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afdlsx

Area forecast discussion...updated aviation
National Weather Service Saint Louis MO
1052 PM CST Thu Dec 5 2019

Short term... (through late Friday night)
issued at 324 PM CST Thu Dec 5 2019

The approaching surface cold front, driven by the mid level
shortwave, will drive light rain into the region late tonight into
early Friday morning. The majority of this rain will stay south
of I- 70, though brief periods of light rain cannot be ruled out
along the Columbia-St. Louis-Salem, Illinois line. Both the front and
light rain exit the area Friday morning, leaving the remainder of
Friday dry. Behind the front, northerly winds will advect cold air
into the region. This cold air advection combined with lingering
low stratus will help keep temperatures much cooler than recent
days, with highs mostly in the 40s. Temperatures on Friday will
peak in the around sunrise before slowly falling through the
morning hours, then remaining steady during the afternoon.

Mrm

Long term... (saturday through next thursday)
issued at 324 PM CST Thu Dec 5 2019

A rapidly moving surface high builds into the region in the wake of
friday's system and keeps the weekend largely precipitation free. As
it moves out of our area Saturday winds will veer to the south and
we will return to above normal temperatures in the 50s Sunday
through Monday.

As the weekend surface high continues eastward out of the Midwest
another surface low, attached to a deepening mid level trough, edges
into the region Sunday night. This system will provide our next
round of precipitation starting Sunday night into Monday night. The
mid level trough deepens as it moves through the County Warning Area on Monday, and
steers the surface low out of the area to the northeast. As the
surface low lifts out of the area Monday parallel to the slow moving
cold front, guidance suggests a lingering chance of precipitation
across the area through Monday night. Some of this precipitation may
end as light snow before moving out of the area completely. A
surface high building into the area in the wake of this strong
surface low will keep the forecast precipitation free Tuesday
through the end of the period.

The passage of this cold front continues to mark a significant shift
in temperatures as highs Tuesday through the end of the period will
top out in the mid 20s to mid 30s. While this isn't particularly
chilly for December, it is about 10 degrees below normal and will
feel cool after the past several days of above normal
temperatures.

Mrm

&&

Aviation... (for the 06z tafs through 06z Friday night)
issued at 1035 PM CST Thu Dec 5 2019

Not a lot of changes from the prev tafs. Still expect MVFR or low
VFR cigs to develop as the cold front pushes south through the
area. Winds will become northerly and increase. Winds will
diminish late Fri afternoon and into the evening. Best chances for
rain are at stl/sus/cps overnight, but do not anticipate visbys
dropping below VFR.

Tilly

&&

Preliminary point temps/pops...
Saint Louis 42 44 30 49 / 40 20 0 0
Quincy 33 38 25 46 / 5 5 0 0
Columbia 36 42 28 50 / 40 10 0 0
Jefferson City 38 43 28 52 / 60 10 0 0
Salem 44 48 29 47 / 50 40 0 0
Farmington 44 49 29 51 / 90 70 0 0

&&

Lsx watches/warnings/advisories...
MO...none.
Illinois...none.
&&

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