Marine Weather and Tide Forecast for Erie, PA

NEAR TERM /THROUGH TUESDAY/

6:21 AM EDT Update...

Forecast remains valid per latest trends in obs and model guidance. No changes appeared necessary.

Previous Discussion...

Aloft, a ridge exits toward the Canadian Maritimes through nightfall Tuesday evening as a shortwave trough shifts NE'ward from the Upper MS Valley to northern QC. Behind the shortwave trough, another ridge builds from the north-central United States through nightfall Tuesday evening. At the surface, the shortwave trough's attendant low moves NE'ward from the Upper MS Valley to northern QC and becomes vertically-stacked with the mid/upper-level low embedded in the shortwave trough overnight tonight through Tuesday. The low's surface warm front sweeps NE'ward through our CWA from about daybreak through this late afternoon, while the low's trailing and arcing surface cold front should sweep E'ward through our CWA from about midday through this late evening. Behind the cold front, a surface ridge builds from the Upper Midwest through Tuesday.

A Wind Advisory remains in effect until 12 PM EDT today for Erie County, PA. Here, a strengthening S'erly low-level jet (LLJ)
through daybreak this morning and mechanical mixing of the boundary layer tapping into the lower-reaches of the LLJ are expected to allow SE'erly to SSE'erly downslope surface winds to gust up to 40 to 50 mph along/near the Lake Erie shore, especially from roughly daybreak through late morning. In addition, diurnal convective mixing of the boundary layer tapping into stronger flow aloft is expected to allow S'erly to SSW'erly surface winds to gust up to 30 to 40 mph within the warm sector late this morning through early evening. Behind the cold front, low-level winds/CAA strengthening with height, respectively, and resulting steepening of low-level lapse rates should allow SW'erly to WSW'erly surface winds to gust up to 30 to 40 mph through this early evening and before the boundary layer begins to stabilize via nocturnal cooling.

Intervals of sunshine/daytime heating and low-level WAA are expected to allow today's daytime highs to reach the mid 60's to mid 70's within the warm sector. Behind the cold front, stabilizing subsidence accompanying the building surface ridge will result in considerable clearing. Thus, the combination of nocturnal cooling and low-level CAA will allow overnight lows to reach the 40's around daybreak Tuesday. Despite mainly clear sky on Tuesday, weakening CAA downstream of the ridge axis at the surface and aloft will limit daytime heating. Late afternoon highs are expected to reach mainly the 60's. However, a weak synoptic MSLP gradient and sufficient daytime heating of surface air over land surrounding ~48F Lake Erie are expected to permit lake breeze development during the late morning through early evening. Therefore, highs in the lower 50's to lower 60's are expected along/very near the lakeshore.

As for the remainder of sensible weather, isolated to scattered showers and thunderstorms are expected to increase in coverage the rest of this morning as the aforementioned strengthening LLJ enhances moist isentropic ascent along the upper-reaches of the warm front and the ascent releases weak to moderate and solely elevated CAPE. As the warm/moist sector boundary layer destabilizes via daytime heating later today, the initially elevated effective inflow layer will become surface-based and boundary layer CAPE is expected to grow to weak to moderate magnitudes. Additional organized showers/thunderstorms are expected along and ahead of the E'ward-advancing cold front late this morning through evening as low-level convergence and moist ascent along the cold front, and downshear outflow boundaries interacting favorably with ambient low-level vertical wind shear release the aforementioned warm/moist sector boundary layer CAPE amidst continued moderate to strong effective bulk shear. A low-level return flow of abundant moisture from the Gulf will be accompanied by unusually-high PWAT's in/near our CWA, which will likely allow showers/storms to produce periods of heavy rainfall. However, flooding concerns are minimal since SW'erly mean mid-level flow as strong as 40 to 60 knots will result in fast shower/storm motions, which in turn will limit the duration of heavy rainfall.

SPC has outlined a marginal risk of severe thunderstorms (risk level 1 out of 5) in our CWA from roughly Knox County, OH to Crawford County, PA and points to the southeast. In this area, greater daytime heating/resulting destabilization of the warm/moist sector boundary layer should yield steeper low-level lapse rates and DCAPE values as large as 500 to 750 J/kg amidst the moderate to strong effective bulk shear. As a result, multicell and supercell thunderstorms capable of producing damaging straight-line convective wind gusts are possible. The severe hail threat appears to be minimal due to the continued presence of weak mid-level lapse rates and MUCAPE in the hail growth zone, respectively. Tornado potential also appears to be minimal since model soundings suggest diurnal convective mixing of the warm/moist sector boundary layer will limit directional vertical shear within said layer and thus greatly limit the magnitude of surface-based ESRH. Once the cold front clears a given location, showers and storms should end quickly and fair weather is then expected through nightfall Tuesday evening as stabilizing subsidence accompanies the aforementioned post-front ridge.

SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/
The short term forecast period continues to look rather uneventful, as most of the active weather will be around the forecast area but not over it. For Tuesday night, high pressure will be over the area and departing to the east. A warm front will enter the area on the back side of the surface high for Wednesday. The best moisture and upper level support continue to be west of the forecast area and will retain a dry forecast with the warm frontal passage. High pressure will build back southwest toward the forecast area on Wednesday night and will keep the area dry. High temperatures on Wednesday will be a mix of 60s and 70s. The next system will approach from the west on Thursday. Southerly flow ahead of this system will continue to pump warmer air into the region and widespread 70s with some potential for lower 80s will be expected.
However, additional moisture will enter the region and some isentropic lift could allow for some scattered rain showers to enter later in the day on Thursday and have PoPs creeping up to a low chance.

LONG TERM /FRIDAY THROUGH SUNDAY/
Unsettled weather continues to be expected for Friday into Saturday, although the trend is slightly later, as the low pressure system and cold front are a bit slower. Therefore, have PoPs ramping up through Friday with the best window for rain on Friday evening and have categorical PoPs then. The front should clear the forecast area by Saturday afternoon and have some residual low PoPs through that time. High pressure will be quick to build in from the west for Saturday night into Sunday and dry weather will be expected. If the slowing trend in the late week system continues, then high temperatures on Friday will be in the 70s. Temperatures would then fall into the 60s behind the cold front for Saturday and Sunday.

AVIATION /12Z Monday THROUGH Friday/
Aloft, SW'erly flow over our region becomes W'erly after 00Z/Tues as one ridge exits toward New England, a disturbance shifts NE'ward from the Upper Midwest to near James Bay through 12Z/Tues, and a ridge behind the disturbance shifts from the northern Great Plains toward the Upper Midwest through 12Z/Tues.
At the surface, the disturbance's attendant low moves NE'ward from WI toward the ON/QC border, just south of James Bay. This low track will allow a warm front to sweep NE'ward through our region through ~19Z/Mon, while an arcing cold front should sweep E'ward through our region between ~16Z/Mon and ~02Z/Tues.
Behind the cold front, a surface ridge builds from the Upper Midwest through 06Z/Tues.

Ahead of the warm front, SE'erly surface winds around 10 to 15 knots are expected and may gust up to 20 to 25 knots at times.
However, along/near the Lake Erie shore in far-NE OH and NW PA, including KERI, SE'erly winds are expected to be as strong as 15 to 25 knots and gust up to 30 to 40 knots at times through ~16Z/Mon. Behind the warm front, our regional surface winds will be S'erly to SW'erly around 15 to 20 knots and gust up to 25 to 35 knots at times. Behind the cold front, SW'erly to W'erly winds around 10 to 20 knots, gusting up to 20 to 30 knots, are expected through ~00Z/Tues. Thereafter, the post-front SW'erly to W'erly winds are expected to ease to around 10 to 15 knots with occasional gusts up to 20 knots through 12Z/Tues.

Widespread low/mid/upper-level cloud cover is expected over our region ahead of the cold front. Ceilings associated with this cloud cover should tend to be no lower than 5kft AGL. Behind the cold front, low-level clouds and resulting ceilings near 5kft AGL are expected to scatter-out from west to east this evening.
Scattered showers/thunderstorms are expected ahead of the surface warm front and along/ahead of the surface cold front.
Brief MVFR/IFR are expected with showers and especially storms.
Erratic/brief surface wind gusts up to 40 to 50 knots are possible with thunderstorms behind the warm front and along/ahead of the cold front. Fair weather returns behind the cold front as the aforementioned ridge builds from the Upper Midwest.

Outlook...Non-VFR possible with scattered rain showers and thunderstorms this Thursday afternoon through Friday.

MARINE
A complex marine weather day expected today and tonight with low pressure moving through the heart of the Great Lakes and a cold front extending across Lake Erie. Ahead of the system, strong offshore flow is expected to develop. Southeast flow over the eastern basin will develop with downslope off the higher terrain of NW PA/W NY and sustained 20 kts or so of wind with gusts of 30 to 35 kts will be expected this morning and will issue a Small Craft Advisory for this region. Further west, southwest flow will increase later this morning through the afternoon and evening hours with sustained winds in the 20 to 25 kt range in offshore flow. This will expand eastward with time and will issue a separate set of Small Craft Advisory headlines for this offshore flow. The cold front will cross the lake by this evening and winds will shift to the west and slowly decrease. Waves will build up for the eastern half of the lake tonight into Tuesday and a new Small Craft Advisory will be needed for the eastern basin. High pressure will build into the region for Tuesday and flow will become variable at 10 knots or less. This high will move east for Wednesday, allowing a warm front to approach the lake and easterly flow will return. This front will struggle to cross the lake until Friday, when a low pressure system will move through the Great Lakes region. South to southeast flow will overtake the lake for Friday.

CLE WATCHES/WARNINGS/ADVISORIES
OH...None.
PA...Wind Advisory until noon EDT today for PAZ001-002.
MARINE...Small Craft Advisory from 10 AM this morning to 10 PM EDT this evening for LEZ142-143.
Small Craft Advisory from 10 AM this morning to 4 AM EDT Tuesday for LEZ144-145.
Small Craft Advisory from 2 PM this afternoon to 10 AM EDT Tuesday for LEZ146-147.
Small Craft Advisory until noon EDT today for LEZ148-149.