204 
FXUS63 KIND 201051
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
551 AM EST Sat Feb 20 2021

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

&&

.SYNOPSIS...
Issued at 300 AM EST Sat Feb 20 2021

After a few flurries early this morning, a dry day is in store 
for central Indiana. A chance for a wintry mix returns Sunday 
afternoon and stick around into Monday, and temperatures will 
slowly increase through the forecast period.

&&

.NEAR TERM /Today/...

Issued at 300 AM EST Sat Feb 20 2021

Early this morning an upper wave is moving 
through the Great Lakes. This is producing a few flurries across 
northern parts of central Indiana, with a light dusting of snow 
possible on the high end. This wave should be off to the east by 
sunrise, and these flurries/very light snow showers should come to 
an end. Cloud cover will erode later this morning due to subsidence 
from the surface high increasing over the area. Weak warm advection 
will begin as the high gets east of the area, and this along with a 
decent amount of sunshine today should allow temperatures to climb 
into the mid 20s to lower 30s, with the snow pack keeping the 
warming from being fully realized.

&&

.SHORT TERM /Tonight through Sunday/...

Issued at 300 AM EST Sat Feb 20 2021

Tonight begins with surface high pressure east of the area and some 
scattered mid to high level clouds. Winds will increase from the 
south on Sunday as the pressure gradient across the area increases 
with high pressure moving from WV to the east coast and low pressure 
strengthening as it moves from Kansas to eastern IA. This will 
induce an area of isentropic lift Sunday that will serve to increase 
cloud cover initially and then bring in chances for precipitation 
from the west as the upper ridge axis over the area to start the day 
moves off to the east. An upper wave will be approaching but has 
trended slower, and thus the forcing for Sunday afternoon will stick 
mainly to that provided by the isentropic lift and surface warm 
front. Models differ in how quickly warm air and moisture can get 
advected in aloft, and thus confidence in precipitation type is 
still low. Rain and snow both look like valid possibilities, and 
there is some potential that with the snowpack and cloud cover 
limiting warming that surface temperatures, while above freezing, 
will be close enough that surfaces could remain below freezing. 
Regardless, precipitation chances for Sunday afternoon/evening are 
lower than previous forecast with onset taking a little longer due 
to dry air and slower arrival of the upper wave. Chances will 
increase from the northwest during the late afternoon/early evening, 
with most of the eastern counties still dry until Sunday night but 
the northwest getting likely to high chance PoPs in the early 
evening hours. For temperatures Sunday, think the northern counties 
will be slower to warm due to the snowpack and the southern counties 
having better proximity to the warm and moist southerly winds. Mid 
30s north with lower 40s south for highs Sunday.

&&

.LONG TERM /Sunday night through Friday/...

Issued at 300 AM EST Sat Feb 20 2021

Widespread precipitation will be continuing through the night Sunday 
night as an upper level trough and associated surface cold front 
pass through the area. During the overnight hours, the strong WAA 
from southerly air will begin to be cut off, especially after the 
frontal passage. Ahead of the front, temperatures and thermal 
profiles look to be warm enough for rain to be the predominant 
precipitation type everywhere except for the far northern counties 
with the WAA being stronger than any evaporative cooling. Antecedent 
ground temperatures though could be a problem with an 8-12 inch 
layer of frozen soil across the area. This could lead to ice forming 
on exposed surfaces along with the snowpack still in place. By the 
late overnight hours, rain will transition to snow and freezing 
rain, but accumulations are expected to be little to none as the 
bulk of the forcing and precipitation will have already moved 
through by then.

For much of the rest of the week, dry and  warmer conditions are 
expected. Model output is suggesting highs into the 50s across the 
southern counties by Wednesday, but feel that is likely overdone 
with the snow still on the ground. Will cut temperatures by a degree 
or 2 across the board through the latter portions of the week when 
the snow should finally melt. A weak system may be moving through by 
late in the week, but confidence remains very low of any impacts at 
this time. 

Temperatures will generally be near to slightly above normal through 
the period.

&&

.AVIATION /Discussion for 201200z TAF issuance/...

Issued at 545 AM EST Sat Feb 20 2021

IMPACTS: VFR thru the period. Can't rule out isolated MVFR
conditions during the first couple of hours.

DISCUSSION: High pressure will build over the area today and
scatter clouds as it does so. Some isentropic lift will arrive by
Sunday morning and this will start to drop ceilings, but at this
time they still look VFR until Sunday night.

CONFIDENCE: Medium confidence in VFR through midday Sunday.

&&

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

$$

SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....White
AVIATION...CP