120 
FXUS63 KIND 160727
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
227 AM EST Thu Feb 16 2023

.Short Term...(Today and tonight)
Issued at 225 AM EST Thu Feb 16 2023

...POTENTIAL FOR SEVERE STORMS ACROSS SOUTHERN INDIANA TODAY...

Today.

By 12Z, the surface low will be centered over southern Missouri and 
will track across the I-70 corridor while gradually strengthening 
through the afternoon hours.  Elevated showers and storms will reach 
the southern counties by 09Z with scattered to widespread showers 
and isolated storms across much of central Indiana by 12Z. 

The forecast area will be north of the warm front during the early 
morning hours with a strong inversion at 3000ft which will limit the 
impacts to just brief heavy rain, small hail, and lightning 
initially.  The freezing layer will only be around 8000ft which will 
further allow for small hail even in the weaker storms. 

By noon the warm front will push as far north as south central 
Indiana with a period of up to 1000 J/kg of surface based instability 
with a rapid warmup into the mid 60s overtaking the inversion and 
allowing for mixing down of storm level winds.  The wind profile 
will then become more southwesterly between 18Z and 21Z as the 
surface low crosses into Indiana which will help to limit the 
tornado threat going into the afternoon hours, but helicity in the 
lowest levels will still be high enough for a quick spin up if an 
organized storm can maintain itself.  Isolated to scattered showers 
and storms are likely in this timeframe with isolated strong to 
severe storms.

Models are then initiating a broken line of showers and storms along 
the cold front between 20Z and 00Z across southern Indiana.  This 
may be the best chance for damaging wind gusts with a more organized 
nature to the convection along with soundings showing much more 
favorable lapse rates between the surface and LCL.

Overall, focus for much of central Indiana will be during the 
morning hours with showers and storms with small hail and lightning 
as the primary threat. As the warm front pushes back north during 
the late morning to afternoon hours, strong to severe storms are 
possible across the southern counties with more discrete cells 
initially followed by a broken line of storms towards the evening.  

The severe threat north of I-70 will be near zero with an isolated 
severe threat to the south.  Think that the majority of the severe 
weather will be closer to the Ohio River, but can't rule out 
damaging winds or even a quick tornado in the far southern counties 
of the forecast area.

Tonight.

A quick blast of colder air arrives tonight, but even that is just 
dropping temperatures to what is normal for this time of the year. 
Northwesterly wind gusts to 30 mph will bring wind chills into the 
upper single digits to low teens the late overnight hours. 
Widespread cloud cover will persist through the night before the 
arrival of drier air aloft tomorrow morning.  Hi-Res models show the 
potential for a few hundredths of an inch of QPF across the northern 
counties tonight associated with the colder portion of the system 
that will bring snow to the Upper Midwest, but think that any 
rain/snow will be north of the forecast area.

&&

.Long Term...(Friday through Wednesday)
Issued at 225 AM EST Thu Feb 16 2023

*********************************************
* Winter temps Friday, some sun late day    *
* Moderating temps, but breezy this weekend *
* Multiple precipitation chances next week  *
*********************************************

Summary...

Model consensus suggests the synoptic pattern aloft will deamplify 
somewhat this weekend and the first part of next week, with quasi-
zonal flow across the midsection of the CONUS into the OH Valley. 
This will create initially more tranquil weather conditions starting 
Friday, although embedded fast moving shortwaves (weather 
disturbances) aloft within the zonal flow could still result in 
multiple quick moving precip makers across central IN early and mid 
next week. However, given this type of pattern, timing and intensity 
of these systems and accompanying precip will remain a bit tenuous 
with model differences expected.

Friday and Friday night...

Today's (Thursday) storm system will depart east of the OH Valley on 
Friday. However, residual low-level moisture and northerly winds off 
Lake Michigan could result in at least morning flurries across 
northern parts of central IN along with mostly cloudy skies. Expect 
winter cold as well with morning temperatures in the 20s and wind 
chills in the teens. During the afternoon, however, as a ridge axis 
of surface high pressure builds east into the OH Valley, skies 
should begin to clear from west to east over central IN. Afternoon 
high temperatures will top out in the lower 30s north and mid 30s 
south. Expect a mostly clear and cold Friday night with lows from 20 
to 25 Saturday morning and wind chills again in the teens. For 
comparison, the normal high and low temperatures at Indianapolis for 
mid February are lower 40s and mid 20s.

Saturday and Sunday...

With surface high pressure centered over the TN Valley Saturday 
before retreating to the Carolinas on Sunday, a S to SW surface wind 
will develop and become breezy with winds about 10-20 mph with gusts 
over 20. Saturday's weather will feature sunshine and slowly 
moderating afternoon temps ranging through the 40s. Late Saturday 
night into Sunday, the first of the fast moving shortwaves is 
forecast to move across the OH Valley. However, this system appears 
very weak with little or no surface reflection and limited moisture 
and lift. Thus, expect more clouds with perhaps a few sprinkles at 
most, but most if not the entire area should be dry. Some sun should 
return during during the day Sunday. Except highs Sunday afternoon 
mainly in the lower to mid 50s.  

Monday and Tuesday...

At least one, if not two weak fast moving weather disturbances are 
shown to move though the OH Valley area early next week, perhaps one 
early Monday and another Monday night or Tuesday. Again, despite 
some model differences, the overall signal suggests a window of 
modest lift and limited moisture transport which could lead to 
scattered showers Monday. By Tuesday, the next system could have 
better moisture advection and lift to work with resulting in a 
higher chance of rain showers. However, the synoptic pattern favors 
surface low development and track over the lower OH Valley, with 
convection and possible heavier rains along or south of the OH River 
if current model solutions hold. Expect afternoon highs both days 
roughly in the upper 40s north and 50s south, which will be affected 
by cloud cover and any precip.

Wednesday and Thursday... 

A return to a more SW flow pattern aloft and approach of a separate 
southern stream shortwave lifting to the NE could bring additional 
and potentially more widespread showers and at least isolated 
thunderstorms either late Wednesday or Thursday across the OH 
Valley, with the best chance for convection to our south. Being 
about a week out in time from now, will monitor this system and 
model changes to it over the next several days.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1147 PM EST Wed Feb 15 2023

Impacts:
-Rain beginning after 10Z, brief periods of MVFR to IFR vsbys.
-Wind shift to the east after 10Z, becoming southwesterly by 18Z, 
then northerly again after 06Z tonight.
-Isolated TSRA 15Z to 21Z, best chances at BMG.

Discussion: 

Quiet conditions expected through 10Z with northerly winds to 10kts. 
Winds will shift to the southeast with periods of light to moderate 
rain after 10Z.  Isolated TSRA is possible before 15Z, but think the 
best chances will be from 15Z to 18Z and at BMG.  Additional TSRA 
possible at BMG after 21Z, but confidence remains too low at this 
time for a second mention in the TAF.  Southwesterly gusts to 30kts 
from 15Z to 22Z before winds become northerly again tonight. Cigs 
will drop to IFR after 11Z and remain MVFR to IFR through the rest 
of the TAF period with MVFR to IFR vsbys during periods of rain.


&&

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

$$

Short Term...White
Long Term...Funk
Aviation...White