Marine Weather and Tide Forecast for Martinsville, IN

.SHORT TERM (This Evening through Saturday)...
Issued at 151 PM EDT Fri May 23 2025

A healthy cu field has established early this afternoon with the colder air aloft over the region...but cloud coverage was most extensive across far northern portions of the forecast area in advance of a weak trailing surface boundary. Radar showing a few light returns indicative of sprinkles. 18Z temperatures were in the 60s with a cool W/NW wind gusting as high as 30mph.

The aforementioned surface boundary will drift across the area into the evening before washing out overnight and being replaced by strengthening high pressure into Saturday. While mid and high level moisture will track periodically across the area through Saturday...the presence of the surface ridge to the north will advect drier boundary layer air into central Indiana and force rain well to our southwest throughout the day.

The diurnal cu field and the area of more concentrated clouds currently across north central Indiana will keep a mix of sun and clouds over most of the forecast area through sunset. The boundary pressing south will be hard pressed to generate much precipitation due to a lack of substantial moisture through about 750mb which is noted nicely via the KIND ACARS sounding...and a warm pocket of air in the mid levels serving as a cap. Low level lapse rates though do steepen further through the rest of the afternoon with very weak CAPE noted below the cap. This may be just enough to produce a few sprinkles in advance of the boundary focused across the northeast half of the forecast area into the early evening.

The surface ridge will build in for tonight and Saturday with dry weather anticipated. The northwest flow regime aloft however will enable mid and upper level moisture to track through the area in tandem with weak waves aloft...resulting in periods with modest mid level cloud cover overnight and Saturday especially focused across the southwest half of the forecast area. There will still be sun at times on Saturday and unlike this afternoon...winds should be much lighter throughout the day at 10mph or less from the N/NE.

Temps...Tonight will be another unusually chilly night for the region with most locations falling into the 40s. Areas northeast of the Indy metro will make a run at 40 once again. Low level thermals will be subtly warmer Saturday and despite the presence of mid and high clouds at times...highs will range from the mid 60s northeast to lower 70s in the southwest.

.LONG TERM (Saturday Night through Friday)...
Issued at 151 PM EDT Fri May 23 2025

A persistent upper level trough will linger over New England west into the Great Lakes with overall broad northwest flow aloft across the region for much of the weekend before subtle ridging develops on Monday. This will be brief as a trailing longwave upper trough extending from the Canadian Maritimes west into the northern Plains will eventually pivot south into the region by the middle of next week. This will trend towards a continued cooler than normal regime across the Ohio Valley through the middle of next week with periodic chances for rain as well.

Saturday Night through Sunday Night

Cloud coverage will gradually increase from the southwest Saturday night as subtle waves aloft riding from the northern Plains within the northwest flow pattern interacting with low level moisture and a warm front that will eventually nudge into the lower Ohio Valley by Sunday. Model trends continue to focus the primary threat for rain to our southwest with a stronger surface high expanding south across the Great Lakes. This will keep a drier N/NE flow across the forecast area through Sunday night with model soundings showing a lack of substantial moisture below the 800-750mb layer.

While isolated to scattered light showers will likely be present Sunday...confidence is high in them focusing primarily across the far southwest portions of the forecast area. The presence of abundant mid level moisture will produce a mostly cloudy day for much of the forecast area that will persist into Sunday night although deeper subsidence will advect south and may enable scattering of the deck over the northeast half central Indiana.

Cool conditions will continue through the second half of the weekend. Highs on Sunday will rise into the mid and upper 60s while both Saturday and Sunday nights see lows exhibit a northeast- southwest gradient across the forecast area ranging from the mid 40s to lower 50s.

Monday into Friday

As mentioned above ridging aloft will briefly establish Monday while at the same time...surface high pressure will drift off to the northeast. Low pressure will ride along the warm front located south of the Ohio River and provide perhaps the best opportunity for more widespread rain and embedded thunderstorms focused primarily Monday night into Tuesday. The focus for greatest convective coverage will again be over southern counties in closest proximity to the warm front and track of the surface low.

Beyond late Tuesday...the forecast becomes increasingly murky as quasi zonal flow gradually returns to an upper trough over the region as the week progresses. Timing individual waves aloft is challenging at this stage but a continuation of the cool and mainly cloudy pattern likely will persist into Wednesday with increasing sunshine for the second half of the work week. The potential for a surface low to track through the region Thursday night and Friday may bring a better convective threat as well late week. Low level thermals maintain highs in the 60s through Tuesday with slow improvement into the lower to mid 70s by next Friday.

The search for a return to more persistent warmth likely is still just beyond the 7-day period with a return to a more typical late Spring/early Summer pattern by the first full week of June.

.AVIATION (18Z TAF Issuance)...
Issued at 1222 PM EDT Fri May 23 2025

Impacts:

- Peak wind gusts to 20-25kts through early evening

Discussion:

Diurnal cu has developed courtesy of surface heating and will remain over the region into the early evening before diminishing. An area of mid level clouds will track southeast over the northeast part of central Indiana over the next few hours and may briefly graze KIND and KLAF. Mid and high level clouds will periodically drift across the region tonight and Saturday as winds veer to the northeast at 10kts or less.

IND WATCHES/WARNINGS/ADVISORIES
None.