693 
FXUS63 KIND 191743
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
143 PM 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

&&

.FORECAST UPDATE...
Issued at 1011 AM EDT Sun May 19 2024

No significant changes to the forecast this morning. Only one minor 
change was made and that was to refine the cloud cover to reflect 
current satellite trends. Continue to expect a very warm day with 
highs in the mid to upper 80s.

&&

.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 (18Z TAF Issuance)...
Issued at 143 PM EDT Sun May 19 2024

Impacts:

- Low chance shower or thunderstorm near LAF this afternoon.
- Low chance ground fog overnight.

Discussion: 

VFR conditions expected through the TAF period, with a possible 
brief exception near LAF.

Cumulus continues to develop this afternoon with the greatest 
concentration near LAF. Guidance shows the possibility of very 
isolated development as the afternoon progresses. Overall, the 
chance of a shower or thunderstorm is very low (under 25 
percent)...so any mention will not be in the LAF TAF itself.

Elsewhere, diurnal cumulus will diminish after 00z leaving mainly 
clear skies (aside from high cirrus) and calm/light winds. A low 
chance of ground fog exits at all terminals by morning.

Winds are expected to be under 10 knots and may even go calm or 
light and variable overnight. A steadier SSW breeze looks to develop 
on Monday with a gust up near 20kt possible.

&&

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

&&

$$

UPDATE...Eckhoff
SHORT TERM...50
LONG TERM...AGM
AVIATION...Eckhoff