175
FXUS63 KIND 100913
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
513 AM EDT Mon Jun 10 2024

.KEY MESSAGES...

- Unseasonably cool Today.

- Warming trend beginning Wednesday, highs near 90 possible by
  Thursday and Friday.

- Low chance of showers/t-storms Thu Night-Friday.

&&

.SHORT TERM (Today and tonight)...
Issued at 303 AM EDT Mon Jun 10 2024

Today...

Surface obs are indicating a backdoor cold front is moving into far
southern parts of central Indiana as seen in a shift from southwest
to northeast winds. Meanwhile, GOES-16 IR satellite loop and surface
obs are showing extensive MVFR/VFR stratocu deck over southern
Wisconsin, northern Illinois and lower Michigan. The deck was
dropping southeast along an ahead of an upper trough that was
rotating southeast across the Great Lakes per H20 vapor imagery
loop. This trough will move southeast of the Ohio River this
afternoon and with broad surface high pressure building in from the
west and a high sun angle, look for the deck to scatter out from
west to east. Despite some afternoon sunshine, cold advection behind
the cold front will translate to below normal temperatures and the
coolest day of the foreseeable future. Temperatures may not even hit
70s degrees over northern and eastern locales, where strato . cu
remains the longest. Normal highs for this time of year are in the
80s. Finally, Hi-Res soundings suggest mixing down of near 20 knot
gusts this afternoon from around 850 millibars.

Tonight...

Winds will drop off quickly after dark as diurnal mixing ceases and
high pressure continues to build in as the pressure gradient
relaxes. In addition, upper ridging will close in from the upper
Midwest. Drying column per soundings along with light to calm winds
will provide efficient radiation cooling and allow for unseasonable
chilly overnight temperatures in the 40s.

&&

.LONG TERM (Tuesday through Sunday)...
Issued at 303 AM EDT Mon Jun 10 2024

A pattern shift towards warmer temperatures is becoming increasingly
likely this week. Northwesterly flow aloft currently prevails and
has been dictating our weather. As such, we`ve seen rather cool
conditions for this time of the year. That changes as ridge-building
occurs to our west. Ensemble guidance is in decently good agreement
showing the resulting ridge gradually translating eastward by the
weekend.

At the surface, high pressure shifts southeast of Indiana by late
Tuesday or early Wednesday. This allows flow to gain a southerly
component and thus beginning the expected warming trend. Modest warm
air advection brings high temps into the mid 80s for most locations
Wednesday afternoon. As the aforementioned ridge edges eastward,
temperatures near 90 are possible Thursday afternoon. However, we
are still likely to be on the eastern side of the ridge at this
point. Flow aloft still retains a northwesterly component to some
extent. Guidance is keen on bringing a system in from the northwest
along with its associated cold front. We may see a shower or
thunderstorm from this feature late Thursday or into Friday.

By the weekend, ensemble guidance depicts the ridge axis shifting
eastward and directly over Indiana. NAEFS/ECMWF ensemble situational
awareness tables give an early look at the potential strength of the
ridge. Both tend to show 250mb heights within the 95th to 99th
percentile range. Such anomalous ridging would lead to very warm
surface temperatures, assuming clouds/precipitation does not impede
warming potential. Readings into the 90s are possible again this
weekend and into next week. Additionally, surface dew points are
likely to increase with sustained southerly surface flow. Heat and
humidity may lead to high heat indices late this weekend and early
next week, and will need to be monitored closely.

Taking a look beyond the long range into the 8-14 day period, we see
a signal for sustained ridging within ensemble guidance. Continued
above-average warmth and humidity is the most likely outcome in such
a scenario. Precipitation anomalies are a bit harder to discern,
however. Guidance is showing a plume of tropical moisture developing
over Gulf late this week, which may lift northward into the ridge.
This may lead to "air mass" type thunderstorms or may interact with
decaying frontal boundaries drifting southward. Deterministic models
show the polar jet well to our north once the ridge develops, so
large-scale organized forcing may be absent most of the time.
Therefore, our rainfall may depend on these subtle interactions that
are harder to pin point this far out.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 512 AM EDT Mon Jun 10 2024

Impacts:

- MVFR ceilings possible 13z-17z

Discussion:

An upper trough will swing through today and bring MVFR ceilings in
this morning. Conditions will return to VFR this afternoon in its
wake and as high pressure builds in from the west.

Winds will be from the northwest up to 10 knots this afternoon with
gusts to near 20 knots possible. Winds will die off afternoon sunset
as mixing ceases and the low pressure gradient relaxes.

&&

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

$$

SHORT TERM...MK
LONG TERM...Eckhoff
AVIATION...MK