textproduct: Binghamton

WHAT HAS CHANGED

Minor adjustments were made to expected rainfall totals with the cold front moving through tonight along with the the light lake effect snow and flurries expected over Central NY into the weekend. Low temperatures tonight were also adjusted as the NBM looked to have the cold air behind the front rushing in too fast, especially across NE PA later tonight.

KEY MESSAGES

1) A cold front will move across the area tonight leading to scattered showers, a few embedded thunderstorms and some locally heavy rainfall. A much colder air mass then moves in behind the front.

2) Occasional lake effect snow showers and flurries will be possible to start the weekend. Otherwise, high pressure will keep conditions largely dry through Monday.

3) There will be multiple chances for showers through at least midweek next week which can lead to rises on area rivers and streams.

DISCUSSION

KEY MESSAGE 1...

After a dry early afternoon with temperatures well above average, building clouds and some showers developing over the next couple of hours will signal the start of changes moving into our area as a cold front approaches. As this frontal boundary pushes from north to south across the CWA, a period of steadier rainfall with a few embedded thunderstorms is expected, especially between 00Z and 08Z before tapering off to some lingering showers and ending from north to south by or shortly after 12Z Friday. Northerly flow will be advecting in much colder air as 850mb temperatures fall from 5C to 10C around 00Z, to 0C to -7C by 12Z Friday. As this colder air pushes in, any lingering showers can mix with or change over to light snow from the Twin Tiers north but little if any accumulation is expected. Gusty winds are also expected both ahead of and behind the frontal boundary with wind gusts of 25-35 mph initially out of the southwest before becoming north- northwesterly.

SPC continues to have most of the area outlooked for a general thunder risk, with a marginal risk for severe storms clipping Steuben and Bradford Counties. Looking at the mesoanalysis, there is currently little surface or elevated instability, about 300 to 500 J/kg of DCAPE, strong 0-6km bulk shear of 50 to 70 knots, strong low-level lapse rates of 8C to 8.5C/km but poor mid-level lapse rates. All of this together leaves the threat for stronger storms, let alone thunderstorms in general, little to be desired. Model guidance keeps the 0-6km bulk shear quite high, over 50 kts, through this evening, but instability is expected to stay lacking. The timing of this system does not favor taking advantage of what instability there is from the heating of the day.

In addition, WPC has the Southern Tier of NY on south under a marginal risk for excessive rainfall. Antecedent conditions remain wet from recent precipitation events, and a general 0.50" to 1.00" of rainfall is expect through early tomorrow morning. PWATs are expected to be between 1.00" and 1.25" and localized heavy rainfall could result in minor hydro issues, mainly in poor drainage areas and where ponding is common. Rivers and streams are low enough that stream flooding is not expected.

KEY MESSAGE 2...

Surface high pressure building in from the west is expected to lead to dry conditions for most areas through the weekend. However, northwesterly winds, continued falling 850mb temperatures (bottoming out between -15C and -17C Friday night into Saturday) and pockets of increased moisture quickly swinging through associated with a couple of weak upper-level shortwaves passing by to the north support occasional light lake effect snow showers and flurries over Central NY Friday night into Saturday. As the flow becomes more westerly Saturday night into early Sunday, snow showers are expected to become more concentrated over Oneida County, where some upslope enhancement can lead to minor accumulations. A wide range in high temperatures is expected Friday with low to mid 30s to the north to the low to mid 40s across NE PA. Saturday's highs will be even colder in the upper 20s and 30s. Overnight lows will be in the teens and 20s. The return of southwesterly flow Sunday will help bring in warmer air as the cold air mass retreats northward. More seasonal temperatures are then expected through the first half of next week.

KEY MESSAGE 3...

As high pressure slides to the east and a more zonal upper level flow develops, multiple disturbances will lead to the chance for showers early to mid next week, especially Tuesday and beyond. The the surface high becoming centered off the coast over the western Atlantic, plenty of moisture can be advected from the Gulf into any system moving across the eastern CONUS. With the rounds of showers moving into an already wet environment, we'll have to monitor area rivers and streams for rises, which are shown in some of the ensemble river forecasts. Temperatures are expected to trend warmer Monday through mid week through the 50s and into the 60s with some valley areas likely making a run at 70 degrees.

AVIATION /19Z THURSDAY THROUGH TUESDAY/

VFR conditions through the afternoon hours.

Rain and an associated cold front will move through the region this evening, starting around 21-22z. The surface is very dry, with dewpoint depressions in to 20-30 degree range, so the initial rain should not introduce any restrictions for at least an hour as the surface saturates. Restrictions will follow, with MVFR/Fuel Alt expected initially, falling to IFR at RME/ITH/BGM after 00z. Confidence in IFR at RME is medium as the NW flow should provide downsloping off the Tug Hill Plateau into the terminal, which would lift ceilings, but with moderate to periods of heavy rain expected from 00z-04z, IFR ceilings cannot be ruled out. ITH and BGM should see IFR ceilings settle in after 00z, and remain into the morning hours as an inversion sets up at the surface and keeps low clouds over the area.

SYR is showing signs for IFR ceilings but trends are pointing towards ceilings hovering above IFR through the period. Ceilings could drop to IFR briefly during heavy rain this evening, but confidence in it occurring is too low to include in the TAF at this time.

Guidance for ELM is showing IFR ceilings, but NW flow is also occurring during this period. When NW flow occurs at ELM, downsloping off high elevations NW of the terminal usually keeps ceilings in the 1200ft range, and this was reflected in the TAF.

AVP will be the last to see the rain and thus restrictions develop at the terminal. MVFR/Fuel Alt conditions should develop after 03z and last into the morning hours.

VFR conditions expected until the late afternoon, where a frontal system will bring rain into the region with associated restrictions. Ceilings and visibility will drop to MVFR/Fuel Alt with the rain, with increasing confidence that IFR conditions may occur towards the end of the period tomorrow evening.

Outlook:

Thursday night...A rainy cold front will drop northwest to southeast through the region with likely MVFR to IFR restrictions. Snow may mix in before precipitation ends late Thursday night.

Friday morning...Lingering ceiling restriction possible early, but improving conditions expected by midday.

Friday afternoon through Sunday...Mainly VFR conditions.

Monday...A low chance of rain showers and associated restrictions.

BGM WATCHES/WARNINGS/ADVISORIES

PA...None. NY...None.