Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 202047
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
347 PM CDT WED JUL 20 2016

.SHORT TERM... (Through Thursday)
Issued at 344 PM CDT Wed Jul 20 2016

Main issue across the area continues to be the heat wave over the
area. The storms responsible for flash flooding in IL this morning
faded away just after 1pm. These storms pushed outflow boundaries
which are noted on radar and satellite pushing southwest into
central missouri. There is a stationary boundary just north of
farmington and just south of columbia. This boundary along with
outflow boundaries could kick off a few isolated showers and
thunderstorms early this evening. There could be some fog in areas
that received heavy rainfall earlier today. This will be dependent
on clearing as light southernly winds are forecast for tonight into
tomorrow. The day tomorrow continues the heat wave with temperatures
in the upper 90s in most areas. The exception for temperatures will
be the ozarks and northeastern missouri and western illinois which
will see mid 90s. The only area that may see a few isolated showers
and thunderstorms would be south of a Belleview to Fredricktown
line. The rest of the area will likely be capped due to higher H7
temperatures.

Kelly

.LONG TERM... (Thursday Night through Next Wednesday)
Issued at 344 PM CDT Wed Jul 20 2016

Hot and humid weather pattern will continue into the weekend due
to a large and strong upper level ridge centered over the southern
Plains, along with persistent south or southwest surface winds on
the backside of a surface ridge southeast of our area.  The ECMWF
and NAM models try to bring a little convection southward into
northeast MO and west central IL late Thursday night or Friday south
of a weakening front.  Will just include slight chance pops over
this area on Friday.  More significant will be the unseasonably hot
temperatures expected for Friday, possibly topping out near the
century mark.  May get some convection Friday night mainly across
west central and southwest IL on the edge of the cap as shortwaves
continue to overtop the upper level ridge.  Should get more shower
and thunderstorm activity by Sunday as the upper level ridge begins
to flatten, the atmosphere over us gets more uncapped, and a cold
front drops southeastward through our area Sunday afternoon and
night as an upper level trough moves eastward through the northern
Plains and Great Lakes region.  Daytime highs should be at least
slightly cooler across northeast MO and west central IL Sunday and
the entire area on Monday, close to seasonal normals.  Will keep the
excessive heat warning going through Saturday for the entire area.
Depending on the timing of the front and the amount of cloud cover
and convection expected on Sunday, the warning may need to be
extended into Sunday for the southern or southeastern portion of the
forecast area. Most of the convection may shift south of the
forecast area by Monday night, then the threat for precipitation
will return Tuesday night or Wednesday ahead of an approaching upper
level trough moving through the Plains.

GKS

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1224 PM CDT Wed Jul 20 2016
A stationary boundary draped to the north of FAM and south of COU
may be the focus of isolated showers and thunderstorm late this
afternoon and early this evening. There could be some fog late
tonight and early tomorrow mainly east of the mississipi
river...but it is unclear if the area will clear out or not
tonight. Otherwise...the rest of the period will be dry with VFR
ceilings and light southernly flow.


Specifics for KSTL:
A dispating outflow boundary to the northeast of the terminal may
provide the focus of isolated showers and thunderstorms late this
afernoon and early evening...but confidence is too low to include
in TAF. Otherwise...the rest of the period will be dry with VFR
ceilings and light southernly flow.

Kelly

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Excessive Heat Warning until 7 PM CDT Saturday 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 7 PM CDT Saturday 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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