000 
fxus63 kind 231458 
afdind 


Area forecast discussion 
National Weather Service Indianapolis in 
1050 am EDT Mon Oct 23 2017 


Update... 
the aviation section has been updated below. 


&& 


Synopsis... 
issued at 400 am EDT Mon Oct 23 2017 


A slow moving frontal boundary and secondary low pressure system 
will move through the area today, followed by a large upper level 
low tonight into Tuesday night. This will provide ample 
opportunity for widespread rainfall and a turn toward much cooler 
temperatures. Another frontal system and reinforcing shot of 
cooler air will come late in the week, bringing additional chances 
for precipitation and continued cool conditions. 


&& 


Near term /this afternoon/... 


Issued at 926 am EDT Mon Oct 23 2017 


Surface analysis late this morning shows low pressure over west 
central Indiana. Radar shows abundant rain showers across the 
forecast area. Aloft water vapor shows a negatively tilted trough 
stretching from the middle Mississippi Valley toward 
Florida...with southeast flow aloft still over Indiana. Goes16 shows 
plentiful cloud cover. Surface front still appears to be west of 
in...as surface flow remains mainly southeasterly. Cooler northwest flow 
was found over Illinois. 


The low pressure system and upper trough are expected to progress 
eastward today...allowing cooler air behind the front to filter 
into central Indiana. Time heights show a saturated column as do 
the forecast soundings and ample lift is expected given the 
dynamics in the area. Given the expected clouds and rain...have 
stuck close to 100 pops. Will also use a non-diurnal temp trend as 
rain and clouds will prevent much heating and cooler air arriving 
late in the day will also allow temps to fall. 


&& 


Short term /tonight through Wednesday night/... 
issued at 400 am EDT Mon Oct 23 2017 


As the secondary low moves north of the area tonight, a much 
larger upper level low will drop into the area and strongly 
intensify the surface low. Showers associated with this upper 
level low will be a threat across the area into Tuesday night. 
Final storm total rainfall amounts of 1 to 1.5 inches, with 
isolated higher amounts, can be expected. 


Windy conditions can be expected with the presence of the intense 
surface low and attendant pressure gradient Tuesday, and wind 
gusts around 30 miles per hour or more will be likely. 


Dry weather will return Wednesday and Wednesday night as weak 
upper level ridging replaces the departing low. 


Temperatures will turn sharply cooler with highs struggling into 
the upper 40s to low 50s across the area and lows in the mid to 
upper 30s. Will have to monitor for frost potential but will 
exclude from grids this far out. Consensus temperatures were 
generally in the ballpark. 


&& 


Long term /Thursday through Sunday night/... 
issued at 343 am EDT Mon Oct 23 2017 


The extended period will initially start out with dry conditions 
due to brief ridging over the area and slightly warmer 
temperatures in the 60s. However, the next system is progged to 
enter the upper Midwest by Friday, increasing rain chances and 
lowering temperatures with an associated cold front. This colder 
air could result in some snow showers mixed in with lingering rain 
showers on Saturday night as a second upper low drops into the 
region. Highs will only top off in the upper 40s/low 50s on 
Saturday and Sunday with lows at the freezing mark on Saturday 
night. 


&& 


Aviation /discussion for the 231500z taf update/... 
issued at 1058 am EDT Mon Oct 23 2017 


Mid morning adjustments made based on current observations. 12z 
discussion follows. 


Poor flight conditions will prevail for the majority of the taf 
period with widespread rainfall across the area. Conditions are 
ranging anywhere from IFR to VFR at this time, but will generally 
be around the MVFR mark. There will be little improvement as rain 
lingers through tonight. Winds will gradually veer to the west and 
northwest with sustained speeds of 5 to 11 kts, and low level 
wind shear will also be a concern this afternoon with frontal 
passage. 


&& 


Ind watches/warnings/advisories...none. 


&& 


$$ 


Synopsis...nield 



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