Granger, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

709
FXUS63 KIWX 261039
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
639 AM EDT Sat Jul 26 2025

.KEY MESSAGES...

- Several rounds of showers and storms are expected through the
  weekend. Isolated pockets of heavy rain and localized flooding
  are possible.

- Heat and humidity will gradually build through Monday. Heat
  indices will be over 100 by Monday.

- A cold front will bring more storms on Wednesday with cooler
  and less humid conditions to end the week.

&&

.DISCUSSION...
Issued at 224 AM EDT Sat Jul 26 2025

A challenging forecast this morning as multiple, subtle MCV`s ripple
through the area along a stalled, weak frontal boundary with an
incredibly moist airmass in place. Hi-res CAM`s continue to struggle
with timing and coverage of convection for today. There is a general
concensus that convection currently entering our western zones will
weaken as it moves into a slightly less moist/unstable environment
over far northern IN/southern MI. However, slight strengthening of
the LLJ will continue to slowly advect better moisture N/NE by later
this morning as some hi-res models (notable the HRRR) suggest
another wave ejecting into the area later today sometime 15-20Z.
This wave would have the benefit of some diurnal destabilization as
well. An alternate scenario would be that convection moving out of
central IL maintains enough strength on the edge of better
moisture/instability to fester over our CWA through morning,
limiting the potential for storms around midday/early afternoon.
There is a general preference for the HRRR solution given that
several of the hi-res models advertising the alternative struggled
to correctly initialize the strength and coverage of storms
currently over IL. However, confidence is not high and another
solution somewhere in between the two camps remains possible. Will
continue to monitor observational trends closely through the early
morning and adjust the forecast as necessary. Heavy rain and
isolated flooding remain the primary concerns. PW values at or above
2 inches, warm cloud layers at or above 12 kft, and relatively light
flow all suggest potential for heavy rain. Many areas saw decent
rainfall yesterday but convection remained sufficiently scattered so
that no one area received an excessive amount. Given continued
uncertainty on the coverage of storms, more progressive nature of
preferred HRRR solution, and overall dry antecedent conditions going
back several weeks, will continue to hold off on an area-wide flood
watch and handle any localized issues with advisories or warnings as
needed. An isolated wet microburst can never be ruled out but lack
of organizing shear/weak flow and performance over the previous two
days suggests the risk is low. Very similar to yesterday, clouds and
precip should keep highs generally in the mid 80s north/upper 80s
south with heat indices in the low 90s north to upper 90s south.
Will therefore hold off on a heat advisory for one more day even
though I suspect our far southern zones could touch 100F if
convection stays confined to mainly central and northern zones.

Uncertainty on daytime convective trends of course spills over into
the forecast for tonight. Details are very sketchy but in this
pattern odds are there will be at least some convection overnight
tonight. Chances are lower for Sunday though, particularly by Sunday
night and into Monday. During this time broad midlevel troughing
over the Great Lakes ejects eastward allowing behemoth 597 dam
ridge over the southeast CONUS to build and retrograde slightly.
Increasing subsidence, particularly over MI, should limit precip
chances. Still expect a few storms in our southern zones during peak
heating Sunday afternoon with a continued marginal heavy rain threat
but overall coverage and risk should be lower than today.

As the ridge builds north, the focus will be on increasing heat and
humidity. Sunday will be a transition day with a bit more sun and
warmer profiles but may still fall just shy of advisory criteria.
Current forecast has max heat indices generally in the mid/upper 90s
with just a few 100+ values in the south. NBM seems to have a slight
high bias in dewpoints along the Wabash river valley suggesting
dewpoints 78-79F while most other parts of our CWA are a more
reasonable 73-76F. Will keep an eye on this period for potential
changes but no headlines planned at this point. Monday still looks
like the hottest day as temps climb into the low 90s with heat
indices over 100F for much of the area. May need to consider a
watch/warning for this period but it is still a bit too early.

Ridge starts to break down and shift further W/SW on Tue but still
expect some 100F heat indices in at least our southern half. Cold
front finally arrives late Wed/early Thu. Some additional storms
likely but details remain unclear this far out. Of much higher
confidence is the return of cooler and much less humid conditions
heading into next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 633 AM EDT Sat Jul 26 2025

Scattered showers were over northern Indiana this morning at
1030Z. The activity should become more numerous with daytime
heating this afternoon. There will be breaks in the showers from
time to time. Occasionally lower ceilings are likely in the
vicinity of the showers and storms. For this reason, went with a
broad time range when storms are possible.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...AGD
AVIATION...Skipper