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Area forecast discussion...updated aviation
National Weather Service Saint Louis MO
525 am CST Tue Nov 12 2019

Short term... (through late Wednesday afternoon)
issued at 254 am CST Tue Nov 12 2019

The main story will be center around the brutally cold air this
morning. Well below normal temperatures stretch through tonight
before a moderating trend begins on Wednesday.

Regional analysis shows the cold front has progressed well to the
south and east with the back side of the stratiform cloud deck
exiting the forecast area. Aside from a few left over mid-level
clouds and isolated flurries, skies will continue to clear out with
surface high pressure building in from the west.

Clear skies and cold air advection behind the front have allowed temperatures to
tumble. Fortunately, the rate of cooling will slow but not before
lows bottom out in the single digits through central and northeast
Missouri, along with west central Illinois. These temperatures
are likely to set some records this morning. Locations further
south will not fare much better with temperatures ranging from the
low to mid-teens. Additionally, the tight pressure gradient will
keep winds fairly brisk through the next few hours. Gusts will
occasionally be around 20 mph before dying off through mid-
morning. Wind and temps have already combined to produce wind
chills near and just below zero this morning. Expect much of the
same to continue through at least sunrise.

Surface winds begin to settle as high pressure builds overhead
today. Despite plenty of sunshine, temperatures will only be in the
low to mid-20s for highs. It remains cold tonight under mostly
clear skies with lows in the teens. High pressure will move east
to turn winds out of the south late this evening, marking the
beginning of a slow upward trend in temperatures through the
course of the week.

The only other item to note will be the potential for gusty winds
Wednesday as the core of a southwest to northeast oriented low level
jet encroaches on the northwestern third of the County Warning Area. Otherwise,
highs will be quite "balmy" with temperatures climbing above the
freezing mark... mid-30s over interior sections of Illinois to the
low-40s through central Missouri.


Long term... (wednesday night through monday)
issued at 254 am CST Tue Nov 12 2019

The extended period continues to look quiet. In fact, the couple of
instances when precipitation chances did exist, trends have leaned
away from this notion. Therefore, expect the main story to be
gradually moderating temperatures, starting out below normal and
returning to near normal by the period's end.

The long term period will begin with an amplified upper ridge
positioned over the western U.S., While the eastern two-thirds of
the nation remain at the base of broad cyclonic flow centered near
the Hudson Bay. A weak and quick traveling shortwave, embedded in
northwest flow, will push in from the northwest late Wednesday. This
will be accompanied by a surface cold front with relatively limited
impact due to lack of moisture and core of cold air remaining north.

Following close behind will be a northeast to southwest oriented
upper trough, which moves overhead Thursday. This, too, has limited
impact in terms of sensible weather with the main result being the
establishment of northwest flow. Aside from a shallow layer of
increased moisture and resulting cloud cover, a building surface
ridge should keep condition's dry.

Northwest flow aloft turns zonal toward the end of the week as the
western ridge builds eastward and becomes less amplified through the
Central Plains. The surface ridge becomes elongated through the
Midwest as high pressure builds southeast in the Great Lakes and
become dominant. A trough extending north to south through the
central U.S. Approaches from the west by Sunday. However, trends
continue to favor dry conditions with little in the way of organized
support for precipitation.



Aviation... (for the 12z tafs through 12z Wednesday morning)
issued at 459 am CST Tue Nov 12 2019

A surface ridge will build into the area today. Northerly winds
will continue to diminish through the day to become light and vrb
late this afternoon and into the evening. Winds will become
southeast to east-southeast tonight. There is some indication that
a few clouds may develop near kcou. If these clouds do develop,
would expect flurries to accompany them. Otherwise, dry and VFR
thru the period.



issued at 346 am CST Mon Nov 11 2019

Today's snowfall, followed by brutally cold air, could challenge
records today and tomorrow. Below is a list of records that have
best potential to be challenged:

November 12th
record low temp | record low Max | record snow depth
St. Louis 12 set in 1911 20 set in 1911 T set in 1995
Columbia 9 set in 1911 17 set in 1911 1 set in 1911
Quincy 10 set in 1986 28 set in 2014 ***

***no official snowfall records for quincy***


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