Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 250720
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
220 AM CDT WED MAY 25 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 219 AM CDT Wed May 25 2016

Wish I could say with confidence how today will play out in terms of
convective coverage and timing, but yet again, it is muddled with
ongoing thunderstorms to our west across the Central Plains and
little help from the plethora of model guidance available to us.
That being said, I do believe we have a better chance of seeing
measurable precipitation across a larger portion of the CWA today
given better synoptic forcing, so have maintained likely PoPs.

The best I can tell is that the convection stretching from central
Nebraska to southeast Oklahoma will slowly edge east this morning in
a weakening state and either completely fall apart across central
Missouri or be reinvigorated by the approaching shortwave and
diurnal instability that develops ahead of it.  There are also signs
in the convective allowing models that some elevated thunderstorms
may develop in an arcing fashion from southeast Missouri to north
central Missouri during the predawn hours as the LLJ veers.  I told
you it was muddled, and therefore I just broadbrushed some likely
PoPs from west to east across the CWA today. As far as the threat
for severe thunderstorms, I would have to say it is conditional on
some surface instability being realized either ahead of the decaying
MCS or behind it, especially across north central Missouri late this
afternoon.  Needless to say, todays forecast will need to be fine
tuned or nowcast as trends become evident.

CVKING

.LONG TERM...  (Tonight through Tuesday)
Issued at 219 AM CDT Wed May 25 2016

Interesting signals in some of the model guidance tonight across
northern Missouri and west central Illinois. Moisture convergence is
maximized between 06Z and 12Z and there is some indication that
convection may train across this region with a threat of heavy
rainfall and flash flooding. Instead of jumping with both feet into
this solution, have decided to increase PoPs to likely across the
northern CWA and mention heavy rainfall. This area may require a
flash flood watch if model guidance continues to show this setup in
the 12Z runs.

This thunderstorm activity should slowly sink/spread south through
18Z on Thursday on the collective outflow and veering low level jet.
Redevelopment will certainly be possilbe Thursday afternoon given
the degree of instabilty forecast, so maintained high chance Pops.

A more widespread shower and thunderstorm setup is still on tap for
Thursday night and Friday as the main upper level trof finally
approaches and lifts through the Midwest.  Temperatures are forecast
to be a bit cooler on Friday given clouds and precipitation.

Threat of thunderstorms does not end with the passage of the trof.
In fact, chances of thunderstorms litter the extended as the upper
level pattern keeps southwest flow alive and well. Weak shortwaves
and a nocturnal low level jet will invigorate convection daily as
the area remains warm and unstable.

CVKING

&&

.AVIATION...  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1148 PM CDT Tue May 24 2016

Timing of storms still hard to pin down. Activity over eastern
KS to make its way east overnight, reaching KCOU by about 12z and
rest of taf sites by 15z. This round of activity to diminish by
midday. Otherwise, VFR conditions outside of storms with south
winds persisting.

Specifics for KSTL:
Timing of storms still hard to pin down. Activity over eastern
KS to make its way east overnight, reaching KCOU by about 12z and
rest of taf sites by 15z. This round of activity to diminish by
midday. Otherwise, VFR conditions outside of storms with south
winds persisting.

Byrd

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     85  70  87  69 /  60  40  50  50
Quincy          83  68  84  67 /  60  70  50  60
Columbia        83  68  84  67 /  70  50  50  50
Jefferson City  84  69  86  68 /  70  40  50  50
Salem           82  69  85  69 /  60  20  50  50
Farmington      81  69  84  67 /  60  20  50  50

&&

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

$$

WFO LSX



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