Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 220757

Area Forecast Discussion
National Weather Service Indianapolis IN
257 AM EST Thu Feb 22 2018

The LONG TERM and AVIATION Sections have been updated below.


Issued at 306 PM EST Wed Feb 21 2018

Wet pattern continues into early Sunday as a series of short waves
ride northeast from Texas up and across the Ohio and Tennessee
Valleys. Rainfall episodes tonight into early Thursday, Thursday
night into early Friday, and again Saturday and Saturday night
will in combination produce 2 to 5 inches of rainfall across the
area, especially south of I-70. High pressure will clear things
out Sunday and bring dry weather into midweek next week.

Temperatures will remain above normal through the next seven days
with tonight and Thursday the coolest in this period.


.NEAR TERM /Tonight/...

Issued at 306 PM EST Wed Feb 21 2018

As the next short wave lifts out to our southwest, the rain area
will expand northward overnight across central Indiana. Rain
amounts over one inch are projected by both the NAM and GFS for
our southern counties which appears reasonable. Given that these
areas have just today started into the rain and that stream
levels are normal there, we do expect a rise in rivers and
ponding in the usual low lying areas but do not anticipate
significant flooding issues.

Further north from Lafayette to Tipton and Muncie, temperatures
will be approaching freezing overnight and thus the precipitation
expanding north will likely be a mix of snow with mostly rain.
Should air temperatures reach freezing a light glazing of ice may
occur on above ground surfaces. At the moment the ground is much
warmer than the air and the likelihood of the ground reaching
freezing by tomorrow morning is pretty low. Will issue a special
weather statement to cover that possibility but at the moment that
does not appear to be a problem.

Forecast lows are near guidance in the lower 30s north and upper
30s south.


.SHORT TERM /Thursday through Saturday/...

Issued at 306 PM EST Wed Feb 21 2018

Wave 1 exits the area Thursday morning. Again a wintry mix of
precipitation may continue into the first few hours after
daybreak before temperatures are no longer an issue. Temperatures
near guidance were followed ranging from maxs near 40 in the north
to near 50 in the south.

Wave 2 enters the picture Thursday night. Confidence in rain
amounts and the axis of heaviest rain is low given differences
between available models. A lean towards a compromise between the
models with a rain maximum axis between I-70 and the East Fork
White River looks best. Rain amounts from this wave near one inch
appear in line.

The final wave arrives Saturday with strong dynamics and continued
thrust of abnormally high moisture and with it, another inch of
rainfall by Sunday but this axis appears more likely to shift back
to our northern counties.

Thus the current flooding in the Upper Wabash will have a respite
from heavy rains into Saturday while the White and East Fork White
receive the brunt of rains tonight and Thursday night. The end
will result in river flooding, possibly major flooding, for some
stretches of the rivers.

As referenced in the synopsis, the period Thursday through
Saturday will remain warmer than normal with forecast temperatures
a blend of available model data.


.LONG TERM /Sunday through Wednesday/...
Issued at 257 AM EST Thu Feb 22 2018

A much deserved break from the active weather regime of late will
dominate much of the extended as high pressure builds in behind
the departing front on Sunday.

Rain will be east of the forecast area by daybreak Sunday with
deep subsidence poised to overspread the region as the
aforementioned high builds into the Ohio Valley. The highly
amplified flow regime aloft across the country will relax as well
with the deeper moisture fetch shifting well south of the region.

Return flow will develop by midweek as the high drifts away to the
east. While differences exist with strength and track of the
developing surface wave amongst the extended models at this early
stage...consensus growing on low pressure tracking into the
region out of the central Plains Wednesday and Thursday bringing
rain into the forecast area.

Temperatures will remain mild with 50s quite common for highs
through the period as we wrap up February.


.AVIATION /Discussion for the 220900Z TAF Update/...
Issued at 257 AM EST Thu Feb 22 2018

Only minor adjustments needed to account for current trends.
IFR conditions have developed under the rain shield early this
morning and will likely expand through daybreak. Current forecasts
have this handled well.

06Z discussion follows.

MVFR/IFR conditions will continue throughout the TAF period as
rain spreads back northward. Conditions could deteriorate even
further tomorrow night at KIND with LIFR conditions as another
wave brings additional rain. Meanwhile, winds will start out
northeasterly then shift to the southeast through the course of
the TAF period at 5 to 10 kts.


Winter Weather Advisory until 10 AM EST this morning for INZ021-



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