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fxus63 kiwx 111814
afdiwx
area forecast discussion
national weather service northern indiana
214 pm edt mon may 11 2026
.key messages...
- a frost advisory has been issued for areas along and north of
us-30 with temperatures having a chance to dip down into the
30s. consider taking steps to protect fragile plants.
- showers and scattered thunderstorms will be possible tuesday
evening. the threat for widespread severe weather is low.
- warm to end the work week, but rain will also be possible.
&&
.discussion...
issued at 207 pm edt mon may 11 2026
with a cold front to our south, 850 mb temperatures have been able
to drop down into the low single digits celsius with a few areas
having been able to reach 0c. this may be enough to allow frost
again tonight. three flies in the ointment appear to be increasing
pressure gradient and potential arrival of clouds inhibiting full
radiational cooling between 10 and 12z in our northwest as a low
pressure system arrives. and the third fly is that the winds come
around to the east, which may act like the sweat mechanism that
could cool things or it could moisten things up. not entirely sure.
it does appear that decoupling of the boundary will occur when
interrogating bufkit forecast soundings of the nam. an interrogation
of models indicates that areas near lk mi have the greatest chance
of seeing frost with how dry it gets, but perhaps some of the
counties north/south of the in/mi border have some chance of seeing
some frost as well. given this explanation of confidence of frost
formation, have gone ahead and issued a frost advisory with some
areas along us-30 and south of the toll road maybe having more
patchy frost rather than areas.
otherwise, our dry weather on tuesday will be replaced by unsettled
weather, especially as a moist axis arrives in the evening. model
soundings at the end of the hrrr run are very dry though,
reminiscent of inverted-v type soundings, which need weaker shear to
generate damaging wind gusts in a dry thunderstorm setup. the other
issue is the instability is very weak at only between 500 to 1000
j/kg of mucape. better mid level lapse rates wait to push into the
area until between 6 and 12z tuesday night. as long as the low level
dry air and minimal instability continue to be modeled that way, it
doesn`t really leave much confidence in severe weather potential for
storms arriving near sunset. however, think the strongest chance for
any strong to severe storms would be gusty winds and maybe some
hail, especially if we can moisten quickly overhead, which is what
models are showing. there is some large scale ascent to work with so
that may help.
negative theta-e advection pushes in tuesday night in conjunction
with a cold fropa. given resultant low level lapse rates as the mid
levels cool and low levels warm, and forcing from a deepening upper
low, wouldn`t be surprised to see some isolated showers around. the
trend will be to dry things out though and so the afternoon brings
lower chances for those showers, especially as a lake shadow begins
to form. mid level heights rise wednesday afternoon as surface high
pressure pushes in especially for thursday, leading to a dry day.
positive theta-e advection returns for later friday but it appears
mid level ridging to our east may have to be overcome before rain
arrives. that and that there`s a deepening and stacked upper low
over the northeast conus. because of this blocking, it appears
there`s quite a bit of uncertainty with when and where rain happens
between friday and the weekend. weaker forcing probably also keeps
much of the rain out of the area on friday, especially the
afternoon. i am skeptical of the quick trough evolution on the
ecmwf, which is an outlier, given the upper low over the northeast
conus. perhaps a slower evolution could provide some rain during the
overnight period as the gfs` trough goes negative. better agreement
exists for the sunday period for rain.
&&
.aviation /18z tafs through 18z tuesday/...
issued at 107 pm edt mon may 11 2026
high pressure moving over the great lakes provides tranquil
conditions for this taf period. cannot rule out a stray gust to
20kts at ksbn this afternoon, but so far these gusts have been
limited to the lakeshore. just beyond this taf period is a
chance for -tsra as a cold front approaches.
&&
.iwx watches/warnings/advisories...
in...frost advisory from midnight edt /11 pm cdt/ tonight to 8 am
edt /7 am cdt/ tuesday for inz005>009-012-014-017-018-103-
104-116-203-204-216.
oh...frost advisory from midnight tonight to 8 am edt tuesday for
ohz001-002-004-005-015-016.
mi...frost advisory from midnight tonight to 8 am edt tuesday for
miz078>081-177-277.
marine...small craft advisory until 8 pm edt this evening for lmz043-
046.
&&
$$
discussion...roller
aviation...brown