Area Forecast Discussion
Issued by NWS St. Louis, MO

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193
FXUS63 KLSX 191728
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1128 AM CST Sun Nov 19 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 345 AM CST Sun Nov 19 2017

The low level cloudiness was finally advecting east of our forecast
area early this morning as a large surface ridge over the Plains was
building eastward into our area. Northwesterly surface winds, albeit
not as strong as yesterday continue to bring colder and drier air
into the forecast area early this morning.  Despite full sunshine
today temperatures will be below normal with northwesterly mid-upper
level flow.  Highs today will be 5 to 10 degrees below normal.  Will
see slightly warmer low temperatures tonight across northeast and
central MO as surface/low level winds back around to a southwesterly
direction as the surface/850 mb ridge shifts southeast of our
region. There may be some high level cloudiness tonight ahead of a
weak northwest flow shortwave.  The coldest low temperatures
tonight, still slightly below normal will occur across southeast MO
and southwest IL.

GKS

.LONG TERM...  (Monday through Saturday)
Issued at 345 AM CST Sun Nov 19 2017

A longwave upper TROF will persist over eastern North America
throughout this period.  This will allow several disturbances and a
pair of surface cold fronts to pass thru our region.

The models continue to depict a series of shortwave disturbances
slated to pass thru our region between Monday and Wednesday, but
also depict the atmospheric column as being too dry to support pcpn.
The best chance for pcpn may be with passage of the second cold
front on Friday night where moisture levels will be somewhat higher
but as it stands now, probs still look low.

Temperatures will see-saw this week, beginning above average with
temps exceeding 60F in places on Monday thanks to breezy southerly
flow and abundant sunshine.  This warm up will be short-lived as a
cold front moves thru on Tuesday with another brief bout of below
average temps Wednesday and Thursday.  A return of southerly flow
towards next weekend will begin the next rebound of temps into the
50s and possibly 60s for Friday.  Another cold front passing thru on
Friday night should result in slightly cooler temps on Saturday.

TES

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1113 AM CST Sun Nov 19 2017

VFR through the period. Initially northwesterly winds at TAF
issuance will gradually back and become westerly to southwesterly
after a surface high pressure center passes to the south of the
terminals. Sustained wind speeds of 10-15kts will decrease after
19/22z and then increase again after 20/09z. Gusts to around
20-25kts are expected after 20/15z.

Kanofsky

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX



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