Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 300643

Area Forecast Discussion
National Weather Service Indianapolis IN
243 AM EDT Sun Apr 30 2017

The LONG TERM Section has been updated below.


Issued at 231 AM EDT Sun Apr 30 2017

A Warm front across Central Indiana will lift north
today...allowing a warm and humid air mass to surge into the
state. As the front passes upper level weather
disturbance will generate showers and storms today. Some of the
showers and storms could produce heavy rain.

As the low over the southern plains begins to move toward the
western Great Lakes will drag a cold front toward
Indiana. This will once again bring chances for more showers and
storms tonight.

The cold front will cross Indiana early on Monday
morning...bringing an end to the heavy rain threat. However light
showers will still be possible as the new work week starts as low
pressure remains across the Great Lakes and Indiana.

A cool and somewhat wet work week lies ahead.


.NEAR TERM /Today/...

Issued at 231 AM EDT Sun Apr 30 2017

Surface analysis early this morning shows deep low pressure in
place over NE Oklahoma...with a warm front stretching northeast
across to central Illinois and central Indiana. Water vapor
imagery shows a plume of moisture riding streaming northward
across Missouri toward Illinois and Indiana.

Confidence again remains very high today to rain...some of which
could be heavy at times. Models are in good agreement lifting the
warm front northward today...aided by an upper level short wave
that was ejected from the deep upper low to the southwest. As
this wave passes across Indiana this morning...another round of
showers and storms are expected. some producing heavy rains. Time
height sections show a deeply saturated column today with
excellent lift. Forecast soundings are also in
agreement...indicating deep saturation and pwats still over 1.7
inches. The 305K GFS Isentropic surface shows excellent lift
again today...with specific humidities in excess of 9 g/kg.
Finally...radar upstream shows quite the massive area of showers
and storms Over Missouri and Arkansas...poised to pushed northeast
within the flow. Thus will continue toward 100 pops today...with
best chances expected during the morning hours with the arrival of
showers and storms from the southwest. Given the expected rain
today will trend highs cooler than MAVMOS...closer to the 3

Given the expected rain...the ongoing flash flood watch is in good


.SHORT TERM /Tonight through Tuesday Night/...

Issued at 231 AM EDT Sun Apr 30 2017

More Active weather is in store tonight. The GFS suggests the deep
upper low over Kansas will continue to pull northeast...and drag a
cold front across Indiana during the overnight showers. Plenty of
moisture should be in place across Indiana as the warm front
should be north of Central Indiana and dew points will surge in to
the 60s amid southerly gulf surface flow. Forecast soundings sing
a similar tune...showing deep saturation through the evening
hours along with the continued very high pwats over 1.6 inches.
Thus will again trend toward 100 pops...particularly during the
evening hours when best influence from the front appears.

GFS shows dry slot intruding across Central Indiana on
the deep low spins to the northwest. Broad cyclonic flow looks to
remain in place across the area on Monday and Monday night. The
dry slot should lead to a dry start to Monday...however the models
suggest the upper low sags a bit southeast by afternoon and wrap
around moisture should arrive across the state. Forecast soundings
by late afternoon Monday and Monday night suggest trapped strato-
cu. With convective temps in the lower light rain showers
in the afternoon and evening cannot be ruled out. THus will trend
toward some low pops at those times.

GFS suggests the upper low lifts completely north of Indiana by
Tuesday morning as a weak ridge of high pressure builds in its
wake. Thus with a lack of upper support and the models trending
toward a dry column...will trend toward a dry forecast on Tuesday
and Tuesday night...working a blend on temps.


.LONG TERM /Wednesday Through Saturday/...
Issued at 242 AM EDT Sun Apr 30 2017

Ensembles continue to key in on an upper trough that is expected to
move across the area during the middle and later portions of the
week. There are still some timing and intensity differences among
the individual members, but overall the spreads are lessening. Most
of the ensembles take the associated surface low through the
Tennessee Valley, keeping the local area in the cool sector.

Will keep PoPs in the forecast for the Wednesday to Friday period
to cover the passage of the upper trough. A few of the slowest
members suggest there may be a lingering shower threat into
Saturday as well, but these solutions are outliers at this time.


.AVIATION /Discussion for 300600Z TAF Update/...
Issued at 1236 AM EDT Sun Apr 30 2017

Poor flying conditions expected within rain and storms otherwise
VFR conditions are likely for much of the period.

Convection will continue to impact the terminals overnight as a warm
front lingers across the region. Restrictions will be possible
within any showers or storms. The warm front will lift back north
during the predawn hours and into the day Sunday in response to low
pressure tracking out of the southern Plains and into the mid
Mississippi Valley. Storms should once again diminish in coverage by
late morning/midday as the nocturnal low level jet weakens and the
warm front lifts into northern Indiana. Winds will veer to a more
S/SE direction in response to the front lifting north.

Renewed storm development is expected during the afternoon and
especially the evening as the low tracks into the Great Lakes with a
cold front moving into the area. Could see winds become gusty during
the evening with the approach of the front. Very likely to see
another round of strong to locally severe convection with the front
during the evening...but too early to address specific impacts in
the terminals at this time.


Flash Flood Watch through Monday morning for INZ021-028>031-



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