Sunrise 5:48 AM   Sunset 8:12 PM Moonrise 3:09 AM   Moonset 3:06 PM

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SLZ022 Saint Lawrence River From Cape Vincent To Saint Regis 1033 Pm Edt Sat May 4 2024
Overnight - South winds 5 to 15 knots. A chance of showers after midnight. Showers likely late. Sunday - South winds 10 to 15 knots. Periods of rain through early afternoon, then showers likely late. Sunday night - South winds 5 to 10 knots becoming light and variable. Showers likely in the evening, then a chance of showers overnight. Monday - Northwest winds 10 knots or less becoming west. A chance of showers in the morning. Monday night - Southwest winds 5 to 10 knots becoming light and variable. Becoming mainly clear. Tuesday - Light and variable winds becoming east 5 to 10 knots. A chance of showers Tuesday night. Wednesday - Northeast winds 10 knots or less. Showers likely. Thursday - Northeast winds 5 to 10 knots becoming southeast. Showers likely.

SLZ005
No data

FXUS61 KBUF 050238 AFDBUF

Area Forecast Discussion National Weather Service Buffalo NY 1038 PM EDT Sat May 4 2024

SYNOPSIS
A wave of low pressure will move from the Ohio Valley across the eastern Great Lakes overnight through Sunday, bringing a round of widespread rain to the region. The rain will gradually taper off to scattered showers from west to east Sunday, before ending entirely Sunday night. High pressure will then build into the Great Lakes Monday with a return to dry weather.

NEAR TERM /THROUGH SUNDAY/
A dreary night on tap as a sharp mid-level shortwave trough slides out of the Ohio Valley overnight and across the eastern Great Lakes through Sunday morning. Deepening moisture and broad scale ascent along the system's strengthening LLJ will cause rain to overspread the forecast area from south to north.
Regional radar and surface obs late this evening indicate the leading edge of this precipitation shield is currently advancing through the Southern Tier towards the Niagara Frontier and Finger Lakes region. While a few widely scattered showers associated with a weaker shortwave linger east of Lake Ontario, the more widespread rain will eventually move into the region in the second half of the night. As it does so, the LLJ will begin to approach its peak expected strength at around 45kts, which will likely cause precip across portions of the North Country to be locally heavier compared to surrounding areas. Otherwise, lowering cloud bases may intersect the higher terrain across the Southern Tier and North Country, leading to patchy fog through Sunday morning.

Owed to a stiff southeasterly surface wind, temperatures tonight will average warmer than normal with mainly upper 40s to low 50s for lows. Across far western NY and along the Lake Erie shoreline, temperatures will be a bit warmer, likely only dipping into the mid/upper 50s.

The system's 850H jet will begin to wane in strength and slowly slide east into central NY Sunday morning. Rain coverage will taper off across the western zones in tandem though remain persistent east of Lake Ontario for most of the day. By Sunday afternoon however, an upstream cold front currently over the central Great Lakes will begin approach western NY. The additional forcing combined with waning diurnal instability should cause an additional round of showers to arrive across from the far western counties by mid to late afternoon. While poor diurnal timing, weak deep-layer shear and a wealth of cloud cover will preclude stronger or more widespread thunderstorm development, 300-500J of SBCAPE building ahead of the front could still allow for a few rumbles of thunder and/or locally heavy downpours.

Rainfall totals overnight through early Sunday afternoon are expected to be greatest east of Rochester and across the North Country, generally averaging 0.5-1" in these areas, potentially exceeding an inch across far eastern Oswego and southern Lewis counties. Rainfall amounts under half an inch elsewhere are expected to the west.

In regards to temperatures...A large spread in daytime highs is expected Sunday, owed to the expected steady rains across the eastern zones during the day. Temperatures will top out mainly in the mid to upper 60s across far western NY and the Niagara Frontier east to Rochester. Across the interior Southern Tier, eastern Finger Lakes, and North Country, a range of 50s is expected.

SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/
A mid level trough will slide across Hudson Bay and into northern Quebec Sunday night...with its associated modest surface low pivoting a weak trailing cold front across our area.
This boundary will generate some additional scattered showers and possibly an isolated thunderstorm or two as it passes through our region. The greatest pcpn potential will be found across the North Country... which will lie in closest proximity to the base of the supporting upper level trough and where the showers may become briefly more numerous during the late evening and early overnight hours. Otherwise expect fairly cloudy skies Sunday evening to give way to some limited clearing across far western New York overnight...with lows ranging from the upper 40s to lower 50s in most places.

By Monday morning the cold front will be making its way across eastern New York. While a leftover spotty shower or two cannot be ruled out across our far eastern zones early in the day...in general the day should feature dry weather along with increasing amounts of sunshine from northwest to southeast as high pressure and drier air over the central Great Lakes ridges eastward into our region. With 850 mb temps ranging from +6C north to +10 south...highs will largely be in the upper 60s to lower 70s...though readings will be cooler along the lakeshores due to onshore flow.

