Marine Weather and Tide Forecast for Long Lake, NY

KEY MESSAGES
1. There is a slight risk (level 2 of 5) and marginal risk (level 1 of 5) for severe thunderstorms late this afternoon into this evening mainly for areas near and north of I-90. Damaging winds, large hail and frequent lightning are the primary hazards from any severe storms.

2. After a stretch of unseasonably warm temperatures through Saturday, temperatures trend below normal Sunday and Monday.
Impactful weather is unlikely through the middle of next week.

DISCUSSION
KEY MESSAGE 1...

While showers and thunderstorms tracked through eastern NY and western New England overnight, an amplifying shortwave trough in the Great Lakes will allow the quasi-stationary boundary that has been overhead the past few days to finally lift north of our region today. This will allow the warm sector to surge northward and lead to one final day of unseasonably warm temperatures. There is at least a 50% chance that areas near and south of I-90 will exceed 80 degrees this afternoon with at least a 75% chance for areas in the mid-Hudson Valley and lower elevations in Litchfield County to exceed 85 degrees. This is about 20 to 25 degrees above normal for mid- April. Our climate section shows record highs for April 16 with POU the only site that may near its daily record today. Otherwise, subsidence due to the building ridge centered well to our south will keep our region mainly dry through mid-afternoon. There is increasing consensus among the guidance that the shortwave trough approaching from the Great Lakes will result in height falls late this afternoon into this evening with its associated sfc low and attendant cold also tracking eastward. Forecast soundings show an elevated mixed layer tracking into areas mainly from I-90 northward today with the inversion eroding this afternoon in response to the approaching height falls. This combined with a very warm and moist boundary layer will generate sufficient surface based instability with guidance showing 1000 - 1500 J/kg developing. As we remain within the northern periphery of broad ridging aloft, fast flow aloft will also maintain impressive deep layer and effective shear ranging 40 to 50kt. The rather unidirectional shear through the column and fast flow will likely also lead to straight lined hodographs.

While most of the day will remain dry, both the NAM and RAP suggest that increasing height falls and decreasing showalter index values late this afternoon towards or shortly after 21 UTC will allow convection to initiate around a potential subtle pre-frontal trough draped near I-90. However, the HRRR maintains mainly dry conditions through 00 UTC so there remains uncertainty if convective initiation be late this afternoon or hold until this evening. Should convection start late this afternoon, weak forcing combined with shear vectors oriented slightly perpendicular to the weak boundary should support a storm cluster storm mode. Although overall instability values are not overly impressive, forecast soundings show the remnant EML and high equilibrium levels likely allows instability to extend deep through the column with DCAPE values rather high near or greater than 500 J/kg. While damaging winds is the primary hazard from any severe storms, the straight lined hodographs also indicate an environment supportive of sustained strong updrafts capable of large hail, frequent lightning, and splitting cells. As the main sfc cold front and stronger height falls arrive this evening, the storm mode should transition to a more linear structure with damaging winds becoming the primary hazard from any severe storms. This all matches well with the Slight Risk (level 2 to 5) and Marginal Risk (level 1 to 5) in SPC's Day 1 Convective Outlook focused near/north of I-90 where the stronger forcing aligns. The severe weather threat should diminish by 03 - 06 UTC as shortwave trough moves overhead and the instability finally diminishes.

KEY MESSAGE 2... Temperatures trend lower Friday and Saturday yet remain seasonably warm. A notable change to the weather pattern then ensues Saturday night into Sunday as a potent cold front marches eastward resulting in a period of widespread stratiform rain. With northwest winds in the wake of the front advecting much cooler air eastward on Sunday, temperatures will drop 20 to 25 degrees compared to the previous few days and remind us it is still only spring. In fact, rain showers may mix with snow in the higher elevations of the southern Adirondacks before ending on Sunday. Continued cold air advection Sunday night into Monday morning also looks to favor upslope snow showers in the Taconics, southern Greens, parts of the Berkshires, northern Catskills and western Adirondacks where there is a 20 to 30% chance for at least 1 inch of snow.
However, given the time of year and higher elevation location, travel impacts are unlikely.



AVIATION /06Z THURSDAY THROUGH MONDAY/
Bands of showers and thunderstorms is moving across the region.
Although most of the activity is now east of KGFL and KALB, the heaviest rainfall is currently impacting KPOU and KPSF. Over the next hour, IFR visibility within rain and thunder will impact KPSF and KPOU and some gusty winds up to 30 kts are possible as well. Behind this activity, flying conditions should generally be VFR through the rest of the overnight hours, with sct-bkn cigs around 4 kft and another layer around 10-15 kft as well.
Light winds are expected for the late night hours. For now, won't forecast any low clouds or fog, although cannot totally rule it out if breaks in the higher clouds were to occur, especially for locations that saw significant rainfall.

During the day on Thursday, flying conditions look VFR for most of the day. Sct-bkn cigs around 4-6 kft will be in place with west to southwest winds of 5 to 10 kts. As a storm system approaches, some scattered thunderstorms are possible during the evening, mainly between 22z and 02z. Within any thunderstorm, brief heavy rainfall may allow for IFR visibility and gusty winds over 30 kts are possible. This activity could impact KGFL, KPSF and KALB, so will include a PROB30 for these sites, but will not mention for KPOU, as activity looks north of there.
Winds will become lighter from a westerly direction for Thursday night.

Outlook...

Friday Night: No Operational Impact. NO SIG WX.
Saturday: Low Operational Impact. Breezy. NO SIG WX.
Saturday Night: High Operational Impact. Breezy. Likely SHRA.
Sunday: High Operational Impact. Breezy
Likely SHRA
RA.
Sunday Night: Low Operational Impact. Breezy
Slight Chance of SHRA
SHSN.
Monday: Low Operational Impact. Breezy. NO SIG WX.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.

CLIMATE
Record High Temperatures(Year Set):

Thursday April 16: Albany: 91(2012)
Glens Falls: 89(2002)
Poughkeepsie: 91(2012)

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