Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 101151
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
551 AM CST Sun Dec 10 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 336 AM CST Sun Dec 10 2017

A surface trough extending from MN south-southwest through eastern
KS will move southeastward through our forecast area today with
little noticeable effect on our weather except a wind shift.  Some
mid-high level cloudiness will drop southeastward through the region
with continued northwesterly upper level flow, and dry conditions in
the boundary/surface layer. High temperatures will be warmer today
and about 5 to 10 degrees above normal.  Lows tonight will also be
warmer, but only slightly above normal.

GKS

.LONG TERM...  (Monday through Saturday)
Issued at 336 AM CST Sun Dec 10 2017

Not a lot of changes from yesterday, but have added some low PoPs.
Still, focus continues to be temps.

Upper level pattern is expected to remain much the same with NW
flow. This is the result of an upper level blocking event over the
wrn U.S. The block is expected to remain in place thru much of the
forecast period. Mdls are in good agreement with the block breaking
down sometime early Fri with more zonal flow thru the weekend. While
mdls tend to break down blocks too soon, latest mdls continue to
depict a developing cyclone early next week along the nrn flank of
the block close enuf that it shud help to break down the block
slightly. The approaching trof later in the week wud then break down
the block. Still, believe this break down is too soon as the
approaching upper jet weakens.

Temps and any precip in the forecast will largely depend on embedded
shortwaves that drop into/near the region. Confidence in any s/w
continues to be low much beyond 48 hrs. Have added low PoPs for Wed
and again Thurs as a stronger trof drops thru the area. Higher PoPs
and/or mention of flurries may need to be added during this time
with future updates.

Have continued to warm temps for Mon with strong swly flow and WAA.
Otherwise, have trended twd a compromise until next Sat when swly
flow returns.

Tilly

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 536 AM CST Sun Dec 10 2017

Weak surface trough extending from northwestern WI southwest
through eastern KS will move southeastward through the taf sites
later this morning. South-southwesterly surface winds will
strengthen later this morning and become gusty, while veering
around to a west-northwest direction this afternoon after passage
of the surface trough. The surface wind will weaken this evening
and back around to a southwest direction late tonight as a weak
surface ridge shifts east of the area. Just some mid-high level
cloudiness will move southeastward through the region today and
tonight.

SPECIFICS FOR KSTL: Weak surface trough extending from northwestern
WI southwest through eastern KS will move southeastward through
the STL area late this morning. Southwesterly surface winds will
strengthen later this morning and become gusty, while veering
around to a west-northwest direction this afternoon after passage
of the surface trough. The surface wind will weaken this evening
and back around to a southwest direction late tonight as a weak
surface ridge shifts east of the area. A south-southwest surface wind
willl strengthen again Monday morning. Just some mid-high level
cloudiness will move southeastward through the region this
forecast period.

GKS

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     49  31  55  29 /   0   0   5   5
Quincy          44  26  48  24 /   0   5  10   5
Columbia        50  30  55  26 /   0   0   5   5
Jefferson City  52  29  56  27 /   0   0   5   5
Salem           47  27  52  28 /   0   5   5   5
Farmington      51  29  58  28 /   0   0   0   5

&&

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

$$

WFO LSX



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