Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 271413
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1011 AM EDT Sat May 27 2017

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

&&

.SYNOPSIS...
Issued at 331 AM EDT Sat May 27 2017

Active weather will continue for most of the holiday weekend as
a frontal boundary oscillates over the region and interacts with
upper level waves moving through the Ohio Valley. Dry weather will
return Sunday night and Memorial Day with the passage of a cold
front. With the exception of a secondary front bringing low chances
for storms Monday night...expect primarily dry weather for much of
next week with seasonable temperatures.

&&

.NEAR TERM /This afternoon/...

Issued at 950 AM EDT Sat May 27 2017

Surface analysis late this morning shows High pressure over
Michigan and a small...weak low over eastern Indiana/Western Ohio.
This was resulting in cooler NW flow across Central Indiana.
A convective cluster was passing to the south...across Kentucky
and Tennessee...and it should stay south of Central Indiana. A
second convective cluster was found over NW Missouri/NE
Kansas...and it is this feature that will bear watching tonight.

Forecast soundings and Time height sections remain dry today.
Subsidence present as weak NE flow is expected as influenced from
the high pressure system building and passing to the north.
Visible imagery showing mainly low cloud across the region. These
clouds should begin to burn off with daytime heating...leading to
partly cloudy skies within 1-2 hours.

&&

.SHORT TERM /Tonight through Monday Night/...
Issued at 331 AM EDT Sat May 27 2017

Forecast challenges primarily focus on convective threats tonight
and Sunday as the frontal boundary returns north and interacts
with waves aloft. Continue to stress that confidence is lower than
desired in this pattern with mesoscale factors heavily influencing
convective timing...location and intensity.

The aforementioned and likely intense convection ongoing over
Missouri this evening will be the primary focus for much of the
region. Axis of strongest instability and shear should focus from
central and southern Missouri into the Tennessee and lower Ohio
Valleys with the core of the convective complex tracking E/SE
through this area during the evening and early overnight. The
greatest threat for significant and widespread damaging winds will
be along this corridor and consequently...largely south of the
forecast area.

With that being said...the surface low will lift east from the
Missouri Valley and into the region overnight...pulling the frontal
boundary back north into the forecast area. The cap will weaken
sufficiently enough through the evening to enable convective
expansion on the northern end of the convective complex into central
Indiana during the evening and overnight. Lower confidence in how
expansive the coverage or intensity of storms will be over the
forecast area...but the threat will exist for strong to locally
severe storms with expansion of the low level jet into the area and
diffluence aloft interacting with the moist and marginally unstable
airmass present over the area.

Storms should diminish Sunday morning as the surface wave shifts
east. Scattered convection will increase again during the mid to
late afternoon ahead of a cold front and the parent upper trough.
Mid level cooling associated with the approach of the trough aloft
will weaken the cap and steepen low level lapse rates. With
instability increasing and plenty of BL shear present ahead of the
cold front...expect scattered strong to severe convection to
impact the forecast area for the second half of the afternoon into
the evening. The cold front will sweep east of the forecast area
Sunday night with rain and storms ending from the west.

High pressure will build in for Memorial Day with mainly dry and
breezy conditions as the Ohio Valley comes under the influence of
cold advection and cyclonic flow aloft. A weak secondary front will
slide into the area late day Monday into Monday night and may
generate a few showers and storms. Moisture is limited however and
hard to justify more than low chance pops at this time.

Temps...held close to a model blend for highs and lows through the
short term as they will be easily influenced by the timing and
location of convective complexes. Overall...expecting highs from the
mid 70s to lower 80s Sunday and mainly in the 70s on Monday. Lows
will fall back into the 50s behind the cold front Sunday and Monday
nights.

&&

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



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