Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 140920

Area Forecast Discussion
National Weather Service Northern Indiana
420 AM EST Tue Nov 14 2017

Issued at 418 AM EST Tue Nov 14 2017

Partly to mostly cloudy skies are expected today, with highs in
the 40s. Otherwise, areas of dense fog are expected for many
areas through late this morning. Freezing fog is possible. Be
careful if driving. The combination of fog and temperatures at or
below freezing may create slick spots on the roads. Additionally,
sudden reductions in visibility are expected. Slow down, use your
low beam headlights, and leave plenty of distance ahead of you.


.SHORT TERM...(Today and Tonight)
Issued at 418 AM EST Tue Nov 14 2017

Dense fog advisory remains in effect for mainly our central CWA as
visibilities linger around 1 mile or less for many locations. Some
areas are seeing visibilities of 1/4 mile or less as of 9z. Freezing
fog is also being reported, though with warmer road temps not
sure how much of an impact this will cause to travel. Still, think
its reasonable to mention the potential for slick spots on the
roads this morning due to the combination of fog and temps below
freezing. At this point don`t think I`ll be expanding the dense
fog advisory, but monitor closely for updates. Even outside of the
advisory area, there is potential for some patchy dense
fog/freezing fog, so have handled that with an SPS for now.

Beyond the fog concern, quiet weather is expected today, with a mix
of sun and clouds expected. Highs will rise into the mid-upper 40s
and low 50s if clouds clear out as well as planned. If not, probably
will see highs in the low to mid 40s, especially in the northeastern
portions of the CWA.


.LONG TERM...(Tuesday Night through Monday)
Issued at 408 PM EST Mon Nov 13 2017

Slight delay with respect to Wednesday convection per good model
agreement with only low chance mention late Tue night western CWA.
Low MUCAPE on order of 100-250 j/kg sufficient for continued
inclusion of slight chance thunderstorms given strong kinematic
field/nose of low level jet riding eastward along I70 corridor, near
KSTL at 09 UTC to west central OH by about 18 UTC. Added thunder
mention with Friday mention as well given markedly deep/progressive
mid level trof passage through CONUS.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 110 AM EST Tue Nov 14 2017

Fog will be the primary aviation forecast concern through mid
morning. Eastward departure of low cloud deck has been followed
by the development of areas of fog across much of northern Indiana
this evening. Despite lingering mid/high clouds, some patchy
dense fog has also formed. As previous discussion mentioned, just
enough trapped low level moisture beneath inversion has allowed
for some decent radiation fog formation despite rather marginal
looking profiles to support dense fog formation. Hires guidance
depicts corridor across north central to northeast Indiana as most
favored for dense fog development overnight. Of the two
terminals, confidence in longer duration significant vsby
restrictions due to fog is higher at KFWA, with some questions as
to some low level flow increases overnight across northwest
Indiana on periphery of anticyclone that might tend to favor a
combo fog/stratus setup. Continued a fairly conservative IFR
approach at KSBN with these uncertainties, but will monitor
trends and may need to amend to a more pessimistic idea. Other
than IFR/LIFR conditions in fog, remainder of the forecast should
be quiet and VFR from late morning through tonight. Conditions to
become more active again just beyond this forecast valid period as
low level moisture return increases in advance of next system
that will bring rain late Tuesday night into Wednesday.


IN...Dense Fog Advisory until 9 AM EST /8 AM CST/ this morning for

MI...Dense Fog Advisory until 9 AM EST this morning for MIZ078>081.

OH...Dense Fog Advisory until 9 AM EST this morning for OHZ001-004-



LONG TERM...Murphy

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