Marine Weather and Tide Forecast for Whiting, IN

DISCUSSION
Issued at 336 AM CDT Fri Oct 11 2024

Through Saturday Night:

Upper air analysis shows a mid level ridge currently extending over Illinois. With persistent southwesterly flow driving better warm air advection, afternoon temperatures are expected to reach into the low to mid 80s. These warmer temps will be accompanied by breezier southwesterly winds that could feature gusts between 25 to 30 mph. Dew points expected in the low to mid 40s will result in relative humidity values in the mid to upper 20 percent range creating an elevated risk for rapid spread of brush and grass fires.

Recent water vapor satellite imagery shows a southwest to northeast oriented cold front over northern Minnesota that is expected to dive southeastward over the area this evening. The main impacts just before midnight and through the overnight will be the winds increasing and sharply veering to the north- northeast, before becoming easterly Saturday mid-morning. The front will continue to sink southward before stalling out somewhere between I-88 and I-80 and turning into a quasi- stationary front Saturday afternoon. This stationary boundary is expected to create a robust afternoon temperature gradient with 60s to low 70s to the north and warmer 70s to even low 80s to the south.

As the front stalls, increased mid level moisture will move in from the west-northwest with a short wave trough passing aloft.
Additionally, models are suggesting decent isentropic ascent along and ahead of the front will provide sufficient lift to support precipitation. With higher res models starting to key in on the amount of moisture available, PoPs were increased to the 40-60 percent range closer to Lake Michigan with the highest PoPs over northwest Indiana. Model soundings are also showing a narrow well of instability aloft Saturday late afternoon through the evening providing the chance for some elevated embedded thunder. As the next reinforcing cold front approaches on Sunday, chances for showers diminish by daybreak.

DK

Sunday through Thursday:

A notable pattern shift is anticipated for the start of the upcoming week as a vigorous upper level wave and closed upper low digs across the broader Great Lakes Region on Sunday. This in addition to a departing developing surface low will usher in a multi-day stretch of cold air advection into the local area.

The tightening pressure gradient associated with the aforementioned surface low will result in a period of gusty northwesterly winds up to 25 to 35 mph, locally highest near the Indiana shore. After our extended stretch of above normal high temperatures, highs on Sunday will be near seasonable with much of the area mainly in the 60s. Expect any lingering showers from Saturday night to shift mainly east of the area by daybreak Sunday with the low, though can't fully rule out a few lingering spotty showers.

This setup is also quite favorable for an extended period of lake effect showers over Lake Michigan Sunday night through Monday as this colder airmass moves over a still warm Lake Michigan. The current wind orientation (NNW) favors the band of showers being focused into northwest Indiana and southwest Michigan. There is a chance for showers into Illinois late Monday as a trailing shortwave rounds the upper trough.

Monday and Tuesday will see the coldest temperatures so far this season for most of the area. In fact, there is the potential for sub-freezing temperatures for part of the area both Monday and Tuesday night (currently favoring northwest Illinois). High temperatures likely remain only in the 50s both days.

There remains a signal for a return to above normal temperatures toward the end of the week as narrow high amplitude ridging translates back over the region.

Petr

AVIATION /06Z TAFS THROUGH 12Z SATURDAY/
Issued at 1235 AM CDT Fri Oct 11 2024

Key Messages:

* Breezy SW winds during the daytime hours * Gusty NE wind shift late evening behind backdoor front

Winds will be light SSW to at times calm/variable overnight.
Expect increased gustiness into the 20-25 kt range out of the SW mid-late morning through sunset. A strong backdoor cold front is then expected to turn winds NE with a return of 20-25 kt gusts during the late evening and overnight hours. Nudged up the time an hour earlier at ORD/MDW based on latest trends, otherwise no major change made with this update. VFR conditions are forecast with increasing high clouds expected later in the day.

Petr

LOT WATCHES/WARNINGS/ADVISORIES
IL...None.
IN...None.
LM...Small Craft Advisory from 10 AM this morning to 4 PM CDT Saturday for Winthrop Harbor to Wilmette Harbor IL.

Small Craft Advisory from 10 PM this evening to 4 PM CDT Saturday for Wilmette Harbor to Calumet Harbor IL.

Small Craft Advisory from midnight tonight to noon CDT Saturday for the IN nearshore waters.