IND issues Area Forecast Discussion (AFD) at Sep 26, 9:49 AM EDT662
FXUS63 KIND 261349
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
949 AM EDT Fri Sep 26 2025
.KEY MESSAGES...
- Locally Dense Fog through 900 AM this morning, across mainly northern
zones...with visibility reductions also over central counties
- An otherwise lovely early autumn day today...clear skies this
afternoon, highs 76-80F
- Dry and unseasonably warm this weekend into next week, highs in
80s through Tuesday
&&
.FORECAST UPDATE...
Issued at 948 AM EDT Fri Sep 26 2025
No significant changes needed to the forecast with the morning
update. Fog continues to diminish across the region with a few
patches remaining, mainly along the Wabash and across our south and
east. Some fog also exists over our northeast near Muncie but this
has become more of a low stratus deck since sunrise. Regardless,
clear skies are expected later this morning for all areas. diurnal
cumulus is likely during the afternoon hours.
&&
.MESOSCALE UPDATE...
Issued at 646 AM EDT Fri Sep 26 2025
Dense Fog Advisory continues through 13Z across the north-
northeastern half of central Indiana, along and north of a Covington
- Danville - Shelbyville - Greensburg line...with a corresponding
SPS for patchy Dense Fog along and north of a Terre Haute -
Bloomington - Seymour line.
While visibility has fallen below 1 SM at several airports early
this morning...fluctuations in VIS between VFR and IFR levels have
been more common. Fog has been most consistent at Anderson,
Crawfordsville, Greencastle, Lafayette, and airports around the
periphery of the Indy Metro (MQJ, TYQ)...with Greenwood now also
falling below 2 SM within the last hour.
Overall continued deterioration of visibility over most northern and
central zones is expected through 12Z, with patchy dense fog along
river, creeks and low-lying areas the most common habit.
Areas of dense fog through the morning commute are most likely along
the upper Wabash and upper White River valleys. Take care and allow
extra time if traveling, not only in thick fog...but also when
approaching low-lying areas where visibility could suddenly change
from no reduction to under 1/2 SM. Clear and calm conditions are
expected to return to all corners of the CWA by late morning.
&&
.SHORT TERM (Today and tonight)...
Issued at 300 AM EDT Fri Sep 26 2025
The main impact in the short term will be the development of fog
over the next several hours through this morning. Broad subsidence
has cleared out skies, with surface temperatures quickly falling
towards saturation. Model soundings continue to show a saturated
near surface layer under a shallow inversion through the morning
hours, especially across the northern half of central Indiana. Given
calm winds and an uniform dew point gradient, there likely wont be
dense fog in all locations across central Indiana, but any low lying
valleys or waterways are likely to fog up quickly over the next few
hours. Given the likely patchy nature of this fog, it should take
long for surface heat fluxes to aid in mixing of the PBL and fog
dissipation by mid morning, but trends will have to be monitored for
possible changes in coverage over mesoscale areas.
For the rest of the day, there should be enough lingering moisture
within the boundary layer will likely support establishment of a
scattered cu field for the afternoon. Temperatures should remain
stagnant from yesterday with highs in the mid to upper 70s. Ridging
continues to build in throughout the day with a slow push of warmer
temperatures for tonight into tomorrow.
&&
.LONG TERM (Saturday through Thursday)...
Issued at 300 AM EDT Fri Sep 26 2025
Dry and warm pattern to prevail through the entire long term as
central Indiana finds itself situated on the southeastern edge of an
amplified subtropical upper ridge...which will steadily build from
the central CONUS up to Hudson Bay over the 6 day period. Stagnant
upper trough contributing the southeastern corner to this overall
omega-type block pattern...will spin about its center which should
remain near the Smoky Mountains...with a weak/small Atlantic
tropical wave likely tracking from the Carolina coast into this
upper trough in the second half of the period.
Broad but weak surface high pressure over much of the central to
eastern US will be rearranged by the building upper ridge...to an
alignment from the Great Lakes to New England by early next week.
This will keep the local region under light northerly winds through
the weekend that will do little to counter H500 thicknesses as high
as 572 dm, with unseasonable afternoon highs about 10 degrees above
normal. Mainly clear skies will promote large diurnal ranges, with
lows under 60F.
The middle of next week will have a couple factors worth
watching, as the amplifying upper ridge should help direct the
southern extents of much cooler Canadian high pressure across the
Great Lakes and into the CWA...providing moderate east-
northeasterly breezes that would promote only slightly above
normal afternoons by Wednesday. Meanwhile, despite decent
agreement in the small tropical wave being ingested into the
southeastern trough...appears cyclonic flow around this feature
should keep any showers south of the Ohio River, although moderate
humidity may return to the local region's southern most counties.
Should the formidable Canadian surface high make a greater plunge
southward, associated isentropic lift might lead to low chances
of RWs, but confidence for this potential is low.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 646 AM EDT Fri Sep 26 2025
Impacts:
- LIFR/IFR at KLAF...MVFR/IFR at KHUF/KBMG due to FG/BR through 13Z
Discussion:
Through 13Z this morning...areas of dense fog/LIFR should stay
confined to northern parts of central Indiana, including KLAF...with
lower confidence in IFR conditions down the Wabash Valley/KHUF...
periods of MVFR likely at KBMG...and occasional MVFR possible at
KIND.
VFR conditions will otherwise prevail near terminals through Saturday
morning as weak, yet stacked ridging slowly builds into the region.
Winds will remain very light and at times variable through the TAF
period, with a predominately northerly direction. Any fog at the
end of the TAF period may bring brief MVFR at KLAF, although
confidence is so far too low to mention in TAF.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Eckhoff
SHORT TERM...Updike
LONG TERM...AGM
AVIATION...AGM
Source:
IND issues Area Forecast Discussion (AFD) at Sep 26, 9:49 AM EDT---------------
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