Marine Weather and Tide Forecast for Mount Morris, NY

KEY MESSAGES
1) Scattered showers possible this afternoon for areas east of Rochester.

2) The potential for scattered showers and thunderstorms increases Saturday night into Sunday. Shower chances then linger through Monday.

DISCUSSION
Key Message 1...Scattered showers possible this afternoon for areas east of Rochester.

Exiting upper level trough, will allow for one more shortwave trough to dive southeast across Ontario, Canada and into central New York this afternoon. As such, expect a few showers to develop across areas east of Rochester this afternoon, where said showers are already beginning to develop northwest of the Saint Lawrence River and southeast of the CWA border as of 1230 this afternoon. A few showers may develop into thunderstorms, however given the lack of greater instability this should prevent them from becoming severe.

Otherwise, surface high pressure centered over the central Great Lakes will support rather dry condition to persist across WNY through Saturday. Additionally, ample radiational cooling from clear skies under the high tonight will support valley fog across the Southern Tier, the Finger Lakes, the Black River and across areas southeast of Lake Ontario.

Key Message 2...The potential for scattered showers and thunderstorms increases Saturday night into Sunday. Shower chances then linger through Monday.

Upper level ridging currently across the Upper Great Lakes will work its way east this weekend, allowing for zonal flow and embedded shortwave troughs to pass across the eastern Great Lakes by late Saturday. Meanwhile at the surface, a warm front will work its way eastward across the Great Lakes reaching WNY Saturday night. Warm moist isentropic lift will support scattered showers to pass eastward across the area Saturday night into Sunday. In addition to the showers, some rumbles of thunder can't be ruled out as there will be enough elevated instability.

Additional shortwave troughs will pass overhead Sunday and Sunday night, supporting the cold front associated with the low supporting the aforementioned warm front to pass across the region. Along and ahead of the cold frontal passage, expect additional showers and thunderstorms. While conditions will be favorable for a few storms to become severe given moderate instability and moderate to strong deep-layer bulk shear, severe storm development will be contingent on a few factors, the biggest one being the degree of diurnal destabilization of the warm sector.

While a ridge will build back into the area Monday, temperatures aloft will cool to around 10C. This combined with the 24C lake waters along with lingering synoptic moisture may support a few lake effect rain showers to develop southeast of Lakes Erie and Ontario.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
VFR conditions across western NY terminals with FEW-SCT mid-level clouds around 4-8 kft developing this afternoon. KART will see scattered showers later this afternoon dropping south out of Ontario, otherwise most terminals will remain dry. Generally light flow and efficient radiation cooling tonight will allow for patchy fog development headed into early Saturday morning. KJHW is the most likely to see reduced visibility, but latest HRRR guidance does show ~40% chance of MVFR conditions at KROC and KART mainly from 7-11z.
Conditions will gradually improve with clearing skies through Saturday morning.

Outlook...

Saturday Night through Sunday Night...Periodic showers and thunderstorms with MVFR or worse conditions expected.

Monday...Isolated rain showers with MVFR possible.

Monday Night through Tuesday...Dry weather and mainly VFR expected.
However, valley fog possible Monday night through about daybreak.

Wednesday...Mainly VFR during the day with showers and storms returning in the evening.

MARINE
Overall, light winds over the lakes today with high pressure building across the lower Great Lakes region keeping waves 2 feet or less. Winds will transition from northerly to easterly during the overnight period headed into Saturday. As high pressure continues to slide eastward, pressure gradients will increase Saturday evening ahead of the next frontal passage with showers and storms into Sunday. Gusty winds and larger waves may be possible in the vicinity of storms. High pressure will build back into the region early next week that will calm winds and waves.

BUF WATCHES/WARNINGS/ADVISORIES
NY...None.
MARINE...None.