Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 301624
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1124 AM CDT Tue Sep 30 2014
Issued at 1117 AM CDT Tue Sep 30 2014
Low clouds have finally halted their progression to the southwest
and are beginning to dissipate over central Illinois. The 12Z KILX
sounding showed a rather shallow frontal inversion, so would
expect remaining clouds to dissipate through the early afternoon
hours allowing for some sun in the north and northeastern counties
today. Still, this should take some toll on the temperatures so
have lowered highs in these areas today. Elsewhere, latest
aircraft soundings from KSTL showed mixing up to 800mb which supports
going forecast highs in the mid 80s over the central and southern
parts of the CWA.
.SHORT TERM: (Through Late This Afternoon)
Issued at 224 AM CDT Tue Sep 30 2014
Focus continues to be temps with one more dry day expected.
Cdfnt shows up well on regional RADAR and currently pushing into nrn
MO and central IL. Mdls are in fairly good agreement with this fnt
slowly sinking swd today, eventually reaching along a line from IRK
to near STL to SLO before stalling. Have made only minor changes to
the prev forecast, trending twd persistence along and S of the fnt.
Area of ST across ern IA and nrn IL continuing to move swd presents
a forecast problem for today. The RAP/HRRR seem to have the best
handle on these clouds currently. However, even these mdls suggest
these clouds will dissipate by Noon today. Therefore, N of the fnt,
have trended near the warmer guidance.
.LONG TERM: (Wednesday through Monday)
Issued at 306 AM CDT Tue Sep 30 2014
Focus quickly turns to precip chances thru the end of the work
Mdls are in very good agreement regarding mass fields thru the
week. Not much change from the prev forecast as there is not much
change to latest mdls from what the day shift had to work with.
It appears the NAM and local WRF have caught up with the other mdl
guidance regarding cdfnt timing later this week. However, the
GFS/ECMWF/GEM have slowed timing of fropa compared to prev cycles.
Have therefore raised temps slightly for sern portions of the CWA
on Thurs. Have also raised PoPs for Thurs night to account for the
slower fropa timing.
Otherwise, much cooler temps advecting into the region for the
weekend and into next week behind the fnt.
.AVIATION: (For the 12z TAFs through 12z Wednesday Morning)
Issued at 603 AM CDT Tue Sep 30 2014
Backdoor cold front stretching from KUIN to K1H2 will continue to
move southwest and bring IFR ceiling and MVFR fog to KUIN by 12Z
and perhaps to STL metro terminals by 15Z. Light and variable wind
to become east/northeast in wake of the front. Expect this layer
of stratus to lift and scatter out this morning.
Specifics for KSTL:
Watching wall of stratus moving southwest toward terminal this
morning behind backdoor cold front. Think we may have at least a
few hours of IFR conditions before stratus lifts and scatters by
this afternoon. Wind to become east/northeast.