Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 221648

Area Forecast Discussion
National Weather Service Saint Louis MO
1148 AM CDT Thu Jun 22 2017

.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 1148 AM CDT Thu Jun 22 2017

Area of showers near Cape Girardeau will continue to move north
northeastward, and may affect parts of southwest and south central
Illinois early this afternoon. Otherwise, there may be some
additional isolated showers and thunderstorms develop through the
afternoon and early evening hours across southeast Missouri into
south central Illinois in the unstable atmosphere ahead of Cindy.
Otherwise, temperatures across the area are already in the upper
70s to low 80s, so have adjusted temperatures accordingly based on
temperature trends.


.LONG TERM...  (Friday through Wednesday)
Issued at 403 AM CDT Thu Jun 22 2017

Showers and thunderstorms can be expected Friday, especially during
the morning and especially across southeast MO and southwest IL as
the remnants of Tropical Storm Cindy moves from AR into TN and a
cold front moves southeastward through the forecast area.  The
convection should be confined to southeast MO and southwest IL,
south-southeast of STL by Friday afternoon.  The precipitation will
move south-southeast of the forecast area by Friday evening as the
cold front shifts southeast of the region, while the remnants of
Cindy moves eastward through the Tennessee Valley region.  A surface
ridge will build into the region with northwesterly winds bringing
cooler and less humid air into our area.  Temperatures will be
cooler Friday night due to low level cold air advection, a clearing
sky, and surface dew points lowering into the 50s.  Lows will be
about 5 to 10 degrees below normal.  A relatively cool weekend is
forecast with northwest upper level flow as an upper level trough
centered over the Great Lakes region deepens and sends a secondary
reinforcing cold front southeastward through our forecast area
Saturday night. It appears that this frontal passage will be dry.  A
northwest flow shortwave may bring some showers to parts of central
and southeast MO late Sunday night.  The relatively cool and mostly
dry weather pattern will continue early next week with continued
northwest upper level flow, and as a large surface ridge moves
slowly through the region.  Should see warmer temperatures by
Wednesday as the Great Lakes upper level trough moves well east of
the region, while southerly low level flow returns as the surface
ridge shifts east of the area.  Increasing low level warm air and
moisture advection may lead to a threat of convection across parts
of northeast and central MO by Wednesday.



.AVIATION...  (For the 12z TAFs through 12z Friday Morning)
Issued at 655 AM CDT Thu Jun 22 2017

Low CIGs currently over southern MO are expected to expand into
STL metro imminently, with STL metro then sitting on the NW edge
of this low cloud region for the next several hours before sliding
off to the east tonight. For now, it looks like CIGs will drop
into the 1500ft-2500ft range for most of today and early tonight
with the lowest IFR CIGs probably staying S and SE of the
terminals. VFR conditions are expected thru this evening at KUIN
and KCOU. Southerly flow will prevail thru today and this evening
with pcpn probs staying low enough to preclude mention in TAFs but
will instead be nowcasted as need be. A cold front will drop down
late tonight and with better rain chances associated with it, have
placed VC mentions in TAFs along with a wind shift from the NW and
a likely return of MVFR CIGs.





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