Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 180811

Area Forecast Discussion
National Weather Service Indianapolis IN
410 AM EDT Sun Mar 18 2018

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


Issued at 312 AM EDT Sun Mar 18 2018

High pressure will provide a picturesque day for central Indiana
today with a return to above normal temperatures. This will be short-
lived, however as a series of low pressure systems will bring
chances of rain or snow to the area early next week and late next
week and weekend. There are several chances for light snow
accumulation starting Monday night over northeast counties.

Temperatures will fall back below normal by Tuesday and briefly
return to near normal by next Saturday.


.NEAR TERM /Today/...
Issued at 312 AM EDT Sun Mar 18 2018

The main focus for the near term will be on fog early and then shift
to temperatures as high pressure and a drying column lend high
confidence to a sunny day with slightly above normal temperatures.

GOES-16 Night Fog curve was showing the clearing has made it all the
way to our southernmost tier of counties at 3 am. The clear skies
and light to calm northeast winds has allowed fog to start to
develop north of the clearing line. The SREF low visibility progs
and GFS LAMP has a handle on this decent fog potential through 12z
or so. Do not think this will warrant a Fog Advisory but will keep
an eye on it. By 12z-14z, expect sunny skies. Low level thermal
progs and full sun support the blend highs in the 50s.


.SHORT TERM /Tonight through Tuesday night/...
Issued at 312 AM EDT Sun Mar 18 2018

Precipitation timing and type will be the primary issues in the
short term.

Today will start off with a weak east coast trough, a high amplitude
Missouri Valley ridge and a western trough. Models in generally good
agreement that an upper low will form within the western trough as
it moves to the Rockies and southern Plains tonight and Ohio Valley
Monday and Monday night. The blend brings increasing clouds with
this system from southwest to northeast tonight. In addition, the
blend has small PoPs after 09z across our extreme southwestern
sections. This has been the case the last several runs, so left the
small PoPs in there. Models then bring higher PoPs in Monday
afternoon and night which looks reasonable. Precipitation type will
be liquid until the low passes tonight. The result will be the rain
will change to snow from north to south tonight. Northeastern
sections could see minor accumulation of less than an inch per the

The precipitation should briefly end Tuesday morning but return
during the afternoon and night over all but the far northwestern
counties as upper system follows the first. Model soundings and low
level thicknesses suggest it will start as rain Tuesday afternoon
before changing to snow Tuesday night. Could see another minor snow
accumulation. Regardless, daytime heating will melt any snow during
the afternoon hours.


.LONG TERM /Wednesday through Saturday/...

Issued at 250 AM EDT Sun Mar 18 2018

The forecast looks mainly dry to start the long term with an upper
trough over the eastern U.S. making its way east. Could see a little
rain/snow mix still hanging around the southeastern counties
Wednesday morning as the system impacting the short term moves off.
High pressure will slide through on Thursday with small chances for
precipitation returning Thursday night. Greater chances will expand
over the area on Friday and into the weekend as a warm front makes
its way toward and across the area. Models show differences in
timing in the arrival of the aforementioned front, but all seem to
indicate this feature is coming near the end of the week or
beginning of the weekend, so made no changes to the blended
initialization. With the temperature profiles forecast, still
looking at rain being the main precip type during the day and then
adding a mix of rain and snow and finally over to snow at times
during the overnight hours.


.AVIATION /Discussion for 180900z TAF issuance/...

Issued at 410 AM EDT Sun Mar 18 2018

KHUF and KBMG have developed MVFR so updated KHUF to reflect this
change. Updated current conditions at KIND and moved development of
MVFR fog faster by an hour to 10z. Previous discussion follows...

GOES-East loop shows cloud deck has moved south of KIND and KLAF
as of 5z and should shortly be south of KHUF. May take another
hour or two to clear KBMG, so will start with MVFR ceilings there.
Could see them bounce between MVFR and IFR ceilings for the first
two hours, but after that they should clear out. SREFS show
potential for some fog at KIND and KLAF, but RAP shows the
potential for lower visibilities at KHUF and KBMG near the lower
cloud deck, and boundary layer dewpoint depressions may be making
the difference here. Thus will put MVFR fog near daybreak at all
sites but KBMG, where it could start and last a bit longer. Expect
improvement to VFR at all the sites by 14-15z. NAM MOS shows some
potential for much lower fog in the hours around daybreak, but
with it being an outlier generally disregarded it.




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