693
fxus63 kiwx 050456
afdiwx
area forecast discussion
national weather service northern indiana
1156 pm est tue feb 4 2025
.key messages...
- freezing rain is expected wednesday night, but some
uncertainty remains with duration and accretion amounts.
- slippery travel conditions are anticipated wednesday night and
thursday morning.
- a wintry mix is expected once again on saturday.
&&
.discussion...
issued at 232 pm est tue feb 4 2025
high resolution guidance has advertised a notable south shift
in the freezing rain risk wednesday night. this does not mean
the freezing rain risk is completely gone from our forecast
area. instead, this southward shift and reduction in forecast
precipitation amounts decreased confidence where fzra will be
most prolonged and where ice accretion will be greatest. in
coordination with wpc, we have decreased forecast precipitation
(and ice) amounts with this forecast package.
this reduction in precip and residence time raises significant
questions with respects to impacts in my northwest forecast area
(e.g. south bend) and my far north (this is in stark contract to
my discussion 24 hours ago). there are some high resolution
scenarios with little to no precip and thus little to no ice
accretion in far southern mi and far northwest in. in contrast,
only a glaze of ice can cause significant impacts. because of
this uncertainty and inherent nuances of fzra events, have held
off on a winter weather advisory one last time.
the southward shift in guidance can be attributed to a few of
things. first, a shallow and less amplified shortwave. second, the
lingering influence of retreating high pressure. third, decreased
poleward moisture transport in the wake of anticipated tennessee
valley warm-sector convection. this certainly throws a wrench in the
forecast where confidence had otherwise been increasing up to this
point.
backing up a moment, a brief period of snow along the southern mi
state line remains in the cards wednesday afternoon. this is
associated with a departing 700-mb jet. this axis of snow has
shifted north slightly. overall, have retained the 20% chance of
snow.
this weekend, a very similar storm track threatens to bring a
wintry mix, including freezing rain, to the forecast area. with
a wrench in the first storm system, i`ll omit any promises for
how this weekend evolves. cooler in the wake of that system,
however, with lake effect snow possible.
&&
.aviation /06z tafs through 06z thursday/...
issued at 1130 pm est tue feb 4 2025
dry air advection out of the northeast was somehow just enough
to be able to scatter out most of the lower clouds under a
rather spectacular subsidence inversion with temperatures aloft
a full 10c warmer than at the base of the inversion. the dry
conditions in the low levels should prevail until around 00z.
even as precipitation develops and lower levels saturate, it
should be some time before ifr clouds are able to develop. with
the warm layer well above +5c, virtually no chance for snow and
not cold enough nor deep enough for sleet, so really solid
support for freezing rain from 02z to 12z.
&&
.iwx watches/warnings/advisories...
in...none.
oh...none.
mi...none.
marine...none.
&&
$$
discussion...brown
aviation...skipper