174 
FXUS63 KIND 011502
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1002 AM EST Sat Jan 1 2022

.Forecast Update...
Issued at 1001 AM EST Sat Jan 1 2022

No major changes needed to the ongoing forecast with conditions 
generally evolving as expected. Bumped up winds some to better 
reflect expected conditions, especially across the NW half of the 
forecast area which should see winds gusts of 20 to 25 mph 
overnight. 

Rain will continue through the day and into tonight and still 
expecting a wintry mix and transition to light snow as rain moves 
out tonight and into tomorrow morning. No change in any snow 
accumulation at this time.

&&

.Short Term...(Today through Sunday)
Issued at 312 AM EST Sat Jan 1 2022

Widespread rainfall can be expected today across central Indiana, 
particularly south, as a frontal boundary slowly sags through the 
area and multiple midlevel disturbances move along the boundary, 
with enhanced upward motion enabled by strong divergence aloft with 
a nearly 200KT jet streak. Precipitation chances will be maximized 
in the south throughout the day, although expect precip to spread 
further north with time as more potent midlevel lift arrives with 
the aforementioned chain of disturbances aloft.

Precipitable water values continue to be forecast in the range of 
one inch or so, near the climatological maximum for the time of 
year, but thankfully the prolonged period of precipitation should 
prevent significant flooding issues aside from perhaps across the 
far south where QPF is maximized near 1.50 inches. Will keep the 
flood watch going here for areal flooding.

Ensemble river flood forecasts continue to suggest that the expected 
precipitation will simply prolong the ongoing high water situation 
and not significantly worsen it.

Tonight, as the boundary continues to move to the southeast and low 
level cold advection begins in earnest, expect precipitation to 
change over to snow from northwest to southeast. Forecast profiles 
are slightly more supportive of a brief period of freezing rain to 
go along with the anticipated hour or two of wintry mix, but still 
believe that this period will be brief and freezing precipitation 
should not have a significant impact.

Snowfall amounts across the far northwestern portion of the area may 
exceed half an inch to near an inch, although recent significant 
warmth may limit how much of this actually accumulates in the 
absence of more significant rates than anticipated.

Lingering precipitation should quickly come to an end late tomorrow 
night into Sunday morning as profiles begin to rapidly dry from 
aloft.

&&

.Long Term...(Sunday night through Friday)
Issued at 312 AM EST Sat Jan 1 2022

Post-frontal continental polar air mass should bring the coldest 
temperatures of the season so far early next week. Since the 
synoptic pattern is still progressive, midlevel height rises/ridging 
will occur Tuesday and flow will veer and strengthen ahead of the 
next shortwave trough. This will cause temperatures to rise above 
normal again, though this warm surge will be much more modified than 
recent highly anomalous warm advection regimes we have experienced. 

Models still vary on amplitude and strength of this next shortwave 
trough, but most generally show it digging/deepening as it crosses 
through on Wednesday. Deeper moisture will be relegated to our north 
Wednesday, but a focused area of ascent near the front could be 
enough for brief light precipitation, probably sub-measurable. 

All guidance has an amplifying shortwave trough evolving immediately 
upstream of the first trough, and have varying placement and timing 
on deeper saturation/ascent, so confidence on snow Thursday is 
moderate at best. Thus, mid-range probabilities of measurable 
precipitation are retained at this time. Thermal profiles will 
support all snow, and in fact this may be a setup for our area with 
fairly deep layer with temperatures in the dendritic growth zone,
driving ratios a little higher than climatology. Those details 
will be examined closer once synoptic-scale details are better 
resolved. 

Regardless of the placement and amplitude dictating the position of 
best precipitation swath and dry conveyor belt, this system should 
be oriented more favorably to dislodge considerably colder cP air 
mass at higher latitudes and send it into our area. Temperatures may 
fall to around zero especially across the northern half of Indiana 
both Friday and Saturday mornings. If snowpack is present, sub-zero 
temperatures will be more likely.

&&

.Aviation...(12Z TAF Issuance)
Issued at 604 AM EST Sat Jan 1 2022

IMPACTS:

* Widespread IFR persisting or developing much of the period.

* Rain changing to a brief wintry mix and then snow late this 
  evening into the overnight, primarily at LAF/IND/HUF.

* Winds becoming northerly 7-12KT through the period.

DISCUSSION:

Poor flying conditions to be the rule throughout the majority of the 
period as widespread precipitation moves through the area along a 
slowly moving cold front. Ceilings will likely be IFR through much 
of the period, with visibilities MVFR or occasionally IFR in the 
heavier precipitation.

Winds will remain or become generally northerly as the front makes 
progress, with sustained speeds becoming 7-12KT as the period wears 
on.

Precipitation will change over to a brief wintry mix and then snow 
at LAF and perhaps IND/HUF late this evening into the overnight as 
colder air moves into the region. LAF is most likely to see very 
light snow accumulations.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 7 PM EST this evening for INZ067>072.

&&

$$

Update...KH
Short Term...Nield
Long Term...BRB
Aviation...Nield