393 
FXUS63 KIND 140703
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
303 AM EDT Wed Jul 14 2021

.Short Term...(Today through Thursday)
Issued at 302 AM EDT Wed Jul 14 2021

Today/Tonight...
The lull in the active pattern has finally arrived with zonal flow 
aloft and high pressure at the surface.  The high pressure is 
centered over the southeast U.S., so strong southwesterly flow on 
the backside will advect much warmer air into central Indiana.  This 
in combination with the ample sunshine will push daytime highs into 
the mid to upper 80s today and upper 80s/low 90s tomorrow as the 
southwest winds gust up to 25 mph.  In addition, the high dew points 
are not going anywhere, so heat index values will reach the 90s both 
today and tomorrow...even upper 90s across western counties 
tomorrow.  Meanwhile, overnight lows tonight will hold steady in the 
low 70s with clear skies. Will continue to trend toward a dry 
forecast across all of the forecast area since ensembles have been 
hinting at that the last several days.

Thursday... Expect mostly sunny skies in the morning.  However, that 
benign pattern will be short-lived as the next upper trough quickly 
enters the region on Thursday afternoon.  It won't take much forcing 
to trigger showers and thunderstorms in an environment with that 
much heat and humidity on Thursday.  So, will lean toward chance 
Pops at this time for the majority of the forecast area during. the 
afternoon.  Also, would not rule out likely Pops with future 
forecast issuances, but will hold off for now since the best 
isentropic lift is progged for Thursday evening/night.

&&

.Long Term...(Thursday night through Tuesday)
Issued at 302 AM EDT Wed Jul 14 2021

The last several runs of model guidance show fairly good consistency 
regarding the potential for an extended period of scattered to 
numerous showers and thunderstorms across central Indiana...as a 
slow-moving upper level short wave and accompanying cold front cross 
the Mid-West from west to east...in the Thursday night-Saturday 
periods.  Overall, there is increasing confidence that the greatest 
coverage of convection will slowly shift focus from northern/western 
to southern/eastern zones throughout this 48-period...following the 
boundary and upper-level forcing's progression.

Details of the system's phasing will determine the location and 
intensity of any small surface low riding along the boundary, likely 
through northern Indiana on Friday.  Given this potential feature, 
as well as the approaching boundary's probably pushing PWATs to near 
2.00" for much of the region, went with likely POPs for all zones on 
Friday. Ensembles then hint at a possible north-south split in the 
mid-level forcing during the later Friday night-Saturday periods... 
which would limit coverage of convective showers...so kept POPs 
under 75% for the first part of the weekend.

Retained chance POPs for Saturday night-Sunday as boundary should be 
through the CWA, but low confidence H500 trough's embedded vorts 
will have completely pushed through.  The remainder of the long term 
should then feature surface high pressure settling across the 
southern Great Lakes, allowing more reasonable heat and humidity to 
infiltrate most of the region on light northeasterly flow.  The 
frontal zone, having settled along the southern edge of the surface 
ridge, may linger across southern Indiana.  With low confidence on 
exactly how stubborn 1.75"+ PWATs may be to leave, kept generally 
slight chance POPs for southern counties.

Temperatures should be generally seasonable in the 80s/60s, as ample 
clouds and then light northeasterly flow promote mild diurnal 
spreads.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1121 PM EDT Tue Jul 13 2021

IMPACTS:
-VFR conditions largely expected through Wednesday evening
-Small threat for brief visibility restrictions in fog overnight and 
near daybreak Wednesday at all terminals except KIND

DISCUSSION: Drier air will advect into the region overnight with 
weak ridging developing. Scattered mid level clouds will remain 
overnight with the potential for some patchy fog formation near 
daybreak. 

Weak high pressure and zonal flow aloft will maintain largely dry 
conditions Wednesday with partly cloudy skies. Expect a healthy cu 
field to develop with diurnal heating for the afternoon. Southwest 
winds will remain less than 10kts. Cu will diminish near sunset with 
mostly clear skies Wednesday evening.


&&

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

&&

$$

Short Term...TDUD
Long Term...AM
Aviation...Ryan