Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Saint Louis MO
250 PM CDT Thu Oct 27 2016
Short term... (through late Friday afternoon)
issued at 246 PM CDT Thu Oct 27 2016
Stratus deck east of the Mississippi River will continue to rapidly
dissipate from west to east this afternoon...leaving only a few high
clouds by sunset. The surface ridge currently over the County Warning Area will move
steadily eastward tonight and light southeasterly flow will
establish itself by morning. With light and variable winds
overnight...there may be some patchy fog especially in river
valleys. Mostly sunny skies on Friday and southerly flow will
allow temperatures to rebound to well above normal levels.
Afternoon highs should range from the lower 70s in south central
Illinois to near 80 in central Missouri.
Long term... (friday night through next thursday)
issued at 246 PM CDT Thu Oct 27 2016
The synoptic pattern at the start of the long term period will
feature broad ridging dominating much of the Continental U.S.. while a few
passing pv anomalies will help to knock the ridge down a bit at
times, it will largely remain in place through at least the middle
of next week.
The main story of the weekend into early next week will be the very
warm temperatures. A strong surface high will be located across the
southeast, as an area of low pressure develops in the Lee of The
Rockies. This will place the Midwest within a fairly tight
southwesterly gradient on Saturday, which will help temperatures
climb into the 80s, perhaps mid 80s in some spots. If mid 80s
values are attained, we could flirt with some record temperatures in
some spots (see the climate section below).
A weak pv anomaly will quickly scoot across the northern plains and
into the Great Lakes on Sunday. This feature will be enough to push
a weak cold front through northeast MO and western IL, but the
boundary will likely stall somewhere across southeast MO/south-
central Illinois (no precip is expected with this front). Therefore,
there will likely be a gradient of temperatures across the region on
Sunday, with mid 60s across north-central MO increasing to the upper
70s over southeastern MO.
On Monday, the upper-level ridge will amplify once again which will
help push the stalled boundary back to the north as a warm front. A
stronger pv anomaly ejecting out into the northern plains will help
induce a surface low across the Dakotas into Minnesota, which will
place eastern MO/western Illinois within a strong southwesterly gradient
once again. Given this setup, have upped winds during this
timeframe as some gusts over 30 mph will be possible across parts of
northern MO. Given these winds and resultant turbulent mixing, have
also upped the temperatures for Monday. Trick-or-treaters won't
have to worry about staying warm this year, as highs on Halloween
will push into the 80s!
Despite the surface low passing well to the northeast by the middle
of next week, it will once again lay out a front that will hang
around northern MO/central Illinois through the middle of next week.
Guidance differs quite a bit on the evolution of the upper-level
regime during this period, so confidence is fairly low on the
timing/evolution of the precipitation along the boundary Tuesday
night through the end of next week, thus will stick with slight/low-
chance pops for now.
Aviation... (for the 18z tafs through 18z Friday afternoon)
issued at 1205 PM CDT Thu Oct 27 2016
MVFR stratus will continue to dissipate this afternoon leaving
only a few high clouds. Light northwest winds will become light
and variable and last overnight as the surface high pressure ridge
moves overhead. As ridge moves off to the east...light southeast
flow will gradually become established by around 12z. Some river
fog may form overnight...but light southeast flow should keep it
away from ksus.
Specifics for kstl: stratus should dissipate by around 20z. Light
northwest winds will become variable overnight as ridge passes
overhead. As the ridge continues eastward...winds will become
light southeasterly by around 10z.
issued at 250 PM CDT Thu Oct 27 2016
With an upcoming stretch of unseasonable warmth expected over the
weekend into early next week, here is a list of record high
temperatures. Although there are no record high temperatures in
the forecast just yet, some record values may be in jeopardy
Saturday and perhaps on Monday.
Stl cou uin
fri10/28 85/1927 85/1927 85/1927
Preliminary point temps/pops...
Saint Louis 48 76 63 83 / 0 0 0 0
Quincy 48 76 62 80 / 0 0 0 0
Columbia 51 79 61 82 / 0 0 0 0
Jefferson City 51 80 62 83 / 0 0 0 0
Salem 45 72 58 81 / 0 0 0 0
Farmington 46 74 59 81 / 0 0 0 0
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