National Weather Service Raw Text Product

Displaying AFOS PIL: AFDIWX Received: 2018-01-12 10:46 UTC


392 
FXUS63 KIWX 121046
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
546 AM EST Fri Jan 12 2018

.SYNOPSIS...
Issued 432 AM EST Fri Jan 12 2018

A wintry mix of rain, freezing rain, sleet and snow this morning
will gradually transition to all snow from west to east. Ice,
sleet and snow accumulations will make travel hazardous today.
Precipitation will diminish late this morning and this afternoon 
from west to east. Temperatures will continue to fall through the
day and should be in the teens to lower 20s this afternoon.
Another system will bring light snow the area Sunday night and
Monday with a few inches of accumulation possible. This will be
followed by more cold air next week as well as lake effect snow in
the snow belt region. 

&&

.SHORT TERM...(Today and Tonight)
Issued at 429 AM EST Fri Jan 12 2018

...Winter Weather Advisory Continues...

Several challenges to short term forecast this morning. Main cold 
front was just exiting our eastern area at 09z. Drastic temperature 
change across the area as Lima was still in the lower 50s while 
Monticello was down to mid 20s at 09z. Shallow arctic air was 
undercutting warmer air aloft but eastward movement has been slowing 
overnight. Last several runs of Hires guidance has been showing this 
with temperatures in the far east not expected to fall to freezing 
until between 14z and 16z. By the time this occurs, deeper cold 
wedge will be arriving and low level thermal profiles begin to 
cool quickly as southern stream wave deepens and pulls colder air 
in mid to late morning. This looks to result in far less freezing 
pcpn over the eastern half of the area with a later transition 
from rain to sleet then snow with only a brief period of freezing 
rain possible as this occurs. 

Farther west, have already seen several reports of snow and UP 
(which is likely sleet) in observations. Of main concern in the 
near term is large area of precipitation moving north through 
eastern IL and western IN that earlier model runs did not pick up 
on. Latest runs of HRRR and RAP as well as 06z NAM show impressive
QPF with this deformation axis/fgen band moving into southwest 
CWA before 12z and spreading northeast. Have used a blend of hires
and WPC QPF to account for this which leads to a bit more
snow/sleet in the west this morning than previous forecast. This 
area will need to be watched closely as 07z hires guidance showed 
QPF over a half inch but likely contaminated by bright banding in
reflectivity output. GOES-16 showed an impressive short wave 
across the deep south with moisture plume streaming north into our
area and responsible for the uptick in pcpn returns and QPF. 

Temperatures expected to continue falling through the day. Have used 
a blend of conshort and HRRR for hourly temperatures and highs for 
the day have already been reached. Have used the RAP for our 
MaxTwaloft grids with some manual adjustments based on report 
locations of snow, sleet and rain. This coupled with the hires sfc 
temps have led to the changes in pcpn types and timing across the 
local area. 

  

&&

.LONG TERM...(Saturday through Thursday)
Issued at 429 AM EST Fri Jan 12 2018

With focus in the short term with ongoing weather, few changes to 
latest blended guidance. Lake effect snow showers expected tonight 
into Saturday over NW Indiana but expecting accums of just a couple 
inches given transitory nature of band which should waver west then 
back east. Flow quickly backs Sunday ahead of potent northern stream 
clipper which will dive into the Great Lakes. Model trends have 
shifted surface low track north slightly but still spreads light 
snow into most of our area Sunday night into Monday. For now looks 
like a general 1 to 3 inch event but will have to watch for further 
deepening as NAM12 shows 1.5 PVU surface dropping down to around 
500mb. Would expect this clipper to be moisture starved in wake of 
current system but some enhancement off of lake possible. A rather 
decent lake effect event is possible Monday night into Tuesday 
with possibility of another Type VI setup as an east-west surface 
trough drops south lending to potential mesoscale low development 
over the central part of the lake Monday night. Low level flow in
wake of this feature becomes northerly suggesting a trailing 
single band possible. Models show various wind directions and 
trajectories so confidence low right now in where this feature 
will come onshore and best chances for accumulations will occur. 
Bumped pops into high chance/low likely category for now across 
most of the NW.

Very cold temperatures to continue for much of the week but next 
moderating trend looks to be on the horizon by late week into next 
weekend. 

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 542 AM EST Fri Jan 12 2018

Strong elevated fgen/deformation axis will pivot through KSBN this
morning and KFWA this morning into at least early this afternoon.
Ptype mainly snow at KSBN through 14/15z before ending, with KFWA
transitioning from freezing rain/sleet to snow by 14z. Mainly IFR
restrictions are expected with this activity before drier air
settles in. Strong northerly winds will be the story otherwise
today with gusts to 25-30 knots possible at times. 

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory until 7 PM EST this evening for INZ007-
     009-018-025>027-032>034.

     Winter Weather Advisory until 1 PM EST /noon CST/ this afternoon 
     for INZ003>006-008-012>017-020-022>024.

MI...Winter Weather Advisory until 7 PM EST this evening for MIZ080-
     081.

     Winter Weather Advisory until 1 PM EST this afternoon for 
     MIZ077>079.

OH...Winter Weather Advisory until 7 PM EST this evening for OHZ001-
     002-004-005-015-016-024-025.

LM...Small Craft Advisory until 4 AM EST Saturday for LMZ043-046.

&&

$$

SYNOPSIS...Lashley
SHORT TERM...Lashley 
LONG TERM...Lashley 
AVIATION...Steinwedel


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