Sunrise 6:09 AM   Sunset 7:55 PM Moonrise 3:48 PM   Moonset 4:00 AM

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SLZ022 Saint Lawrence River From Cape Vincent To Saint Regis 358 Pm Edt Fri Apr 19 2024
Tonight - Southwest winds 15 to 20 knots diminishing to 5 to 15 knots. Showers likely early. Saturday - Southwest winds 5 to 15 knots. Scattered showers in the afternoon. Saturday night - Southwest winds 5 to 15 knots. A chance of rain showers in the evening. Sunday - Southwest winds 5 to 15 knots increasing to 15 to 20 knots. Mostly Sunny. Sunday night - Southwest winds 15 to 20 knots becoming northwest 5 to 15 knots. Partly cloudy. Monday - Northwest winds 5 to 10 knots becoming south. Mainly clear, then becoming partly cloudy. Tuesday - South winds 10 to 15 knots. A chance of rain showers during the day, then rain showers Tuesday night. Wednesday - Southwest winds 10 to 15 knots becoming northwest. Rain showers during the day, then rain showers likely with a chance of snow showers Wednesday night.

SLZ005
No data

FXUS61 KBUF 200539 AFDBUF

Area Forecast Discussion National Weather Service Buffalo NY 139 AM EDT Sat Apr 20 2024

SYNOPSIS
A trough will pass over the eastern Great Lakes Saturday with scattered showers. A few of these showers may produce some small hail or graupel. Dry weather will return Sunday through much of Tuesday as high pressure builds east across the Ohio Valley and Mid Atlantic. Cool temperatures and gusty winds this weekend will give way to a warming trend early next week.

NEAR TERM /UNTIL 6 PM THIS EVENING/
Composite radar shows a broken line of weak echos stretching from northern New York to northern Ohio late tonight. This is mainly mid-level moisture as it has been hard to find any observed precip. This activity will move east and weaken overnight with partial clearing across western NY to the Saint Lawrence Valley by daybreak.

Saturday, a sharp mid level trough will move from the central Great Lakes in the morning to western New England by evening, with a strong vorticity maxima crossing the eastern Great Lakes in the afternoon. An associated cold front will cross the region in the afternoon. While forcing will be strong with this feature, it will be moisture starved.

Cold air aloft will contribute to strong low/mid level lapse rates with daytime heating and support diurnal showers from late morning through early evening. Expect a classic lake breeze boundary and stable lake shadow configuration to the showers Saturday. The most concentrated band of showers will likely be from the Niagara Frontier extending ESE into the western Finger Lakes where enhanced and channeled WSW flow off Lake Erie converges with WNW flow found just south of Lake Ontario. The cold air aloft and steep lapse rates suggest a few of these showers may contain graupel or small hail, even in the absence of thunder. Meanwhile, stable lake shadows over and east of Lake Erie and Lake Ontario will keep shower chances lower, and the amount of sunshine higher for areas east of the lakes.

Temperatures Saturday will run close to 10 degrees below average, with highs ranging from the upper 40s for lower elevations to the low to mid 40s across higher terrain. It will be quite breezy again as well, with gusts of 25-35 mph across the area.

SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/
Broad mid-level troughing across the lower Great Lakes and the Northeast Saturday night will allow a shortwave trough to round the base of the trough Sunday. The passage of the shortwave will pull the longwave trough northeast, allowing for mid-level ridging to spread across the Great Lakes.

Despite the deep cyclonic flow overhead, expansive high pressure centered over the Central Plains and expanding east across the Ohio Valley will support mainly dry weather throughout the weekend into the start of next week. However, with the passage of the shortwave and the longwave trough axis aloft, a couple of moisture starved cold fronts will push southwards across the region Saturday night and then Sunday night. While both of these fronts will be precipitation free, cold air will advect into the region supporting below normal temperatures Sunday and Monday. Highs Sunday and Monday will range in the 40s across the North Country and upper 40s to low 50s elsewhere.

