Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 222030
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
330 PM CDT FRI JUL 22 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 322 PM CDT Fri Jul 22 2016

The main question for tonight is the threat of additional showers
and thunderstorms in the wake of this morning`s decaying MCS. The
outflow boundary from this mornings storms has pushed well to the
south of the CWA and extended from eastern TN across southwest MO
into far eastern KS at mid-afternoon. Although dew points have
recovered some since this morning and heating is ongoing, the air
mass has become only weakly unstable and remains capped to surface
based convection.

We will need to keep an eye on 2 areas this evening. The first is an
expanding area of storms in north central KS. Present indications
are this cluster should if anything eventually take a south-
southeast turn across eastern KS in conjunction with north-
northwesterly deep layer shear vectors and winds in the cloud-
bearing layer, a southerly LLJ providing convergence/lift on the
forward flank, and into the most unstable air residing along/west of
the outflow boundary. Another smaller area of scattered storms in
southeast IA is drifting south-southeast and I think this will
eventually dissipate. I think the best threat of storms albiet low
will occur overnight across northeast MO and west central IL, and
this is provided upstream activity develops later tonight in eastern
NE and western IA. The mid levels weren`t much of a hinderence last
night and they are cooler tonight. Low level winds /850 mb/ across
the CWA however were impacted by this mornings activity and
currently have a northerly component. The northern CWA is the only
part of the region they recover late tonight to provide a more
convergent signal and perhaps aid southeast moving convection. All
in all however the forecast confidence is low.

Glass

.LONG TERM...  (Saturday through Next Friday)
Issued at 322 PM CDT Fri Jul 22 2016

After a bit of a bust on temps on Friday due to storms and cloud
cover, Saturday to rebound back into the 90s for highs. Dewpts in
the 70s will continue to create heat indices well over 105. Same
conditions can be expected on Sunday. So no changes to heat
headlines at this time.

As for precipitation chances over the weekend, it will be
conditional on Saturday. It will depend on any development
tonight. So for now have slight chance pops early Saturday
morning over northeast MO/west central IL. Then some
isolated/scattered activity possible Saturday afternoon, though
despite decent instability, not a lot out there to trigger
activity. Then a break Saturday night with main frontal boundary
finally sinking south across region on Sunday. With such slow
movement to the front, it will not exit forecast area til midday
on Monday. Best chances of rain through this period will be Sunday
night and Monday.

Frontal boundary to stall out over far southern Missouri through the
first part of the work week. Will see just see isolated/scattered
storms along and south of I-70 through this period. Then by
Wednesday, boundary to begin lifting back north with increasing
chances of showers and storms. As for temperatures, will see highs
near normal Monday through Friday.

Byrd
&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1237 PM CDT Fri Jul 22 2016

The complex of showers and thunderstorms this morning has all but
dissipated, and has pushed an outflow boundary well to the south.
Stable air prevailed in its wake, and this suggests that the
threat of additional showers and storms at any of the terminals
this afternoon and early evening is rather remote. VFR flight
conditions should prevail through at least evening. The overnight
forecast is a little more tricky. If we don`t get good heating and
breaks in the clouds this afternoon there could be some fog
concerns. Will also have to keep an eye on any thunderstorm
complexes dropping south late tonight out of IA. If this should
occur then KUIN would have the greatest threat of showers and
storms, however confidence is quite low and therefore nothing has
been mentioned in the TAF.

Specifics for KSTL:

VFR flight conditions are expected throught the forecast period.
The complex of showers and thunderstorms this morning has pushed
an outflow boundary well to the south with stable air currently
dominating. While destabilization is expected with heating this
afternoon, the threat of additional showers and storms at KSTL
this afternoon and evening is rather remote.

Glass
&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     79  98  79  97 /  10  20  10  30
Quincy          76  96  77  94 /  20  20  10  20
Columbia        76  96  76  96 /  10  20   5  20
Jefferson City  76  98  77  98 /  10  20   5  20
Salem           74  92  76  94 /  20  20  10  30
Farmington      74  94  75  93 /  10  30  10  30

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Excessive Heat Warning until 8 PM CDT Sunday for Audrain MO-
     Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-
     Gasconade MO-Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln
     MO-Madison MO-Marion MO-Moniteau MO-Monroe MO-Montgomery MO-
     Osage MO-Pike MO-Ralls MO-Reynolds MO-Saint Charles MO-
     Saint Francois MO-Saint Louis City MO-Saint Louis MO-Sainte
     Genevieve MO-Shelby MO-Warren MO-Washington MO.

IL...Excessive Heat Warning until 8 PM CDT Sunday for Adams IL-Bond
     IL-Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-
     Jersey IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-
     Montgomery IL-Pike IL-Randolph IL-Saint Clair IL-Washington
     IL.

&&

$$
WFO LSX


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