Marine Weather and Tide Forecast for Mayfield, NY

KEY MESSAGES
1) Below normal temperatures through tomorrow then there is a low to medium chance for weather conditions on Thursday that can favor enhanced fire spread.

DISCUSSION
KEY MESSAGE 1...Isolated to widely scattered convectively driven showers continue this afternoon tracking from northwest to southeast as our upper trough and associated cold pool tracks overhead. With 850-700hPa lapse rates steepening to 7.5C/km or greater, any taller showers can produce brief periods of graupel. Given temperatures in the 30s in the hill towns and higher terrain areas today, any steadier showers can lead to wet-bulb cooling and mix or briefly change to wet snow.
However, the brief nature of any snow showers plus the April sun angle will likely prevent any appreciable accumulations.

Snow showers diminish towards sunset with the loss of daytime heating and strong subsidence building into the Northeast from the Ohio Valley. Ridging and high pressure tonight will support clearing skies and near ideal radiational cooling resulting in chilly temperatures. As discussed in the previous discussion, we leaned on the cooler end of guidance for overnight lows tonight given probabilistic guidance showing greater than 75% chance for overnight lows throughout much of eastern NY and western New England falling below 30 degrees. Despite last week's warm up, the growing season does not officially begin until May 1 in the Hudson Valley so frost/freeze products will not be issued.
GFL and POU may tie or break their respective record lows for April 21 but Albany will likely be out of reach. See our climate section for details.

Tuesday starts off quite chilly with morning sun mixing with increasing afternoon clouds as moisture spills overtop the ridge axis. While dew points will turn quite low supporting RH values dropping to 25 to 30%, winds will be rather low with gusts under 20kts so not expecting an increased risk of fire spread. Southwesterly return flow will allow temperatures to warm into the 40s to low 50s but this is still 5 to 10 degrees below normal for late April. A warm front then approaches from the southwest heading into tomorrow night. This front looks to get hung up around the I-84 corridor if not slightly south as high pressure remains parked off the New England coast and a weak low moves along the boundary. Weak warm air advection in the low and mid-levels should support a period of showers overnight focused south of I-90 closer to stronger forcing and moisture. Latest NBM probabilistic guidance for greater than 0.01" of precipitation Tues night remains rather low at only 20 to 25% and confined to areas mainly south of I-90 suggesting that incoming precipitation will be quite light. With dew points still near or below freezing Tues night, the incoming light showers could allow the column to cool in response to wet- bulbing supporting a rain/snow or even wet snow in the eastern Catskills, Taconics, NW CT and Berkshires where southwest flow can upslope the terrain. Even still, the light amounts will likely mitigate any impacts.

Drier weather returns Thursday and Friday as an omega block develops upstream over the Great Lakes and dry, northwest flow persists. While temperatures finally trend warmer becoming more seasonably for spring, deep boundary layer mixing and a weak surface pressure gradient on Thursday should also support gusty winds and with RH values dropping under 40%. We will closely monitor winds and RH as weather conditions may favor enhanced fire spread.

AVIATION /18Z MONDAY THROUGH SATURDAY/
Through 18z Tuesday...VFR conditions are mainly expected to prevail through the TAF period except for possible brief MVFR conditions associated with scattered snow and rain showers in the wake of a cold front. HiRes guidance shows the best chance for -SHSNRA is at KGFL (until about 22z) and KPSF (until about 01z) with probabilities of 30-50% due to upsloping. These chances are shown in a PROB30. If showers occur, within the heaviest is where MVFR vis could occur.
Low level stratocumulus will gradually begin to dissipate this evening after sunset with all terminals clearing around 05z as high pressure builds in from the west. Winds this afternoon will be west/northwest around 8-14 kt with gusts of 20-25 kt. Winds will begin to taper off around sunset and become light and variable overnight before shifting south/southwest and picking back up with speeds 5-10 kt tomorrow morning.

Outlook...

Tuesday Night: Low Operational Impact
Slight Chance of SHRA
SHSN.
Wednesday: Low Operational Impact. Slight Chance of SHRA.
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.

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.