Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 200920

Area Forecast Discussion
National Weather Service Saint Louis MO
420 AM CDT MON JUN 20 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 314 AM CDT Mon Jun 20 2016

As a shortwave drops southeastward through the northern portion
of the Great Lakes region it will send the cold front currently
extending from northwest WI southwest through central Nebraska
southward into northeast MO and west central IL this afternoon.
Scattered convection is expected along this front, especially
this afternoon as the atmosphere becomes quite unstable. A few
storms could be severe as wind shear increases as a mid level wind
max moves through the Great Lakes region. High temperatures will
be similar to yesterday and above normal with plenty of solar
insolation during the morning hours.


.LONG TERM...  (Tonight through Sunday)
Issued at 314 AM CDT Mon Jun 20 2016

Scattered convection will continue tonight along the cold front
which will sag southward into central MO and southern IL. Hail
will be possible with a few of the storms due to elevated
instability over and south of the front. The threat for convection
will continue on Tuesday as the upper level ridge continues to
retrograde southwestward with the front becoming oriented
from northwest to southeast and the best coverage of precipitation
across northeast MO and west central and southwest IL. The front
will begin lifting slowly northeastward as a warm front with the
majority of the convection across west central and southwest IL
Tuesday night into Wednesday morning with low-mid level warm air
advection over the front due to a southwesterly low level jet.
Most of the showers/storms should shift northeast of the forecast
area by Wednesday afternoon. With southwest surface/low level flow
and plenty of solar insolation during the afternoon on Wednesday
temperatures will get into the middle 90s over portions of the
area along with heat indices as high as 100-105. Isolated to
scattered convection is expected on Thursday as a weakening cold
front drops southeastward through the area, with scattered
convection on Friday mainly across central and southeast MO as a
shortwave moves through the area. Only slightly cooler
temperatures are expected on Friday. The GFS model has a deep
upper level trough moving eastward through the northern Plains
this weekend sending a cold front southeastward through our area
late Saturday night and Sunday with convection expected along
this front. The ECMWF model has a weaker solution with this system
and hence less QPF.



.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1148 PM CDT Sun Jun 19 2016

VFR fcst thru the prd with clear to mostly clear skies overnight.
Winds will become WSW tomorrow in advance of an approaching cold
front with some diurnal cu dvlpng late mrng. The front enters
nthrn MO and W cntrl IL later aftn into early evng with some
scttrd SHRAs/TSTMs dvlpng. Front slowly sags S drng the evng and
stalls near I-70 overnight. Best chance of precip for these areas
appears to be after 06Z.

Specifics for KSTL:

VFR fcst thru the prd. Winds turn WSW Mon in advance of an
approaching cold front. There is the potential for some scttrd
convection near the terminal Mon night...mainly after 06Z...but
not confident enough in coverage or timing to include in the TAF





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