Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 271735
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
135 PM EDT Sat May 27 2017

.UPDATE...
The SYNOPSIS...NEAR TERM and SHORT TERM Sections have been updated below.

&&

.SYNOPSIS...
Issued at 134 PM EDT Sat May 27 2017

A pair of weather disturbances are expected to pass through the
region bringing showers and thunderstorms Central Indiana Tonight
and again on Sunday afternoon and evening. Some of the storms
could be severe...particularly across southern Central Indiana.

Weak high pressure is then expected to slowly build across Central
Indiana from Monday through the middle of the work week. This will
bring dry weather along with cooler temperatures for much of next
week.


&&

.NEAR TERM /Tonight/...

Issued at 134 PM EDT Sat May 27 2017

Surface analysis early this afternoon shows High pressure in
place across the Great Lakes. A weak trough of low
pressure/boundary was in place from Central Ohio...across Indiana
to southeast Missouri. Visible satellite imagery continues to
show linger low cloud across the area...however this is expected
to dissipate through the late afternoon. GOESR Shows a convective
cluster over Eastern Kansas...and it is this feature that we will
need to watch closely.

Dry weather will be expected through much of the evening hours as
forecast soundings and time heights keep a dry column in place
across the area. GFS and NAM have change a bit with the handling
of the approaching short wave...focusing best development to the
south...toward southern Indiana after 03Z. We will expect a sharp
cut-off across our forecast area on precip...with northern areas
perhaps seeing little to no rains overnight...much high pops
expected from I-70 southward as forecast soundings in these
locations show deep saturation as the upper wave passes. All of
this plus the surface boundary that appears in place seem
reasonable include high pops across the southern parts of the
forecast area...but tapering quickly lower to the north.
Again...given the convective nature of the expected MCS severe
storms...mainly due to straight line winds will not be ruled out.
As for temps will trend toward expected wet bulbs or use a blend.

&&

.SHORT TERM /Sunday through Tuesday/...

Issued at 134 PM EDT Sat May 27 2017

Mainly dry weather will be expected on Sunday morning as the
previous wave should be exiting or will have already exited
Central Indiana by 12Z Sunday as suggested by the GFS. Thus the
day should start out dry. However models suggest that our second
short wave and an associated cold front will sweep across Central
Indiana during the afternoon. Forecast soundings have begun
hinting at much more instability available on Sunday afternoon
than previous runs showing steep lapse rates. GFS IND soundings
suggests CAPE of 2500-3700 J/KG through the afternoon with easily
attainable convective temperatures in the upper 70s. MAVMOS
suggest good surface moisture available with dew points in the
lower 60s. Thus as daytime heating progresses on Sunday...and the
dynamics advance through the afternoon...storm chances will
increase. Will trend toward a categorical Pop by late afternoon
given the expected instability and dynamics lining up. Will stick
closer the the MAVMOS on Highs.

Convection across the area should continue into the early evening
hours as the previously mentioned forcing departs prior to 03Z.
Thus will need to continue to carry pops across the
area...especially across the southeast...where forcing will depart
last. After 06Z...forecast soundings suggest drying within the
column along with subsidence. Thus will trend to dry pops
overnight.

Model then suggest broad lower level cyclonic flow across the
area Monday...around low pressure well north of Indiana...near
northern Ontario. A weak trough looks to pass across Indiana on
Monday...however the forecast column appears very dry. Thus will
try to get to a dry forecast on Monday. A blend on temps will
work fine.

Monday night through Tuesday also appears dry as forecast
soundings suggest a dry column. At the surface...high pressure
over the central plains appears to slowly move east...building
across the Ohio valley. Support aloft remains minimal...as best
forcing within the broad cyclonic flow remains well north of
Indiana...over Ontario and the great Lakes. Thus will continue to
trend toward a dry forecast here along with a blend on temps.

&&

.LONG TERM /Tuesday through Friday/...
Issued at 220 AM EDT Sat May 27 2017

The consensus forecast from Region will be used with moderate to
high confidence.

The main models agree in many respects,reducing the chance of big
errors. It is not always clear when there will at least some chance
of rain and when the weather will be completely dry. Potential POP
errors are about 10 percent. Potential temperatures errors, which
are related to chances for rain and clouds, are 1-3 degrees.

&&

.AVIATION (Discussion for the 271500Z KIND TAF Update/...
Issued at 1011 AM EDT Sat May 27 2017

Fairly widespread ceilings 012-015 in the vicinity of the KIND
terminal, although starting to see some breaks in the cloud cover
based on satellite. Expecting these lower ceilings to gradually lift
into the VFR category around the midday hours.

Previous discussion follows.

Expect areas of IFR ceilings and local VLIFR visibilities in fog
early to give to exclusively VFR conditions by 16Z. Clouds will
rise to 10 thousand feet or higher by evening.

Thunderstorms are expected to develop tonight as a front approaches.
As storms increase, MVFR ceilings should become widespread. There
may locally be much lower conditions. Strong winds and hail are also
possible in storms tonight, especially over southern parts of the
area.

Winds outside storms should be mainly less 6 knots or less.


&&

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

$$

SYNOPSIS...Puma
NEAR TERM...Puma
SHORT TERM...Puma
LONG TERM....JK
AVIATION...JK/JAS



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