Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 221748

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1248 PM CDT Sat Oct 22 2016

1248 PM CDT

Through Sunday...

Skies continue to clear from west to east this afternoon as high
pressure shifts east.  High temperatures still appear on track
near seasonal norms in the upper 50s to low 60s. Patchy high
clouds will drift overhead tonight ahead of a shortwave that will
move east along the Canadian border. With high pressure departing,
low level southwest flow will continue tonight along with warm air
advection and support warmer lows tonight in the 40s.

12z NAM and GFS runs suggest that the cold front will hold off for
most of the day across northeast Illinois and northwest Indiana.
Another impressive thermal ridge ahead of the front coupled with
gusty southwest winds will allow all areas to reach the upper 60s
and many areas having a good shot at 70 (and higher south),
especially from the metro area southward. A late October 925 mb
temperature climatology has a median around 70 for ORD. Some late
day cooling is possible north where hitting those higher numbers
may not occur if the front speeds up a bit.



314 AM CDT

Sunday through Friday...

Quiet conditions on Sunday will continue into early next week.
Despite low pressure quickly shifting through the region Sunday
into Sunday night, dry conditions will limit precip development. A
quick push of warm air during the day Sunday will support high
temps around 70 for most locations, with lower 70s possible south
of I80. Another minor cool push then occurs again Sunday night
into Monday as high pressure builds across the region. Next precip
chances still appear to be towards mid week as low pressure
approaches the region. Fairly consistent signal among model
guidance and so have maintained categorical pops over much of the
CWA, centered around the Wednesday period. Did keep thunder
wording in the grids, however, did back off a little. Instability
and moisture look to be rather limited but with anticipated strong
forcing, at least isolated thunder still remains a possibility. At
this time, do think this will only be possible during the day
Wednesday though, as this system quickly shifts to the east
Wednesday night.



For the 18Z TAFs...

- Gusty SW winds Sunday shifting to W and NW through the afternoon

VFR deck in the 7-10kft range will move east through the
afternoon. We will maintain a SW wind tonight into Sunday as high
pressure moves east of the area. The gradient will tighten Sunday
morning ahead of low pressure that will drop southeast through the
upper Midwest and into southern WI Sunday afternoon. The low will
shift to eastern MI late Sunday afternoon with gusty winds
shifting more westerly and northwesterly late. There is a cold
front behind this low that most guidance keeps just north of the
terminals through at least mid Sunday afternoon. If this front
speeds the shift to northerly winds may occur a bit quicker, but
for now current guidance keeps the shift out of the 30 hr ORD TAF



157 AM CDT

Ridge axis will move east of the lake today allowing winds to back
to southwest. Low pressure will move across the lake late Sunday
with a brief period of moderately strong northerlies developing
behind the low, late Sunday afternoon spreading to southern
portions of the lake early Sunday evening. Winds should begin to
subside by late Sunday night and Monday as high approaches from
the west. Strong low pressure is forecast to develop the central
plains Tuesday and track east toward the mid-Mississippi Valley
region midweek. Current models suggest the low will track south of
the lake setting the stage for strong easterly winds developing
Tuesday night and continuing into Thursday. Depending on eventual
track of the system, could see a period of easterly gales midweek,
but confidence is still fairly low.






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