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LEZ041 Expires:202312092215;;173937 Fzus51 Kbuf 091548 Nshbuf
nearshore marine forecast national weather service buffalo ny 1048 am est Sat dec 9 2023
for waters within five nautical miles of shore
waves are the significant wave height - the average of the highest 1/3 of the wave spectrum. Occasional wave height is the average of the highest 1/10 of the wave spectrum.
lez040-041-092215- buffalo to ripley along lake erie- 1048 am est Sat dec 9 2023
.small craft advisory in effect from Sunday morning through Sunday evening...
This afternoon..South winds 10 to 15 knots. Mostly cloudy. Waves 2 feet or less.
Tonight..South winds 10 to 15 knots becoming southwest. Rain. Waves 2 feet or less.
Sunday..Southwest winds 10 to 15 knots becoming west 15 to 20 knots. Rain likely in the morning, then a chance of rain in the afternoon. Waves 1 to 3 feet building to 3 to 6 feet. Waves occasionally around 7 feet.
Sunday night..West winds 15 to 20 knots becoming northwest. A chance of rain in the evening, then a chance of rain and snow overnight. Waves 3 to 5 feet subsiding to 2 to 4 feet. Waves occasionally around 6 feet.
Monday..Northwest winds 15 to 25 knots becoming southwest. Snow showers likely during the day, then a chance of snow showers Monday night. Waves 4 to 7 feet subsiding to 3 to 6 feet. Waves occasionally around 9 feet.
Tuesday..Southwest winds 15 to 25 knots becoming west. Partly cloudy, then becoming mostly cloudy. Waves 4 to 7 feet subsiding to 3 to 6 feet. Waves occasionally around 9 feet.
Wednesday..West winds 10 to 15 knots. Partly to mostly cloudy. Waves 2 to 4 feet.

LEZ005
No data

FXUS61 KCTP 100119 AFDCTP

Area Forecast Discussion National Weather Service State College PA 819 PM EST Sat Dec 9 2023

SYNOPSIS
A relatively mild and tranquil start to the weekend will precede a strong frontal system that will bring a soaking rainfall of 1 to 2 inches, accumulating/elevation dependent snow and 30-40 mph wind gusts Sunday into Monday. Seasonably colder air and snow showers downwind of Lake Erie will linger through Monday night; otherwise the weather pattern from next Tuesday through Friday will feature seasonal temperatures and high confidence in an extended period of dry weather/no precip.

NEAR TERM /THROUGH SUNDAY/
18Z visible satellite loop shows eroding stratus in the lower Susquehanna Valley being topped layered clouds associated with warm advection ahead of strong cold front moving into northwest OH. A couple of light rain showers/sprinkles well out ahead of the cold front have moved over the western and central Alleghenies this afternoon with only trace amounts reported at a few sites/observed locally.

A very mild night ahead for early December with considerable clouds and precip probs ramping up from west to east after midnight through early Sunday morning. There will be a weak instability axis accompanying a strong 40-50kt LLJ and 1" pwat plume across the CWA overnight which could result in some rumbles of thunder and enhanced rain rates. Will not mentioned thunderstorms explicitly in the fcst given very low risk, but wanted to at least call it here in the AFD. Low clouds and fog/drizzle/mist may redevelop early tonight across the interior central and eastern valleys, but will eventually be scoured out by an increasing southerly gradient flow.

Lows will range from the upper 30s in the east central ridge/valley areas to the upper 40s (+25F above climo) along the spine of the Alleghenies.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/
*Flood watch in effect for a portion of east-central PA from Sunday afternoon through Monday afternoon

There is good agreement in the aforementioned cold front moving across CPA on Sunday as the associated longwave mid/upper trough becomes negatively tilted and waves of low pressure ripple north along the boundary. This setup now appears to favor an anafrontal type precipitation regime, allowing cold air to change rain to snow across the forecast area Sunday night into early Monday morning.

Focus for heavy rain has shifted a bit to the east this cycle with max QPF coming down from around 3" to just over 2" storm total. Overall, QPF amounts have come down across the board with less than 1" now forecast over the NW mtns.

The heaviest rain (~2 inches) is still expected over the far eastern portion of the CWA (lower Susq to Sullivan County)
where isolated minor (urban/poor drainage and river) flooding is most likely. Flood watch remains in effect (see hydro section for more info).

Colder air will pour into the area behind the front Sunday night behind increasingly gusty NW flow. This will result in a rain to snow transition from west to east across the entire CWA between 00-12Z Monday. There is still some uncertainty in how this baroclinic zone translates to snowfall amounts as the colder air catches up to backside of the precip axis.

Marginal temps above 32F also reduces confidence to some extent especially from the central ridges to the the Susquehanna Valley - which is where the latest HRRR shows the greatest accumulation. The HRRR also shows the heaviest burst of moderate snow early Monday morning occurring over the central to eastern part of the CWA - but with temps still above the freezing mark in most areas. This should result in a reduction in snow accums and travel impacts especially concerning road wx conditions particularly at lower elevations.

