646
FXUS63 KIND 020700
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
300 AM EDT Sun Jun 2 2024

.KEY MESSAGES...

- Potential for patchy fog this morning and again tonight
  into Monday morning

- Warmer next week with periodic thunderstorm chances.
  The best chances will be Wednesday.

&&

.SHORT TERM (Today and tonight)...
Issued at 257 AM EDT Sun Jun 2 2024

Early this morning mid-lvl water vapor was still at a maximum over
Central Indiana, with some drying noted upstream across
Illinois/Missouri. The lack of a pressure field coupled with the
moist boundary layer is allowing some lingering drizzle or mist to
continue; however, this should become more widespread during the pre-
dawn hours. This opens the door to potentially seeing fog
development. The moist/damp surface from earlier showers will couple
with the shallow stratus deck loosing the upward energy and sinking,
then the lack of a pressure gradient to encourage mixing of
saturated parcels or at least causing any additional vertical motion
sets the stage for early morning fog to develop. VWP from KIND
already indicating most targets under 5kts, with the only lingering
wind above 3kft agl but this area is also decreasing. Some
encouraging guidance is that many hi-res members displayed within
DESI suggests only patchy dense fog developing and only the HRRR has
been more suggestive of greater coverage. This helps with confidence
to lean towards only patchy fog developing from the sinking stratus
deck. But once any fog does develop, due to a lack of
mixing/isallobaric field would suggest it will linger through mid-
morning before burning off.

Today... Boundary layer will continue to be moist through midday,
perhaps into the afternoon hours. Lack of a gradient from a weak
anti-cyclonic feature arriving should delay the erosion of any
shallow stratus/fog from early in the morning. Which could cause a
slower response for temperatures due to the shielding lingering
longer. The mid-lvl flow does flatten out, with indications that
perhaps an increase to the forward propagation will occur and help
to push the departing moist layer east. But the caveat is that the
surface remains disjointed and will not realize this upper level
flow through much of the day. So temps will likely remain in the 60s
perhaps around 70 by the afternoon hours, then once the stratus deck
erodes enough the surface parcels should quickly respond and push
temps into the mid/upr 70s quickly.

Given the quasi-sinking air overhead this afternoon, not expecting
development to a cumulus field. Which should inhibit our potential
for seeing any convection let alone see rain become organized. So
will maintain the dry forecast.

Tonight... Could see a repeat setup for fog late tonight. With a
lack of diurnally induced mixing scouring any moisture from the
surface/boundary layer in the afternoon/evening hours, expect more
optimal conditions for fog to develop. Again the wild card will
be winds aloft. While the boundary layer appears to be lacking any
substantial pressure gradient with guidance suggestive of minimal
isallobaric pressure change in place, this should lay the
foundation for fog development after sunset. But flow in the mid-
lvls and aloft do appear to be more zonal and could be just enough
to limit the fog growth tonight if perhaps only allowing patchy
fog to occur.

&&

.LONG TERM (Monday through Saturday)...
Issued at 257 AM EDT Sun Jun 2 2024

The long term period will be warm, with highs in the 80s, for much
of the week before temperatures drop back into the 70s for the
weekend. There will be periodic chances for showers and
thunderstorms through the week as multiple shortwaves and then a
larger trough moves through into the Great Lakes region while an
upper high settles into the southern plains and SW states.

South to southwest flow at the surface for most of the week will
advect warm and moist air into the region. Models still don`t have
great agreement with precipitation through the period but generally
expecting to see chances for rain Monday night into Tuesday followed
by another wave Late Tuesday into Wednesday. A break between waves
may be possible. As the high over Mexico moves into the south-
central to southwest portion of the CONUS, the large upper low near
the Dakotas will progress towards the Great Lakes. The associated
cold front looks to advance through central Indiana sometime
Thursday night into Friday and lower temperatures for the weekend.
Additional precipitation may form along the front and another
rain chance possible over the weekend. Severe weather is not
expected at this time but can`t rule out a few storms producing
some gusts midweek.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 226 AM EDT Sun Jun 2 2024

Impacts:

- Poor flying conditions through daybreak
- IFR flight conditions will slowly improve to VFR midday

Discussion:

Stagnant airmass overhead has allowed the nearly saturated moist
layer to become baggy and sink towards the surface. This has
resulted in some lingering sprinkles or mist along with a shallow
stratus layer that is within a few hundred feet of the surface.
Guidance suggests that the shallow stratus may become in contact
with the surface with fog otherwise being observed, but some
guidance indicates the fog may only be scattered to perhaps patchy.
The KIND VWP is still indicating some largest aloft at 10 kts, which
could be enough friction to inhibit fog development, but the
question is what will occur in the next few hours. Have a few points
seeing fog development with VSBY down to around 3sm, but this may
need to be adjusted should VWP begin to show nearly calm conditions
aloft sooner.

Expect after daybreak a slow and steady improvement to the CIGs with
a light northerly flow helping to dry the near surface environment.
This should translate into VFR conditions developing by midday or
perhaps early afternoon.


&&

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

$$

SHORT TERM...Beach
LONG TERM...KF
AVIATION...Beach