LOT afd went into some detail regarding the winds from the remnants of Helene. Nothing really high end, but not something you see all the time from tropical remnants around here.
There's still a strong core of winds just off the deck on Friday, so if mixing is a little better than progged, then it's possible that winds would be more solidly into advisory criteria. But for now, reaching advisory criteria looks borderline.
The main change in the forecast message for Friday is the
increasing likelihood of strong northeasterly winds, especially
south of I-80 and along the Lake Michigan shore.
Helene`s strong extratropical remnants, possibly still
technically partially tropical into Friday morning, will track
to the Ohio Valley by Friday evening, still at 990 mb or a bit
less. Given the unusually strong surface low pressure butting up
against 1015+ mb high pressure over the Great Lakes, the
pressure gradient will quickly tighten through the day on
Friday.
Exceptionally dry air in the 700-500 mb layer and down to the
low levels will be tough to erode. This will not only slow the
northward progress of (and eat away at) the northwest fringe of
the precip shield, but also present supportive conditions for
efficient mixing, as the drier low levels will keep lapse rates
fairly steep. Model forecast soundings today were in solid
agreement depicting 35-45 kt flow atop the mixed layer, highest
in our southern CWA, closest to the center of Helene`s remnants.
The wind field should peak in magnitude in the mid afternoon
through the early evening hours.
There`s some uncertainty on how thick the mid and high cloud
cover will be north of Helene`s remnants, which could modulate
how warm temps get, how much dew points mix out, and how
effectively the higher momentum aloft can be tapped into. With
that said, the signal was consistent across the guidance today
(along with showing a general uptick in the robust EPS suite) to
support ramping up wind speeds to 15-25 mph and gusts into the
35-40+ mph range. The best chance for any gusts approaching 45
mph advisory criteria is, as noted earlier, primarily pegged for
our southern CWA. Occasional gusts up to 40 mph appear probable
near the lake, though there it`s looking like more of a
stronger sustained wind off the frictionless lake, and gusts not
much higher than the sustained winds. A Marine section will be
added below with details on the large waves and dangerous
conditions expected on the lake.
The interesting "fujiwara" interaction and then merger with a
larger upper low does still look likely to take place with
Helene`s remnants, but limiting factors for appreciable rain in
our area discussed the past few to several days have not
materially changed. Strong mid-level ridging extending across
the northern Great Lakes will likely be a road-block and prevent
the gradually weakening, but still very large extratropical
cyclone, from getting much farther north than the general Ohio
Valley area.