area and trimmed back across the southern part of our area where forcing looks weaker. Instability should diminish behind this first round of convection, reducing the severe threat later in the evening.
However, wind shear still looks impressive tomorrow afternoon and evening, so we can't totally rule out a stronger storm or two with the second round of convection if there is more instability than forecast.

There is also a threat for heavy rain with any thunderstorms tomorrow, as PWAT values remain elevated at between 1.2-1.4" per the latest HRRR. However, storm motions will be faster with strengthening flow aloft, and areas north of the I-90 that are expected to see the greatest convective coverage have received very little rain over the past 5 days. This should limit the threat for hydro issues, although any storms moving over urban/poor drainage areas could still result in some ponding of water. WPC has placed areas north of I-90 in a marginal risk ERO tomorrow. Highs will be mainly in the 70s to around 80, and it will be muggy again with dew points in the 50s to mid 60s.

Saturday night through Sunday night...The cold front tracks through the region Saturday evening and early overnight.
Convection comes to an end within a couple hours of sunset, and a much cooler airmass will infiltrate the region behind the front. There will be some scattered showers lingering, especially during the day on Sunday, with the upper low and associated cold pool aloft tracking across upstate NY. It will be much cooler with overnight lows in the 40s to 50s Saturday night and 30s to 40s Sunday night. Daytime highs Sunday will be mainly in the 50s to 60s with lower humidity. West winds also become breezy with the surface low tracking to our northeast and broad high pressure building out of Canada towards the Great Lakes.

LONG TERM /MONDAY THROUGH FRIDAY/
Monday through Tuesday night...The upper low moves off to our northeast, but we remain in persistent NW flow aloft. High pressure remains northwest of our region, which will keep breezy conditions around through this timeframe. Temperatures remain below normal for this timeframe, with 50s to 60s during the day and 30s to 40s each night for lows. There could be a few lingering showers across the ADKs or southern Greens, but by and large most areas will remain dry.

Wednesday through Friday...Chances for rain increase for the middle of the week, as guidance is in relatively good agreement on an upper shortwave tracking across the TN valley interacting with retrograding northern stream energy, eventually forming a closed upper low. At the surface, an area of low pressure will likely develop and track near the east coast, so we have included likely PoPs for Wednesday and Thursday. The details and timing will still need to be ironed out, including how quickly the upper low and lingering precip depart to our east Thursday night and Friday. Nevertheless, with a storm track to our south and east, we will likely see continued below normal temperatures each day. CPC is expecting below normal temperatures and above normal precip to continue for days 8-14.

AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
Through 18z Saturday...VFR conditions are in place across all terminals this afternoon with decreasing clouds across the region. This afternoon, MVFR conditions will be possible with passing showers and some isolated non-severe thunderstorms. With differences in the guidance on just where these will develop and track, it was difficult to pin down exactly when and where these showers and storms could potentially impact terminals. So, input TEMPOs and PROB30 groups at KALB and KGFL where these are most likely this afternoon and this evening. KPOU and KPSF should remain dry, though a light shower or two crossing through their vicinity is possible. Any MVFR conditions from precipitation should improve to VFR once again tonight before some fog/low stratus is expected to develop everywhere. This will especially be possible where winds go calm and at terminals that see rain this afternoon. MVFR to IFR conditions are expected with this and IFR ceilings will continue into the end of the 18z TAF cycle even after visibilities improve tomorrow morning. Otherwise, winds will be relatively light and variable out of the south with sustained speeds ranging from about 5-10 kt.

Outlook...

Saturday Night: Moderate Operational Impact
Chance of SHRA
TSRA.
Sunday: High Operational Impact. Windy With Gusts To 30 kts. Likely SHRA.
Sunday Night: Low Operational Impact. Breezy. Slight Chance of SHRA.
Monday: Low Operational Impact. Breezy. NO SIG WX.
Monday Night: Low Operational Impact. Breezy. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Moderate Operational Impact. Chance of SHRA.

ALY WATCHES/WARNINGS/ADVISORIES
CT...None.
NY...None.
MA...None.
VT...None.