Area Forecast Discussion

FXUS63 KIWX 182021
Area Forecast Discussion
National Weather Service Northern Indiana
321 PM EST Sun Nov 18 2018
Issued at 319 PM EST Sun Nov 18 2018
Shower activity will come to an end early this evening as high 
pressure builds into the area. Lows tonight will drop into the 20s 
and low 30s. Other than a few chances for snow Monday night and 
Tuesday night, expect dry conditions and partly to mostly cloudy 
skies. Highs Monday through Thursday will be in the 30s and low 40s. 
A warm up is expected this weekend, with high temperatures in the 
mid to upper 40s. There are chances for rain Friday afternoon into 
.SHORT TERM...(This Evening through Monday)
Issued at 319 PM EST Sun Nov 18 2018
A surface high pressure ridge will nose its way into the area 
tonight in the wake of an exiting wave and linger into Monday. This 
will keep the short term pretty quiet weather wise. Any lingering
rain/snow showers this afternoon will diminish by early evening. 
Tricky low temperature forecast tonight as we will see a brief 
period of clearing before the cloud cover begins to increase ahead
of an approaching system. Winds will be fairly light as well, so 
would think temps could bottom out pretty quick once the skies 
clear out. North of US 24 lows may fall into the low to mid 20s. 
Areas south will see highs ranging from the mid 20s to around 30F.
.LONG TERM...(Monday Night through Sunday)
Issued at 319 PM EST Sun Nov 18 2018
The broad upper level trough and associated low over Hudson Bay will 
linger over the Great lakes until Thursday, when it finally shifts 
eastward and a high amplitude ridge builds in. Until that occurs, 
we'll deal with a couple of shortwaves rotating around the upper low 
and the subsequent surface troughs/lows. 
The first of these arrives on Monday night, with a weak surface low 
developing over the MN/WI area. This low will drift eastward in time 
and pretty much wash out as it merges with another system lifting 
along the eastern CONUS. The associated cold front moves through our 
forecast area, bringing chances for precipitation-especially along 
and north of US 30. This will be in the form of all snow, with the 
exception of locations close to Lake Michigan where the temps are in 
the mid 30s early in the evening. In the wake of the cold front, 
850mb temps drop to around -10C and winds become more northerly. 
Some of the models suggest a lake effect response with this but I 
have lower confidence given moisture dwindles pretty quickly, and 0-
2km delta theta-e values stay above zero K/km. Kept chance to 
slight chance pops for now-ending by 12z Tue.
High pressure centered over the central plains will build into our 
area during the day Tuesday and linger through the evening. High 
temperatures will be in the 30s. Meanwhile, surface low pressure 
over the canadian prairie takes a dive southeastward as it deepens, 
crossing eastern Upper Michigan around 06z Wed, and reaching the 
lower Great Lakes by 18Z Wed. This will bring yet another cold front 
across the CWA Tuesday night, but it will be pretty weak given most 
upper level support is in central Michigan. Moisture is fairly 
limited as well. Best shot for snow will be mainly north of the toll 
Precipitation chances come to an end for the region Wednesday, with 
a 1040 hPa sfc high building into the Great Lakes. This high will 
gradually drift towards the eastern seaboard through Friday 
afternoon in advance of another low pressure system developing in 
the central Plains. Thanksgiving travelers will be grateful to 
know that weather Wednesday into early Friday morning will be of 
little concern with partly to mostly sunny skies and highs in the 
mid-upper 30s and low 40s. 
Unfortunately, the forecast from Friday through the weekend is one 
of low confidence, especially with respect to precipitation 
chances/timing. The good news is-if you are traveling Friday 
afternoon or this weekend, the precipitation type should be in the
form of rain. Fans of warmer weather will be happy, as we'll see 
high temperatures rising into the mid to upper 40s during this 
The problem is that models are showing significant differences in 
the timing and location of even larger scale features. For now, have 
the best chances for rain Friday evening into Saturday afternoon. 
Confidence in any precipitation occurring Sunday is low. Consensus 
pops were way overdone, so cut them down to about 30% and confined 
them to the western CWA for now.
.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
Issued at 1240 PM EST Sun Nov 18 2018
The jet streak that enhanced the snow band across northern IN is 
exiting the region this aftn. Latest radar trends show the snow 
band pushing esewd into OH with KFWA still reporting MVFR vsbys. 
Expect the snow to mainly end mid aftn at KFWA with perhaps 
lingering flurries. Satellite imagery has shown KSBN in temporary 
clearing but anticipate this to fill in a cu field has been 
developing over nw IN early aftn. As winds become nwly later 
today expect improving cigs and vsbys later tonight as drier air 
filters into the region.
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