textproduct: Binghamton

WHAT HAS CHANGED

Adjusted overnight lows lower tonight and tomorrow night with the surface high building in closer with better chances of winds calming after sunset.

KEY MESSAGES

1) A cold air mass moving in will linger through Tuesday, with a threat of widespread frost tonight, and potential freeze tomorrow night.

2) Another trough of low pressure moves in Wednesday into Thursday, keeping the cooler weather around, but with rain and clouds, temperatures will likely remain above freezing.

3) A pattern change late week into the weekend will allow for warmer air to return to the Northeast.

DISCUSSION

KEY MESSAGE 1...

A cold air mass is working its way into the region today, with 850 mb temperatures falling below freezing, to around 1C to 3C below 0. Water vapor imagery is also showing dry air aloft, with falling dew points this afternoon across western NY. As the clouds continue to clear the rest of this afternoon, that drier air will also mix down across CNY into the Twin Tiers. Southern NEPA may hold on to clouds long enough that there would not be enough solar heating to mix down the drier air. With the dew points mixing down below 32, and a surface high nudging in from the west helping the surface winds to diminish, efficient radiational cooling will result in lows near freezing for much of the area. Overnight lows were lowered from model guidance and frost advisories may need to be expanded depending on how quick the temperatures begin to fall this evening.

Tomorrow is similar to today, with a small chance at some afternoon rain showers with instability generated by the strong solar heating under the cold air aloft. Overnight lows will be colder tomorrow night than tonight as high pressure will be centered closer so radiational cooling will be more efficient. Freeze warnings may be needed for tomorrow night as the upper 20s are possible in portions of the Catskills into the Twin Tiers.

KEY MESSAGE 2...

Brief ridging builds in Tuesday into Wednesday with flow aloft becoming Southwesterly, bringing in warmer air ahead of another trough digging into the Great Lakes region. This trough will have more moisture to work with, and it does not have much cold air. With clouds and rain late Wednesday into Thursday, temperatures will remain below average for this time of the year but at least there is not going to be much of a threat for frost or freezes. Even though there will be better moisture with this trough, with PWATs between 0.5 and 0.8 inches, so rainfall amounts will be less than a half inch for most of the region.

KEY MESSAGE 3...

Once this trough is through late week, 500 mb heights slowly rise and 850 mb temperatures climb back towards 10C. Zonal flow sets up aloft with southerly flow from the gulf through the central US could mean the pattern will remain active with frequent chances of showers and thunderstorms. At least day time highs will be back near the 70s and lows in the upper 40s and 50s. Looking beyond this next weekend, there are hints that the pattern could completely flip from the current pattern with ensembles showing greater odds of Western US troughing and east coast ridging.

AVIATION /00Z MONDAY THROUGH FRIDAY/

VFR conditions are expected for much of tonight at all TAF sites. There is the potential for some shallow fog to form at ELM early tomorrow morning, generally after 06Z-08Z through 12Z, but confidence in this is low. NAM soundings show a moist, shallow low-level inversion along with light winds. However, this afternoon's sunshine combined with the northerly wind and drier air mass overhead would have allowed for much of the surface moisture to evaporate, making it more difficult for fog to form. Model guidance also shows the edge of some high clouds overnight getting close to ELM adding to the uncertainty.

Clouds are expected to increase tomorrow afternoon and early evening with isolated to scattered showers. Confidence on location and timing was too low to add to any one terminal at this time, but any showers are expected to be on the lighter side, so restrictions are not expected at this time. West to northwest winds increase for the afternoon with gusts of 15-20 knots.

Outlook:

Monday night through Tuesday evening...VFR, except shallow valley fog again possible towards dawn Tuesday at KELM.

Late Tuesday night through Thursday...Showers likely with associated restrictions as low pressure pivots into the region.

Thursday night and Friday: Slow lifting and clearing of restrictions toward VFR. Timing still somewhat uncertain.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Frost Advisory from midnight tonight to 8 AM EDT Monday for PAZ038-039. NY...Frost Advisory from midnight tonight to 8 AM EDT Monday for NYZ009-022>025-036-037-044>046-055>057.