Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 241157

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
657 AM CDT Sat Mar 24 2018

.SHORT TERM...  (Through Late Tonight)
Issued at 400 AM CDT Sat Mar 24 2018

Low pressure over eastern Kansas will continue moving east-southeast
today and tonight.  The warm front associated with this system
extends from eastern Kansas through west central Missouri, then dips
south across the eastern Ozarks into west central Arkansas.
Occasional rain with a few thunderstorms continues along and north
of the warm front across our forecast area...and should continue for
much of today.  The low is forecast to track to the south of St.
Louis today, so areas along and north of the I-70 corridor in
Missouri and most if not all of our southern Illinois counties will
stay in the cold sector of this system which will keep temperatures
in the 40s to low 50s.  However, some of our eastern Ozark counties
will probably end up in the warm sector as the low moves through
this afternoon.  Temperatures in the warm sector are likely to reach
the low to mid 60s before crashing back down into the 40s behind the
low.  Rain will taper off and end from northwest to southeast
tonight...and most models show little or no precipitation remaining
in our forecast area by 06-09Z.  Anything lingering over southwest
or south central Illinois by that time should be very light and
probably not measurable.


.LONG TERM...  (Sunday through Friday)
Issued at 400 AM CDT Sat Mar 24 2018

Main focus thru the forecast period will be precip chances and
amounts late Sun night thru Tues.

Mdls are in fairly good agreement thru the period. However, some
timing/placement differences do exist. Period begins with upper
level ridge building into the area with SW flow aloft by Mon
morning. Mdls continue to suggest a wrmfnt lifting north thru the
area Mon morning with WAA precip just ahead of it. With the wrmfnt
north of the area open to the Gulf and deep swly flow, expect good
moisture return into the area. Mdls still suggest PWs around 1.25 to
1.50 inches across parts of the CWA Mon night into Tues. Mdls do
differ slightly on timing for this event, with the GFS probably a
little too fast. Mdls also differ on precip amounts, with the GFS
probably on the high end as well. However, given the available
moisture and with at least some potential for TS, much of the area
could see 2 to 4 inches of rain. This may lead to some flooding on
area rivers, especially the the smaller and fast reacting tribs.

With a longer period of rain, then with the upper trof settling over
the region, have generally trended twd the cooler guidance thru the



.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 636 AM CDT Sat Mar 24 2018

A wide swath of IFR flight conditions extending from southwest
Illinois through central Missouri and north into Iowa and
northwest Illinois will likely continue to prevail through
today...and likely spread south into our eastern Ozark counties.
The low pressure sysem which is causing these low flight
conditions and precipitation will continue to move east-southeast
to near the boot heel of Missouri by 00Z. Rain will continue to
develop ahead of the low today...but most of the measurable
rainfall should be ending from west to east through this afternoon
into the early evening. Think ceilings will be slow to improve
even aftern the low moves into the Tennessee Valley this evening...but
most guidance suggests that the majority of the IFR celings will
be out of northern Missouri and west central Illinois before 12Z
Sunday with continuing improvement during the daylight hours of


IFR flight conditions will prevail at Lambert today and
tonight with intermittent rain...and possibly another rumble of
thunder or two before sunset. Think low ceilings will be slow to
clear, even after the precip ends. Current indications are that
Lambert will be socked in IFR ceilings until at least 08-09Z
Sunday, and likely below 2,000 ft ceilings until sunrise or
shortly thereafter.



Saint Louis     47  33  48  38 /  90  50   5  10
Quincy          40  29  44  34 /  90  50   0  10
Columbia        52  31  48  40 /  60  20   5  40
Jefferson City  56  32  49  41 /  60  20   5  40
Salem           43  33  48  36 / 100  60   5   5
Farmington      59  33  48  38 /  60  30   5  20




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