Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 151735

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1235 PM CDT SAT OCT 15 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 357 AM CDT Sat Oct 15 2016

A stratus cloud deck has spread across the entire forecast area
early this morning with patchy fog and drizzle, mainly across
southeast MO and southwest IL.  Despite this low level cloud cover
southerly winds will lead to warmer highs today than yesterday,
about 10 degrees above normal for mid October.  At least scattered
showers and storms can be expected tonight across northeast MO and
west central IL due to low level moisture convergence on the nose of
a southwesterly low level jet.  Mild temperatures are forecast
tonight due to the cloud cover and continued southerly winds along
with relatively high surface dew points.


.LONG TERM...  (Sunday through Friday)
Issued at 357 AM CDT Sat Oct 15 2016

A RIDGE aloft is expected to re-establish by Sunday over the south-
central and southeastern CONUS and should persist into the middle of
next week.  At the same time, pieces of energy are expected to come
ashore into the Pacific Northwest beginning today with the final
piece holding off until Monday night.  Overall, a warm and dry
period is expected thru Tuesday as the RIDGE axis located just to
our south is largely expected to win out and deflect these Pacific
disturbances to our north during this time.

Leftover pcpn that may initially develop to our north from a frontal
boundary edging near the area may linger into Sunday morning over
parts of southern IL, otherwise dry wx is expected thru at least
midday Tuesday.

Otherwise, the main story Sunday thru Tuesday will be the
unseasonably warm temps, with max temps above 80 each day (15 to 25
degrees above average), approaching or exceeding record maxes from
Sunday thru Tuesday, depending on the exact location.  See the
CLIMATE section for record values.  The warmest day is anticipated
to be Monday, where sunny skies and a breezy south-southwest wind
will combine to allow most places to reach into the upper 80s or
even lower 90s for parts of STL metro, and record max temps are
currently forecast for UIN, COU and STL.

A surface cold front is expected to at least enter our region on
Tuesday--but here is where the models begin to diverge--with the EC
taking a very slow southeastward progression of this front and the
GFS and NAM more progressive.  There is reason to consider the
slower EC progression with an unfavorable mid level flow which
remains out of the southwest during this time and lack of much pcpn
expected with this front until at least Tuesday night.  If this
trend continues, further adjustments will be needed.

Even further model divergence occurs heading into mid to late next
week, with significant disagreement on how to handle that last piece
of Pacific energy as it moves into the central CONUS, with the GFS
persistently the most aggressive with its deepening and featuring
the slowest eastward progression and the EC the least developed and
most progressive to the east.  It will probably take another couple
of days to achieve any sort of real consensus to develop on this,
and in the meantime, the best route will be to advertise pcpn
chances but keep them in the chance category at this time, while
scaling temps back towards average.  Certainly if the slower more
wound-up GFS solution pans out, will be also evaluating for heavy
rainfall potential, but lots of time to keep an eye on this for now.



.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1229 PM CDT Sat Oct 15 2016

Earlier stratus has quickly dissipated leaving a clear to mostly
clear sky for the terminals. Wind gusts around 20 knots are
possible through late this afternoon out of the south. For
tonight...MVFR stratus looks to affect KUIN along with a chance of
showers and perhaps a rumble of thunder. Maintained PROB30 group
in for late tonight for this. Elsewhere...believe dry conditions
along with light southerly winds will continue. Ceilings should
stay VFR though cannot rule out MVFR conditions late tonight and
very early Sunday morning.


Stratus from this morning is now long gone with a clear to mostly
clear sky currently overhead. Quiet/VFR conditions expected over
the next 30 hours. Ceilings late tonight will lower to around 4000
feet but should stay just above MVFR threshold. Weak front will
move into NE MO late tonight with some scattered showers and a few
rumbles of thunder. While I cannot rule out this activity
affecting Lambert Field very late tonight and early on Sunday
morning...probabilities too low to mention in the TAF.



Issued at 343 AM CDT Thu Oct 13 2016

Unseasonably warm conditions are expected to persist through
the weekend and into early next week and may approach record
territory. The following lists record high temperatures and
record high minimum temperatures for St. Louis, Columbia and
Quincy from Sunday to Tuesday.

St. LouisColumbiaQuincy

10/16   High Low:65/196566/196867/1968

10/17High Low:66/199864/196566/1935

Tuesday High:87/195386/195387/1924
10/18High Low:68/198564/197166/1938




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