Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 302009

Area Forecast Discussion
National Weather Service Saint Louis MO
309 PM CDT TUE AUG 30 2016

.SHORT TERM...  (Through Late Wednesday Afternoon)
Issued at 308 PM CDT Tue Aug 30 2016

Active thunderstorm complex has moved south to I-70 with the outflow
pushing to the south.  Still expect these thunderstorms to continue
to push south and east through late this afternoon and evening
before they diminish with the loss of daytime heating.  Chances
tonight will continue as there will be weak low level moisture
convergence ahead of the surface cold front coming down from the
north.  There will be some weak mid level support from a mid level
trough that will move into the area from the north.  The chance for
thunderstorms will continue into tomorrow over the area before they
begin to end from the north as drier air begins to filter in behind
the front.

There may be some fog over the area tonight with the abundant low
level moisture over the area.  MOS temperatures look reasonable
tonight and tomorrow.


.LONG TERM...  (Wednesday Night through Next Tuesday)
Issued at 308 PM CDT Tue Aug 30 2016

The actual airmass change will begin taking place on Wednesday night
as drier air filters south.  Think there will likely be scattered
convetion continuing on the dew point boundary during the evening,
but there probably won`t be enough convergence on the boundary to
sustain precipitation after 03-06Z with the loss of diurnal heating.
Dew point temperatures should fall into the 50s and lower 60s as
high pressure builds across the Upper Midwest and Great Lakes
region.  Persistent low level northeast to easterly flow will keep
cool and dry air over the region through the end of the week and
probably through Saturday as well.  Temperatures should be below
normal with highs in the mid to upper 70s and lows mainly in the mid
50s to around 60.

Guidance is indicating that the high will be trying to move off the
East Coast on Sunday (possibly slowed by a tropical system), but it
should be far enough east that we get back into return flow.
Southerly flow persists through the end of the forecast period
Tuesday afternoon.  Air temperatures and humidity will be more
typical of mid August with highs climbing back into the mid 80s by
early next week with dew point temperatures rising back into the mid
and upper 60s.  GFS and ECMWF print out precip Monday and
Tuesday...primarily over northern portions of the area, but there
are differences in the mass fields of the two models so this is low
confidence at this time.



.AVIATION...  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1254 PM CDT Tue Aug 30 2016

Thunderstorms will continue move east across the area early this
afternoon affecting all of the terminals. These storms will be
capable of producing heavy downpours with MVFR/possible IFR
visibilities and ceilings. Expect some diminishment with the loss
of daytime heating. There will be some areas of fog and low
ceilings late tonight and early on Wednesday morning.

SPECIFICS FOR KSTL: Thunderstorms just northwest of the terminal
will move through the airport between 19-20Z. Additional storms
are developing over central MO that will move through the terminal
mid-late afternoon. Expect some dry and VFR conditions this
evening before MVFR clouds move back into the airport for a short
time early Wednesday morning.



Saint Louis     75  85  64  81 /  40  40  10   0
Quincy          69  82  58  78 /  40  30   5   0
Columbia        69  81  60  78 /  40  40  10   0
Jefferson City  70  83  62  80 /  40  50  10   0
Salem           71  84  61  80 /  40  50  20   0
Farmington      71  83  61  78 /  40  50  20   0




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