Blaine, Indiana Weather Forecast Discussion

632
FXUS63 KIWX 171015
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
615 AM EDT Wed Sep 17 2025
.KEY MESSAGES...
- Areas of dense fog early this morning across portions of
  northwest Ohio and possibly extreme northeast Indiana.
- Remaining warm and dry through the first portions of the weekend
  with highs well into the 80s.
- Rain shower chances (20-40%) arrive later this weekend into
  early next week.
&&
.DISCUSSION...
Issued at 350 AM EDT Wed Sep 17 2025
A weak low level anticyclone across the eastern Great Lakes will
continue to be the dominant weather feature locally. Weak easterly
low level flow in southeast portion of this anticyclone is advecting
some slightly higher amounts of near sfc moisture from the
eastern Great Lakes westward across NW Ohio/far NE IN this
morning. The combination of this near sfc moisture advection,
light winds, and clear skies should be a favorable setup for fog
formation and westward advection of fog across these locations
this morning. Given trends in obs/satellite, have gone ahead and
issued a Dense Fog Advisory for Putnam, Defiance, Henry,
Paulding, and Allen OH Counties through 14Z. It is possible a
slight westward expansion of the advisory may be needed into far
NE Indiana and will continue to monitor observational trends.
Otherwise for today, persistence forecast remains intact with a
similar synoptic scale setup in place.  Upper level longwave ridging
across the western Great Lakes will shift slightly eastward into the
southern Great Lakes by this evening and will continue to provide
broad weak synoptic scale mid level subsidence. Mostly sunny skies
and highs in the mid to upper 80s are expected, with slightly
cooler conditions near Lake Michigan vicinity given expectation
of another lake breeze development.
A stagnant weather pattern continues into Thursday and Friday. An
upper level trough tracking across southern Ontario will allow a
weak sfc trough to drop across the southern Great Lakes. With
limited upper support with southward extent, this trough should wash
out across the southern Great Lakes with little effect to temps.
High temperatures Thursday and Friday should once again rise into
the mid-upper 80s.
By Saturday, attention will turn to a slow moving negative upper
height anomaly currently across northern Wyoming. A vort max is
expected to track through southern portions of this upper low with a
second diabatically enhanced mid/upper circulation likely to
develop across the Central Plains by early Friday morning. Some
uncertainty remains regarding strength/speed of this feature
given the diabatic link, but have noted that 00Z GFS
deterministic is now on board with majority of other
deterministic/ensemble guidance in a slower and a bit more
sharp upper trough. This evolution would likely keep Saturday
dry with better low level moisture displaced to the west, and
have accepted blended guidance trend of removing mentionable
PoPs Saturday.
By Sunday, upstream upper level wave may tend to weaken across the
local area, but better low level moisture should accompany the
approach of this feature. See no reason to deviate some
isolated PoPs for Sunday with above normal highs in the low-mid
80s.
A more strongly forced pattern still looks on track for early next
week as a pronounced Pacific jet digs across the northern
Plains. However, a large spread persists in
deterministic/ensemble solutions on strength/track of
accompanying mid/upper level trough, so have maintained
broadbrush 30-40 PoPs for Monday-Tuesday. Some isolated
convection will also be possible during this period. Temps
should trend back to near normal toward end of this forecast
period.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 612 AM EDT Wed Sep 17 2025
Lake Erie modified air mass continued to trek southwest through
northwest Ohio, with stratus and fog present on satellite. This
stratus deck is now in eastern Allen County as of this writing,
thus, a degradation in conditions should occur within the hour
at KFWA followed by improvement after sunrise.
At both sites today, mostly clear skies and wind less then 10
knots. Guidance is hinting at a lake breeze near 21z at KSBN,
resulting in  in a wind shift to northwest but still light.
Will pass this on to the next shift for further consideration.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Dense Fog Advisory until 10 AM EDT this morning for INZ018-027.
OH...Dense Fog Advisory until 10 AM EDT this morning for OHZ004-005-
     015-016-024-025.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Marsili
AVIATION...Brown

NWS IWX Office Area Forecast Discussion