Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 200330
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1130 PM EDT Thu Oct 19 2017

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

&&

.SYNOPSIS...
Issued at 220 PM EDT Thu Oct 19 2017

High pressure will provide dry and warm weather through Saturday.
Then, a pair of low pressure systems will bring wet weather to
central Indiana late weekend and into next week. The second cold
frontal passage will bring much cooler weather to the area by next
Tuesday.

&&

.NEAR TERM /Overnight/...
Issued at 943 PM EDT Thu Oct 19 2017

Nice evening as central Indiana resides underneath high pressure.
Other than some wispy cirrus drifting across the area...skies were
clear this evening. 0130Z temperatures ranged from the mid 50s to
the lower 60s.

No changes needed as the forecast is in excellent shape. High
confidence in dry weather and mainly clear skies overnight as
high pressure continues as the dominant influence. Light and
variable wind flow will support very good radiational cooling and
expect lows will bottom out in the upper 40s in the normal cool
spots and lower 50s in the urban areas.

Zone and grid updates out.

&&

.SHORT TERM /Friday through Sunday/...
Issued at 220 PM EDT Thu Oct 19 2017

High confidence in warm and dry weather through Saturday as surface
high pressure moves slowly eastward across the eastern states. Then,
a change is in store as a frontal system is expected to move just
west of central Indiana Sunday afternoon. The 12z ECMWF has now
caught up with the faster 12z GFS. They both bring the cold front to
near a Rockford to St. Louis line by 12z Sunday. The deepest
moisture and best lift both arrive Sunday per similar model output.
That supports the likely to categorical blend pops on Sunday.
Meanwhile, blend small pops west overnight Saturday night look
reasonable as well. Confidence in overall trend is high if not exact
timing. Also, good confidence in temperature trends with above
average highs in the lower and middle 70s through Sunday.

Models were hinting there could be some weak elevated instability
over parts of the area Saturday night and Sunday. However, at this
time, feel the limited instability is not enough to mention thunder.

&&

.LONG TERM /Sunday Night through Thursday/...
Issued at 242 PM EDT Thu Oct 19 2017

The long term period will be wet through middle of next week and
turning much cooler.

Models move a high amplitude upper trough slowly east across the
area during the long term.   These actually start out two separate
systems...one being an upper disturbance over the lower Mississippi
valley and a stronger upper low over central Canada.  Models tend to
merge these systems over time as the upper low over Canada digs
towards the great lakes and the southern system being absorbed by
the northern system as it moves to the northeast.

Models are in general agreement...but there are timing differences
with the southern system as the GFS and Canadian are a little faster
with the southern system and are not as wet Monday on.  The Euro on
the other hand is quite wet and slow with the southern system.
Because of uncertainty...will go with a model blend for now with
chance of showers through the middle of next week and then dry by
Thursday.

Temperatures will become progressively cooler through the middle of
next week with highs in the upper 50s to lower 60s by Tuesday and
the lower to middle 50s by Wednesday.  Overall superblend
temperatures seem reasonable and only a few minor tweaks were made.

&&

.AVIATION /Discussion for 200600Z TAF Issuance/...
Issued at 1130 PM EDT Thu Oct 19 2017

VFR conditions expected through the period.

High pressure at the surface and ridging aloft will remain across
the Ohio Valley through Friday night...maintaining dry weather and
mainly clear skies for central Indiana. Winds will be predominantly
from the south through the period...peaking at 5-10kts during the
afternoon. May see very brief restrictions develop from fog towards
daybreak Friday...but confidence in any impacts at the terminals are
too low to include in the forecast at this time.

&&

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

&&

$$

SYNOPSIS...MK
NEAR TERM...Ryan
SHORT TERM...MK
LONG TERM....JH
AVIATION...Ryan



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