Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KLSX 030440

1140 PM CDT Sat May 2 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 340 PM CDT Sat May 2 2015

Low-mid level warm air advection ahead of weak shortwaves will bring
mid-high level cloudiness to the forecast area tonight.  Most of the
showers should be across northeast MO and west central IL where
better low level moisture along with instability exists, although
there may be a few sprinkles further south.  Low temperatures will
be warmer than the previous night, and at least slightly above
normal for early May, due to the cloud cover and southerly surface


.LONG TERM:  (Sunday through Next Saturday)
Issued at 340 PM CDT Sat May 2 2015

An upper level RIDGE will begin building over our region early next
week with it effectively in control after Monday and continuing thru
the work week.  This will result in an extended period of above
average temps with above average moisture thru the column--where
disturbances or areas of forcing will have not too much trouble
resulting in rain or thunderstorms.  As a result, we were hard
pressed to find any days next week with PoPs too low to mention.

Some sprinkles were possible for areas mainly N and W of STL metro
Sunday morning in a moist column, very weak forcing regime, but
otherwise PoPs look to be too low for measurable pcpn at this time.

A surface cold front will be the primary focus for Sunday night thru
Monday night as it drops into far northern MO Sunday night and
stalls during this period.  While at least high-end chance PoPs look
justified for areas near the front, they should taper off rapidly
heading towards I-70 with an absence otherwise of any forcing.

With a more traditional warm-sector setup for late Monday night thru
late Wednesday, this period looks warm but dry.

Finally, a more persistent period of forcing from upper level
disturbances and eventually a surface front will join with enhanced
levels of moisture for what should be the best widespread chances
for rain over the next seven days...from Thursday thru Saturday.

Persistent southerly flow and an ever-strengthening May sun angle
should help to propell temps over 80 just about each day during next



.AVIATION:  (For the 06z TAFs through 06z Sunday Night)
Issued at 1128 PM CDT Sat May 2 2015

VFR flight conditions are expected to continue through Sunday.
Very light showers continue to drift southeast over parts of the
area. Shower activity should continue to diminish slowly through
the rest of the night. Showers are so light that there should be
no impact to operations if one does move over an airport. Low
level wind shear is a good possibility especially over central and
northeast Missouri as well as west central Illinois. Models are
indicating that the wind will increase to around 30kts between
400-800 ft providing +/- 20-25 kts of shear from the surface to
those altitudes. Shear values look to fall off further east/southeast.
Expect increasing south-southwest wind on Sunday morning with
gusts to around 20kts during the afternoon.

Specifics for KSTL:

VFR flight conditions are expected to continue through Sunday.
There may be a sprinkle or two through the rest of the night, but
airport operations are not expected to be affected. Some low level
wind shear still looks possible at Lambert, but values do not look
high enough to warrant a mention in the TAF at this time. Wind
will increase from the south-southwest Sunday morning with gusts
to around 20kts during the afternoon.





WFO LSX is the U.S. government's official web portal to all federal, state and local government web resources and services.