Marine Weather and Tide Forecast for Geneva, NY

NEAR TERM /THROUGH SUNDAY NIGHT/
700 PM Update...

Showers are progressing over the eastern portion of our area with decreasing instability as the sun sets. Made small adjustments to Pops tonight as showers linger over our northern counties. Made changes to temperatures and dew points using current observations to show the progression of the front. Also updated sky grids by blending current obs with the latest NBM.

430 PM Update...

A cold front has made its way through much of the Finger Lakes with the severe thunderstorm watch ended for the counties that are north of the front.

1245 PM Update...

After an initial round of thunderstorms this morning across CNY, the skies have largely cleared with plenty of sunshine.
Surface based CAPE has been rising through the morning, with much of the region over 1000 J/kg already with minimal capping.
Right now, looking at water vapor, there is a good amount of dry air aloft in the mid levels behind this mornings warm front as well as lower mid level lapse rates so that will limit updraft acceleration from 700 mb to 500 mb. So far morning showers have struggled to get much above 20,000 feet for echo tops. Visible satellite shows a surface trough that is propagating eastward through western NY and PA. This has started triggering storms and as the instability increases across our region, should be the focal point of stronger storms in the early afternoon. A cold front lags behind the surface trough back in OH that will likely bring a second round of storms later this evening.

Shear has been around 30 to 40 knots this morning and based off of forecast soundings and hodographs, should stay in that 30 to 40 knot range. Low level lapse rates will get to near 10C/km this afternoon as LCLs rise to around 1250 to 1500 meters. This will support more of a wind threat than other severe risk later today as dry air in the mid levels will help with the development of stronger downdrafts and the steep lapse rates will allow them to reach the surface with little impediment.
The lack of steep mid level lapse rates and high LCLs will be limiting for hail growth and tornado potential.

Tonight, a cold front moves through with good cold air advection for this late in the spring. 850 mb temperatures fall to near 0C with wrap around precipitation. Late tonight through tomorrow will consist of breezy NW winds with frequent rain showers for the Twin Tiers and northward.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
12 PM Update...

Very little change to the short term forecast. High pressure builds in with cool, but dry conditions over the region, with gusty NW winds during the day. Winds should decouple at night and with clear skies and an already cold air mass in place, temperatures will drop off quickly after sunset. Frost and possibly a freeze in some areas may occur. NBM forecast lows were lowered with a blend of the ADJMET guidance. MET guidance does have lows down to the upper 20s to low 30s, so have started to trend down the overnight lows with this update and will mention the chance for a frost/freeze in the HWO.

Tuesday will be dry with high pressure overhead and highs only in the upper 50s to low 60s.

315 AM Update

This period will feature mostly dry, but cooler than average weather across the region. There will be a slowly departing upper level low for Sunday night, some lingering slight chances for rain showers in the evening give way to partial clearing overnight. Northwest winds remain steady between 5 to 15 mph overnight, so this should help eliminate the potential for any fog or frost formation. Cool overnight lows in 40s expected areawide; except some localized upper 30s in the coldest high elevation valleys of the Catskills and northern Oneida county.

Monday features a cool north-northwest flow pattern over the area, with subtle upper level height rises and weak surface ridging present. This will lead to mostly sunny skies, and allow the area to finally dry out some. With 850mb temperatures hovering near 0C, daytime highs will be cooler than average, only in the 50s to lower 60s...except 65-70 for the Wyoming Valley. This is about 5 to 8 degrees below average for mid May. Northwest winds will also be quite breezy, sustained between 10-18 mph with gusts up to around 25 mph at times.

Monday night will be chilly under mostly clear skies and weak surface high pressure. Winds try to decouple in the sheltered valleys, but remain northwest 5 to 10 mph elsewhere. Did add in a mention of frost into the weather grids; again mostly for the colder, sheltered valleys of Steuben county...the Catskills, Susquehanna region of NY and northern Oneida county. The growing season has begun for our entire forecast area as of May 11th; so if confidence grows in frost formation, advisories will be issued where needed. Forecast lows range the mid-30s to around 40.

Central NY and Northeast PA will be between weather systems on Tuesday, with a cool and dry northerly flow continuing. Expect partly to mostly sunny skies, lighter winds and seasonably cool highs between about 55 to 65 over the forecast area. Tuesday night will have increasing clouds with a chance for rain developing late at night as the next low pressure system approaches from the Ohio Valley; not quite as cool as Monday night, with lows in the 40s for most locations expected.

LONG TERM /WEDNESDAY THROUGH SATURDAY/
12 PM Update...

No changes made from the previous forecast and stuck with NBM for days 4-7. A very cool and likely wet pattern will be in place from mid week into next weekend.

315 AM Update

Unsettled, cool and wet weather is expected through this long term period as a series of slow moving, nearly cut off upper level lows meander around the forecast area.

On Wednesday the 500/700mb low will be centered over lower Michigan as it develops and strengths through the day. Surface cyclogenesis will take place, with a primary surface low tracking across western NY and a new, secondary low developing over the DELMARVA. This will bring periods of rain to the entire forecast area, spreading slowly south to north through the day, along with overcast and very cool conditions. Temperatures are likely to be stuck in the 50s to perhaps around 60 all day with the thick cloud cover, cold temperatures aloft and periods of rain. Surface winds will be southeasterly at 8-15 mph. Rainfall amounts are forecast to be upwards of a half to three-quarters of an inch. By Wednesday night and Thursday the large, expansive upper level low remains stalled over the area with additional periods of rain expected (70-85% PoP). Thursday looks to be even cooler, as 850mb temperatures bottom out around +1C. Temperatures are likely to remain nearly steady in the mid-40s to mid-50s overnight and through the daytime hours.

The main upper level low passes directly overhead on Friday, as it continues to very slowly spin east. This will mean more clouds and numerous rain showers for Central NY and Northeast PA, with temperatures perhaps nudging up a few degrees into the mid-50s to low 60s...overall it still looks mainly cloudy and unsettled.
Rainfall amounts are not looking very high, with generally less than a half inch expected each day (after Wednesday). By Saturday, the upper level low looks likely to stall over northern New England and southern Quebec. More upper level energy and shortwave disturbances still rotate south into our area through the day. Scattered to numerous showers are still in the forecast, with mainly cloudy skies and continued cool temperatures in the upper 50s to mid-60s expected.
There could be some modest instability by Saturday, but for now left out any mention of thunder in the forecast. Rounding out next weekend, from this early vantage point it looks like there could be more dry time on Sunday (but still shower chances) and a gradual warming trend with highs back in the 60s to around 70 possible. Overall it is looking unsettled and cooler than average for most of the upcoming Memorial Day Weekend.

AVIATION /00Z SUNDAY THROUGH THURSDAY/
The thunderstorm threat has ended with rain moving out of the area by 7Z to 8Z. With a cold front through, low cigs and more precipitation moves in late tonight into tomorrow morning. IFR cigs are likely at all NY terminals but ELM and AVP stays south of the lower cigs. Showers will be persistent much of the day with MVFR to IFR vis with passing showers. Dry air begins to work back in late in the afternoon with slow improvements

Outlook...

Sunday afternoon...Scattered rain showers possible, especially at the Central NY terminals, which may result in occasional restrictions.

Sunday night through Tuesday...Mainly VFR expected.

Wednesday into Thursday...Restrictions likely with rain showers.

BGM WATCHES/WARNINGS/ADVISORIES
PA...None.
NY...None.