Marine Weather and Tide Forecast for Ithaca, NY

KEY MESSAGES
1) Labor Day continues the dry Fall-like pattern that developed over the weekend.

2) Warming is forecast Tuesday into Wednesday, ahead of a frontal system projected to pass through with showers late Wednesday into Thursday, perhaps with some embedded thunder.

3) Generally dry benign weather returns towards the end of this week.

DISCUSSION
KEY MESSAGE 1...

We round out the extended Labor Day weekend with a continuation of dry and cool Fall-like weather. Stacked low pressure which had been over New England, is drifting away through the Canadian Maritime Provinces, leaving high pressure to settle over our region today. Shallow patchy fog can be found in some valleys early this morning, thanks to radiational cooling offered by the clear sky. With even less moisture than the already quite dry atmosphere of the last couple days, just a few tufts of diurnal cumulus are anticipated today in otherwise full sunshine with highs of lower-mid 70s after starting off chilly in the mid 40s-lower 50s at dawn. A very weak wave embedded in northwest flow aloft will send scattered high thin clouds into the area tonight, yet still enough radiational cooling of the dry air to get temperatures into the upper 40s-mid 50s for lows.

KEY MESSAGE 2...

Temperatures will trend warmer Tuesday into Wednesday, as initial ridging is then followed by warm air advection well ahead of an approaching front which will bring eventual rain.
Highs top off in upper 70s-lower 80s by Wednesday, yet with dewpoints getting well into the 60s and thus a bit of mugginess by then.

In the big picture, low pressure is projected to track from the Northern Plains into Canada during midweek. A cold front will trail distantly from that low, moving through our region around Wednesday night into Thursday. The ridge begins to flatten later Wednesday, with a ribbon of higher precipitable water values pooling with the approaching front. Shortwaves may run out ahead of the surface front as well, so chances of showers will begin in Central NY Wednesday afternoon before spreading across the Twin Tiers and then Wyoming Valley- Poconos Wednesday night.
Models continue to differ for whether the front pauses its progress briefly late Wednesday night-early Thursday, before a better-defined upper wave finishes sending it through later Thursday. Thus while highest likelihood for rain is Wednesday night with the anticipated front, at least a chance of showers will continue Thursday for at least the Twin Tiers-I88 corridor and especially Wyoming Valley-Poconos- Catskills.

Timing of front, and limited nature of instability, still keeps stronger convection chances on the lower side though there could be some embedded thunder. However, the higher precipitable water environment could yield a pretty good batch of rain.
Current model ensembles show 50-75 percent odds of more than half an inch for the NY Thruway counties closer to forced ascent of jet support as the front settles through, and even nearly 50 percent probability of an inch toward the Tug Hill area. Finger Lakes-Twin Tiers southward may not get at much as farther north, but rain is still expected, with a few to several tenths of an inch a reasonable expectation during the Wednesday night through Thursday timeframe.

KEY MESSAGE 3...

Despite uncertainty for how long the frontal zone lingers into Thursday, there is solid confidence for dry high pressure to pay a visit to end the week. However, the generally zonal flow aloft will keep features moving along, so by Saturday we will already enter a warm air advection regime in the return flow behind the departing high.

AVIATION /12Z MONDAY THROUGH FRIDAY/
LIFR restrictions due to fog at ELM and ITH should clear out around 13-14z with VFR conditions through the evening hours.
Another night of fog with IFR-LIFR conditions is expected at these terminals with high pressure overhead.

High pressure overhead will allow for RME/SYR/AVP/BGM to be VFR through the TAF period.

Outlook...

Tuesday through Tuesday night...Mainly VFR; areas of low clouds and fog possible early each day.

Wednesday through Thursday...Potential cold front passage with wind shift and showers. Highest chance for showers later Wednesday through Thursday morning.

Friday...Mainly VFR with high pressure building into the region. Morning fog will be possible.

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