Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 160831

Area Forecast Discussion
National Weather Service Indianapolis IN
430 AM EDT Fri Mar 16 2018

.UPDATE...The Aviation section has been updated below.


Issued at 326 AM EDT Fri Mar 16 2018

A low pressure system will move from the Mississippi Valley to the
Ohio Valley on Saturday. This system will bring widespread
precipitation to central Indiana tonight and early Saturday. Areas
near and north of Interstate 74 will see a wintry mix with mainly
freezing rain. Meanwhile, areas south of Interstate 74 will see just

High pressure will bring dry weather to the area Saturday night into
Sunday night. Then, a southern system will result in a wintry mix
starting early next Monday. Finally, dry weather will follow for the
middle and late parts of next week as high pressure moves in.

Look for below normal temperatures through Saturday, above normal
temperatures Sunday and Monday and then below normal temperatures
for the middle part of next week.


.NEAR TERM /Today/...
Issued at 326 AM EDT Fri Mar 16 2018

Whether or not precipitation will reach southwestern parts of
central Indiana late today will be the main focus for the near term.

Models in general agreement that an upper ridge will keep it mostly
dry today. However, the 00z GFS and ECMWF runs both have some small
QPF near and west of a Brownstown to Clinton line after 18z. The
blend picked up on this as well with low POPs across far
southwestern counties. Can not rule this out as a low pressure
system will be moving into the central Plains and models hint at an
upper impulse ejecting from this system into the Wabash Valley.
Regardless, sky cover should be increasing this afternoon from
southwest to northeast ahead of this system.

Despite a degree of morning sunshine, low level thermal lend high
confidence on below normal blend temperatures with highs expected to
only reach the lower and middle 40s.


.SHORT TERM /Tonight through Sunday night/...
Issued at 326 AM EDT Fri Mar 16 2018

The main concern for the short term will be overnight and Saturday
morning, when freezing rain will be possible over northern and
eastern sections of the forecast area as a low pressure system moves
into the middle Mississippi Valley and then Ohio Valley on Saturday.
The 00z NAM looked to be a slow outlier, otherwise 00z model blend
looked good and suggests areas near and north of a New Castle to
Anderson to Lafayette line could see precipitation start off as or
switch to a wintry mix of rain or snow this evening. However, after
06z, as the precipitation becomes widespread and increases in
intensity, top down method suggests the main precipitation type in
this area will be freezing rain. Forecast builder and WPC suggest
our far northeastern counties could see over a tenth of an inch of
ice. That said, above normal road temperatures and barely below
freezing forecasted temperatures tonight lend low confidence to icy
roads. Thus, will stick with a Special Weather Statement to handle
things as opposed to a Freezing Rain Advisory. If the models come in
colder with their 12z runs, this would increase confidence in icy
roads and thus an advisory could still be needed with the afternoon

High confidence that the precipitation will be ending from northwest
to southeast Saturday afternoon. Any linger wintry precipitation
will change back to rain by Noon. After that high confidence in dry
weather through Sunday under the influence of high pressure. Can not
rule out light rain far southwest overnight Sunday night as another
low pressure system moves into the central Plains. That said,
confidence is low.

After a cool start to the weekend, low level thermals and increasing
sunshine support temperatures returning to normal on Sunday.


.LONG TERM /Monday through Thursday/...

Issued at 306 AM EDT Fri Mar 16 2018

The long term starts out a couple degrees warmer than normal with
highs in the 50s on Monday, but then reality sets in as a cutoff
upper low moves in to reinforce the upper trough over the eastern
U.S. This will plunge central Indiana back into a below normal
temperatures and a wintry pattern for the rest of the long term.
Short waves will move through the aforementioned upper trough and
bring chances for mainly rain during the day and a wet snow during
the night from Monday through Wednesday night. Timing of the
individual shortwaves is still pretty variable, so generally went
with the blended initialization which should smooth out the
individual model differences.


.AVIATION /Discussion for the 160900Z TAFS/...
Issued at 430 AM EDT Fri Mar 16 2018

Updated current conditions only. Previous discussion follows...

No significant cloud cover and unrestricted visibility expected at
the terminals through early afternoon Friday. Could see some
precipitation move in near the end of the period that should be rain
for most of the sites but could be freezing rain or sleet mix at

Surface winds 010-040 degrees at 7-11 kts overnight will gradually
veer around to 080-100 degrees at 10-13 kts by early afternoon




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