548 
FXUS63 KIND 101504
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1104 AM EDT Mon Apr 10 2023

...Updated Aviation Discussion...

.Forecast Update...
Issued at 955 AM EDT Mon Apr 10 2023

Short Wave embedded in broad ridging will bring some cirrus across 
central Indiana today per GOES-16 imagery. Otherwise, BUFKIT 
continues to advertise a dry column below 20K foot. BUFKIT also 
reveals light winds even at the top of the inversion, so little will 
mix down. 13z temperatures mostly in the 50s are well on their way 
to afternoon highs in the upper 60s to around 70 degrees.

&&

.Short Term...(Today and tonight)
Issued at 236 AM EDT Mon Apr 10 2023

- Sunny and warmer today 
- Dry weather through Tuesday (at least…)

Surface analysis early this morning shows a large area of high 
pressure centered over NY state extending south toward the middle 
Atlantic States. This large high pressure system was influencing the 
weather across the eastern third of the United States, including 
central Indiana. Light easterly surface flow was in place across 
Central Indiana along with mostly clear skies.  GOES16 shows an area 
of high cloud stretching from the western Great Lakes to KS and NB. 
Aloft, water vapor shows a ridge of high pressure over Indiana 
stretching toward Quebec while a second ridge was found over the 
Rockies. Between the two systems a weak trough was found and this is 
where our few clouds were present. 

Today...

Another mostly sunny and slightly warmer day will be in store today. 
Models suggest the ridge axis aloft will continue to sag  southeast 
today. This will allow the arrival of some higher clouds by late in 
the day, arriving from the northwest. These clouds will not amount 
to much, as subsidence still remains in place across the area. 
Meanwhile at the surface the previously mentioned strong high 
pressure system will sag southward also to the middle Atlantic 
States and continue to dominate the weather across the eastern half 
of the country. Forecast soundings and time heights continue to show 
a dry column with subsidence and unreachable convective 
temperatures. Thus after a sunny morning, only a few high clouds may 
arrive from the west, but these will have little impact. Mostly 
Sunny will work well. Given return of southerly flow today as the 
surface high sets up east, highs should be slightly warmer than 
persistence. Thus highs in the upper 60s to around 70 will be common 
across Central Indiana.

Tonight...

The second upper ridge over the Rockies is expected to push east 
toward the plains states Tonight. This will once again set up 
northerly flow aloft over Central Indiana along with lee side 
subsidence. The result of this subsidence will be the strengthening 
of the surface high pressure system as it sets up over KY/TN/NC/VA. 
Again, this large high pressure system will dominate the weather 
across the eastern half of the United States, providing dry weather 
for much of the week ahead. Forecast soundings tonight continue to 
indicate a dry column. Thus mostly clear should would well to 
account for any passing CI aloft. Ideal radiational cooling 
conditions will be in place tonight. Thus will trend lows toward the 
middle 40s.

&&

.Long Term...(Tuesday through Sunday)
Issued at 236 AM EDT Mon Apr 10 2023

Mid week dry air and warmth: 

As discussed previously, the upper level blocking pattern has 
amplified the upstream ridge, leading to the build up of well above 
seasonal temperatures over the lower Canadian Plains and Upper Great 
Plains. This will cascade over the Great Lakes and Ohio Valley over 
the next few days, leading to much warmer low to mid levels Tuesday 
through Thursday. This in combination with a return to modest 
southerly surface flow on the eastern edge of a high will lead to a 
long stretch of well above normal temperatures. Hedging above 
guidance both Wednesday and Thursday given the pattern and set up 
for efficient diurnal warming both days.  

Cloud Cover:

With the ridge axis centered over the Ohio Valley on Tuesday, any 
cloud cover will be brief and remain in the upper reaches of the 
troposphere. However, by Tuesday night, LLJ development on the super-
geostrophic side of the 850-700mb high should lead to scattered mid 
level clouds. This increased cloud cover and LLJ induced WAA may 
keep northern portions of the region slightly warmer, with lows near 
50 rather than the mid 40s.  

By Thursday, the high should be far enough east to extend the 
southerly flow through 2-3km above the surface. In return, low to 
mid level moisture maximums and steep surface lapse rates should 
lead to diurnal cu both Thursday and Friday afternoons. 

Late Week Rain:

As mentioned, diurnal cu is expected to develop Thursday and Friday 
afternoons as surface temperatures exceed the convective temperature 
threshold. However on Friday, there are still a few members with 
enough moisture return and mid level lapse rate cooling for an 
isolated thunderstorm/shower. Chances of this occurring look low, and 
have not been included in the forecast at this time, but is 
something to watch in the coming days. 

Also of note will be a push towards a meridional pattern by next 
weekend. The aforementioned amplifying ridge will create a cascading 
effect upstream, with troughing developing over the northern Pacific. 
This will eventually make its way east, leading to more uncertainty 
in conditions next weekend. The ensemble trend does point towards a 
more unified channel of moisture reaching Indiana sometime Saturday 
into Sunday, with a more organized low pressure system shortly 
after. Chances for rain are there throughout the weekend, but best 
chances look to be Saturday night through Sunday. 

Cold Snap Next Week:

In the wake of the aforementioned low, a push of cold dense air looks 
likely somewhere over the central to eastern CONUS. It is still too 
far out to determine where the axis of cold air will reside, but 
there will be potential for a period of overnight lows near freezing 
early next week.

&&

.Aviation...(12Z TAF Issuance)
Issued at 1104 AM EDT Mon Apr 10 2023

Impacts:

- VFR flying conditions through the TAF period with high confidence

Discussion: 

Subsidence associated with broad high pressure over the eastern 
states along with a mostly dry column will result in VFR flying 
conditions through the TAF period. The only clouds expected are 
passing cirrus related to a broad upper trough and possibly a few 
puffs of diurnal cu Tuesday afternoon.

Winds will be from the south around 5 knots today and switch to the 
southwest and increase to around 10 knots Tuesday afternoon.

&&

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

$$

Update...MK
Short Term...Puma
Long Term...Updike
Aviation...MK