Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 280011
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
611 PM CST FRI NOV 27 2015
.SHORT TERM: (Through Saturday)
Issued at 333 PM CST Fri Nov 27 2015
A strong wound-up storm system over the Great Basin region of the
western CONUS is expected to move little during this period,
maintaining an active southwest flow aloft over our region, with
disturbances training along. This will all intersect a pretty moist
airmass in place still over our region and result in high probs for
precipitation, especially for areas near and south of the I-70
First, will keep the FFA going as-is. Despite rain tapering off in
central and now east-central MO, the rain is cycling to an extent
and should try to fill back in further north into central MO this
evening and overnight. Also, flooding effects are typically
delayed from when the rainfall occurs and so the flood threat does
not end right when the rainfall tapers. Will let the evening and
overnight shifts re-evaluate and cancel early as needed once the
effects on the area are better realized.
Second, surface temps will once again approach the freezing mark
across parts of northeast MO and west-central IL and with current
and expected vertical temp profiles, would be supportive of a brief
period of light freezing rain or sleet. Fortunately, much of the
threat for measurable pcpn will be south of this area and any
amounts, should they occur, should be very light. PoPs here are
Preferred the higher end of MOS temps for mins tonight and lower end
of MOS for maxes Saturday with extensive cloud cover in place.
.LONG TERM: (Sunday through Next Friday)
Issued at 345 PM CST Fri Nov 27 2015
(Sunday - Monday)
As the wound-up western CONUS storm begins to stir eastward, the
pattern over us remains status quo, with an active southwest flow
aloft and additional disturbances tracking thru, overrunning
moisture well to the north of the old surface boundary.
This should result in another widespread rain event, but QPF will be
light, with around a tenth of an inch forecast and should have
minimal to no impact on flooding concerns.
Good agrement then continues on what to do with the storm system
center, bringing it out into the Plains by Monday and track it to our
north Monday night. During this process, a strong disturbance will
rotate around the southern periphery and impact our area Monday. QPF
looks low, with a tenth of an inch or less forecast for this event,
but probs remain on the high side, with likely PoPs forecast.
Temps will be at or a tad below average for daytime maxes, but remain
above average for nighttime mins--all because of the extensive cloud
cover that continues to be forecast.
(Tuesday - Next Friday)
Good model agreement begins to go away by late Wednesday, with a
pair of dry days expected Tuesday and Wednesday.
GFS is showing a stronger storm system trying to take shape on
Thursday than the EC, but this system at first glance looks to be
moisture starved and have kept PoPs on the dry side for now.
Consensus then re-achieved for Friday with building heights and
With cold air forecast to continue to be locked up well north, temps
will begin this period around average but trend warmer by the end of
the week with the building heights aloft and southerly flow at the
.AVIATION: (For the 00z TAFs through 00z Saturday Evening)
Issued at 609 PM CST Fri Nov 27 2015
IFR ceilings will continue to prevail through the night and into
Saturday morning. Expecting slow improvement from north to south
on Saturday...tho IFR will probably continue to prevail across
most of southeast Missouri and southern Illinois through the end
of the day. Rain will slowly taper off to a few showers or patchy
drizzle from north to south as well...but will likely hang around
most of the day across southeast Missouri and southwest Illinois.
North-northeast flow will prevail across the area through 00Z
Specifics for KSTL:
IFR ceilings are likely to prevail at Lambert at least through the
night and and Saturday morning. There will likely be occasional
breaks in the IFR, but I think those breaks will be few and far
between. Guidance does indicate that ceilings will rise above
1000 FT Saturday afternoon and the rain should come to an end
during the late morning or early afternoon as well. Expect MVFR
ceilings with heights below 2000 FT to prevail during the
afternoon and into the Saturday evening.
MO...Flood Watch through Saturday morning FOR Crawford MO-Franklin MO-
Iron MO-Jefferson MO-Madison MO-Reynolds MO-St. Charles MO-
St. Francois MO-St. Louis City MO-St. Louis MO-Ste.
Genevieve MO-Washington MO.
IL...Flood Watch through Saturday morning FOR Clinton IL-Madison IL-
Monroe IL-Randolph IL-St. Clair IL-Washington IL.