Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 221935

Area Forecast Discussion
National Weather Service Saint Louis MO
235 PM CDT FRI APR 22 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 234 PM CDT Fri Apr 22 2016

The stratus cloudiness across northeast MO should continue to become
more cumuliform late this afternoon with continued daytime heating
and mixing and the rising of the boundary layer.  Elsewhere
scattered diurnal cumulus clouds have developed.  It appears that
any convection will be east of the forecast area late this
afternoon, associated with the upper level trough over the OH Valley
region, although could not rule out isolated showers or at least a
few sprinkles mainly across the IL counties of our forecast area.
Most of this cloudiness will dissipate this evening due to the loss
of daytime heating.  There may be a little fog late tonight with
good radiational cooling as the north-northwest wind becomes light
with surface ridging extending from the Great Lakes region south-
southwest into our area.  Lows tonight will be similar to the
previous night or slightly cooler, and close to seasonal normals for
late April.


.LONG TERM...  (Saturday through Next Friday)
Issued at 234 PM CDT Fri Apr 22 2016

No major changes to the forecast through the weekend as surface
ridge to shift to east on Saturday allowing southerly winds to
return by Saturday afternoon. Temperatures to moderate through the
weekend with highs in the 70s on Saturday and in the upper 70s to
low 80s on Sunday.

Timing of next weather system is similar to yesterday`s model runs
with precipitation moving in Sunday night. Front to stall out over
southern portions of forecast area on Tuesday before moving back
north as a warm front on Wednesday. Models are still indicating
decent instability, CAPES in excess of 1500 J/kg and shear with
system Wednesday afternoon, Wednesday night as main surface low/cold
front slides through region. All of this still points to our first
real potential severe weather day this spring, but a lot can happen
in 5 days. Stay tuned to further updates.

Once system exits region on Thursday, will see precipitation taper
off. Extended models beginning to indicate another system
approaching region on Friday, but timing is hard to pin down. So for
now kept slight chance pops.


.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1106 AM CDT Fri Apr 22 2016

Stratus deck around 1000 feet in height across northwest MO
appears to be dissipating on its forward edges as it tries to
advect into UIN and COU late this morning. This trend should
continue this afternoon with daytime heating, mixing and drying.
Diurnal cumulus clouds should develop across the area this
afternoon. Could not rule out an isolated shower in the St Louis
metro area this afternoon, but it appears the probability is too
low to include in the tafs. North-northwest surface wind will
become light tonight with surface ridging building southward into
the area from the Great Lakes. Could not rule out some light fog
late tonight/early Saturday morning due to the light winds and
little if any cloud cover. Surface wind will become southeasterly
in UIN and COU Saturday morning and in STL Saturday afternoon as
the surface ridge axis shifts east of the area.

Specifics for KSTL: It appears that the stratus cloud cover
dropping southward through northern IL will dissipate before it
makes it into STL, although scattered diurnal cumulus clouds
are expected to develop this afternoon. North-northwest surface
wind this afternoon will become light tonight. With a light wind
along with little if any clouds there may be some light fog late
tonight/early Saturday morning. Light surface wind will become
southeasterly Saturday afternoon.


Saint Louis     49  74  58  81 /  10   0   0   5
Quincy          46  72  56  81 /   5   0   5  10
Columbia        51  77  57  80 /   5   0   0  10
Jefferson City  51  78  57  82 /   5   0   0  10
Salem           47  72  53  79 /  10   0   0   0
Farmington      47  74  53  79 /  10   0   0   0



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