Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 230915

Area Forecast Discussion
National Weather Service Memphis TN
415 AM CDT Mon Oct 23 2017

Early morning GOES water vapor imagery showed an upper low over
the Midsouth, lifting slowly east. The associated elevated warm
conveyor belt, which supported more widespread rain, had lifted
into middle TN, with only light showers or drizzle occurring over
the Midsouth in the predawn hours.

The upper low and associated clouds will lift out this afternoon,
in time for the arrival of a reinforcing push of drier and cooler
air this evening. This evening`s cold frontal passage will occur
as deep midlevel height falls occur, leading to the formation of a
longwave trof over the eastern half of the U.S. For the Midsouth,
cooler than normal temps will persist through Thursday, when the
longwave trof lifts out and brief shortwave ridging occurs over
the lower MS River valley.

A deep northern branch trof will swing through the Midsouth on
Friday, helping to drive a strong surface cold frontal passage.
This morning`s 00Z models indicated less robust low level
moisture return ahead of this system. Rain still appears on tap
for Friday, mostly post-frontal, but late week thunder chances
appear to have decreased a bit.

The GFS depicts a lobe of colder air (1000-500mb thicknesses of
516dm into the Ohio River valley) by Sunday, while the ECMWF keeps
the coldest air confined to the Great Lakes. In any case, given
expected prime radiational cooling conditions, subfreezing low
temps will be possible this weekend to the north and east of the
Memphis metro.



06Z TAFs

A cold front is moving into North Alabama and Middle Tennessee.
Only a few light showers remain behind the front and will not
likely impact aviation. Winds are from the Northwest behind the
front generally around 10kts and will likely remain near that
speed for the remainder of the night. Cigs immediately behind the
front dropped to IFR but have improved a bit. However...expect
cigs to fall back to IFR levels later tonight...JBR may be the
exception. Nevertheless, cigs are expected to be variable so
Amendments may be needed. Winds should keep the threat for
widespread diminished vis down. Winds will shift from the West
tomorrow. Cigs will improve during the morning hours and VFR
conditions are expected tomorrow afternoon into tomorrow night.




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