Marine Weather and Tide Forecast for North Riverside, IL

DISCUSSION
Issued at 156 PM CDT Fri Jun 13 2025

Through Saturday night:

Water vapor imagery depicts the center of an expansive vertically- stacked low pressure system was located over Southern Missouri.
Regional radar imagery hints at several small-scale perturbations (MCVs) within the broad circulation and trough axis extending northeastward into the Lower Great Lakes, which are responsible for the myriad of showers across the region this afternoon. With the exception of a sliver of northwestern Illinois, expansive cloud cover has marred diurnal temperature rises today with most locations currently residing in the lower 70s. Perhaps more interesting is a stationary front draped across northern Illinois and northwestern Indiana at press time, which delineates the northern edge of a pool of humid air (dew points in the upper 60s).

Over the next 12 to 18 hours, forecast guidance depicts the center of the low moving east-northeastward toward southern Illinois.
As this occurs, the highest coverage of showers should similarly shift east-northeastward and away from our area. With flow from the surface to 20kft easing along the northern periphery of the low, do have some concern that any lingering MCV could stall within the seasonably moist airmass (PWATs near 2"). Should this occur, a focused area of nearly stationary showers would be prone to developing and pour over the same area overnight contributing to a threat for flooding of fields and low-lying areas (picture a wet rag getting wrung out). These types of scenarios can be notoriously difficult to forecast and often result in false alarms, but do have to mention there is subtle support in a few select CAM runs. Given the inherent low confidence in the forecast regime, opted to simply advertise lingering chances for showers through the overnight hours across much of the area in favor of letting the evening shift watch trends. For most areas, however, the night should be characterized by mostly cloudy skies and a few showers.

Tomorrow, the center of the low pressure system will meander through southern Illinois and into central Indiana. Increasing northeasterly flow on the northern side of the circulation should transport a wedge of locally drier air from Lower Michigan into our area, seemingly preventing any near-surface based instability from developing. As a result, do favor a dry forecast tomorrow accompanied by partly cloudy skies and highs around 80 degrees. Tomorrow night looks similarly quiet as short-wavelength ridging builds into the Great Lakes behind the vertically-stacked low pressure system. A shortwave rounding the crest of a building upper-level ridge in the central US may encourage a cluster of storms to erupt and race through Minnesota and Iowa overnight, though the orientation of the instability axis should guide any remnants well west of our area should they even survive that far.

Borchardt

Sunday through Friday:

Medium range models are in good agreement on a transition to a more zonal flow across the U.S. early next week. An increasingly moist and unstable air mass will build northward across Mississippi Valley as southerly flow off the Gulf become established early next week. Pattern looks favorable for a couple of MCSs to develop along the southern flanks of the stronger flow aloft. These early week MCSs will likely be ignited by low amplitude synoptic short waves which are going to be difficult to predict timing/track of at this distance, but our CWA certainly looks to be in the area potentially affected by one or two of these convective clusters.

By Tuesday night into Wednesday, there is growing consensus among the various medium range models and their respective ensembles that a more amplified synoptic short wave trough will emerge over the central Plains and track east into the mid-upper Mississippi Valley. ECMWF and GFS both have a 50-60kt 500mb jet streak associated with this trough which given the potential magnitude of available instability is quite concerning. There are a lot of mesoscale details that won't be able to be resolved this far in advance, the bigger picture synoptic pattern (as advertised by latest guidance) looks quite favorable for potentially significant severe weather event somewhere in the Midwest Wednesday-Wednesday night. It is still 5 days out so there is still plenty of time for guidance to reverse course and trend weaker with this synoptic wave. There are also a lot of ways prior convection could disrupt destabilization Wednesday. Bottom line is that the Wednesday time frame will need to be closely watched in coming days for the potential for severe weather either in or near our CWA

There is some signal that we could see some temporary ridging and a break in the daily shower and thunderstorm chances in the wake of that midweek system.

Temperatures will be a bit tricky next week. Generally, looks like a warm to very warm and increasingly humid period with temperatures warming well into the 80s and dewpoints climbing into the lower 70s. However, convective debris or convective cold pools could push the effect boundary farther south and disrupt the warmth at times next week. Given the uncertainties, no changes were made to NBM grids for next week. If convection doesn't disrupt warmth, then temps could even make a run at 90 next Tue or Wed.

- Izzi

AVIATION /06Z TAFS THROUGH 12Z SUNDAY/
Issued at 1230 AM CDT Sat Jun 14 2025

Key Aviation Forecast Messages for the 06Z TAFs:

- Period of IFR ceilings likely through sunrise, improving to VFR by midday.

Early morning surface map shows low pressure centered just south of KSTL, with a nearly stationary frontal boundary extending northeast along/just south of a KCMI-KDNV-KMIE line. North of this front, relatively cool, moist northeast flow was in place across the terminals. While an area of showers will remain largely south of the area this morning, a few spotty light sprinkles can't be ruled in the KMDW/KGYY vicinity for the next few hours. Within the moist northeast flow, surface and satellite observations indicate increasing low-level cloud cover developing off of Lake Michigan into northeast IL. Model guidance strongly supports the development of IFR ceilings which may linger through sunrise before gradually improving through MVFR during the morning. VFR conditions are expected by late morning/midday. Model guidance indicates KRFD may develop a low-end MVFR ceiling of around 1000 feet toward sunrise, before also then improving to VFR later in the morning.

Winds through the period are expected to be generally northeast around 10 kts, eventually becoming more light/variable later Saturday night.

Ratzer

LOT WATCHES/WARNINGS/ADVISORIES
IL...None.
IN...None.
LM...None.