Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 011604
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1104 AM CDT Wed Oct 1 2014
Issued at 1103 AM CDT Wed Oct 1 2014
Area of showers and thunderstorms has moved into northeast
Missouri, and will eventually cross the river into west central
Illinois. This area is being driven by an modest level moisture
convergence that will persist into the afternoon hours. Have upped
PoPs to accordingly to cover going trends this morning, and have
likely PoPs going over central and northeast Missouri and west
central Illinois this afternoon. Lowered highs a bit over the far
northwestern part of the CWA today where persistent rain is most
likely to hold down temperatures.
Still looks like greatest chance of any severe weather will be
later today into this evening when instability will be the
greatest. Most likely it will be near the outflow boundary from the
current convection as deep layer shear increases over the area.
.SHORT TERM: (Through Late This Afternoon)
Issued at 226 AM CDT Wed Oct 1 2014
As expected the convection stayed west of the CWA overnight with
parts of northeast Kansas, eastern Nebraska, western Iowa, and
northern Missouri picking up some hefty precipitation totals from
training convection. Model guidance depicts a slow eastward movement
to the convection this morning, with additional storms likely firing
during the afternoon across northwest or central Missouri. The
front that settled to our south yesterday evening will lift north as
a warm front today, allowing temperatures to rise well above average
.LONG TERM: (Tonight through Tuesday)
Issued at 226 AM CDT Wed Oct 1 2014
Thunderstorms should increase in coverage and intensity tonight
as next upper level disturbance rounding the base of the large
scale trof at the moment lifts northeast across the southern
Plains into the Midwest. Combine this synoptic lift with a
strengthening low level jet and the result should be some hefty
convection across northern Missouri into west central Illinois.
Training convection could lead to some rainfall totals in excess
of 2 inches and the threat of flash flooding will need to be
monitored. Will not issue a watch due to dry antecedent
conditions. Slight risk of severe thunderstorms from SPC reaches
into central and northeast Missouri. Could certainly be some
reports of large hail and damaging winds with the strongest cells.
Complex of thunderstorms will be weakening and exiting into WFO ILX
area Thursday morning with attention turning to the cold front
moving into Missouri from the west. Thunderstorms again expected to
develop, maybe in waves on Thursday, along and ahead of the
front. These storms will be capable of producing the full gamut
of severe weather, especially given the favorable shear profile.
The exact timing, location, and severity of convection will be
modulated by mesoscale features such as outflow boundaries.
Expect most of the convection to be exiting the area by 06Z Friday
with only a few showers lingering after midnight as the cold front
sweeps across the CWA.
Friday looks windy and much colder as upper level low moving
southeast across the upper Midwest deepens the long wave trof as it
slides east of the CWA. Colder than normal conditions expected on
Saturday with temperatures only rising into the 50s.
Temperatures to slowly warm the remainder of the extended but there
is some indications that this long wave trof will stay parked to our
east, keeping northwest flow alive and well overhead. A disturbance
moving southeast within that flow could bring few sprinkles or rain
showers to the CWA on Sunday/Sunday night.
.AVIATION: (For the 12z TAFs through 12z Thursday Morning)
Issued at 629 AM CDT Wed Oct 1 2014
Focus will be precip chances thru the period with VFR conditions
expected outside of TSRA. Ongoing convection over wrn MO is
expected to move newd, remaining W of COU/UIN. Some question about
TSRA potential this afternoon with a S/W currently over OK.
However, with greater chances overnight, have focused mention of
VCTS and tempo groups with that timing. COU/UIN could see multiple
rounds of precip thru the period.
Specifics for KSTL: No much change from the prev TAF. Winds are
expected to be light and sely today. VFR conditions expected
outside of any TSRA. Still some uncertainty regarding timing of
precip, but best chances are around and after Midnight tonight.
Have kept only mention of VCTS due to uncertainty in coverage.