Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 182329
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
729 PM EDT Wed Apr 18 2018

.UPDATE...

The Aviation section has been updated below.

&&

.SYNOPSIS...
Issued at 239 PM EDT Wed Apr 18 2018

A low pressure system is expected to move through the area late this
afternoon and evening. In the wake of this system, high pressure is
expected to build in through the weekend. Another low pressure
system may affect the area by early next week.

&&

.NEAR TERM /Rest of This Afternoon and Tonight/...
Issued at 239 PM EDT Wed Apr 18 2018

Low pressure over Illinois is expected to move across the forecast
area later this afternoon into the early evening hours. Short term
models suggest some convection may develop in the next several hours
along the trailing cold front, but don`t see anything imminent at
this time.

Will keep some chance PoPs going through about 182300Z-19000Z, when
surface system should pass off to the east. Some threat for wrap
around light precipitation associated with the upper trough to move
through mainly the northern zones later tonight. Will keep some
chance PoPs going later tonight in those areas. Still appears there
may be some mixed precipitation late tonight as thicknesses lower and
the boundary layer cools, but accumulations not expected at this
time.

May be a period of wind gusts 35-40 mph later this afternoon and
evening in the wake of the surface system, especially over the
southern zones, where pressure rises and mixing will be maximized.

Low level thicknesses suggest the GFS MOS lows tonight may be a
little on the warm side. Will nudge the guidance lows down a bit.

&&

.SHORT TERM /Thursday through Saturday/...
Issued at 239 PM EDT Wed Apr 18 2018

A dry period is expected as a large surface high slowly drifts
through the Great Lakes. Lingering lower cloud should gradually
clear out during the day Thursday, given the strong  as models dry
advection. Some more substantial mid and high cloud may move into
the area by Saturday.

Progged low level thicknesses suggest the GFS MOS temperature
guidance for the next couple of days looks reasonable, so any
adjustments will be minor. Potential for freezing temperatures
exists by early Friday morning.

&&

.LONG TERM /Saturday Night Through Wednesday/...
Issued at 236 PM EDT Wed Apr 18 2018

Models are close enough that the model blend initialization
was accepted for most items.

The remainder of the weekend will be dry with high pressure in
control. Early in the week, the southern forecast area might get
grazed by a few showers from an upper low to the south of the area.

There are some differences in timing and location of the rain with
this feature, so confidence is lower here.

By mid-week, another upper low will move in from the northwest,
bringing more rain chances to all of the area.

Temperatures will be near normal to a little below normal for the
period.

&&

.AVIATION /Discussion for the 19/00Z TAFs/...
Issued at 730 PM EDT Wed Apr 18 2018

VFR initially at all but LAF will quickly give way to MVFR
conditions later this evening and overnight, perhaps with a period
of IFR at LAF and IND.

Area is in the clear slot of a compact low pressure system moving
through the area, and expect ceilings to return and lower as the
associated upper low moves through the area tonight into Thursday
morning. Ceilings will predominantly be MVFR although a period of
IFR is possible at least at LAF and IND.

A few showers cannot be ruled out with the upper low but should be
light. Visibilities will be unrestricted throughout, outside of
any potential showers.

Winds will be a significant impact during this period with gusts
in excess of 30KT possible especially early in the period. Gust
speeds will drop off gradually overnight into Thursday, although
winds will remain gusty much of the period.

&&

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

&&

$$

SYNOPSIS...JAS
NEAR TERM...JAS
SHORT TERM...JAS
LONG TERM...50
AVIATION...Nield



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