Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 191403
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1000 AM EDT Sat Aug 19 2017

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

&&

.SYNOPSIS...
Issued at 302 AM EDT Sat Aug 19 2017

A weak frontal system will drop southeast of central Indiana today
as an upper wave pivots through from the west. These features will
trigger a few morning thunderstorms over central Indiana. Then, a
broad area of surface high pressure will bring dry weather to the
area through Monday. Strong storms are possible next Tuesday and
Tuesday night as another system swings through. The rest of next
week will be cooler and dry as high pressure builds in in the wake
of the cold front.

&&

.NEAR TERM /Rest of Today/...
Issued at 1000 AM EDT Sat Aug 19 2017

Weak frontal boundary moving through central Indiana this morning
with little fanfare. Earlier scattered showers had diminished over
the forecast area with primary convective focus over southeast
Illinois and southwest Indiana. Small area of convection had been
steadily decreasing in intensity over the last hour or two as it
tracked across central and eastern Illinois. 14Z temperatures
were generally in the low to mid 70s.

The front will continue to push southeast of the area through
midday with the trailing upper wave axis following in short order.
Not completely out of the question that the ongoing convection
over the lower Wabash Valley grazes our southwest counties over
the next hour or two...but otherwise expecting little if any
additional convective impacts over central Indiana. The
aforementioned area of precip weakening over eastern Illinois may
not even make it into the forecast area at this point. Will hang
onto low chance pops for the next 2-3 hours to account for any
rogue activity that can develop in vicinity of the boundary moving
east.

Remainder of the day will see a resumption of the quiet weather
experienced of late as high pressure returns in the wake of the
upper trough axis and frontal boundary. While convective temps will
likely be out of reach later today...presence of a lingering low
level thermal trough in wake of the upper wave supports development
of some cu this afternoon...especially over the southeast half of
the forecast area. Bumped high temps up a couple degrees as most
area should warm into the mid 80s.

Zone and grid updates out.

&&

.SHORT TERM /Tonight through Monday night/...
Issued at 302 AM EDT Sat Aug 19 2017

Main focus for the short term will be cloud trends, especially
Monday for the eclipse, as well as timing and coverage of convection
Monday night.

Models in good agreement that zonal flow will be over central
Indiana through Monday night overtop a broad dome of high pressure
over the southern states. At the surface, broad high pressure
will shift east of the area on Sunday allowing light return flow
and gradually warming. Upper impulses will interact with residual
low level moisture and could produce scattered diurnal cu and a
few mid and high clouds Sunday per cu development progs and rh
time sections. Although, 850 millibar moisture thins on Monday, rh
time sections hint at increasing mid and high clouds. Still,
think partly cloudy will do both days and the eclipse will still
be viewable. Although, the eclipse could briefly retard
temperatures, 21 degree 850 millibar temperatures suggest 90
degrees is possible Monday, mainly south. It will feel very warm
and humid regardless for those outdoors. Blend temperatures look
reasonable and will be accepted.

By Monday night, models hinting at more numerous waves in the zonal
flow along with an approaching frontal system and increased moisture
and instability. Thus, should see a few evening storms northwest
with more coverage overnight and beyond per the blend. Confidence in
exact timing is not great but in the trend is good.

&&

.LONG TERM /Tuesday Through Friday/...
Issued at 232 AM EDT Sat Aug 19 2017

Ensembles are in good agreement with the upcoming weather pattern
during this period. Short wave energy is expected to drop southeast
through the Great Lakes on Tuesday, eventually carving out a long
wave trough over the eastern parts of the country for the rest of
the extended.

Will keep PoPs in the forecast for Tuesday and Tuesday night as the
upper trough and associated cold front move through. In the wake of
this front, it appears a drier and more stable air mass will move
into the area. Will go dry after Tuesday.

&&

.AVIATION /Discussion for the 191500Z TAF Issuance/...
Issued at 1000 AM EDT Sat Aug 18 2017

Only minor adjustments needed based on current obs but overall
terminals are in good shape at this time. 12Z discussion follows.

Good confidence VFR conditions will dominate the bulk or all of the
TAF period. Radar trends support VCTS at BMG and IND only and not
later than 14z. Should only see some diurnal cu today and tomorrow
along with patches of cirrus. Would not rule out MVFR or worse fog
after 09z Sunday.

Winds will variable 5 knots or less.

&&

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

&&

$$

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



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