Marine Weather and Tide Forecast for Poestenkill, NY

KEY MESSAGES
1) Mainly scattered showers and thunderstorms this afternoon into early this evening. A few storms may become severe.

2) Isolated to scattered showers and thunderstorms are expected Monday and Tuesday, especially near and north of I-90.
Temperatures will be below normal.

3) Chances of showers and thunderstorms return later this week, along with temperatures warming back to normal.

DISCUSSION
KEY MESSAGE 1...

An upper level trough over our region will deepen today, with a closed low centered near Georgian Bay. Occluded front steadily progressing eastward across our area this afternoon, which is providing some forcing, along with falling heights aloft for showers and some thunderstorms to continue developing.

There remains a Marginal Risk (level 1 of 5) for severe storms across the entire region today. CAMs and radar trends indicating storm mode to be mainly cells/cluster, with perhaps a few lines developing as shear increases later this afternoon. Breaks of sunshine have allowed for destabilization. SPC Mesoanalysis page indicating SBCAPE of 1000-1500 J/Kg and effective shear of 30-35 kt. Environment is conducive for isolated severe storms, with mainly damaging wind gusts and perhaps an instance of large hail if storms can grow tall enough. Convection should dissipate shortly after sunset this evening, as instability wanes and a small-scale low level ridge builds in from the west.

KEY MESSAGE 2...

The core of an anomalously strong upper level low (500 mb height anomalies of -2 to -3 STDEV) will gradually track east near the far southern Ontario/Quebec border on Mon. A short wave disturbance rotating around the periphery of the upper low core is expected to move across our area. This will result in additional mainly scattered showers and a few T-storms Mon afternoon into early evening. Coverage looks to be most numerous across the Adirondacks, where there will be upslope/lake-effect enhancement with a cold core aloft moving overhead and W-SW flow developing over a very warm Lake Ontario (surface temperatures +20C to 22C). Due to anticipated low-topped convection associated with limited instability < 700 J/Kg, the threat for severe storm is low. However, there is potential for a few storms to produce small hail and/or gusty winds due to steepening lapse rates beneath the cold core aloft.

The core of the upper low will track NE across southern Quebec on Tue, as the trailing trough axis moves east across our region. This will result in additional showers developing, although there should be lower coverage compared to Mon except over the W. Adirondacks where lake-effect/upslope enhancement will persist. It will become breezy, with westerly winds gusting 20-25 mph at times in favored areas. Temperatures will remain below normal through Tuesday.

KEY MESSAGE 3...

Tranquil weather returns on Wed, as the upper level trough finally shifts east and high pressure builds in across the region. Unsettled conditions look to return on Thu, as the next upper level trough approaches from the west. Potential for multiple disturbances and surface fronts make timing details difficult this far out, but there is at least enough confidence to mention likely showers/T-storms developing Thu afternoon/evening. There may end up being a threat for some severe storms depending on timing and sufficient instability/shear. Will continue to monitor trends over the next few days. The broad upper level trough still looks to be in place on Fri, so there will be continued threat for showers/T-storms. Coverage may not be as much as Thu if the main cold front pushes east of the region by Fri morning.
Temperatures should warm back to normal levels Wed-Fri as well.

AVIATION /00Z MONDAY THROUGH FRIDAY/
A mixture of VFR/MVFR conditions start the TAF period due to passing rain showers. VFR conditions should continue at KALB through 8z to 11z when patchy fog can develop bringing brief periods of MVFR conditions. For KPSF and KPOU, rain showers can move through the TAF sites through 1z where brief IFR conditions could occur. Then patchy fog could develop between 6z to 11z bringing a fluctuation of IFR/MVFR conditions. For KGFL, VFR conditions continue through 4z when patchy fog can develop bringing IFR/MVFR conditions through 12z. Winds continue to range to between light and variable to west/southwest between 5 and 10 knots through the 12z timeframe. Then, winds increase tomorrow afternoon to the south/southwesterly with gusts ranging between 15 and 20 knots.

Outlook...

Monday Night: Low Operational Impact. NO SIG WX.
Tuesday: Moderate Operational Impact
Chance of SHRA
TSRA.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Moderate Operational Impact. Breezy
Likely SHRA
TSRA.
Thursday Night: High Operational Impact
Likely SHRA
TSRA.
Friday: Moderate Operational Impact
Chance of SHRA
TSRA.

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