Marine Weather and Tide Forecast for Long Beach, IN

DISCUSSION
Issued at 1014 AM EDT Mon May 18 2026

Main focus this forecast period is on the severe potential for today and on Tuesday. For today, seems the one limiting factor for today's storms will be the available shear, with values of Bulk Shear is around 20 to 30 kts, this should keep organization of storms minimal and current convective allowing guidance and thinking points to a more linear feature moving northeastward into the area over the next couple of hours from central IL. A plume of dew points in the mid 60s is pushing northeastward ahead of the convection currently pushing across central IL. Surface based CAPE values will run about 2000 to 2500 J/kg over the CWA With environmental profiles drier near the surface and a moist plume maxing out around 850 mb this creates an inverted-V sounding which is indicative of gusty outflows/winds with thunderstorms this is further illustrated with Downdraft CAPE values around 1000 J/kg. Storm relative helicity values look to remain below the 100 m2/s2 threshold but there is the possibility for an isolated tornado or two. This first batch of storms will move through after Noon EDT and push through the area into this evening til around the 8 PM EDT timeframe. Moderate to heavy rainfall will accompany these storms with precipitable water value sitting around 1.70 inches.
Of course, the storm motion speed will be important as if the line moves through quicker that will limit the rainfall amounts but either way looks like we should get a pretty good slug of rain with today's event as trailing stratiform will bring some moderate steady rainfall behind the initial line of thunderstorms as it pushes eastward through the area. Storm totals over the next two days looks to see some areas seeing close to an inch of new rainfall.

A break in the action takes place tonight into the overnight period before the better looking set up arrives tomorrow in the form of a cold front associated with a low pressure circulation centered over northern WI. SB CAPE values will be around 1500-2500 J/kg, surface dew points will get into the upper 60s with a few locations seeing lower 70s, bulk shear values 30-40 kts, and mid level lapse rates around 6 deg/km and helicity values of 100-200 m2/s2. At this time it looks as if all threats will be on the table with the better helicity and shear values associated with the close proximity of the frontal boundary that will push eastward through the area. The exact timing is still a bit hazy but current indications have the frontal boundary approaching the western portions of our CWA around 1 PM EDT and exiting the area by early morning Wednesday.
SPC currently has our entire area in a slight risk for severe thunderstorms for Tuesday. Heavy to moderate rainfall will once again be possible with the thunderstorms and as stated earlier that around 1 inch of new rainfall will be possible with these two batches of storms and locally heavier amounts if the residence times of thunderstorms linger.

In the wake of the cold front a more zonal flow develops over the region on Wednesday and cooler and drier conditions will arrive. Highs on Wednesday will only get into the 60s which is about a 20 degree drop from the 80s today and Tuesday. Upper level ridging begins to push into the region by Thursday and will start to see a gradual increase in temperatures into the weekend. Highs Friday and Saturday will be in the 70s. Sunday into the beginning of next week highs will return int 80s.
Chances for afternoon showers and thunderstorms will also increase over the weekend and at this time the best chances will be Friday afternoon and evening with a trough pushing through the area but periods of showers/t-storms will be possible each day into next week.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
Issued at 1149 AM EDT Mon May 18 2026

Primarily weather concern is an incoming squall line from the west. Observation stations have had episodes of G30KT, with at least one unofficial report of 58mph gust toward central IL.
Timing was adjusted to TSRA to align with the latest storm motion. Behind this line, dry for the overnight hours unless stratiform rain back builds over KFWA (low confidence, but will monitor). Additional TSRA Tuesday, especially at KFWA, but just beyond this TAF period.

IWX WATCHES/WARNINGS/ADVISORIES
IN...None.
OH...None.
MI...None.
MARINE...None.