283
fxus63 kiwx 181014
afdiwx
area forecast discussion
national weather service northern indiana
614 am edt thu sep 18 2025
.key messages...
- remaining warm through the weekend with above normal high
temperatures in the 80s.
- chances of rain return for the weekend, especially later
sunday into early monday (50-60%).
&&
.discussion...
issued at 330 am edt thu sep 18 2025
a warm and dry weather pattern will continue through friday. an
upper level ridge will move very little over the next 24 to 36
hours and will remain situated from southwest ontario into the
ohio valley. this ridge is positioned between a larger negative
upper height anomaly across the northern plains and a broad
upper trough across southeast canada. a weak short wave dropping
southeast on the southern periphery of this southeast canadian
height anomaly will allow a weak sfc front to drop across the
southern great lakes tonight, but this front will become
divorced from the stronger southeast canadian forcing.
otherwise today, low level thermal fields remain similar to that
of yesterday. some minor increases in mid level moisture may
spill over the ridge into the southern great lakes, but any mid
cloud cover should be limited and not have any significant
impact on highs today. persistence forecast utilized once again
today for a first estimate of today`s high temps, generally in
the mid 80s but a little cooler near lake michigan where a weak
lake breeze should develop once again.
aforementioned sfc trough should gradually lose its integrity as it
drops across the southern great lakes tonight. main impacts from
this front locally could be a slightly more favorable setup for fog
development tonight, particularly across northeast half of the area
where low level flow trajectories could once again aid in a weak low
level moisture influence from lake huron/erie. given what has been a
favorable fog pattern, and perhaps some better near sfc rh from
effects of this weak front, will go ahead and include a patchy fog
mention tonight.
for late friday into saturday, main forecast challenge will be
resolving the magnitude of moisture return and extent of mid/upper
level forcing that is able to advance eastward from the plains. a
mid/upper level disturbance across the northern plains this morning
will continue to be enhanced diabatically today with additional
convective development across the central plains later today
helping to sharpen a lead short wave that should work into the
western great lakes later friday into saturday. run to run
consistency in guidance has been a challenge in this pattern
given dependence on diabatic processes, but trend over past few
guidance iterations has been for enough elevated moisture return
due to the lead central plains short wave and northern plains
dampening upper disturbance to allow for at least isolated
shower potential late friday night into saturday. broad flow
pattern with northeast conus anticyclone may also enhance some
broad low level confluence that could aid in isolated shower
development.
best chances of rain still appear to be in the later sunday/monday
timeframe as additional pacific energy allows stronger southwesterly
flow to advect some anomalous deep layer moisture into the
region. of low confidence is the strength of this next pacific
short wave late weekend/monday but better advective
forcing/anomalous moisture seem to support a trend in ensemble
guidance of greater measurable rain chances late sunday into
monday.
the predictability in the precip forecast wanes sharply post-
monday. medium range guidance is in general agreement of a
significant negative upper height anomaly closing off in a
blocked pattern across central conus middle of next week, but
placement/depth of this feature is of very low confidence so an
extended period of low-mid chance pops was left for much of the
remainder of the long term period. this overall pattern should
favor trend of temps back to more seasonable levels next week.
&&
.aviation /12z tafs through 12z friday/...
issued at 611 am edt thu sep 18 2025
plenty of mvfr to ifr visibilities being reported across
northern indiana and adjacent areas. duration of these reduced
visibilities have generally be brief and highly variable.
existing tafs remained on track at this hour.
&&
.iwx watches/warnings/advisories...
in...none.
oh...none.
mi...none.
marine...none.
&&
$$
discussion...marsili
aviation...brown