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Displaying AFOS PIL: AFDIWX Received: 2018-03-13 10:15 UTC

FXUS63 KIWX 131015

Area Forecast Discussion
National Weather Service Northern Indiana
615 AM EDT Tue Mar 13 2018

Issued at 358 AM EDT Tue Mar 13 2018

Another round of numerous snow showers is expected across the area 
today and into this evening. Accumulations around an inch are 
possible in the heavier showers. Highs today will be in the mid 30s. 
Dry conditions are expected tomorrow through the weekend with 
seasonably cool temperatures.


.SHORT TERM...(Today and Tonight)
Issued at 358 AM EDT Tue Mar 13 2018

Lake effect snow struggling immensely this morning. This is due to 
more substantial ridging/subsidence in between shortwaves than 
previously expected and a slightly more backed wind profile that has 
cutoff good Superior connection and limited fetch over Lake 
Michigan. Correspondingly...forecast soundings are much drier near 
the surface and aloft. Also little...if any...convergence over the 
lake given cold water and moderate flow. Surface winds actually 
slightly divergent earlier overnight...resulting in no measurable 
precip. A few more intense cells have managed to develop over 
southern Lake Michigan and move inland during the last few hours. 
Some decent rates within these cells as they capitalize on moderate 
instability/inversion heights but they remain disorganized with very 
little convection (even cloud cover) noted upstream. These heavier 
showers should not last very long in any one location and suspect 
lake effect will remain disorganized/cellular through the day with 
limited accumulation. 

Do still expect numerous snow showers to develop across the entire 
CWA today as next shortwave approaches and re-activates 
moist/unstable boundary layer. Conditions will be similar to 
yesterday. Temps still looking colder than yesterday but not as cold 
as previously suggested. Still cold enough for snow as dominate 
precip type but more melting now possible (especially on roads) 
given highs in mid 30s. Quick accums of around an inch are possible 
in the heavier showers. These heavier showers will remain scattered 
but could occur across the entire CWA given the degree of low level 

A second shot of lake effect may then be possible this evening but 
many of the same organizational limitations from this morning will 
be present again. Inversion heights only around 6-7 kft at best and 
dropping rapidly through the night. Theta-e profiles also 
increasingly stable after 03Z. Potential is there for brief, 
stronger band(s) to develop 00-03Z (per latest HiRes-ARW) but that 
potential appears low. Snow showers will likely shut off entirely by 
09-12Z Wed morning.

This leads to a difficult predicament vis-a-vis inherited winter 
weather advisory. It will snow and there will almost certainly be 
travel impacts in the heavier snow showers but snowfall totals in 
those counties may struggle to get above an inch through this 
evening with equal if not greater impacts to counties away from the 
lake. Simply cannot justify holding onto an advisory for 1-2" at 
best...especially for an area that has already seen over 80" of snow 
this season. Will cancel advisory and handle any stronger cells with 
SPS's as needed.


.LONG TERM...(Wednesday through Monday)
Issued at 358 AM EDT Tue Mar 13 2018

Rest of the forecast period exceptionally quiet with next decent 
chance of precip not until Mon/Tue of next week. A few more 
shortwaves will dive into the eastern Lakes Wed-Fri but appear weak 
enough and east enough to prevent measurable precip in our CWA. A 
few flurries may be possible Thu morning but highly unlikely. Latest 
deterministic models consistent in showing a dry/subsident 
environment locally with elongated surface ridge building into the 
region Thu-Sat. Will have to keep an eye on initial wave shearing 
east on Sat. Models have been struggling with evolution of large 
western CONUS negative height anomaly and downstream effects. This 
wave could clip our area Sat...but held with dry conditions for now. 
Temps do remain on the chilly side through the week with a 
persistent northerly component to the flow and no good SW flow/WAA 
for the foreseeable future.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning)
Issued at 614 AM EDT Tue Mar 13 2018

Vort lobe rotating southeast through northern Indiana and a moist
boundary layer will generate scattered to numerous snow showers 
again today, especially in KSBN this morning through early 
afternoon and KFWA during the afternoon hours. Flight conditions 
will vary as a result with brief LIFR/IFR conditions possible with
heavier snow showers. Otherwise, daytime diurnal heating will 
allow winds to increase later this morning and afternoon with 
gusts near 20 knots expected.


LM...Small Craft Advisory until 11 AM EDT Wednesday for LMZ043-046.




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