Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 230730

Area Forecast Discussion
National Weather Service Indianapolis IN
330 AM EDT Mon Apr 23 2018

The LONG TERM section has been updated below.


Issued at 317 PM EDT Sun Apr 22 2018

Most of the short term period will be cloudy and rainy as a
closed low tracks from the Central Plains through the Tennessee
and Ohio Valleys. The strongest dynamics should stay south of
central Indiana though, so will continue to only keep rain
showers in the short term forecast for now. After a lull in
activity around mid-week with high pressure, the next system and
associated cold front will bring additional rain chances and
cooler temperatures Thursday night through Friday.


.NEAR TERM /Tonight/...
Issued at 919 PM EDT Sun Apr 22 2018

Area of rain over the southwest sections of the forecast area is
gradually drying up as lift diminishes. Short term model guidance
suggests little in the way of significant lift over the area until
about 230800Z, when more organized lift, and resultant better
precipitation threat, moves in from the south.

Based on above, will delay the higher PoPs until the early morning
hours of Monday, and also push the northern extent of the PoPs a
little farther south.

Previous discussion follows.

The main focus of the near term period will be rain chances mainly
across the southern half of central Indiana.

Current IR sat imagery shows an area of low pressure situated over
the Lower Mississippi Valley with a large plume of Gulf moisture
being ejected northward ahead of it. This correlates well with the
current radar imagery, too, which shows all returns over Kentucky
and Illinois. As the aforementioned low shifts east/southeastward
tonight though, that moisture will start entering central Indiana
from the south. As a result, stuck close to the latest blended
initialization which matches this trend well. Rain chances will
gradually increase throughout the night from the south with
definite chances across the southernmost counties by daybreak.
This is a moderate to high confidence forecast. Meanwhile,
temperatures tonight will be at or slightly above normal with
readings in the mid 40s (N) to low 50s (S).


.SHORT TERM /Tomorrow through Wednesday/...

Issued at 317 PM EDT Sun Apr 22 2018

Focus for the short term period will remain on the system
mentioned in the near term period.

Rain chances will stay in the forecast from tomorrow through
Tuesday as the low takes a northeastward jog toward the Tennessee
and Ohio Valleys.

The highest chances for rain across central Indiana will be across
the southern and eastern portions of the forecast area mainly from
Monday morning through Monday evening. A strong low level jet
ahead of the system will help to generate the rain, but again the
best forcing will remain across Kentucky. Nonetheless, it should
be just enough for some decent rain showers early Monday.

As the system moves farther into the Ohio Valley on Tuesday, rain
will taper off across central Indiana and subsidence will increase
with approaching high pressure. So, most of the area will be dry
by Wednesday. This, too, is a medium to high confidence forecast.
High temperatures through the period will generally be in the
upper 50s/low 60s with lows in the upper 40s/low 50s.


.LONG TERM /Thursday through Sunday/...
Issued at 330 AM EDT Mon Apr 23 2018

Main focus for the long term will be timing of synoptic features and
resultant QPF.

Although the 00z GFS and ECMWF have some difference in synoptic
waves in the mean eastern trough, confidence is increasing that
Friday and possibly Friday evening will see a shower threat, while
the rest of the period will be dry. Models agree that a frontal
system and upper trough will move through Friday and Friday evening.
After that, the GFS is the fastest of the models and ensemble means
in moving an upper ridge toward the Ohio Valley. With the GFS the
outlier, prefer a blend of the non-GFS.

The approach of the upper ridge will result in warmer temperatures.
The blend has above normal temperatures by Sunday. Confidence on
exact timing is moderate at best, so will not make any changes to


.AVIATION /Discussion for the 230600Z TAFS/...
Issued at 1138 PM EDT Sun Apr 22 2018

Short term model guidance suggests organized lift will begin
moving over the KHUF/KBMG terminals towards sunrise, with the lift
gradually drifting north, reaching the KIND terminal around the
midday hours of Monday. As a result, expecting potential for
mainly light rain to increase at these terminals very late tonight
and on into the daylight hours of Monday.

Ceilings expected to remain in the VFR category at least into the
late morning hours of Monday, owing to continued dry advection
from the east at the lower levels of the air mass. Ceilings may
fall into the MVFR category at the more southern terminals towards
the late morning or midday hours of Monday.

Surface winds 060-090 degrees at 8-12 kts overnight will become
090-120 degrees at 10-14 kts by midday Monday. Occasional surface
gusts around 18 kts possible towards midday as well.




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