Marine Weather and Tide Forecast for Chatham, NY

KEY MESSAGES
1) Aside from showers tonight into tomorrow, dry weather expected through the end of the week with initially cool temperatures moderating closer to normal for the end of the week.

2) The combination of breezy and dry conditions on Thursday may lead to an elevated risk for fire spread.

DISCUSSION
KEY MESSAGE 1...
As of 1:50 AM EDT...Current sfc analysis shows a 1028 mb sfc low centered over central NY, downstream of upper ridging as seen on GOES 16 WV imagery. This sfc high should continue to slide eastwards into this morning, with clear skies and diminishing winds through early this morning. This will lead to very favorable radiational cooling conditions and low temperatures in the 10s (terrain) to 20s (valleys). Continued the trend of going colder than NBM guidance for temperatures through early this morning. Heights continue to rise aloft today which will result in large- scale subsidence and dry conditions as the sfc high slides off to our east. Temperatures will be several degrees warmer than yesterday, but still below normal, with 40s for the terrain and low to mid 50s for valley areas.
Given expected deep BL mixing today, we did lower dew points and RH from the NBM, but relatively light winds should prevent any fire weather concerns.

Tonight into tomorrow, a warm front will approach from the southwest, stalling near or just W/SW of our forecast area. An area of low pressure will track along the low-level thermal gradient in association with an upper shortwave embedded within the NW flow aloft. While we remain on the cool side of the front, we will still see mid-level warm advection/isentropic lift with a strengthening southwesterly LLJ leads to increasing moisture advection into our region, especially for the southwestern half of our area. Guidance also shows a band of low to mid-level FGEN along/just northeast of the warm front where there is some convergence at the nose of the LLJ. Given increasing moisture and forcing, we felt NBM PoPs and QPF were too low, and adjusted both up in collaboration with surrounding WFOs. QPF now looks to be on the order of a few hundredths of an inch possibly up 0.1 or 0.2" with the highest amounts in the Catskills. Some wet snow or freezing rain/sleet could mix in over the highest elevations of the ADKs, Catskills, and southern Greens, but any accumulations look very minor. Some showers will likely linger into tomorrow morning, especially across the Mid Hudson Valley and southwestern New England, but the trend through the day should be for drier conditions as the sfc low and upper support move off to our south and east. Temperatures Wednesday will be in the upper 40s to mid 50s rea-wide with overnight lows dropping back into the 30s to around 40.

Thursday through the end of the week, fairly high confidence in dry weather with an omega block developing across the northern half of the country. We will be on the downstream side of the upper ridge, favoring large-scale subsidence as a ridge of high pressure builds overhead at the sfc. We should moderate closer to normal for temperatures Thursday and Friday. Confidence decreases for the weekend into early next week, as some sources of guidance keep the block in place with any precip remaining west of our region, while other sources of guidance have more shortwave energy tracking towards us from the west as the upper ridge gets pinched off to our north over Canada. Given complexity of the upper flow pattern it will likely take a couple more days before this part of the forecast begins to come into better focus. Temperatures look to remain near to slightly below normal, with a better chance for below normal temperatures if we end up seeing more rain/clouds around.

KEY MESSAGE 2...Thursday, a tightening pressure gradient ahead of an area of high pressure building into the region will result in breezy conditions. Guidance has come into better agreement on wind gusts up to around 25 mph, and the current forecast winds may even need to be bumped up if these forecast trends continue over the next day or so.
Deep mixing will also allow for RH values in the afternoon dropping to 30-40%. While fuel availability may be somewhat influenced by how much rain falls tonight into Wednesday, the meteorological conditions look to potentially favor an elevated risk for fire spread Thursday afternoon across eastern NY and possibly western New England, although at levels likely below critical/red flag thresholds.

AVIATION /06Z TUESDAY THROUGH SATURDAY/
Through 06z Wednesday...VFR conditions expected to prevail through the 24 hour TAF period. SKC will occur through the rest of the night, with gradually increasing high/mid level clouds during the day. An approaching front will bring scattered -SHRA towards the end of the TAF period later this evening, so will mention PROB30 starting between 03z-05z. Winds will initially be variable less than 5 kt, becoming south-southwest around 5-10 kt by later this morning.

Outlook...

Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Low Operational Impact. Breezy. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: Low Operational Impact. Slight Chance of SHRA.
Saturday: Moderate Operational Impact. Chance of SHRA.
Saturday Night: Moderate Operational Impact. Chance of SHRA.
Sunday: Low Operational Impact. Slight Chance of SHRA.

CLIMATE
Record Low Temperatures for April 21:

Glens Fall, NY: 20 degrees set in 1925 Albany, NY: 20 degrees set in 1875 Poughkeepsie, NY: 26 degrees set in 2018

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