Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 230755

Area Forecast Discussion
National Weather Service Indianapolis IN
355 AM EDT Fri Mar 23 2018

The LONG TERM Section has been updated below.


Issued at 325 PM EDT Thu Mar 22 2018

A low pressure system will bring wintry weather to parts of central
Indiana later Friday night into Saturday. Another frontal system
will bring frequent chances for rain next week. After a cold
weekend, temperatures will return to near average next week.


.NEAR TERM.../Rest of This Afternoon and Tonight/
Issued at 325 PM EDT Thu Mar 22 2018

Quiet weather will continue across central Indiana into the evening
hours with high pressure remaining in control. Clouds will slowly
increase across southwestern sections of the area as lift continues
east of a warm front across Missouri.

Some of the isentropic lift associated with the warm front will
brush the far southwest forecast area late tonight, so will include
some slight chance PoPs there late tonight.

Went a little cooler than the blend for lows tonight east where
clouds will be fewest. Elsewhere stayed close to the blend.


.SHORT TERM.../Friday through Sunday/
Issued at 325 PM EDT Thu Mar 22 2018

Models are close enough that the model blend initialization
was accepted for most items.

An upper level system will move southeast across the area Friday
night into Saturday as a weakening area of surface low pressure
moves into Kentucky. An upper level jet will move into the area on
Saturday as well.

There will be plenty of forcing with this system, and a low level
jet will bring in plentiful moisture. PoPs will increase from the
southwest Friday afternoon into Friday evening, with high PoPs
looking good later Friday night into Saturday as the best forcing
moves through.

There will be a tight temperature gradient aloft across the area,
with the southwest getting several degrees above zero at 850mb while
the northeast remains near to below zero. At the surface, an
easterly wind will work to bring in cooler and drier air.

Expect rain across the southwest forecast area thanks to the warm
air aloft. Across the remainder of the area, soundings show
isothermal conditions near freezing. Thus am expecting snow with
some rain mix for the most part, with big bust potential either way
if temperatures change even just a degree.

Additional complicating factors for precipitation type including
potentially heavy precipitation rates with some frontogenetical
forcing and some weak instability. This would trend the
precipitation to change into heavy snow at times. Drier air at the
surface may not only make evaporative cooling northeast Saturday but
also dry up some of the precipitation before it reaches the ground.
Finally, SREF means are warmer than the other models which could
produce more rain.

Thus am not confident enough to do anything more than continue the
watch at this time. Amounts still look to be in the 3 to 7 inch
range, with locally higher amounts possible if banding sets up.
Looks like the heaviest band shifted southwest just a bit, so will
add Johnson County to the watch. Timing still looks good.

Wouldn`t rule out a little freezing rain late Friday night & early
Saturday morning, but with temperatures rising to above freezing
don`t see many issues for roads.

Precipitation will move off Saturday evening, with dry conditions
expected Sunday.


.LONG TERM /Sunday through Thursday Night/...

Issued at 353 AM EDT Fri Mar 23 2018

Ridging over the Great Lakes Region will result in dry conditions
early in the extended period. However, rain showers will slowly
start entering the southern portions of central Indiana early
Monday morning ahead of the next low pressure system over the
Central Plains. Significant Gulf moisture will be pulled into
central Indiana ahead of this system, resulting in heavy rainfall
at times on Monday and Tuesday along with embedded thunderstorms
in the warm sector. Latest blended initialization highlights
these periods well, so no adjustments were needed. The forecast
will remain active through the end of the extended period as a
trailing cold front moves through on Tuesday night followed by an
upper low late in the period. Meanwhile, temperatures will
initially start out below normal, but they will quickly climb
above normal due to strong warm advection with aforementioned


.AVIATION /Discussion for the 23/06Z TAF Issuance/...

Issued at 111 AM EDT Fri Mar 23 2018

VFR conditions through 00Z Saturday, MVFR afterwards.

VFR conditions are expected for the rest of the night and through
the day tomorrow as a low pressure system approaches central
Indiana.  Rain will move into BMG and HUF after 00Z Saturday and
will spread to LAF and IND by 06Z.  Rain will slowly transition to
snow at LAF and IND at the end of the TAF period with ceilings
rapidly dropping at all terminals.  Winds will generally be light
and variable tonight and will be easterly at less than 10 kts
through the day tomorrow.


Winter Storm Watch from late tonight through Saturday evening
for INZ021-028>031-035>049-054>057-063>065-072.



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