Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Text Only | 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 021704

1204 PM CDT FRI OCT 2 2015

Issued at 1203 AM CDT Fri Oct 2 2015

Area of low clouds will continue to progress westward into early
afternoon and will eventually begin to scatter out per the RAP RH
fields. With the clearing and the mixing, we should begin seeing
the wind gusts occurring. Highs in the middle to upper 60s still
look good for this afternoon.



.SHORT TERM:  (Through Late This Afternoon)
Issued at 311 AM CDT Fri Oct 2 2015

Relatively strong surface ridge extends from northwestern WI south-
southwest into north central OK.  Gusty northeast winds can be
expected today due to the fairly tight surface pressure gradient
across the region.  East-northeasterly low level, 850 mb winds will
bring increasing moisture and cloudiness westward into portions of
east central and southeast MO and southwest IL later today north-
northwest of the mid-upper level low and associated weak inverted
surface trough over the Gulf Coast states into the Tennessee Valley
region.  These clouds along with weak low level cold air advection
and 850 mb temperatures of only about 8-10 degrees C over our area
will hinder daytime heating today.  High temperatures today will be
a tad cooler than yesterday, and about 5 degrees below normal for
early October.


.LONG TERM:  (Tonight through Thursday)
Issued at 311 AM CDT Fri Oct 2 2015

Cutoff low forming over the southeast U.S. in the base of the
eastern CONUS longwave trof is forecast to wobble southeast over the
next few days and nights, and eventually interact with Joaquin as it
works its was north from the Bahamas.  The very slow eastward
progression of this feature. along with the development of the upper
low over the southwestern U.S., means very little movement of
weather features across the central CONUS over the next few days and
nights. This atmospheric traffic jam will keep surface ridging
locked over the area tonight into Monday.

Low level moisture which begins to work into the area today should
increase tonight and into the weekend due to an intensification
of the easterly flow produced by the increase of the pressure
gradient between aforementioned surface ridge and lowering
pressures over the southeast U.S. 00z guidance supports earlier
model trends of indicating a westward surge of this low level
moisture, and plan view RH progs as well as forecast soundings
suggest this cloudiness gradually spreading west across the FA
tonight into Sunday morning. Have attempted to tweak temp trends
to reflect this increase in cloudiness, with clouds tending to
limit the diurnal swing in the mercury as they move into an area.

Can`t totally rule out a slight threat of showers with increase of
low level moisture, but at this point will keep forecast dry as
moisture is rather stratified with an apparent lack of any
pronounced dynamics/lift over the mid-Mississippi Valley.

Upper pattern over the CONUS should become progressive once again early
next week as the combo of Joaquin and southeast U.S. cutoff begin
to propagate up the east coast and into the western Atlantic.
Specifics of medium range forecasts remain rather chaotic, but
there does seem to be some agreement that remnants of low over the
southwest U.S. will press into the central CONUS by Wednesday
night/Thursday, so have continued some low PoPs during this time



.AVIATION:  (For the 12z TAFs through 12z Saturday Morning)
Issued at 538 AM CDT Fri Oct 2 2015

Persistent surface ridge extends from northwestern WI south-
southwest into north central OK with a tight surface pressure
gradient over MO and IL. Nely surface winds can be expected
through the forecast period, gusty at times during the late
morning and afternoon hours. Low level clouds at 2500-3500 feet in
height across southern IL will shift westward into the St Louis
metro area early this morning and possibly also into UIN as well.
These clouds will likely rise in height with diurnal heating.
Should also get the development of diurnal cumulus clouds across
the area late this morning and this afternoon as low level
moisture increases across much of the area.

Specifics for KSTL: Low level clouds around 2500-3500 in height
across southern IL will advect westward into STL early this
morning. These clouds will gradually rise in height through the
day and may scatter out this afternoon with diurnal heating,
mixing and drying. Nely surface winds can be expected through the
forecast period, gusty at times during the late morning and



Saint Louis     66  51  65  53 /   5   5   5   5
Quincy          65  44  63  47 /   0   0   0   5
Columbia        65  44  64  47 /   0   0   0   5
Jefferson City  67  45  66  47 /   0   0   0   5
Salem           66  51  63  53 /  10  10  10  10
Farmington      64  48  63  50 /   5   5   5   5




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