Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 010551

1151 PM CST MON NOV 30 2015

Issued at 855 PM CST Mon Nov 30 2015

In the process of making generally minor tweaks to forecast to
reflect latest surface ob, radar and satellite trends. Primary
PoPs (in the chance category) for the remainder of the night
should be along and ahead of front/wind shift line, although with EAX`s
88D imagery is still indicating spotty -RA exiting KC Metro will
maintain slight chance PoPs in the wake of the wind shift until
low clouds begin to break up.

Regarding clouds...clearing line has just worked across the MO/KS
border in west central MO over the last hour. Extrapolation of
the clearing based on low cloud satellite imagery suggest clearing
working into mid MO between 05-06z, and reaching STL metro in the
08-09z time frame. Lower clouds rotating around the upper low over
the mid Missouri Valley may spin their way back into our far
northern counties, so sustained clearing in this part of our CWA
not as certain as the clearing expected along and south of the I70



.SHORT TERM:  (Through Late Tonight)
Issued at 245 PM CST Mon Nov 30 2015

Upper level low over Nebraska will move northeastward into northwest
IA later tonight with its associated surface low over northeast
Nebraska moving into southwest Minnesota.  The surface low will drag
an occluded front eastward through our forecast area this evening.
The best chance of measurable rain should occur across west central
IL with mainly just a little light rain or intermittent drizzle
elsewhere, mainly this evening.  The rain and drizzle will finally
come to an end late tonight as the dry slot moves northeastward into
the area south of the upper level low, along with low level drying
behind the occluded front.  Should be some clearing late tonight
into central MO.  Low temperatures tonight will be a little colder
than the previous night across northeast and central MO and west
central IL as lower surface dew points advect southeastward into
this area.


.LONG TERM:  (Tuesday through Next Monday)
Issued at 245 PM CST Mon Nov 30 2015

Clouds are expected to clear from most areas during early Tuesday
morning, and from all areas by late morning.  With plenty of
sunshine in its wake, a breezy WSW surface flow which should
promote relatively deep mixing for this time of year, and only
a weak push of cooler air behind passage of the occluded front
the previous night, should see a robust temp recovery for areas near
and south of I-70.  Started with the highest MOS values for daytime
max temps, and adjusted another deg or two higher for areas near
I-70 and south.

An actual cold front will move thru Tuesday night and should at
least bring with it increasing clouds, including a field of low
clouds.  Of perhaps more interest is in addition there will be a
strong upper level disturbance rotating around the southern
periphery of the still wound-up storm system to our north that will
track thru much of our northern CWA later Tuesday night and
Wednesday morning.  While the column will be rather dry overall,
the forcing/upper level support provided by this feature along with
cyclonic flow at the low levels and the likely presence of a field
of low clouds should at least provide for the potential of a seeder-
feeder setup and the threat for falling pcpn from this.  While
keeping PoPs for measurable pcpn low at this time, have introduced
the mention of pcpn into the forecast beginning late Tuesday evening
thru late Wednesday morning.  The atmosphere will be cold enough for
any pcpn to fall as snow--the only mention of snow in this forecast
package.  For now have drawn the southern boundary of the flurries
mention to just north of a Mexico, MO to Salem, IL line.

Otherwise, after one day of below average temps on Wednesday
following passage of the cold front Tuesday night, we should then
see an extended period of above average temps Thursday thru early
next week with a synoptic pattern that keeps the cold air locked
up well to the north.  Friday and Saturday look especially favorable
for well above average temps, where some locales may see low 60s.

On a side note during this period, the models seem to have come into
better agreement on handling of the development of a storm system
for the southeastern CONUS on Thursday, and largely making it a
non-issue for our area.

Another strong Pacific storm system still looks set to become cutoff
and affect our area for early next week, with slower timing
preferred amongst the models considering a jet stream ridge will be
also developing over the central CONUS.  Should hold off until after
the weekend, and we have it impacting our area instead on Monday.



.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1141 PM CST Mon Nov 30 2015

IFR flight conditions will continue to clear from west to east
through the rest of the night. Some lingering drizzle/light rain
will clear out with the wind shift as the cold front which is just
west of the Mississippi river continues moving east. Clearing
line should be through KCOU within minutes of 06Z and up to the
Mississippi river by 09-10Z and through southwest into south
central Illinois by 12-15Z. VFR flight conditions are expected to
prevail after the clouds clear out acros the majority of the area.
Another round of clouds will rotate south out of Iowa across the
area Tuesday night. At this time, it looks like the clouds will be
at or above 3500 FT.

Specifics for KSTL:

Think the IFR ceilings are just about ready to clear out of the
terminal. Should see ceilings above 1000FT by 07Z. Clearing line
is over central Missouri now...and should be at the terminal
between 09-10Z. VFR flight conditions with west-southwest flow
will prevail after the ceilings clear. Looks like we could see
some wind gusts to 20-25kts through Tuesday. Another Batch of
clouds will rotate down toward Lambert Tuesday night, but current
indications are that the ceilings will be above 3000 FT.





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