Marine Weather and Tide Forecast for Risingsun, OH

NEAR TERM /THROUGH SATURDAY NIGHT/
9:30 PM Update...

The forecast remains on track for the overnight. The steadiest rain is gradually moving eastward, so tweaked the timing of the back edge of the higher PoPs. Most areas will see a break in the 04-6Z timeframe before some additional showers drop into the region in the 08-15Z timeframe as the cold front and associated mid/upper trough axis slide overhead.

6:30 PM Update...

Convection has reached peak intensity and organization and will gradually subside with sunset as the atmosphere becomes increasingly worked over from widespread precip. Expanded categorical PoPs eastward faster this evening based on radar trends. The biggest impact over the next 2 hours or so will be locally torrential rainfall rates since these are relatively low topped cells with low LCL heights, PWATS over 1.2 inches, deep warm cloud layers for April, and some repeated development/training. Will continue to monitor for localized flooding. A small area of enhanced shear in NE Ohio characterized by effective bulk shear values of 30-35 knots and 0-1 Km SRH of up to 150 J/Kg has led to a couple of rotating cells, but luckily the relatively higher LCL heights in that area has kept that under control. This will also be monitored, but again, expect convection to begin to diminish with sunset.

Original Discussion...

Active weather late this afternoon and this evening. Showers and storms are pushing in from the west/southwest and also developing and increasing in coverage across the local area ahead of an approaching shortwave and cold front. Activity will be peaking in coverage and intensity through 8 or 9 PM. There is just enough instability and shear that we've noted a few weakly rotating updrafts on radar...still not expecting a notable severe weather threat this evening, though given the weak rotation noted to this point, will need to make sure a cell or two doesn't rotate/intensify a bit more than we've observed so far. Gusty winds and small hail would be the main threat, with any tornado threat pretty unlikely and of the brief/weak variety if something were to happen. The fairly widespread coverage of storms should cause instability to start waining by 6 or 7 PM, so any very marginal severe threat should begin decreasing at that time. Storms are slow-moving, with some back-building noted across Northwest OH. The environment supports efficient rain rates, with radar estimating up to 2.50" of rain thus far in parts of Seneca/Wyandot Counties. While we aren't expecting widespread flooding, will need to continue to monitor for training/back-building convection, which could cause localized 2-3" totals in a short time and pose an isolated flash flood risk if it occurs over an urban or otherwise prone area.

The cold front sweeps through late this evening from west to east, with a secondary trough pushing southeast overnight tonight. The bulk of the convection this afternoon/evening is pre-frontal, with a secondary line of showers possibly accompanying the front. There will likely be some drizzle or showers with the secondary trough, especially downwind of Lake Erie, with this activity lingering into Saturday morning in Northeast OH and Northwest PA. Otherwise, we'll all be cloudy or mostly cloudy to start Saturday, with gradual clearing from the west Saturday afternoon into Saturday night. It will likely take until some point Saturday night for clouds southeast of Lake Erie to clear out.

Lows tonight will dip into the mid 40s to lower 50s. Not much temperature rise on Saturday, with highs ranging from the upper 40s/lower 50s in Northeast OH and Northwest PA to near 60 along the I-75 corridor. Lows Saturday night will mainly dip into the 30s (with a few 40s along the Lake Erie shoreline)...conditions are somewhat favorable for radiational cooling Saturday night with clearing skies and high pressure building in. However, winds may take most of the night to decouple. There will likely be some frost in low-lying areas away from Lake Erie, particularly in parts of North Central and Northeast OH, though a combination of the lingering wind and some question of how quickly clouds downwind of the lake clear does lead to some question of where/how widespread any frost is at this point.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
This short term period will favor quiet weather with high pressure in control. A Canadian high pressure system will track across the eastern Great Lakes region Sunday and continue onward towards the Mid-Atlantic Region on Monday. High temperatures on Sunday will range from the upper 50s to middle 60s with mostly sunny skies.
Temperatures will again be fairly cool Sunday night with overnight lows in the upper 30s over far NEOH and NWPA to the mid 40s over NWOH. There could be some patchy frost in the colder spots of NEOH and NWPA Sunday night. A light southerly flow on the backside of the high pressure will return on Monday. High temperatures Monday will be warmer in the lower to middle 70s. There may be a lake breeze Monday that tries to move off the lakeshore during the afternoon.

LONG TERM /TUESDAY THROUGH FRIDAY/
The main concern for next week will the severe weather potential on Tuesday. A rather strong shortwave trough will track across the Great Lakes region Tuesday. At the surface, a cold front will slide southeastward into the lower Great Lakes and Upper Ohio Valley Tuesday afternoon and evening. High temperatures will be in the upper 70s and lower 80s due to strong warm, moist air advection.
Thermodynamics will favor for the development of strong to severe thunderstorms. Moderate to strong instablilty will develop with MLCAPE values 1500 to 2000 J/kg. Lapse rates will exceed 7 C/km over the region. Surface dewpoints will climb into the mid 60s.
Sufficient shear will support multiple storm clusters and perhaps a couple supercells.

The front will move through the region Tuesday night and high pressure will build over the Great Lakes region on Wednesday.
Temperatures will be cooler Wednesday with highs in the upper 50s to middle 60s. Another shortwave trough will track across the Midwest into the Ohio Valley Thursday. A warm front will lift back northward across the region late Thursday with showers and storms.

AVIATION /00Z Saturday THROUGH Wednesday/
Widespread showers will continue the rest of the evening, with mainly VFR cigs but MVFR or lower visibility at times where locally heavier rain occurs. Some embedded thunder will continue another hour or so around KCAK and KYNG, but the threat for thunderstorms is rapidly decreasing. Expect the bulk of the rain to end from west to east in the 04-06Z timeframe, but then the focus will shift to low cigs overnight into Saturday morning due to lingering low-level moisture and the axis of the mid/upper trough rotating overhead. Brought in solid MVFR conditions overnight, with IFR to LIFR looking increasingly likely at KMFD, KCLE, KCAK, KYNG, and KERI. Additional light showers are also expected in the 08-16Z timeframe with the trough axis and cold front. Cigs will gradually improve Saturday afternoon, but NE Ohio and NW PA are likely to stay MVFR through the end of the TAF cycle.

Winds will turn more westerly late this evening and early tonight then northwesterly late tonight as the cold front crosses the region. NW winds will increase to 15-20 knots Saturday, with gusts of 20-25 knots at times.

Outlook...Non-VFR clouds will gradually improve by Saturday night. Non-VFR possible in showers and thunderstorms Tuesday.

MARINE
A weak area of low pressure will track across Lake Erie this evening followed by a cold frontal passage tonight. Northwest flow will increase 15 to 20 knots behind the cold front late tonight into Saturday. A Small Craft headlines will likely be needed for much of the central and eastern basins of the lake Saturday into the evening. High pressure will build over Lake Erie on Sunday with lighter winds. A light southerly flow will return over the lake by Monday. The next opportunity for potential Small Craft conditions might be on Tuesday ahead of a cold front, with offshore southwest flow of 15 to 25 knots expected to develop. Will also need to monitor the potential for a few strong to severe storms to impact the lake Tuesday afternoon and evening. High pressure builds back over the lake on Wednesday.

CLE WATCHES/WARNINGS/ADVISORIES
OH...None.
PA...None.
MARINE...None.