Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 211348
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
948 AM EDT Sat Apr 21 2018

.UPDATE...
The NEAR TERM and AVIATION Sections have been updated below.

&&

.SYNOPSIS...
Issued at 330 AM EDT Sat Apr 21 2018

High pressure will keep dry weather in place across central Indiana
through tonight. By Sunday evening low pressure from the plains will
approach and bring increasing chances for rain from the south. Rain
chances should continue off and on through Friday as a series
of upper waves move through. Temperatures should run near normal.

&&

.NEAR TERM /Rest of Today/...
Issued at 948 AM EDT Sat Apr 21 2018

Mid and high level clouds spilling into the northern half of
Indiana this morning with mainly sunny skies further south.
Temperatures this morning were starting out warmer than the last
few days. 1330Z temps ranged from the mid 40s to low 50s in most
areas.

Forecast in excellent shape with only minor adjustments needed.
High pressure remains in control over the Ohio Valley with
ridging aloft. Moisture however is riding up and over the ridge
and spilling across the region this morning in the form of mid and
high clouds with the lowest 10-15kft remaining dry. Expect this
to continue through the rest of the day with increased cloud cover
over the northern half of the forecast area and less further
south. Highs will be similar if not just slightly warmer than
Friday. Despite the clouds...the warmer start this morning should
enable much of the area to warm into the lower to mid 60s. The
warmest reading will likely be found over far southern counties
where sunshine should be most prevalent.

Zone and grid updates out.

&&

.SHORT TERM /Tonight through Monday night/...
Issued at 330 AM EDT Sat Apr 21 2018

Another dry night is in store for central Indiana with high pressure
off to the east. Skies should be partly to  mostly cloudy though so
not as much cooling expected. On Sunday low pressure over the plains
starts to move east toward the area, bringing low chances for
showers to the southernmost counties late Sunday night. Models show
the upper low meandering about the Tennessee and Ohio valleys,
slowly making its way northeast. There is some disagreement on the
exact placement of the low and thus how far north the precipitation
with it gets, and thus generally low confidence on rain shower
chances initially with slightly better chances Monday afternoon and
Monday night across the southern and eastern counties. Temperatures
look near normal through the period.

&&

.LONG TERM /Tuesday through Friday/...
Issued at 250 AM EDT Sat Apr 21 2018

The challenge to the extended will be timing and spacial issues
regarding shower chances as models and ensembles members are having
differences in time, space and strength of a departing southern low
and trailing southeast diving western Canadian systems. One example
is the 00z GFS has an upper low over southeastern Missouri at 06z
Thursday April 26. At the same time, the ECMWF had a much quicker
and weaker wave over southwestern Ohio. Another example would be by
00z Saturday April 28, when the 00z GFS has an upper low over
southern Lake Michigan. Meanwhile, the 00z ECMWF has a trough over
the western Great Lakes and upper low over western Ontario.

Model differences aside, confidence is high in below normal
temperatures through the period as these latter features carve out a
mean trough over the Ohio Valley and Great Lakes.

All three of the aforementioned systems will support shower chances
to all or parts of the area through most of the long term. The blend
has the best chances next Wednesday and also Thursday night and
Friday. With model differences in timing of QPF, confidence is low
on any one solution, so will just accept the blend with minor tweaks.

&&

.AVIATION /Discussion for the 211500Z TAF Update/...
Issued at 948 AM EDT Sat Apr 21 2018

No changes needed. 12Z discussion follows.

High pressure, model rh time sections and SREF and GFS LAMP lend
high confidence in VFR conditions through the TAF period with just
high clouds.

Winds will vary from 070 to 110 degrees at 5 to 10 knots.

&&

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

&&

$$

SYNOPSIS...CP
NEAR TERM...Ryan
SHORT TERM...CP
LONG TERM....MK
AVIATION...MK/Ryan


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