Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 182351

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
651 PM CDT Sun Mar 18 2018

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 402 PM CDT Sun Mar 18 2018

A strong shortwave over the Four Corners Region is moving east int o
the Great Plains and forcing cyclogenesis over eastern Colorado this
afternoon.  A broken band of showers and thunderstorms has already
formed over Oklahoma in the warm sector ahead of the low.  Short
range mesoscale models look to be handling the current weather
pretty have leaned heavily on them for timing and coverage
of precipitation tonight into Monday.  The band of showers over
Oklahoma should continue to spread northeast into Missouri this
evening, though current indications are that it will weaken and
potentially even dissipate as it moves into central and southeast
Missouri late this evening.  Focus then turns to precipitation on the
actual cold/warm front early Monday.  Guidance is showing strong low
level moisture convergence along the front wrapping back into the
triple-point and the occlusion as the low moves along the
Missouri/Arkansas border on Monday.  This will be the best chance
for rain as the occluded front moves through southeast Missouri late
Monday morning into the afternoon with lingering deformation zone
showers during the late afternoon into the evening.  Temperatures
will be very dependent on clouds and precip through Monday, but
expect it to be similar to today with highs perhaps a couple of
degrees warmer due to the warm advection ahead of the low.


.LONG TERM...  (Monday Night through Next Sunday)
Issued at 402 PM CDT Sun Mar 18 2018

Monday`s storm system will continue heading east at a good clip and
will be over North Carolina by early Tuesday morning.  Low level
north/northwest flow with with plenty of clouds in the wake of the
low.  Models show northwest flow over the Midwest with several
subtle shortwaves rippling south across our forecast area Tuesday
and Wednesday.  There should be sufficient moisture in the wake of
the low on Tuesday for these disturbances to produce a few sprinkles
or light showers...primarily across parts of southern Missouri.  The
persistent northwest flow will eventually dry up the low levels
Wednesday night...but another low is forecast to begin developing
on Thursday night into Friday which will turn the 850mb flow back
to the southwest. Guidance spits out QPF due to 850mb moisture
convergence along and east of the Mississippi River on Thursday
night into Friday. Beyond that...medium range guidance diverges
quite sharply with the GFS being much faster than the ECMWF in
bringing the low through the Midwest. Generally speaking though,
the pattern looks showery, tho timing is obviously low confidence.
Temperatures should be at or above seasonal normals.



.AVIATION...  (For the 00z TAFs through 00z Monday Evening)
Issued at 636 PM CDT Sun Mar 18 2018

Band of SHRA currently across srn KS, thru swrn MO is expected to
gradually diminish as they move north. Have kept a VCSH for COU as
some of the latest guidance suggests the band may hold together
enuf to impact the terminal late tonight. These showers shud
remain south of SUS/CPS as they move east. Another band of
showers, perhaps with TS, is expected to develop along the wrmfnt
and move north which shud impact the terminals Mon morning and
thru much of the afternoon hours.

SPECIFICS FOR KSTL: MVFR cigs are expected to remain in place thru
the TAF period. The current band of showers is expected to
dissipate and remain south of the terminal. However, as this
happens, a second round of showers is expected, perhaps with TS,
that will impact the terminal Mon morning thru the afternoon



Saint Louis     41  52  34  48 /  30  90  80  10
Quincy          39  53  31  44 /   5  40  30   5
Columbia        41  50  33  48 /  40  80  60  10
Jefferson City  42  50  35  49 /  50  90  60  10
Salem           41  54  33  47 /  20  90  80  10
Farmington      42  52  35  49 /  70  90  70  20




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