Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 220316
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1116 PM EDT Fri Apr 21 2017

.UPDATE...
The AVIATION Section has been updated below.

&&

.SYNOPSIS...
Issued at 130 PM EDT Fri Apr 21 2017

High pressure over the Dakotas will give way to a developing storm
system over the southern High Plains in the next 12-24 hours.
mid/upper level jet steam is extending south/southeast over the
Rockies and will extend eastward across the southern Plains/lower
MS Valley tonight. That will develop a positively tilted trough
over the lower MS Valley and associated surface low along the
quasistationary front that extends east/northeast across southern
and east central KY. Low pressure will move along this frontal
boundary over the next 24-36 hours and spread rain/rainshowers
across mainly the southern half of IN as early as tonight and
likely Saturday.

&&

.NEAR TERM /Tonight/...
Issued at 940 PM EDT Fri Apr 21 2017

Latest radar loop was showing decent showers coverage near and south
of Interstate 70 with more solid showers moving in from south
central Indiana. Thus, raised pops to categorical far south and too
the egdge of the slight pops a little bit further north to around
Tipton and Frankfort.

Previous discussion follows...
Issued at 238 PM EDT Fri Apr 21 2017

Timing of rainshowers tonight is a bit challenging as satellite
imagery shows a few convective boundaries has pushed the frontal
boundary southward along the TN/MS/AL border area. But, what
raises the confidence is that the mid/upper level low that will be
developing over the lower MS Valley will develop a surface low
along/just north of the boundary. System will have sufficient
dynamics with it to provide widespread rainshowers north of the
boundary into southern sections of IN later this evening and
gradually spread northward by Saturday morning. Given the clouds
that wil moving over the area, have also brought lows up a few
degrees trending towards the upper 40s.

&&

.SHORT TERM /Saturday through Monday/...

Issued at 238 PM EDT Fri Apr 21 2017

Looks like a period of rainshowers coming to most of central and
southern IN on Saturday. As the mid/upper low develops over the TN
Valley region and swings from a positively tilted system to more
neutral, then will deepen the low at the surface and increase the
coverage of rainshowers through the area. It may also lead to
occasional moderate rainshowers over the southern third of the
area. Currently, projections are just under 1.00 inch across the
southern tier, but would not be surprised to see isolated areas of
maybe up to 1.50 inches on Saturday. Rainshowers will move out of
the area Saturday evening/night with clearing skies allowing
temperatures to fall into the low/mid 40s by Sunday morning.

Sunday will be the start of a period of nice days as temperatures
get back into the mid 60s over the entire area and into the low
70s on Monday.

&&

.LONG TERM /Monday Night Through Friday/...
Issued at 258 PM EDT Fri Apr 21 2017

Ensembles suggest a short wave trough will lift through the western
Great Lakes around the middle of next week. Will keep some PoPs
going from Tuesday night through Thursday to cover this feature.

Otherwise, ensembles indicate upper pattern may become highly
amplified by late next week, with a deep long wave trough centered
over the Rockies and high Plains, and a sharp upper ridge along the
East Coast. Depending on the eventual strength and position of the
upper ridge, the midweek frontal system may stall out or dissipate
over the area by next Friday. Will keep some PoPs in the forecast on
Friday for now, but if upper ridge starts to come in stronger on
later model runs, it may cutoff precipitation potential late next
week.

&&

.AVIATION /Discussion for 22/06Z TAF Issuance/...
Issued at 1116 PM EDT Fri Apr 21 2017

Radar and High Resolution Rapid Refresh suggest the showers will be
isolated or scattered to start, even at BMG. Then, expect widespread
showers to reach at least BMG after 08z. IND and HUF will be near
the northern edge. The shower threat will continue through 00z
Sunday and possibly beyond as the southern system lifts northeast
along a Tennessee Valley front, and an upper system moves over the
Ohio Valley. Good confidence LAF should see VFR with dry weather.
The other sites should see mostly VFR per the SREF, but could see
MVFR in showers at times.

Northeast winds less than 10 knots will become 10 to 15 with gusts
to 20 after 15z.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...DWM
NEAR TERM...DWM/MK
SHORT TERM...DWM
LONG TERM....JAS
AVIATION...MK


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