IND issues Area Forecast Discussion (AFD) at Sep 5, 9:29 AM EDT848
FXUS63 KIND 051349
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
929 AM EDT Fri Sep 5 2025
.KEY MESSAGES...
- Low threat for additional rain late today into Saturday, mainly
across the south
- Dry and much cooler this weekend, near record lows in the low 40s
for Central and North Central Indiana
- Slow warming trend back to the 80s next week, abnormally dry
weather continues
&&
.FORECAST UPDATE...
Issued at 929 AM EDT Fri Sep 5 2025
Hazy morning ongoing courtesy of the smoke aloft from fires in the
Pacific Northwest. A cold front was moving through central Indiana
currently with gusty winds already noted with its approach and
passage across the northern Wabash Valley. 13Z temperatures ranged
from the upper 50s to mid 60s.
The frontal boundary will press southeast through the forecast area
over the next few hours with winds veering to westerly and become
gusty. Peak gusts to 30-35mph are possible at times focused
especially across the northern half of the forecast area. Despite
the frontal passage...CAMs progs highlight the layer of smoke
lingering for much of the day as it gradually shifts southeast in
response to an amplifying upper level trough over the upper Midwest.
May see some improvement to the haze from the north by later in the
afternoon.
Even as the boundary shifts south of the Ohio River by late
afternoon...broad moisture advection from the southern Plains will
ride northeast along the boundary and may generate lighter showers
by late day into the evening focused primarily over south central
Indiana.
There will be a broad range in highs dependent on timing of the
frontal passage. Expect a range from the upper 60s in the northern
Wabash Valley to near 80 across far southern portions of central
Indiana. Zone and grid updates out.
&&
.SHORT TERM (Today and tonight)...
Issued at 236 AM EDT Fri Sep 5 2025
A cold front approaches Central Indiana from the northwest today
bringing an increase in clouds and a chance for rain over portions
of the area by tonight. But first, relatively dry conditions are
forecast during the day, despite an incoming system, due to such dry
antecedent conditions. Mainly clear skies are seen over Central
Indiana this morning, but as the front approaches, expect high level
clouds to increase this afternoon and evening. A strong N-S
temperature gradient will likely exist this afternoon as the front
pushes in from the north. Highs over North Central Indiana may
struggle to reach 70 due to increasing clouds and winds becoming
west northwesterly earlier in the day. Further south along and south
of the I-70 corridor, greater boundary layer heating and more
southwesterly flow will promote warmer highs ranging from the mid
70s to the lower 80s. Before clouds overspread the region, expect
hazy skies as upper level smoke from wildfires in the PNW advect in
overhead. Any smoke is expected to remain above the surface and not
cause visibility or air quality issues locally.
The main focus in the long term will be the slight chance for rain
later this evening for South Central Indiana. Latest satellite
imagery clearly depicts the incoming system over the Upper Great
Lakes and associated cloud cover and cold front in Wisconsin and
Illinois. Further southwest, energy from a wave along the trailing
cold front in the Panhandle of Texas spreads east today as the cold
front becomes elongated and sags southward toward the Ohio River.
This is not the best set up for precipitation in Central Indiana as
the main upper level system and better dynamics remain north of the
region as everything pivots around a large upper trough in Southern
Ontario. ACARs soundings locally show very dry environment through
the column. Weak moisture return ahead of the front is likely not
enough to saturated the environment enough before FROPA to support
much, if any, precipitation develop. The aforementioned wave in
Texas rides along the frontal system this evening and tonight,
working to increase moisture advection along the front and provide
just enough forcing for rainfall development. By this time, the
front will have pushed south of the Ohio River, keeping the best
chance for rain over Kentucky, while cool and drier air advects in
behind the front. Guidance over the past several days has hinted at
the possibility of moisture overrunning the front, bringing low rain
chances to Southern and South Central Indiana. Today's guidance has
backed off on PoPs somewhat, keeping much of the region dry tonight.
