Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 230048

Area Forecast Discussion
National Weather Service Northern Indiana
848 PM EDT Sun Jul 22 2018

Issued at 845 PM EDT Sun Jul 22 2018

Expect scattered showers through this evening as a low pressure
system lingers overhead. On Monday there are additional chances
for showers and storms, mainly over northwest Ohio. Otherwise,
expect mostly cloudy skies. Lows tonight will range from 59 to 64.
Highs Monday will be in the middle to upper 70s, coolest near
Lake Michigan. Drier conditions are expected Tuesday into
Thursday, with partly to mostly cloudy skies and highs in the 80s.


.SHORT TERM...(This Afternoon through Tuesday)
Issued at 204 PM EDT Sun Jul 22 2018

Weak surface based instability, ample boundary layer moisture, and
ascent provided by an approaching pv anomaly from the northeast
(yep, from the northeast. Late July?) will keep scattered
showers/isolated storms going late this afternoon mainly along/south
of US 30 in Indiana. Cooler and more stable/dry low level air now
just reaching our northeast zones will spread southwest into the
rest of the forecast area this evening.

The vigorous disturbance rotating west into Lake Huron and central
MI this afternoon will help refocus/reorient the mid level trough
axis (possibly closing back off at 7/5H) back west over the local
area by later tonight and Monday. This will keep clouds and somewhat
cool conditions in place, with stable airmass and weak convergence
limiting shower coverage/intensity to light iso-sct showers at best.
The one exception could be in the our far east
(Lima/Ottawa/Napoleon) where a heavier shower could sneak in late in
the day near the sfc portion of the trough.

The above mentioned pv center and associated deeper moisture will
settle southeast toward the Eastern OH/TN Valleys by Tuesday. Weak
ridging will settle into areas west of I-69 behind this feature
resulting in dry/warmer conditions. There remains a low chance for
iso-sct afternoon convection to the east as a weak low-mid level
trough axis remains left behind amid increasing diurnal instability.


.LONG TERM...(Tuesday Night through Sunday)
Issued at 204 PM EDT Sun Jul 22 2018

Shear/moisture axis will finally get a slight bump off to the east
by Tuesday night/Wednesday in advance of an approaching Upper
Midwest shortwave trough. The result will be dry conditions and what
should be the warmest day of the 7 day forecast on Wednesday. A cold
front is then progged through on Thursday in response to a round of
height falls through the Great Lakes region. Limited moisture
return/large scale support and poor diurnal timing favors nothing
more than a low (10-20%) PoP with the fropa at this fcst range.
Broad troughing/suppressed height field then supports a
cooler/mainly dry pattern Friday into next weekend.


.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 839 PM EDT Sun Jul 22 2018

Primarily VFR conditions through the forecast period, save for
late morning MVFR ceilings owing to higher dewpoint depressions
with cu development after sunrise.



LONG TERM...Steinwedel

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