Marine Weather and Tide Forecast for Sunbury, OH

NEAR TERM /UNTIL 6 PM THIS EVENING/
Patchy low clouds and fog will continue to dissipate and lift this morning, leaving mostly cloudy skies. A moist environment, along with modest surface heating, will again spark scattered showers and a few storms from midday into the late afternoon. Highest coverage today will be across the east... or on the favorable east side of the upper trough axis. Movement will be slow, so can't rule out a few soakers with isolated flooding possible.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/
A pronounced decrease in precipitation can be expected Wednesday evening, as the diurnal cycle wanes, and forcing associated with the upper trough moves further off to the east.

On Thursday, there will be a significant increase in deep-layer SSW flow over the Ohio Valley, as an elevated mixed layer advects into the area from off to the west. While instability will begin to build as a result, a strong cap is very likely to keep things dry through Thursday afternoon -- the forecast will just begin to bring some low-end PoPs in by late in the day. Additional concerns for Thursday night will be discussed in the Long Term AFD section below.

In a changing air mass, highs on Thursday are expected to get into the lower 80s -- maybe mid 80s in some spots.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
The long term period features two severe threats within the first two days, followed by lower thunderstorm chances and lower temperatures into the weekend and early next week. Additional chances for showers and thunderstorms are mentioned early next week as the next system moves through the Plains and into the Midwest, but guidance remains split on how the meridional pattern evolves. The below discussion focuses on the two rounds of severe weather Thursday night and Friday/Friday night.

Severe potential (Round 1): A shortwave trough and cold front move into region late Thursday evening, progressing through during the overnight hours. A very unstable air mass is in place across the Ohio Valley, but it is capped by an inversion near 700 mb. This will make it challenging for surface air to rise into the very steep mid- level lapse rates that would allow for intense updrafts. A more likely solution will be for thunderstorm development occurring earlier in the evening across Illinois and into Indiana, advancing eastward toward the late evening into northeast Indiana and northwest Ohio. If a well-organized cold-pool can become established, this may help to continue thunderstorm production into the local area toward midnight, especially west-central and central Ohio. Therefore, the highest PoPs are focused across the northern portions of the local area (I-70 and north) closer to the better forcing in the lower Great Lakes. Otherwise, to the south, isolated elevated thunderstorms are expected through the overnight as the front moves through. Given the steep mid-level lapse rates and strong shear, any storm will have the capability of producing large hail. The larger damaging wind threat would likely be isolated to the areas where a more established cold- pool is maintained.

SPC's Day 2 SWO outlines the entire area in either a level 1 (Marginal) or level 2 (Slight) risk out of 5. If storms are able to persist within the expected environment, the potential for severe weather is present, but the overall coverage may ultimately end up being underwhelming. As a result, future outlooks likely won't change much.

The thunderstorms likely diminish in spread throughout the overnight into Friday morning...

Severe potential (Round 2): After the shortwave slides off to the northeast, height falls fail to continue Friday morning, providing some doubt into how many classic "cold front" effects are observed.
Instead, low-level moisture remains in place, with southwesterly flow continuing throughout Friday morning. This southwesterly flow will assist in moisture advection northward into the Ohio Valley, with upper 60 to low 70s dewpoints established across the area by Friday afternoon. With yet another EML providing steep mid-level lapse rates, another pool of very high instability is expected across portions of southern Indiana, southwest Ohio, and portions of northern Kentucky. The shortwave will likely trigger convective development west of the area, but also within the area as well given the unstable air mass in place and less of a cap (inversion).

How exactly the convective patterns evolve throughout the afternoon and evening remain in question. Regardless, confidence continues to increase in a more organized event Friday evening/Friday night with higher severe potential when compared to Round 1. If a more organized feature can form, the environment will support all threats, including a more widespread severe damaging straight line wind threat and several QLCS tornadoes. Another concern for this event is that much of the severe weather may occur after dark. For location, confidence remains highest in the tri-state area, including southeast Indiana, northern Kentucky, and southwest/southern Ohio. But given the shortwave location, severe weather should be anticipated across the entire area Friday night before activity moves out by Saturday morning.

SPC's Day 3 SWO continues to highlight the highest confidence areas for severe weather with a level 2 (Slight) out of 5, however, this particular event could see severe probabilities increase as confidence grows in the coming days.

AVIATION /13Z WEDNESDAY THROUGH SUNDAY/
Patches of IFR/LIFR ceilings and visibilities are impacting the airports early this morning, with some periods of VFR also mixing in.
This will continue to be the case through 14Z, after which time VFR conditions are expected. Prevailing VFR is forecast through the rest of the TAF period.

Scattered showers, and a few storms, will develop today -- although coverage will be lower than yesterday. Have included -SHRA with PROB30 for thunder at the Columbus TAF sites, but with lower confidence at the other airports. Dry conditions are expected after 00Z.

OUTLOOK...Thunderstorms are possible at times from Thursday night through Saturday.

ILN WATCHES/WARNINGS/ADVISORIES
OH...None.
KY...None.
IN...None.