Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 150724

Area Forecast Discussion
National Weather Service Northern Indiana
324 AM EDT Fri Sep 15 2017

Issued at 248 AM EDT Thu Sep 14 2017

Areas of fog, possibly dense in some locations will remain
possible through sunrise before lifting. Mostly sunny skies will
allow highs to reach the upper 70s to lower 80s with even warmer
temperatures into the weekend. The next chance of showers and a
few thunderstorms will arrive for Sunday afternoon.


.SHORT TERM...(Today and Tonight)
Issued at 248 AM EDT Fri Sep 15 2017

Main focus will be fog coverage and possible impacts on the
morning commute.

Thus far, a handful of observation sites have shown brief drops in
visibility from what is likely rather shallow ground fog. 7Z obs
showed 3 sites in the quarter to half mile range. Most locations
were now at or below their crossover temperatures in the upper 50s
to lower 60s, suggesting that fog may begin to increase in
coverage over the next several hours. Past grids had patchy fog
mentioned NW third with areas of fog after 9Z in SE 2/3rds of the
area. See no reason to deviate for now and potential for dense
fog still exists. No headlines will be issued at this time, but
may be needed over the next couple of hours.

Any fog should dissipate quickly Friday morning with the
continuation of above normal temperatures in store. Somewhat
warmer overnight lows Friday night and a slight increase in
boundary layer winds should reduce fog potential for the area.


.LONG TERM...(Saturday through Thursday)
Issued at 248 AM EDT Fri Sep 15 2017

Above normal temperatures look to dominate the period as trough to
the west digs into the plains and generally remains west of the
region. A weak cool front will attempt to pass through the area
with a chance of showers (thunder?) Sun afternoon into Sunday
night. Models agree on this eventually washing out Monday with
trough digging even further. Weak ripples in the trough could
bring sporadic shower chances to the area into the middle of the
week as dewpoints reach into the 60s providing at least some
limited instability for the waves to interact with. With the
longwave pattern not set to modify much, no more than slight chc
to chc pops warranted at this point.


.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1240 AM EDT Fri Sep 15 2017

Main concern conts to be vsbys this morning. Wk pressure gradient
over the area combined with shallow low level moisture should
result in fg/br developing early this morning. Latest model
guidance conts to suggest low level moisture a little more
plentiful and pressure gradient a little weaker at fwa than sbn,
so previous tafs of lower visibilities at fwa still seem
reasonable and no sgfnt changes planned with tempo ifr at sbn and
lifr at fwa expected. Given shallow moisture over the area,
fog should burn off quickly after sunrise, followed by just sct
diurnal cu later today. Southerly pressure gradient expected to be
a little stronger tonight which should keep vsbys from dropping
as low as this morning, though at least some mvfr restrictions
still psbl after 06z.




LONG TERM...Fisher

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