674
fxus63 kiwx 090939
afdiwx
area forecast discussion
national weather service northern indiana
539 am edt mon mar 9 2026
.key messages...
- warming temperatures early this week with record or near-
record high temperatures today and tuesday.
- an enhanced risk of severe storms, mainly late tuesday
afternoon into the overnight hours tuesday night. all severe
hazards are possible late tuesday afternoon into the early
overnight, eventually transitioning to a heavy rain/flooding
threat late in the night.
- a frontal boundary across the region will interact with
several other systems for periodic chances of rain and snow
late week.
&&
.discussion...
issued at 355 am edt mon mar 9 2026
the overall messaging from previous few forecast cycles remains
intact. mild conditions today and tuesday with record to near record
highs today and tuesday. attention remains focused on potential
severe weather event tuesday afternoon into late tuesday night.
a low amplitude flow pattern persists across northern third of conus
this morning with a cut off upper low level low gradually working
into baja of ca region today. a strong eastern pacific jet
nosing into the pacific northwest this morning will be the
feature that allows amplification of mid and upper level trough
across the northern rockies. in the meantime, a westerly low/mid
level flow regime will advect modified warmer low level air in
the lee of the rockies into the area for much warmer
temperatures today in the upper 60s to around 70. this would
approach or break daily record highs for the date (67 degrees at
fort wayne set back in 2016 and 70 at south bend set back in
2000).
for tonight, a weak mid level trough is expected to kick east out of
the central plains allowing for some backing of low/mid level winds
and a northward surge of higher low level theta-e air from the
lower/mid ms valley. this should manifest as an increased low
level cloud deck tonight, but forecast soundings do suggest at
least the potential of some weak elevated instability being
realized for an isolated shower potential. the persistent
westerly flow regime today does advect in an elevated mixed
layer that could pose some weak convective inhibition for an 850
mb based parcel. given these uncertainties did include just a
slight chance of showers tonight into early tuesday following
this initial theta-e advection push.
the main focus for this forecast will continue to be on the later
tuesday afternoon/tuesday night period for severe weather potential.
by midday tuesday, the pacific northwest upper trough will gradually
amplify across the northern rockies inducing strengthening southwest
low level flow from eastern ks into west central indiana. this
resultant northward warm/moist advection will help accentuate
low level baroclinicity as a low level cold frontal boundary
will gradually stall across the southern great lakes early
tuesday morning. this evolution will allow for the sharpening of
a southwest to northeast oriented sfc trough tuesday from
northern missouri into northwest or west-central indiana. a
strong instability gradient is likely to accompany this synoptic
setup with 1000-2000 j/kg mlcapes to develop from central il
into portions of far northwest indiana during the afternoon. one
of the lower items of confidence with the severe potential
tuesday is timing of convective initiation due to potential
weak convective inhibition from the elevated mixed layer that
overspreads the area. while greatest chances of convective
initiation are toward tuesday evening, cannot rule out some
isolated convection developing with renewed low/mid level
theta-e advection over the pre-existing baroclinic zone during
the mid-late afternoon. some question as to whether these storms
in an earlier initiation time would be surface-based, but would
have some potential to produce hail given steep lapse rates
aloft even to the north of the sfc boundary.
one of the ingredients of concern for severe weather for this
particular event late tuesday is the kinematic wind fields. forecast
soundings continue to indicate large 0-1 and 0-2 km hodographs
given decent low level veering and strengthening speed shear
atop this stronger warm advection layer. 0-1 srh values in the
100-200 m2/s2 range appear possible in this setup. the
combination of these wind profiles, weakening of the surface-
based cin late afternoon/early evening, and presence of the
mixed layer aloft raise concern for early stages of this
potential event in discrete storm development and a supercell
mode. current indications may suggest best chance of this
initial development just to the west of the local area, but
close proximity of the instability gradient will make these
early stages something to closely monitor. besides the potential
of weak cin, lack of a clear synoptic wave to latch onto in
terms of dynamics makes onset time of threat of lower
confidence. the intensification of the low level jet during the
evening and associated strong low level moisture flux
convergence still lead to higher confidence in storms after 23
or 00z.
all severe weather hazards will be possible particularly from
onset of the event through around 06z when best instability will
be in place. in addition to tornado threat, some very large
hail up to 2" in diameter cannot be ruled out given steep lapse
rates aloft and favorable supercell wind profiles. all of the
forecast area has a severe risk tuesday night, with the greatest
chances of these higher end threats currently expected roughly
along and west of in-15 where best juxtaposition of
instability/shear profiles may exist. there remains some
uncertainty as to positioning of the low level
boundary/instability gradient, but in these setups, severe
threats can extend a ways north from the boundary position. the
western portion of iwx forecast area in northern in has been
upgraded to an enhanced risk of severe storms (level 3 of 5).
overall, confidence is on the medium to higher side regarding
severe weather occurring in the local area, but more of a medium
confidence in exact locations (depending on boundary placement)
and low to medium confidence in onset threat timing (mid
afternoon vs mid evening).
after 06z, the expectation is that boundary parallel wind fields
will allow for congealing storms and gradually lessening of higher
end severe threat potential, and a transition to heavy rain/isolated
wind threat into early wednesday morning as the stronger low level
flow helps to create weak mbe velocities locally. one trend in
guidance has been toward less phasing of pacific short wave and cut-
off sw conus upper trough, allowing for slightly more
progression of low level features into wednesday and instability
axis being shunted se of the area by midday. this should act to
keep main severe threat southeast of the local area during the
day wednesday, but a concern for pockets of heavier rain will
shift across southeast areas early wednesday am.
no major changes were made to the long term period as a very active
eastern pacific pattern continues with several short waves moving
across the region with brief episodes of enhanced pacific origin
moisture. given progressive nature of these successive short waves
and strong baroclinicity, confidence in track/precip types is
low at this time but periodic higher chances of rain and snow
will continue thursday into early next week. after brief warmup
for friday. temps should cool back to more seasonable levels for
weekend with indications of below normal winter-like temps
toward day 7-8.
&&
.aviation /06z tafs through 06z tuesday/...
issued at 538 am edt mon mar 9 2026
a quiet and dry day is ahead with no changes needed for the 12z
tafs. southwest winds may frequently gust as high as 20-25 kts
today (especially this afternoon and evening) as a tightening
pressure gradient develops over the great lakes. winds diminish
after sunset tonight.
&&
.iwx watches/warnings/advisories...
in...none.
oh...none.
mi...none.
marine...small craft advisory until 2 pm edt this afternoon for lmz043-
046.
&&
$$
discussion...marsili
aviation...johnson