Monday night the axis of the surface ridge will slide directly overhead...promoting dry and tranquil weather along with excellent conditions for radiational cooling. This will allow lows to dip into the 40s areawide...with a few readings in the upper 30s not out of the question across the North Country.

On Tuesday the surface ridge axis will slowly drift east across New England...while the leading edge of a sprawling mid level trough and associated surface low over the north-central states slowly works its way into the Upper Mississippi Valley
As this does so
a warm frontal boundary snaking southeastward from this system will slowly push northeast across the Ohio Valley. While this latter feature could draw close enough to support the potential for a couple widely scattered showers across the Southern Tier later on in the afternoon...the day should otherwise feature continued dry weather with just a modest increase in cloud cover across far western New York. With our airmass starting to warm again highs should generally range through the 70s...though it will again be a bit cooler along the lakeshores due to onshore flow.

Tuesday night the various guidance packages suggest that the warm frontal boundary will lift further northeastward and into our region while also becoming increasingly wavy as a supporting mid-level shortwave ripples eastward across the central/eastern Great Lakes.
This will bring a general southwest-northeast increase in cloud cover and eventually the likelihood of some showers as the night progresses...with a few thunderstorms also becoming possible due to the arrival of some weak elevated instability. Otherwise it will be a notably milder night with lows ranging from around 50 across the North Country to the mid and upper 50s south of the NYS Thruway.

LONG TERM /WEDNESDAY THROUGH SATURDAY/
A wet pattern for the long term period with at least a chance of showers for the entire forecast area each day. A mid/upper level low over the northern Rockies will slowly track east, opening to a large scale trough through the second half of the week.

Earlier in the week with the trough/mid-level low to the west, periods of weak ridging over the region will give way to developing sfc lows and shortwave troughs that will bring an influx of GOMEX moisture north into the region. Moisture and large scale synoptic lift will provide for periods of showers with some breaks in the precip.

The larger trough will setup over the region by Friday, and persist through at least the weekend. This will provide for several rounds of showers, especially as different shortwave troughs track through/around the larger trough. Cyclonic flow and the trough in general over the region will also result in cooler temperatures.

Embedded thunderstorms will be possible at times, especially during the middle of the week when instability will be a bit better than later in the week.

Temperatures will start out well above normal with highs in the mid 60s to near 80 from the higher terrain east of Lake Ontario to the lower elevations of WNY respectively. Day-to-day cooling is then expected through the rest of the period as the trough moves into the region. Below normal high temperatures are expected for Saturday with temperatures only reaching the low 50s to near 60 for the afternoon.

AVIATION /03Z SUNDAY THROUGH THURSDAY/
Flight conditions across the forecast area will slowly deteriorate from mainly VFR to a mix of MVFR and IFR tonight as a low pressure system tracks out of the Ohio Valley and across the eastern Great Lakes. This system will bring a large shield of rain through the region from southwest to northeast, with locally heavier embedded showers. While the precipitation and increasing saturation of the boundary layer will cause CIGS and VSBYS to decrease, a stiff southeasterly breeze off the higher terrain areas should prevent IFR conditions from developing at the TAF sites with the exception of KJHW. Meanwhile, IFR CIGS are expected to develop across the higher terrain areas of the Southern Tier and east of Lake Ontario. Patchy fog with IFR VSBYS is possible where the lower CIGS intersect the hilltops.

The widespread rain will taper off across much of western NY Sunday morning while remaining steady east of Lake Ontario for much of the day. CIGS are expected to remain in primarily MVFR range through the day as precipitation coverage becomes sparser, while IFR conditions linger across the higher terrain areas. An approaching cold front will then likely cause additional showers and possibly a few thunderstorms to redevelop later in the afternoon in the vicinity of the far western terminals (KIAG/KJHW/KBUF), which may cause brief IFR conditions.

Outlook...

Sunday night...VFR/MVFR. A chance of showers, mainly early.

Monday and Tuesday...VFR.

Wednesday...VFR/MVFR. Chance of showers with a chance of thunderstorms.

Thursday...VFR/MVFR. Showers likely with a chance of thunderstorms.

MARINE
Moderate southeast winds through Sunday morning will produce choppy conditions on the lakes, mainly in the offshore and Canadian waters given the largely offshore wind component. Winds will then become southwest and decrease from west to east Sunday as a weak trough moves across the eastern Great Lakes.

Generally light winds are then expected Monday through Tuesday with a weak pressure gradient in place across the eastern Great Lakes.

BUF WATCHES/WARNINGS/ADVISORIES
NY...None.
MARINE...None.

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