Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 171020

Area Forecast Discussion
National Weather Service Northern Indiana
620 AM EDT Tue Apr 17 2018

Issued at 303 AM EDT Tue Apr 17 2018

Flurries will gradually taper off this morning with dry conditions
expected by afternoon and highs generally in the upper 30s to low
40s. Highs will be warmer tomorrow but there is a chance of light
rain in the afternoon. This rain could end as a period of light snow
early Thursday morning but little to no accumulation is expected.
The rest of the period will be quiet and dry with temperatures
slowly returning to normal.


.SHORT TERM...(Today and Tonight)
Issued at 303 AM EDT Tue Apr 17 2018

Large negative height anomaly will begin to pinwheel out of the area
today and signal an end to nuisance snow showers. One more sheared
vort max will push through southern Michigan this morning and
maintain some flurries generally north of US-30. Steadily increasing
subsidence and dry air advection (particularly by late morning) will
limit precip rates/accumulation and support completely dry
conditions by afternoon. Also expect decreasing clouds through the
day and high April sun should push most locations to around 40F by
late afternoon despite little/no WAA and thermal profiles similar to
yesterday. The exception may be in far N/NE where clouds linger
longer and 925mb temps remain near -5C. Nearly ideal radiational
cooling conditions for at least a time overnight with surface ridge
axis sliding straight through the CWA and mostly clear skies. Leaned
toward cooler raw guidance with mid/upper 20s for most locations.


.LONG TERM...(Wednesday through Monday)
Issued at 303 AM EDT Tue Apr 17 2018

Main focus for the long term will be robust midlevel wave that
crosses the southern Lakes on Wed and sets up another period of
cyclonic NNW flow upstream of redeveloping New England closed low.
00Z deterministic and ensemble runs have trended further south with
track of associated surface low. This results in cooler temps and
better precip chances and have trended the forecast in that
direction. Lowered Wed high temps significantly and may need even
further cuts. Best forcing/precip will be tied to deformation band
in left exit region of mid/upper level jet. That deformation zone is
still expected to remain just north of our CWA...but we will get
clipped (especially in N/NW zones) as it pulls ESE Wed night. Early
Thu morning will be the period to watch for possibility of a quick
burst of snow...but very marginal thermal profiles and warm ground
would suggest low accumulation/impact potential. Chance for
isolated, light rain/snow showers will then continue through late
Thu morning but subsidence and dry air quickly build and doubt there
will be anything measurable after 12Z.

Rest of the long term looking exceptionally quiet as split flow
develops and leaves our region with persistent high pressure and dry
conditions. Temps will start off well below normal on Thu but begin
a slow and steady crawl back toward normal by early next week.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning)
Issued at 618 AM EDT Tue Apr 17 2018

Flight conditions may tend to bounce around between high MVFR and
low VFR through the morning as lake enhanced flurries continue in
cold wnw flow. Drier air makes better inroads late morning and
beyond with dry/VFR conditions anticipated. Westerly gusts up to
25 knots will once again be common today, becoming light/variable
tonight as sfc ridging builds in.


LM...Small Craft Advisory until 5 PM EDT this afternoon for LMZ043-




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