Marine Weather and Tide Forecast for Oneonta, NY

NEAR TERM /THROUGH THURSDAY NIGHT/
935 PM Update...

Little change has been to the forecast overall through tomorrow night. Temperatures have been a little slow to drop off early this evening so blended in the latest obs and a bit of the HRRR to the next few hours. A round of spotty showers is still expected later tonight through tomorrow morning, generally through about 14Z, for CNY, especially around the Finger Lakes region. Taking a look at the latest forecast soundings, the chance for showers and thunderstorms remains isolated tomorrow afternoon and evening from south of the I-90 corridor to the Twin Tiers beginning around 19-20Z, but any thunderstorm that does manage to pop up could produce locally gusty winds and even some small hail.

313 PM update...
Main concerns/challenges in the near term are focused on the potential for rain showers late tonight across the northern lake plain of the Finger Lakes and then some redevelopment of scattered light showers and even a few weak thunderstorms from Steuben County, along the southern Finger Lakes into the northern Catskills Thursday afternoon. Severe weather is not expected. Temperatures will be some of the warmest so far this season.

A low amplitude upper level ridge axis at 500mb is moving east across the Northeast US this afternoon and working in conjunction with a narrow ribbon of dry air and a weak surface ridge to produce dry weather conditions and mostly sunny skies today. A more robust plume of moisture is currently situated farther to the west over the central Great Lakes and will combine with a passing weak upper s/w that will move across the western Great Lakes and northern NY later tonight.

The air mass this afternoon is currently being modified by weak warm air advection from the southwest and this pattern will slowly continue tonight and even more so Thursday during the day. Temperatures have climbed into the 60s for most of the forecast area with highs expected to top out in the lower 70s in the Chemung Valley and Wyoming Valley in the next couple hours.

Clear skies tonight will lead to some radiational cooling tonight and drop lows into the upper 30s to mid 40s. Cannot completely rule out patchy fog...with model forecast soundings indicating a very sharp and well-defined low level inversion...but confidence is not high enough to include in the official forecast at this time given the relatively lack of near-surface available moisture.

As mentioned above, a weak short wave is forecast to move quickly from western NY into northern NY late tonight and potentially trigger a few light rain showers during this time.
The forcing along this wave is quite weak and deep moisture is on the lower side as well. Any precipitation with this wave will be only a couple hundredths of an inch.

Temperatures are expected to rise quickly into the upper 60s and lower 70s before noon Thu and then into the mid to upper 70s, close to 80 by the mid afternoon time frame. With dew points in the upper 40s close to 50, boundary layer conditions will be on the dry end of the spectrum...which could limit the potential for rain to make it to the ground. A weak surface boundary and slightly stronger warm air advection in the mid levels from the SW could help develop a few isolated showers and weak thunderstorms along the southern tier of NY, into the Finger Lakes and northern Catskills. ML CAPE values are only expected to rise into the 200-300 J/kg range with a minimal amount of shear. Soundings are highlighting the large amounts of dry air in the mixed layer with an inverted v signature...and also rather dry air aloft too, so the main threat if any convection does get going will be for gusty downburst winds.

The boundary layer stabilizes Thursday evening as large scale suppression dominates ahead of the next low pressure system expected to move in later on Friday.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/
245 PM Update...

An area of low pressure moves through Southern Canada with a warm front lifting north through NY. Timing of the front is still a little uncertain but there is more ensemble members that have the warm front lifting through in the early to mid morning. With the timing ahead of much solar heating, the region should be mostly dry outside of the Finger Lakes region into northern CNY where some instability may develop.

Saturday night has a better chance for widespread precipitation as a 50 mb shortwave moves in with better accent. Warm and humid air advecting in at 850 will provide enough moisture for elevated instability so thunder has been added to the weather grids for overnight. The instability is not great, largely less than 300 in most forecast soundings, but deep enough to get some cloud ice and charge separation.

A strong cold front moves through Saturday with most of the precipitation ending by mid to late morning. 850 mb temperatures fall through the day, likely below 0C by the late afternoon. A tight pressure gradient and boundary layer winds will be strong enough overnight to keep overnight lows a little warmer, likely above freezing area wide.

LONG TERM /SUNDAY THROUGH WEDNESDAY/
245 PM Update...

Long term starts off chilly with the cold air mass aloft though already on Sunday, temperatures aloft begin to recover and with sun for much of the day, temperatures quickly moderate. Sunday night looks like it may be colder than Saturday night as there is a surface high building in with clear skies aloft.
Temperatures were lowered to the NBM 10th for now and may need to be lowered farther if dew points can mix low during the day Sunday. Ridging builds back in early next week with temperatures rising back above seasonal averages by Tuesday. Tuesday into Wednesday has some potential for severe thunderstorms as Ensembles all have a strong low passing through Southern Canada with the region in the warm sector and mean shear approaching 40 knots. Mid level lapse rates have trended steeper in global models (now >6C/km) and ensembles have trended upwards with mean CAPE (>400 J/kg).

AVIATION /02Z THURSDAY THROUGH MONDAY/
VFR conditions are expected to continue through the TAF period.
Some clouds will stream in late tonight with isolated showers through tomorrow morning for the NY Terminals, mainly around ITH, SYR and RME, but no restrictions are expected. A few pop up showers and perhaps a thunderstorm or two are possible tomorrow afternoon and evening, mainly after 19-20Z, but confidence was too low to include at any TAF site at this time. If any thunderstorm does develop, any restrictions would be brief.

Winds will be becoming light and variable tonight, shift more southerly tomorrow and eventually west-northwesterly late in the period.

Outlook...

Thursday night...Mainly VFR.

Friday through Saturday... Showers with possible restrictions.

Saturday night through Monday...Mostly quiet and dry with high pressure overhead.

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