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Area forecast discussion
National Weather Service Indianapolis in
345 am EST Wed Nov 20 2019

the long term and aviation sections have been updated below.


issued at 305 am EST Wed Nov 20 2019

A series of low pressure systems will bring precipitation chances
late tonight through Saturday and then again Tuesday. Thursday will
see above normal temperatures. Otherwise, look for below normal
temperatures into next week.


Near term...(today)
issued at 305 am EST Wed Nov 20 2019

Early this morning, stratus and fog were across central Indiana.
Visibility varied greatly, with values as low as a half mile.
Visibility also has varied over time at any one location.

Expect the fog to continue with nothing to really scour it out.
Given the variability in the fog, do not see a need for a dense fog
advisory at this time, but will continue to monitor closely.

After the fog, the main concern today will be sky cover. Satellite
shows the back edge of the stratus across eastern Illinois was
trying to move east but having a hard time doing so. High pressure
will move across the area today, and this could very well trap the
low clouds at least through the morning.

Will continue to monitor the back edge, but plan on going
pessimistic with cloud cover, especially this morning. This will be
a compromise between the high cloud cover of the nbm and the blend
of other models. Will allow skies to become partly cloudy most areas
this afternoon, but will have to watch as nbm keeps clouds in all

With the more pessimistic cloud cover, went cooler than the blend
for highs today.


Short term...(tonight through Friday night)
issued at 305 am EST Wed Nov 20 2019

Models are close enough that the National blend of models
initialization was accepted for most items.

Clouds will increase again tonight with the approach of a low
pressure system. By late tonight enough forcing will arrive for some
low pops most areas.

On Thursday a 50kt 850mb jet along with a surface warm front will
bring enough forcing and moisture to go likely or higher category
pops to most areas by mid to late morning. Pops will diminish most
areas in the afternoon as the jet exits the area, and the better
forcing moves north of the area closer to the upper system.

Thursday evening a cold front will move through, and this could
bring another area of rain. Will have high chance or low likely pops
with this.

The front will then settle south of the area Friday and Friday
night. Waves will ride along the front, and an upper low will
approach the area as well. This will keep the threat of
precipitation around for most areas, especially south.

Confidence is not great though as there remains uncertainty on how
exactly things will come together and the location where the front
will stall out.

Enough colder air may sneak into the area Friday night for some snow
to mix in with any rain, but there shouldn't be any accumulation.


Long term /Saturday through Wednesday/...

Issued at 342 am EST Wed Nov 20 2019

Chances for precipitation, possibly a rain/snow mix, continue into
Saturday as an upper wave moves across the region. Models then
indicate that a surface high pressure system, centered across the
south, will influence the Ohio Valley Sunday and Monday. This will
lead to a couple days of dry conditions and winds out of
southwest. A potent and deep trough will make its way down across
the central US then towards the Great Lakes region. This system is
expected to bring in rain and gusty winds for Tuesday and
Wednesday. Models agree in the presence and general timing of
this strong system, but lack agreement in finer details for now.
Accepted guidance for the majority of the long term forecast, but
increased the sustained winds for Tuesday and Wednesday to match
the expected conditions which could see values near 20 kts and
gusting above 30 kts.


Aviation /discussion for 20/06z taf issuance/...
issued at 342 am EST Wed Nov 20 2019

Updated for current conditions and to account for fog and low
ceilings causing a range of MVFR to LIFR conditions across the taf
sites. Previous discussion follows...

The GFS lamp and sref and current trends now strongly support the
GFS lamp and sref MVFR and worse flying conditions, mostly ceilings,
through at least 16z Wednesday. This lends to good confidence in
poor conditions through late morning.

Winds will be light and variable or calm overnight and southeast up
to 6 knots late today..


Ind watches/warnings/advisories...



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