867
FXUS63 KIND 190703
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
303 AM EDT Sun May 19 2024

.KEY MESSAGES...

- Isolated showers and storms across parts of the northern forecast
area this afternoon and evening

- Unseasonably warm Sunday-Tuesday, highs in the mid to upper 80s

- Increasing threat for at least 1-2 rounds of strong/severe t-
storms late Tuesday through Wednesday

&&

.SHORT TERM (Today and tonight)...
Issued at 302 AM EDT Sun May 19 2024

Early This Morning...

Skies were clear across central Indiana early this morning, and
winds were calm or very light. Dewpoint depressions continue to
decrease. Thus, expect some fog to still develop across the area.
Questions remain though on how widespread any dense fog will become.

Based on trends so far, widespread dense fog does not look likely.
Will continue to mention patchy to areas of fog, with most coverage
near sunrise.

Today...

An upper level ridge will continue to strengthen across the area
during the day today. Meanwhile, a weakening surface cold front will
move into northwest Indiana.

The front may make it as far as the northwest corner of the forecast
area before it stalls. As noted earlier, there will be no upper
support with a ridge overhead. Surface dewpoints will remain in the
60s, and highest dewpoints may be in the northwest with some weak
pooling of moisture along the front. This moisture plus temperatures
in the 80s will create instability over the area.

Late this afternoon, there may be some influence from a lake
boundary coming off of Lake Michigan that could increase convergence
along the front in the far northwest.

Thus, feel that isolated showers and storms may develop in the far
northwest, mainly mid to late afternoon. Will continue with some
slight chance PoPs there.

Some cumulus will pop up today, but there will be plentiful
sunshine, which will boost temperatures in the mid 80s most areas
today.

Tonight...

Similar conditions to late afternoon will persist into the evening,
with the old front in the northwest. Will keep some slight chance
PoPs going in the north this evening before instability diminishes
with loss of heating.

Otherwise tonight will be quiet with the upper ridge in place. Lows
will be in the 60s.

&&

.LONG TERM (Monday through Saturday)...
Issued at 302 AM EDT Sun May 19 2024

Monday and Monday Night...

A pronounced, yet positively-tilted upper subtropical ridge aligned
from Texas to the New England coastline will include Indiana in its
attempt to bring summer temperatures and humidity to the region well
ahead of time.  Plentiful sunshine will oversee light southerly
breezes Monday slowly building dewpoints through the 60-65F range. A
small weakening/lifting wave slicing through the northern extents of
the ridge should cross the northern Midwest Monday night...which
could set-off isolated RW/TRW.  Can`t rule out a lone marginally
strong/severe storm grazing the Upper Wabash Valley given adequate
instability, although confidence in this potential is very low.
Temperature will follow Sunday`s precedent with highs around 85-87F
followed by lows around 65-67F.

Tuesday and Wednesday...

Latest guidance is continuing to show Tuesday as a transition day
from the summer-like warmth and moderate humidity amid increasing
southerly breezes...to the beginning of a 2-3 period strong/severe t-
storm threat late Tuesday and Tuesday evening.  Confidence in timing
of the storm threat is so far low given the lifting nature of the
supporting, first, vort max into the Upper Midwest.  Instability,
lapse rates, shear should all be adequate for at least scattered
strong storms amid the deep moisture of the antecedent air mass`
warm sector.  An MCS may develop along the instability gradient
during the Tuesday overnight period near our region...which could
well linger, perhaps as more of a heavy rain threat, into Wednesday
morning hours.  A second round of more linearly-aligned cells would
be the concern Wednesday...although this second threat would be
dependent on boundaries and instability levels influenced by any
first round.  Suspect at least a few strong cells by late Wednesday
with the system`s cold front expected to slowly drag across the CWA
from west to east around the PM hours ahead of the second vort
advancing into the Great Lakes.  Temperatures should again push well
into the 80s Tuesday, with overnight lows approaching record level
in the 65-70F range...clouds/rain Wednesday would promote temps
noticeably milder, yet above normal.

Thursday through Saturday,,,

A zonal-type upper ridge will bring a return to overall dry and more
seasonable conditions to end the work week...although with lower
heights still retracted well north of the region readings will
likely trend slightly above normal.  Central Indiana may find itself
amid a squeeze play of sorts between a weaker disturbence`s showers
along the Ohio Valley/south around the Friday timeframe...before the
next northern-stream front slowly arrives during the weekend.  Too
early to assess details of any corresponding storm threat, but
extended southerly fetch would likely boost precipitable water over
1.50 inches, setting the stage for the next page in this spring`s
wet pattern.  The normal max/min at Indianapolis through the long
term is 75/56.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 113 AM EDT Sun May 19 2024

Impacts:

- Areas of fog should lead to IFR or worse conditions at most sites

Discussion:

Clear skies and light winds will lead to some fog formation again
tonight, but confidence on similar conditions as Friday night is
low. Still though, some IFR fog is likely to move in at times at all
but KIND. KIND shouldn`t see worse than MVFR.

Fog will mix out by 14Z leaving VFR conditions. Some scattered to
broken cumulus will then develop ahead of a weak front. An isolated
storm is possible near KLAF in the afternoon, but odds are much too
low to include.


&&

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

$$

SHORT TERM...50
LONG TERM...AGM
AVIATION...50