Kept chance wording for rain in South Central Indiana this evening
into the overnight hours, but have lowered PoPs overall, taking out
any "rainfall likely" wording to the forecast. PoPs drop off rather
quickly as one heads north, with low confidence in any measurable
rainfall along and north of I-70.
&&
.LONG TERM (Saturday through Thursday)...
Issued at 301 AM EDT Fri Sep 5 2025
Despite light rain over the past day or two, abnormally dry
conditions persist through the next 7-14 days for Central Indiana
with little to no chances for precipitation in the extended
forecast.
The period begins with large upper troughing over the entire Great
Lakes and NE CONUS this weekend. The surface low is located in
Ontario while high pressure stretches from the Canadian Prairies
southeastward into the Midwest, keeping northwesterly flow through
Indiana. Troughing overhead results in a much cooler Canadian
airmass aloft with well below normal heights and temperature
anomalies. Despite sunny skies this weekend, below average
temperature anomalies through the column will only support highs in
the upper 60s across the north to low to mid 70s further south. The
main focus for this weekend will be near record lows once again
Sunday and Monday morning as good conditions for radiational cooling
and a cold airmass aloft set the stage for temperatures in the low
to mid 40s those morning's. Coldest locations will be across the
Wabash River Valley and in North Central Indiana, where a stray
upper 30s observations could be possible, especially Monday morning.
The overall pattern begins to shift going into next week, leading to
a slow warming trend back to the 80s... but still without any rain
chances locally. Upper troughing pulls off to the northeast with
increasing heights toward seasonal norms by Monday. Surface high
pressure briefly moves overhead Monday then moves off to the
northeast, switching low level flow around to the south and
advecting warmer air northward. Upper level height increases and
slowly warming 850mb temps indicate a pattern favorable for a
warming trend through the week with highs reaching the upper 70s to
mid 80s Tuesday through Friday. Dry conditions will still lead to
larger diurnal ranges as temperatures quickly fall after sunset,
with lows in the upper 40s to low 50s Tuesday then increasing to the
mid to upper 50s by late in the week.
Forecast confidence somewhat decreases toward the end of the period
as longer range guidance and ensembles struggle to resolve how this
pattern evolves as weak storm systems approach from the west. For
now, higher confidence exists in a warmer, drier forecast through
much of next week and beyond.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 633 AM EDT Fri Sep 5 2025
Impacts:
- Wind gusts near 20kt this afternoon and evening
- Borderline low level wind shear conditions through 14z
Discussion:
VFR conditions are expected through the period. Satellite imagery
this morning shows an area of clouds along a cold front over the
Great Lakes region and a separate area of clouds and showers further
west over Kansas. Expect these upper clouds to slowly push into
Central Indiana through the day, but with such dry air in the mid
and lower levels, cloud bases should stay above 20 kft through this
evening. Even overnight tonight, cigs are expected to remain VFR.
An increasing nocturnal low level jet ahead of the front will create
borderline LLWS conditions early this morning as surface winds
remain weak through around 14z. Expect southerly winds of 5-10 kts
this morning, then by late morning winds become westerly and
increase to 10-15 kts with gusts of 20-25 kts at times. The front
pushes south of the region tonight with a wind shift to the WNW and
speeds diminishing to 6 kts or less. Winds/clouds should prevent
ground fog formation overnight at KHUF/KBMG, but odds are nonzero.
Dry air should inhibit precipitation development along the front,
with the exception of South Central Indiana. Added VCSH tonight up
to the I-70 corridor including KIND and KHUF, but not expecting any
impacts to cigs or vis as any rainfall should be scattered and
fairly light. Best chance for any rain this evening and tonight is
at KBMG, but cigs and vis will likely remain VFR as well.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...Ryan
SHORT TERM...CM
LONG TERM...CM
AVIATION...CM
Source:
IND issues Area Forecast Discussion (AFD) at Sep 5, 9:29 AM EDT---------------
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