Elevation will be a significant delineating factor for snow accums. Official expected forecast shows at least few inches (borderline advisory) the from the Laurel Highlands into the Endless mtns/western Poconos. The most consistent signal for advisory level snow has been over Sullivan County. It's possible some of the highest terrain over east-central PA picks up a couple inches with a large spread or gradient between ridgetop and valley. Snowfall amounts have trended lower over the NW mtns inkind with weaker ensemble QPF signal. These areas could pick up the best snow once the lake effect kicks into gear.

Peak wind gusts late Sunday night into Monday (especially later Monday morning and Monday afternoon as the colder air dramatically deepens and taps stronger winds aloft) are forecast in the 35 to 40 mph range (just under Wind Advisory Criteria).

Pattern eventually transitions full-send to seasonably cold NW flow with snow showers likely on Monday before fading into Monday night.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
SHSN diminish at the beginning of the long term as winds back to the SW and dry air establishes itself. High pressure will then provide an extended stretch of dry weather. There does look to be one shot of reinforcement to the cold air arriving Tues PM which could make some SHSN in the NW. So, while temps will moderate a few degs on Tuesday to maxes of 35-45F, we'll drop back 3-5F on Wed. Then, temps crawl back up into the 40s for Fri. The next significant chance for precip will be at the very end of the long term or even day 8 or 9 when many models begin to generate a coastal low in/near the Carolinas. At this point, it looks like mainly rain, with snow on the higher elevations.
Plenty of time to watch the potential development there.

AVIATION /01Z SUNDAY THROUGH THURSDAY/
For the first few hours of the TAF period (through 05z Sun), IFR conds will mostly be limited to the southeast, where low level moisture trapped beneath a stout inversion is giving way to patchy fog. Farther west, MVFR cigs will continue at BFD, then eventually push eastward towards JST and AOO between 06z and 09z. The lower clouds will be solidifying and expanding both from west to east and southeast to northwest during the predawn hours, with IFR/LIFR conditions becoming common by sunrise.

Low level wind shear will pick up between 00z (west) 06z Sunday (east) as SW flow at 2000 ft increases to approx 40 kts. LLWS conds will diminish by the afternoon on Sunday as the low level jet pushes east of the area.

Expect rain to become widespread over OH and slide into NWrn PA before 05z, nearing BFD. However, the forcing will be weak and precip will be moving into a more stable airmass, so much of the precip will be light and tend to break up through 08-09Z. After 09z, the favorable right entrance region of the jet streak will move into PA, promoting more widespread rain through the morning and early afternoon Sunday.

A cold front will arrive from the west around 11-12Z at BFD and shortly after at JST. By 18-19Z Sun, it should be passing thru MDT. However, a wave should be developing over VA/MD and could slow the front significantly as it tries to move into ern PA.
That could allow for more precip back in the cold air over central PA Sunday night, resulting in a changeover from rain to snow at most sites by 06Z Mon. Thus, it is worth preparing for a long (6-9hr) period of IFC in low clouds and SN Sunday night, esp at IPT, and SNRA for MDT and LNS (thanks to a milder start).

NW flow will start to supply dry air and help cut off any snow in the east Monday morning. It will also cause Lake effect and upslope SHSN over the Alleghenies (BFD) and Laurel Highlands (JST). Accumulations should be generally minor, but 1-3" are likely on the higher terrain. So, IFR and LIFR are a given (100%) for multi-hour periods at BFD and JST Sunday night and Monday.

Outlook...

Mon...SHSN and MVFR and ocnl IFR N/W. Gusty west wind (15-20 sustained with gusts 25-30KT).

Tue-Thu...Mainly dry with VFR conditions.

HYDROLOGY
With generally dry soil conditions and near to below average streamflows over east-central Pennsylvania, 1-2" rainfall will be largely beneficial in nature. However, with rainfall forecast to exceed 2 inches in some areas, there may be runoff impacts given cold season hydrologic conditions. The threat of flash flooding remains low given modest rainfall rates less than 1 inch per hour owing to lack of instability. Minor urban, poor drainage, and small stream flood impacts remain a possibility and would be the most likely scenario.

Forecast rainfall between 1 and 2 inches will likely cause within-bank rises of a few to several feet on rivers and streams across east central Pennsylvania. Response time will be quicker on small streams (Sunday night-Monday) and longer on larger main stem points (Monday-Tuesday). A few small streams may approach/exceed action or caution levels, such as Swatara Creek at Harper Tavern. A flood watch remains in effect, but no river flooding is forecast at this time.

CLIMATE
It has been 316 days since the last measurable snowfall (>=0.1") at Harrisburg. This ranks as the 3rd longest run on record.

1. 330 days ending 12/13/2020 2. 328 days ending 01/21/2007 3. 317 days ending 12/08/2023

CTP WATCHES/WARNINGS/ADVISORIES
Flood Watch from Sunday afternoon through Monday afternoon for PAZ042-051>053-057>059-065-066.

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