IND issues Area Forecast Discussion (AFD) at Jun 20, 10:29 AM EDT ...PROLONGED PERIOD OF HOT AND HUMID CONDITIONS EXPECTED...447
FXUS63 KIND 201429
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
1029 AM EDT Fri Jun 20 2025
.KEY MESSAGES...
- Heat Advisory in effect Saturday through Tuesday; hottest
conditions of the season thus far expected this weekend into next
week, with heat index values peaking in the low 100s multiple days
in a row
&&
.FORECAST UPDATE...
Issued at 1029 AM EDT Fri Jun 20 2025
Another hot and humid day on the first official day of summer across
Central Indiana... in fact, today may be the "coolest" day over the
next week to 10 days as an anomalously strong ridge builds over the
Ohio Valley.
Latest satellite imagery and surface analysis show surface high
pressure and subsidence over much of the Southeast CONUS with a
weakening MCS over Iowa and Illinois. ACARs soundings confirm that
high pressure over the region is keeping the atmosphere too dry to
support any precipitation locally. As the upstream MCS pushes
southeast toward Indiana, it will be moving away from a strong 50 kt
low level jet supporting it and into a dry, more stable, and weakly
sheared environment, so expect this complex to fall apart over the
next several hours. Main weather impacts from this MCS will be
increasing higher clouds from the northwest through the afternoon.
Potential is there for an isolated shower in Northwester portions of
Central Indiana as the system weakens, however confidence is low on
that. Higher clouds may keep highs down a few degrees in the lower
80s for the north and west, while south of the I-70 corridor gets
better solar insolation.
&&
.SHORT TERM (Today and tonight)...
Issued at 314 AM EDT Fri Jun 20 2025
Today looks to be the most pleasant, if still seasonably warm and
humid, day of the forecast period, with highs in the mid 80s, as
opposed to highs in the 90s, in play for most if not all of central
Indiana over the next week.
Expect mostly clear skies today with a few small fair weather
cumulus and some passing high clouds as heights begin to build
across the area. Some guidance does suggest a weak convective
complex over the upper Midwest could survive or possibly diurnally
reintensify long enough to make it into the area on the periphery of
the building ridge, but this seems unlikely given increasing
subsidence aloft and dry air just off the surface promoting good
convective inhibition. The most likely impact of this activity is an
increase in high cloud late today into tonight.
Temperatures today will be typically mid-summer-like, in the mid 80s
with mid 60s dewpoints producing warm but not stiflingly
uncomfortable conditions. Lows tonight will likely fall to a couple
degrees either side of 70, as the aforementioned high cloud keeps
readings just a few degrees above anticipated overnight dewpoints in
the mid to upper 60s.
&&
.LONG TERM (Saturday through Thursday)...
Issued at 314 AM EDT Fri Jun 20 2025
...PROLONGED PERIOD OF HOT AND HUMID CONDITIONS EXPECTED...
An upper high/ridge will strengthen and build into the region this
weekend and remain into early next week, bringing with it subsidence
and widespread high temperatures from around 90 to the lower 90s.
Southwest winds on the back side of high pressure will bring a
return of unpleasant dewpoints in the low to perhaps mid 70s. This
will result in peak afternoon heat indices ranging from the upper
90s to low 100s each day from Saturday onward, with Sunday through
Tuesday appearing likely to be the hottest days of the stretch.
Subsidence will help keep the area dry through Monday. Given the
hot and humid conditions, can't absolutely rule out a pop up
isolated shower or storm near peak heating if there is a weakness in
the subsidence, but for now odds remain much too low to mention.
The upper high/ridge will drift off to the east into mid-week next
week, and this may just be enough to allow for some convection to
develop in the heat of the day. If it slides far enough away,
convection riding around the ridge could impact parts of central
Indiana. Either way, will keep some PoPs around Tuesday into
Thursday.
Hot and humid conditions will persist into mid-week next week, but
some additional clouds may temper it a bit by mid to late week.
Highs will remain around 90 into the lower 90s.
The prolonged period of these conditions will lead to a cumulative
effect and a higher risk for heat related illnesses, especially for
the more vulnerable populations. Experimental NWS HeatRisk levels
are at least Major/Level 3 (on a 0-4 scale) for part or all of
central Indiana from Saturday onward, with several days of
widespread Extreme/Level 4 heat-health impact potential, resulting
from both hot days and warm/humid nights as lows fall only into the
low to mid 70s.
As a result of the prolonged period of impactful heat, with multiple
days of heat index values in the low 100s, have gone ahead with a
heat advisory for all of central Indiana from Saturday through
Tuesday, despite strict advisory criteria likely only being
transiently met if at all during this period.
Those with outdoor plans for the coming weekend into next week, and
especially those without access to adequate cooling and/or
vulnerability to heat illness should pay close attention to the
forecast and conditions each day and take action/alter plans as
necessary for safety.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 647 AM EDT Fri Jun 20 2025
Impacts:
- Brief fog dissipating quickly at LAF
Discussion:
Some fog with variable visibility has occurred at LAF overnight. It
appears to be beginning to mix out with sunrise, but may persist
another hour or so into the period. Will carry a TEMPO MVFR group at
LAF, but otherwise, VFR is expected throughout the period.
An increase in mid and high cloud can be expected today as debris
cloudiness from dissipating convection upstream overspreads the
area. Mostly clear conditions with just some scattered cirrus will
return by this evening.
Winds will generally be out of the southwest through the day,
turning more southerly tonight, with sustained winds in the
afternoon around 8-12KT. A sporadic gust to the mid teens is
possible but will be too infrequent to mention.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM Saturday to 8 PM EDT Tuesday for INZ021-
028>031-035>049-051>057-060>065-067>072.
&&
$$
UPDATE...CM
SHORT TERM...Nield
LONG TERM...Nield/50
AVIATION...Nield
Source:
IND issues Area Forecast Discussion (AFD) at Jun 20, 10:29 AM EDT ...PROLONGED PERIOD OF HOT AND HUMID CONDITIONS EXPECTED...---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
