Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 191805

Area Forecast Discussion
National Weather Service Northern Indiana
105 PM EST Sun Feb 19 2017

Issued at 100 PM EST Sun Feb 19 2017

Unseasonably mild conditions will continue through much of the
upcoming week. Weak winds associated with a departing ridge of
high pressure will likely lead to fog formation once again
tonight, with a potential of some dense fog late tonight into
early Monday morning. Dry conditions will continue through Monday
afternoon, but rain will become likely Monday night into early
Tuesday. There is another chance of rain Wednesday as a system
tracks north of the area, but the greater chance of showers and a
few thunderstorms is expected by Thursday night and Friday as a
stronger storm system takes shape across the middle of the
country. Wednesday is expected to be the warmest day of the week,
with highs reaching into the 65 to 70 degree range. Low
temperatures tonight will range from the mid 30s to lower 40s.
High temperatures on Monday will range from the mid to upper 60s
across northwest Indiana, to the mid to upper 50s across south
central lower Michigan.


.SHORT TERM...(Today and Tonight)
Issued at 424 AM EST Sun Feb 19 2017

Weak cdfnt extending sw from low over srn Quebec has stalled out
over our cwa and will dissipate this morning as ridging builds in
from the west. In the meantime, low level moisture advecting ne to
the south of the front has resulted in a rather large area of
stratus and fog that was overspreading our srn counties.
Diminishing wind field associated with the ridge will result in
slow erosion of stratus today. Latest HRRR suggests the
stratus/fog will reach as far north as Route 30 early this morning
and then slowly diminish late morning and early afternoon. Still
expect sufficient heating for most of the cwa to reach the 60s
today, but did lower highs a couple of degrees across the south
due to the clouds influence this morning. Light gradient will
allow a lake breeze to develop nw holding temps there in the 50s.
Sfc ridge will move east of the area tonight with weak waa
developing. Still, mainly clear skies will provide decent
radiational cooling allowing temps to fall to the mid to upr 30s
over most of the area. Some patchy fog may develop again but held
off adding to fcst attm.


.LONG TERM...(Monday through Saturday)
Issued at 424 AM EST Sun Feb 19 2017

Deep trof over the swrn U.S. will lift ne to the upr Midwest on
Monday. WAA ahead of this trof and increased gradient mixing with
S-SE flow should result in temps reaching the mid to upr 60s over
most of the area but only in the upr 50s ne where gradient flow
should back more easterly due to Lake Erie lake breeze influence.
The wkng upr trof and associated weak cdfnt will move across our
area late Monday night and/or Tue morning causing some showers as
it moves through. Still sgfnt timing differences in models on
speed of this system which precludes higher pops in this
timeframe. Flow behind this wkng trof quickly becomes zonal with
only brief CAA transitioning to WAA by Tue aftn. Aided by an
unusually warm start to the day, highs expected in the 60s.

Weak shrtwv/cdfnt movg east in the zonal flow from the nrn plains
will provide waa and decent swly low level winds Wed. This should
result in another day with near record high temps in the mid to
upr 60s across the area. The front should drop into our area Wed
night and stall out as a stronger low develops over KS. Only
slight chances of rain as the front moves in, but rain chances
increase Thu as convergence and over-running develop along the
strengthening stalled boundary. The stalling front should result
in a little cooler temps Thu, but still well above normal.

Strong low expected to lift ne to the wrn grtlks Fri and into
Quebec Sat causing showers and possibly thunderstorms in our area
Thu ngt and Fri. Showers will end Friday night as the cdfnt moves
east of our area, hwvr, some wrap around rain showers
transitioning to light lake effect snow showers psbl into Sat nw.
Temps will be much colder Saturday, but, only near normal for late


.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
Issued at 100 PM EST Sun Feb 19 2017

Fog and stratus have diminished across the terminals early this
afternoon with VFR conditions expected to persist through early
evening. Weak gradient associated with the ridge of high pressure
and large lake/land thermal differentials should support lake
breeze formation and eventual preference to west-northwest wind
directions at KSBN later this afternoon. Sfc ridge axis will
depart to the east tonight allowing for weak low level return flow
and some re-orientation of low level theta-e gradient which will
likely become positioned from southwest lower Michigan into
northwest Ohio overnight. Weak flow and very favorable moisture
profiles with height should support another night for fog
formation for both terminals. Given medium to higher confidence in
this scenario did trend terminals to IFR/LIFR vsbys in fog
overnight into early Monday morning. Conditions should begin to
improve after the 15-16Z timeframe Monday morning.





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