FXUS63 KIWX 051916
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
316 PM EDT Thu Aug 5 2021

.SYNOPSIS...
Issued at 1221 PM EDT Thu Aug 5 2021

Dry and pleasant conditions will slowly be replaced by warmer,
more humid and at times wet conditions into the weekend. Highs 
will creep closer to 90 by Sunday and possibly into the 90s next 
week. 

&&

.SHORT TERM...(This Evening through Friday)
Issued at 309 PM EDT Thu Aug 5 2021

Ridging overhead with sfc high pressure moving through will act to 
keep overall shower activity suppressed this evening. Despite mixing 
heights up to 850mb, only weak (10 to 15 mph) wind gusts are 
expected with the low level jet over IL and WI. Dewpoints may try to 
approach the low 60s before day's end so tonight's lows drop into 
the low to mid 60s with a few low level clouds around. 

The low level jet over IL and WI this evening is more overhead on 
Friday as a large scale trough moves overhead. This allows us to be 
able to introduce a chance for showers and perhaps a few 
thunderstorms Friday afternoon mainly west of I-69 where the better 
instability resides. The NAM and, to some extent, the GFS holds on 
to some MUCAPE west of IN-15 along with some low level moisture 
convergence and mid level lapse rates over 6C/km hinting at the 
potential for thunderstorms to continue into the evening as the 
NAMNEST indicates. The boundary parallel flow and slowing moisture 
convergence hint that the boundary moving through Friday evening may 
slow down in the northwest perhaps allowing for training of storms 
within a profile supportive of flooding with 850 Tds above 10C and 
some large scale ascent to work with, although the atmospheric 
column is a little dry in the low levels. There's still some 
uncertainty about if we can even get some convection in the area 
tomorrow evening though so will continue with the 40 PoPs that the 
midnight shift had. Mixing heights up around 850mb again provides 
temperatures in the low to mid 80s on Friday, but with the low level 
jet overhead, Friday, wouldn't be surprised to see gusts approach
20 mph during the afternoon.

&&

.LONG TERM...(Friday Night through Thursday)
Issued at 309 PM EDT Thu Aug 5 2021

The long term period will be characterized by increasing 
temperatures and humidity as well as times of showers and storms. 
This is as a building southeastern US ridge couples with a building 
ridge over Canada early next week to provide additional Gulf 
moisture and warmth to the region while also allowing shortwaves to 
come in from the west setting off afternoon/evening showers and 
storms in a setup similar to the ring-of-fire pattern. 

Closer to home, the large scale trough mentioned in the short term 
discussion lumbers on vacating the area by the midday to early 
afternoon time frame, Saturday, allowing for some suppression of 
showers during the late morning hours into the afternoon. While a 
few showers during the afternoon can't be ruled out with some areas 
of differential heating and low level vorticity moving through, the 
better focus for showers and storms comes during the evening time 
frame as a weakening shortwave moves in from the west and has some 
instability to work with. With minimal shear to work with, another 
wet microburst/ flooding setup seems likely here. 

Sunday appears to provide a reprieve in the chances for showers and 
storms as ridging and a period of warm air advection moves in ahead 
of our next wave moving in for between Sunday night and Monday. The 
usual suspect (GFS) of introducing rainfall chances too early occurs 
during this period so would rather side with the EC/CMC grouping in 
terms of timing things through. This would wait to introduce PoPs 
until Monday morning and carry them through the rest of the day. One 
thing we'll need to watch is that the GFS introduces an EML-like 
area of 7.5 to 8.5 C/km mid level lapse rates during Monday 
afternoon into Tuesday morning period, but the EC does not. 
Additional chances for showers and storms are possible into Thursday 
morning before more ridging/ high pressure moves in. 

Temperature-wise, the Sunday through Wednesday period is expected to 
see increased humidity with dew points rising into the 70s. This 
paired with temperatures rising into the upper 80s to low 90s and 
perhaps around 95 degrees will make for some hot days and warm, 
likely unpleasant without AC, nights. Heat indices during this 
period rise into the low 90s with Monday, Tuesday, and Wednesday 
having pockets of 100 degree max heat indices forecast.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1220 PM EDT Thu Aug 5 2021

VFR diurnal CU will continue to develop this afternoon,
dissipating around sunset. A bit of an increase in mid and high
clouds will start later tonight into Friday in advance of the next
system. A stray shower is possible at KSBN towards the end of the
period, but most likely will wait till outside the current period. 


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...Fisher 
SHORT TERM...Roller
LONG TERM...Roller
AVIATION...Fisher


Visit us at www.weather.gov/iwx

Follow us on Facebook...Twitter...and YouTube at:
www.facebook.com/NWSNorthernIndiana
www.twitter.com/nwsiwx
www.youtube.com/NWSNorthernIndiana