LONG TERM /TUESDAY THROUGH FRIDAY/
Soggy weather will return to the forecast as we move further into the workweek, with a cooler airmass wrapping back into the region leading to a couple of days of temperatures running a few degrees below normal.

High pressure will shrink off the eastern seaboard Tuesday as a positively tilted shortwave pivots out south-central Canada and into the northern Plains/upper Midwest region. As this feature moves east into the Great Lakes region Tuesday night, it will partially phase with a deeper closed low wobbling about the vicinity of Hudson Bay.
This will cause the southern trough to dig southward and progressively become more negatively tilted as it marches east though Wednesday. Concurrent broad surface cyclogenesis will lead to an elongated area of low pressure that will extend from the Midwest all the way northeast across Quebec. Deep southerly flow out ahead of the system's main cold front will allow it to tap into a plume of GOMEX based moisture, with a subsequent wide swath of rain showers plowing through the region Tuesday night into Wednesday. Cooler air will filter into the region behind the system, though strong high pressure building across the Great Lakes should taper off the potential for wrap-around precipitation fairly quick. With the loss of sunlight and cooler air moving in, rain could briefly mix with wet snow across the Tug Hill Wednesday night before ending. Mainly dry weather and clearer skies are then expected Wednesday night through Friday.

Long range guidance can be fairly sensitive to these types of partial phasing setups, which can quickly lead to poor model consensus and large run-to-run jumps in projected solutions. In this case, the latest from the ECMWF/CMCNH are in decent agreement are less bullish on the amount of phasing between the northern and southern stream waves, in stark contrast to the operational GFS which has consistently been more aggressive in this regard. Have leaned on the former which show a slower arrival time of precip Tuesday afternoon and evening. Both operational models advertise areawide dry weather until rain showers move into WNY after sunset, though have stayed close to NBM and left Chc PoPs for Tue afternoon as there remains uncertainty in the exact timing at this range. Less phasing of the two systems also implies the deeper cold air staying confined to the north in Canada, with just seasonable cool advection in the wake of the system. Should this favored trend hold, the already tenuous potential for wet snow on the backside of the system will be minimized even more.

In regards to sfc temps...Tuesday should be on the mild side in the upper 50s and low 60s as the area sits within the warm sector of the incoming system. Wednesday through Thursday will then be much cooler with highs in the upper 40s to low 50s. Owed to good radiational cooling conditions, temps Wednesday night will be quite chilly, bottoming out in the upper 20s to low 30s. High pressure moving east of the region should then initiate a warming trend by late next week.

AVIATION /05Z SATURDAY THROUGH WEDNESDAY/
VFR conditions will prevail across western and north central NY overnight. A brief shower or sprinkle is possible east of the TAF sites through daybreak.

The boundary layer will become well mixed Saturday as an upper level trough moves overhead. Diurnally driven rain showers will form outside of the stable lake airmasses. A convergence zone will likely set-up inland and south of Lake Ontario where the medium confidence of scattered showers will be located, mainly from KIAG/KBUF to KROC and eastward. Small hail may mix in with some stronger showers around midday. Prevailing VFR conditions are expected however ceilings will be between 030-050 ft especially south of Lake Ontario. Showers will dissipate towards evening with dry conditions Saturday night.

Outlook...

Monday...Mainly VFR.
Tuesday...Mainly VFR. A chance of showers later in the afternoon.
Tuesday night and Wednesday...Areas of MVFR with showers.

MARINE
Another trough will cross the eastern Great Lakes Saturday, producing another round of solid westerly flow Small Craft Advisory conditions on Lake Erie and Lake Ontario. Winds will temporarily diminish again Saturday night, then increase again Sunday with another period of solid westerly flow Small Craft Advisory conditions on Lake Erie and Lake Ontario. Overall, a poor weekend for boating with chilly temperatures, strong winds, and high waves much of the time.

BUF WATCHES/WARNINGS/ADVISORIES
NY...None.
MARINE...Small Craft Advisory from 10 AM this morning to 8 PM EDT this evening for LEZ020.
Small Craft Advisory from 7 AM this morning to 11 PM EDT this evening for LEZ040-041.

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