FXUS63 KLOT 192312
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
612 PM CDT Sun May 19 2019

.SHORT TERM...
259 PM CDT

Through Tonight...

Through the Late Afternoon:
Cold front is sweeping across the area approaching the 3pm hour.
Despite veering winds and dew points dropping behind the front,
there is sufficient forcing for post frontal showers primarily
south of I-80 after showers over northeast IL exit over the lake.
With better moisture and instability axis quickly shifting
eastward, threat for any additional isolated strong/severe storms
over the next hour or so will be primarily over northwest Indiana
counties. Main risk will be gusty to locally damaging winds. The
other concern is the strong west-southwest winds, gusting up to
35-40 mph over the next few hours. There have been a few gusts
into the 40-45 mph range over the past hour or so, but peak wind
gust speeds should gradually subside toward sunset.

This Evening-Overnight: 
There will be a secondary cold front/wind shift to northwest along
with fairly stout cold advection. Out ahead of this, there's a
pretty good signal on high-res/near-term guidance for widely
scattered light showers from I-80 and south, so carried low chance
category PoPs for this. Any lingering shower activity should end
by an hour or two after midnight. Breezy west-northwest winds and
cold advection will drive temperatures down into the 40s by early
Monday, so quite a change from the pleasant readings early this
evening.

Castro

&&

.LONG TERM...
120 PM CDT

Monday through Sunday...

The break following the current system looks to be relatively
short lived as another powerful shortwave emerges out into the
southern Plains later Monday into Monday night. This cyclone is
forecast to occlude with a deep vertically stacked forecast to
track due north across the central Plains Tuesday into Tuesday
night, with a Fujiwara type interaction depicted with another
closed low digging southeast into the Intermountain West. 

The warm conveyor belt of this significantly occluded system is 
forecast to arc out well ahead of the storm and move across the 
CWA Tuesday night into Wednesday morning. Despite strong shear 
profiles that should be in place, this activity is likely to 
outrun the better instability with the warm sector likely pinched 
off to our south, so thinking the severe threat will be minimal 
with this activity Tuesday night. 

Deep longwave trough is expected to remain anchored over the
western U.S. through the remainder of the long term period, with
this midweek cyclone expected to lift north to the northern Plains
before shearing eastward around the periphery of an unusually
strong early season sub-tropical ridge forecast to develop over
the southeast U.S. We should be on the periphery of the upper
ridge with nearby baroclinic zone probably fluctuating around the
region. Should get into the warm sector Wed into Thursday with a
period of above average temperatures. Temps and precip chances
heading into next weekend will hinge on the exact placement of
this boundary, which is going to be very hard to pin down with 
much certainty this far out. 

- Izzi

&&

.AVIATION...
For the 00Z TAFs...

Quieter weather is expected tonight and on Monday. Gusty westerly
winds will gradually ease in intensity through the night as the
storm system continues to move away from the region. Surface high
pressure will set up over the area during the afternoon and
evening on Monday. This will set up lighter winds, which will 
gradually shift northerly by early afternoon. A lake breeze will 
then likely shift inland over the eastern terminals by mid 
afternoon, with a period of east-northeasterly winds likely in its
wake. 

Aside from the winds, expect a deck of MVFR CIGs, currently to our
west, to shift eastward over the area later this evening. These
lower clouds look to persist into at least Monday morning, before
possibly scattering out some in the afternoon.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&

$$

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