480
FXUS63 KIND 270045 AAA
AFDIND

Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
845 PM EDT Sun May 26 2024

.KEY MESSAGES...

- Another round of thunderstorms arrives tonight, especially south.

- Some of these storms may be severe with damaging winds the primary
  threat.

- Shower chances and cooler temperatures Tuesday-Wednesday
- Dry and Seasonable Thursday and Friday
- Rain chances on Saturday and Sunday

&&

.MESOSCALE UPDATE...
Issued at 845 PM EDT Sun May 26 2024

Initial convection in our area near Vincennes appears to be rooted
within a deeper low-level moist layer returning northward.
Effective shear is sufficient for storm sustenance but so far
this cluster of multicells has not required organized rotation,
thus it is being carried by the mean cloud layer wind
northeasterly at about 35-40 mph. If it becomes rooted more
solidly within the near-surface layer, it would slow and turn
right with an easterly motion at about 25-30 mph. WoFs storm-scale
modeling shows limited signal in low-mid layer UH probabilities
so at this time such transition appears to be less likely.
Nevertheless, a marginal hail/wind threat may accompany these
multicells as move toward Bloomfield and Bedford over the next
hour.

Further west, and organized QLCS has evolved with a distinct rear
inflow jet and bowing segment now approaching Olney. Near the apex
of this bow and northward there is a low potential for
mesovortices, but 0-3-km shear vector magnitude and orientation
are only marginally supportive at best. Damaging winds will be
the main concern as this line crosses into Indiana around or just
before 10:00pm. The northern end of this line may tend to weaken
as it progresses north of returning richer low-level moisture and
instability. So the greatest severe threat is south of a Sullivan
to Bedford line, with a lower probability northward toward I-70.

&&

.SHORT TERM (This evening through Monday)...
Issued at 234 PM EDT Sun May 26 2024

Rest of This Afternoon...

Showers and lingering thunderstorms will continue to exit central
Indiana to the east and north into mid-afternoon. Behind this,
clouds will also gradually decrease from the south and west.
Temperatures will be able to rebound some, especially southwest.

Convective inhibition will persist for much of the afternoon as the
atmosphere recovers from the previous convection. Without much of a
trigger and with the inhibition, will keep PoPs low behind the
initial line for much of the period.

Later this afternoon, more convection will fire west of central
Indiana. Latest hi-res models have been slowing down this
convection`s arrival time into central Indiana, but will still
increase PoPs higher into the chance category southwest by 23Z or
so.

Tonight...

An upper wave will be responsible for the forcing that generates the
convection to the west late this afternoon, and it will continue the
forcing into the area this evening. Southwest winds at the surface
and a continued moist flow at 850mb will bring in instability and
moisture to the area.

However, best instability will remain south of central Indiana, and
the storms should turn into that fuel.

Will go highest PoPs tonight in the south. Questions remain on
whether the southern storms will rob enough moisture to keep the
northern area from having much rain. With this possibility in play,
will go lower PoPs north with higher uncertainty.

The return of instability on southwest flow will keep the threat of
severe storms across central Indiana this evening. The main threat
will be across southern sections of the area where shear is best.
Depending how fast storms turn southeast into the better
instability, the threat could be farther south. Will monitor
closely, but stay weather aware.

After the initial complex of storms moves out of the area,
additional, weaker convection may develop as a cold front moves into
the area. Will keep PoPs going through the night.

Monday...

Most forcing will be east of central Indiana by 12Z Monday, but
enough may linger east for a few showers in the morning. Will keep
some slight chance PoPs there.

Otherwise, any forcing from the next upper wave should wait until
Monday night, so will go dry during the afternoon all areas.

Temperatures will get into the mid 70s for highs.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 234 PM EDT Sun May 26 2024

Tuesday and Wednesday -

Models show strong ridging aloft over the Rockies and a broad upper
trough over Ontario and the Great Lakes. This cyclonic flow aloft
looks to impact Central Indiana on Tuesday and Wednesday as several
upper level forcing features pass within the flow on Tuesday,
Tuesday night and Wednesday. Meanwhile within the lower levels,
surface low pressure over the Great Lakes on Tuesday is expected to
push toward Quebec by Tuesday. This feature looks to keep cyclonic
flow across Central Indiana on through this time with several weak
surface trough axes looking to pass. Deep moisture fails to arrive,
especially given our northwest continental flow, but forecast
soundings show some weak instability. Thus at least a small chance
for showers and storms seem reasonable. Again, washout days are not
expected, but pop-up showers with diurnal heating and weak forcing
aloft cannot be ruled out yet. Cooler northwest flow will allow
highs to remain below normal, within the lower to middle 70s.

Thursday and Friday -

The previously mentioned upper ridge of high pressure is expected to
build east across the Great Lakes and Ohio Valley on Thursday
through Friday night, with a ridge axis passing across Indiana on
Friday Night. An associated area of strong surface high pressure
will also pass across our region. Forecast soundings show a very dry
column through this period indicative of ongoing subsidence. Thus
mostly sunny days and mostly clear nights will be expected. Again
southerly return flow does not begin until Friday Night. Thus temps
will remain below normal with highs in the middle 70s.

Saturday and Sunday -

The upper ridge and surface high are expected to exit east on
Saturday, allowing for southerly warm and moist gulf flow to
Indiana. Aloft, a deepening trough is expected to be found over the
plains states, providing southwest flow aloft and ejecting embedded
forcing toward central Indiana within the flow. Mid levels suggest
sufficient moisture available as a broad area of saturation is shown
to pass across the region. Timing at this point appears a bit
uncertain, thus ongoing pops through the period look reasonable.
Slightly warmer temperatures will be expected on Saturday as
southerly flow is predominate, but rain and a more westerly flow on
Sunday may result in cooler highs.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 637 PM EDT Sun May 26 2024

Impacts:

- More strong to severe storms possible with the biggest threats
  KHUF and KBMG

- SW winds will become W Memorial Day, in the wake of a cold
  front

- Winds gusting to around 20 knots at times and much higher in
  the strongest isolated convection, where 50+ knots is possible

- MVFR and briefly worse conditions possible in convection

- MVFR ceilings overnight and Memorial Day morning

Discussion:

Another round of strong to severe storms will arrive near and after
sunset. The strongest cells could see wind gusts in excess of 50
knots and large hail with the highest probabilities at KHUF and KBMG
but even higher probabilities southwest of all the terminals. MVFR
and briefly worse flying conditions will accompany the convection
and MVFR ceilings are also expected in the wake of the activity. A
cold front will move through Memorial Day morning with the rest of a
southwest to west shift in the winds.


&&

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

$$

MESOSCALE...BRB
SHORT TERM...50
LONG TERM...Puma
AVIATION...MK