Sunrise 5:45 AM   Sunset 8:12 PM Moonrise 3:08 AM   Moonset 3:05 PM

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SLZ022 Saint Lawrence River From Cape Vincent To Saint Regis 344 Am Edt Sat May 4 2024
Today - East winds 5 to 10 knots. A chance of showers early. Tonight - East winds 5 to 10 knots becoming south. Showers likely late. Sunday - South winds 10 to 15 knots. Periods of rain. Sunday night - South winds 5 to 15 knots becoming southwest. Showers likely in the evening, then a chance of showers overnight. Monday - West winds 10 knots or less. A chance of showers during the day. Tuesday - North winds 10 knots or less becoming northeast. A chance of showers Tuesday night. Wednesday - Northeast winds 5 to 15 knots. Showers likely.

SLZ005
No data

FXUS61 KBUF 041839 AFDBUF

Area Forecast Discussion National Weather Service Buffalo NY 239 PM EDT Sat May 4 2024

SYNOPSIS
A weakening trough will produce a few spotty showers this afternoon, but most of the time will be rain free. A wave of low pressure will then move from the Ohio Valley this evening 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 weak trough will bring a small chance for showers this afternoon, with the best chances along a convergence boundary across the Niagara Frontier and Lower Genesee River Valley.
Later this afternoon, very limited instability could support a few showers in the Western Southern Tier. However, the vast majority of the day will be rain free, with afternoon highs averaging about 10 degrees above normal.

A well defined mid level shortwave will then move from the Ohio Valley this evening northeast across the eastern Great Lakes overnight, generally following the path left by the remnants of the trough that washes out over the area today. A 45+ knot southerly low level jet ahead of the trough will bring a period of enhanced convergence and low level moisture transport overnight. This will combine with forcing from the shortwave to produce a fairly widespread area of rain moving from southwest to northeast across the region. Low stratus may intersect some of the higher hills overnight through Sunday morning, resulting in patchy fog across higher terrain.

Sunday, the mid level trough and associated forcing and deep moisture will continue to move slowly northeast. Widespread rain early in the day will gradually taper off to scattered showers from west to east. The widespread rain should end in Western NY fairly early in the day, while it will continue most, if not all day east of Lake Ontario.

While the widespread rain will end across Western NY, an upstream cold front will move into the far western end of the state by late afternoon. This will combine with modest diurnal instability and lake breeze convergence zones to support a few more scattered showers in the afternoon and evening. Enough instability may develop to support a few thunderstorms as well across Western NY.

Storm total rainfall amounts should average around a half inch, but locally higher amounts of around an inch are possible east of Lake Ontario where the rain will last longer.

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 /19Z SATURDAY THROUGH THURSDAY/
VFR will prevail for the bulk of the area this afternoon, although there will be some lingering MVFR cigs across the Southern Tier. A wave of low pressure will move from the Ohio Valley this evening across the eastern Great Lakes tonight. This will bring a period of fairly widespread rain spreading from southwest to northeast across the area from late evening through the overnight. CIGS will deteriorate to widespread MVFR/IFR shortly after the rain begins. Any pockets of moderate rain will bring short term VSBY restrictions, and the low stratus may intersect some of the higher hilltops overnight through Sunday morning with some patchy fog/mountain obscuration across the high terrain.

Steady rain will taper off from west to east, with cigs also lifting some into the MVFR/VFR flight category during the afternoon. Some instability will develop in the afternoon, with widely scattered thunderstorms possible across Western NY.

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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