National Weather Service Raw Text Product

Displaying AFOS PIL: AFDIWX Received: 2017-10-19 10:33 UTC

FXUS63 KIWX 191033

Area Forecast Discussion
National Weather Service Northern Indiana
633 AM EDT Thu Oct 19 2017

Issued at 159 AM EDT Thu Oct 19 2017

Mostly sunny skies will give way to high temperatures in the upper
60's and low 70's today. Lows tonight will be in the mid to upper
40's. Quiet weather will continue through Saturday, with
temperatures warming to well above normal. Highs through the rest
of the week will range from the upper 60's to the mid to upper 


.SHORT TERM...(Today and Tonight)
Issued at 159 AM EDT Thu Oct 19 2017

A colossal upper level ridge will expand expeditiously over the 
forecast area later today into Friday as the vertically stacked low 
pressure system over Hudson Bay drifts eastward. A weak cold front 
that was sprawled across Upper Michigan, WI, IA, and into the plains 
last night will progress southward today and across our north 
central CWA-but gradually wash out. This will ensure a lack of 
precipitation through the short term, and the first portion of the 
long term.

Things are heating up temperature wise on Friday. Highs today will 
be in the upper 60's and low to mid 70's. Friday we'll see highs in 
the 70's, with the southwest portions of our CWA seeing highs into 
the upper 70's. Most areas will see temperatures about 5-15 degrees 
above normal for the end of October. 


.LONG TERM...(Friday through Wednesday)
Issued at 159 AM EDT Thu Oct 19 2017

High pressure will linger over our CWA through Saturday, where we
will mainly see a slow increase in cloud cover as the next system
approaches the area. Highs will be in the low to mid 70's, and 
lows Saturday night will drop into the mid-upper 50's.

Our stellar spell of warmer, dry weather will come to an end 
Sunday morning as the first of two cold fronts swing through the 
area. Models are still a little in disagreement with regards to 
the exact timing with the first front, but confidence in the 
general pattern is higher than it has been previously. Decent 
upper level divergence takes place in our far northwestern CWA 
thanks to the right entrance region of a 300MB Jet, and a mid 
level shortwave swings through along the western periphery of our 
eastward drifting ridge. The best lift, per 850-500mb Qvector 
convergence is focused north of US 30 (and actually better aligned
over Lower Michigan), but PWATS climb to nearly 1.6 inches as 
return flow around the high to our southeast assists with moisture
transport from the gulf. That being said, we should still see 
precipitation chances along the entirety of the surface cold front
as it moves through our area from west to east. High temperatures
on Saturday will be a little cooler due to precip and cloud 
cover-mainly in the 60's west, and the low 70's across the central
and east. 

After the first frontal boundary moves through Monday morning, may 
see a brief break in the precipitation for the afternoon before the 
next system arrives (depending on whether the ECMWF is correct or 
the GFS). Unfortunately, this is where the disagreement between 
models leads to much lower confidence. Both the 12Z ECMWF/00Z GFS 
develop a cut off low near the gulf, and develop a separate trough 
to the west of our area. However, the ECMWF has precipitation 
developing over our area Monday afternoon with the surface low 
pressure as it lifts northeastward and merges with our first front. 
The GFS has this occurring slightly east from the ECMWF, placing 
most of the precipitation outside of our CWA. So Monday is still a 
bit uncertain, as is Tuesday into Wednesday in terms of exact 
precipitation locations-but it appears both models form a decent 
upper level low that lingers over the Great Lakes region through 
Wednesday night. Behind the secondary push of cold air Monday, we'll 
see 850 mb temps fall just below zero. With sufficient instability 
off the lake, kept the higher pops near Lake Michigan as models hint 
at a few bands of lake effect rain showers developing. Given the 
projected pattern, feel this is a likely scenario. Highs towards the 
end of the week will only be in the low to mid 50's. 


.AVIATION...(For the 12Z TAFS through 12Z Friday Morning)
Issued at 626 AM EDT Thu Oct 19 2017

VFR conditions through the period with winds 10 knots or less,
becoming calm tonight. 





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