627 
FXUS63 KIND 210310
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1010 PM EST Thu Jan 20 2022

...Updated Aviation Discussion...

.Forecast Update...
Issued at 909 PM EST Thu Jan 20 2022

Sufficient PBL moisture along with weakly confluent surface flow 
with steep low-level lapse rates is resulting in ongoing 
intermittent flurries. As low-level flow veers resulting in drier 
trajectories (not augmented by Lake Michigan), weak confluence 
will shift west and lapse rates will improve also. Shallow 
convection driving the flurries should continue decreasing through
the tonight. Regardless, non-measurable amounts are expected. The
previous forecast looks good and only minor adjustments were 
needed, mainly to spatial coverage of flurries and their duration.

&&

.Short Term...(This evening through Friday night)
Issued at 229 PM EST Thu Jan 20 2022

Lake enhanced clouds were across much of central Indiana this 
afternoon, aided by cold air aloft across the area. Scattered 
flurries accompanied the clouds, and temperatures were in the 20s.

Clouds and flurries should continue through the remainder of this 
afternoon. However, as flow turns more northeast, lake moisture will 
be cut off. This, plus the loss of heating, will allow for some 
decrease in clouds this evening and the end of any flurries. 

However, time height cross sections show lingering moisture in the 
low levels, so do not expect skies to become completely clear. Winds 
will diminish as high pressure begins to move into the area, but 
they will not go calm. Thus, feel that the MOS guidance low 
temperatures in the single digits for many areas look too cold. Will 
go with some single digit lows northwest, but mainly 10-15 
elsewhere.

Although an upper trough will move through on Friday, there will be 
no moisture or any surface reflection with high pressure building 
in. Will go dry, and will go with skies becoming sunny as subsidence 
scours out lingering cloudiness. Sunshine will help temperatures 
recover into the 20s.

Some increasing high clouds and southerly winds will prevent 
temperatures from bottoming out on Friday night, but readings will 
still be cold and in the lower teens most areas.

&&

.Long Term...(Saturday through Thursday)
Issued at 305 PM EST Thu Jan 20 2022

The long term period will feature mid-winter cold while continuing 
to exhibit quick opportunities for flurries/isolated snow showers 
every 1-3 days as moisture-starved northern-stream waves continue to 
circulate around a broad, stagnant Hudson Bay upper low.  Although a 
more intriguing scenario possibly surrounds the late Monday-Tuesday
timeframe when southern energy will pose a slightly more organized
potential for frozen precipitation. 

A couple opportunities for light snow will cross the region this 
weekend...with more scattered flurries expected Saturday, before 
better chances of snow showers in the Sunday timeframe courtesy of a 
deeper wave, broader field of H700 relative humidity over 90%, and 
even weak surface circulation amid the northwest flow.  Northern 
energy will then attempt to pick up some southern stream moisture 
following the early week ejection of a small H500 cut-off from 
northwestern Mexico.  Limited confidence so far in any details 
surrounding the potential for generally light mix to frozen 
precipitation in the Monday Night-Tuesday timeframe given several 
ensemble members dissenting with the cut-off staying well south 
while skirting east along the Gulf coast. However, saw no need to 
change the Blend's mainly chance POPs for two periods with this 
rather weak system's slower pace and PWATs possibly briefly 
climbing to 0.50-0.75 inches. Appears all three precipitation 
opportunities would favor snow for most locations as precipitation
type with H850s generally in the -3 to -12 Celsius 
realm....although rain or mix to start the Monday night wave 
would be possible following height rises Monday. The end of the 
long term should favor a drier trend with a mid-level flat ridge 
pattern more likely amid an overall broadening upper trough.

Temperatures will be generally slightly below normal through the 
long term...with occasional milder/and/unseasonably cold days 
before/and/after each wave and arctic frontal boundary. Monday is
progged to be the warmest day, and may be the only that climbs 
above 32F for all zones. Overnight lows in the teens will be 
common in the Wed-Thu timeframe as strong high pressure builds 
into the Mid-West following the Tuesday system. The normal 
max/min for the long term at Indianapolis is 36/20.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1010 PM EST Thu Jan 20 2022

IMPACTS:

-- Winds at all sites will gradually veer from northerly to 
east-northeasterly. 

DISCUSSION: 

Stratus is expected to remain within the VFR range and should 
decrease during the morning as drier upstream air mass moves in. 
This is due to veering low-level flow (more east-northeasterly). 
This change in wind direction will be gradual. Any residual 
flurries this evening should diminish later tonight. Until then 
they are not expected to be significant enough for visibility 
reduction.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Update...BRB
Short Term...50
Long Term...AGM
Aviation...BRB