Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 270543

Area Forecast Discussion
National Weather Service Northern Indiana
143 AM EDT Mon Mar 27 2017

Issued at 127 AM EDT Mon Mar 27 2017

Rain chances will increase later this afternoon and tonight as
another system approaches from the west. An isolated thunderstorm
is also possible tonight. Dry conditions are expected from
Tuesday afternoon through Wednesday evening before another storm
system brings increasing chances of rain for late Wednesday night
through Friday. High temperatures today will range from the lower
to mid to upper 50s across southwest lower Michigan, to the lower
to mid 60s across northwest Ohio. Lows tonight will range from
then lower 40s to around 50.


.SHORT TERM...(This Evening through Monday)
Issued at 325 PM EDT Sun Mar 26 2017

Agitated cyclonic flow will continue to result in likelihood of
showers with a few embedded thunderstorms this afternoon/early
evening. A lull in precip chances is then expected for later this
evening through Monday morning before precipitation chances ramp up
once again Monday afternoon/night.

A lead upper level short wave will continue to lift north-northeast
across the southern Great Lakes this afternoon. Rain showers have
diminished in coverage somewhat over past few hours to a more
scattered-numerous nature. Looking upstream, a smaller scale and
more compact upper vort max associated with parent upper level
circulation should work across northern Indiana this evening. Weakly
confluent low flow/moisture convergence downstream of this vort max
should yield a weak instability axis across north central Indiana
this afternoon. These factors should cause some enhancement to
shower and iso-sct tstorm coverage later this afternoon. Weak
instability will also be aided by differential temperature advection
as pocket of colder upper level air builds northward from the
Ohio Valley into far northeast Indiana/northwest Ohio. Will keep
likely rain shower/slight chance to chance thunder PoPs going
through early evening. Passage of this second vort max later this
evening should result in mainly dry conditions later this
evening/overnight with slow southeast sagging of frontal boundary
from mid MS Valley across the southern Great Lakes. Did add
mention of some marine fog and across far northern locations later
tonight into early Monday, with some inland potential with fog in
closer proximity to this weak boundary.

Upper level short wave ridging will result in a mainly dry Monday
morning, but progressive nature to this pattern and fast approach of
next upper level short wave will allow for increasing isentropic
lift to develop from west to east Monday afternoon. Have continued
idea from previous forecast with west to east PoP ramp up Monday,
particularly later Monday afternoon into Monday evening. Another
1 inch plus PWAT axis will advect across the region Monday
afternoon via a modest 30-40 knot southwesterly low level jet.
Combination of column moisture on the higher end for late March
and approaching short wave should allow for expanding rain
coverage into Monday evening. Difficult to discount at least
isolated thunder potential particularly southern half of the area
given track of short wave and low level features. Given rainfall
of past few days, and potential for some convective rains Monday
evening, may need to monitor for some ponding/minor flood


.LONG TERM...(Tuesday through Sunday)
Issued at 325 PM EDT Sun  Mar 26 2017

Monday night system will be departing the area Tuesday, with
gradual southward advance of drier low level air. Residual low
level moisture/inversion may be enough to prolong cloud cover a
bit longer than expected, with better chances of more widespread
decrease in cloud cover by Tuesday night/Wednesday as low level
drying and synoptic scale subsidence become more pronounced.
Latest guidance continues to support the idea of continued active
progression of short waves late week/next weekend in cut-off
pattern. Medium range guidance continues to advertise more
amplitude with Thursday short wave, which may allow TROWAL feature
to prolong rain chances for much of Thursday-Friday. Forecast
soundings do suggest perhaps a low end potential of a very brief
period of wintry mix at precip onset early Thursday, but with
large low level dew point depressions during this brief period of
wintry mix potential, will keep precip as all rain. Temps are
expected to remain at or above seasonable norms through next


.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 127 AM EDT Mon Mar 27 2017

Shower activity has moved east of the terminal sites tonight
with residual drizzle at times. Currently MVFR cigs at both
sites with surface obs show MVFR and IFR cigs still upstream.
The stratus deck should keep cigs from tanking but otherwise
ideal conditions for fog development with light winds...low level
moisture and drying aloft. Cigs will trend up later
today but next wave quickly approaches late afternoon into early
evening and KSBN likely to see rain and lowering CIGS/VIS around
00Z Tue and KFWA around 02Z Tue.




SHORT TERM...Marsili
LONG TERM...Marsili

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