Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 270925
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
325 AM CST Tue Jan 27 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 325 AM CST Tue Jan 27 2015

Satellite data at 08z showed the backedge of an area of clouds near
the MS river breaking apart, but a new batch of clouds was already
oozing southward from northeast IL and southeast IA.  To the west,
skies were clear, with cloudy skies covering much of our region east
of the MS river.  Temps were mild for late at night in late January,
with readings in the 30s.  Otherwise, NW flow prevailed aloft with
NW winds also at the surface, thanks to an area of weak low pressure
to the east and a weak ridge of high pressure to the west.

No upper level disturbances or fronts are expected today with weak
high pressure insteady building into the area.  With a dry
atmospheric column, the result will be dry wx.

The main forecast problem will be clouds and their impact on temps.
Flow at cloud level is expected to be out of the north this morning
with a transition to negligible wind flow in the afternoon as the
ridge builds in.  Even though the backedge of the clouds near the MS
river has collapsed, a new batch of clouds further to the north is
expected to drop south into our region and create a new backedge to
the cloud shield near the MS river again.  The afternoon should
feature some retreat of the cloud edge back to the east again as
weak subsidence from the high pressure ridge moves in.  Some
question on whether or not the surviving clouds to the east will get
moved back to the west if the ridge catches up and passes it too
fast tonight.

Max temps were forecast strongly favoring the lower MET MOS numbers
in much of southwest IL, with a MOS blend for the MS river region
and max temps at or slightly above the higher MAV MOS for central
MO.

TES

.LONG TERM:  (Tonight through Monday)
Issued at 325 AM CST Tue Jan 27 2015

(Tonight through Thursday)

Main focus thru the period is temps with little in the way of
precip.

Mdls are generally in good agreement thru the period. However, some
differences emerge late in the period regarding the speed and depth
of the approaching trof. Mdls have come into better agreement with
thermal profiles. Have trended slightly cooler tonight with clouds
expected to clear out of the region for at least a portion of the
night. No changes to temps for Wed. While latest mdl guidance
suggests much of the region is not expected to mix above 950 mb,
mdls have struggled to warm fast enuf with these types of systems
lately. Heights lower quickly as the sfc ridge settles over the area
and have trended cooler late in the period.

Only precip expected is light precip associated with the system late
Wed night into Thurs morning. With such a strong s/w associated with
this system, enuf cold air my push in behind the system that the
precip may be SN. However, will keep p-types as RA for now until
mdls come into better agreement with precip placement and thermal
profiles with the precip.

(Friday through Monday)

As the sfc ridge remains in control thru the remainder of the week,
temps remain cooler ahead of the next approaching system. Focus
quickly turns to this system as mdl solns have finally come into
better agreement and are finally more consistent from cycle to
cycle. The leading s/w ejects into the srn Plains and spread precip
across the region on Sat as the sfc low develops ahead of the main
trof. Mdl solns are currently in very good agreement, tho some
differences in timing continue. Current track of this system shud
bring SN to at least portions of the CWA while. This system will
likely shift as it approaches and will be one to monitor. Much
colder air will move into the region behind this system as the
arctic sfc ridge builds into the area.

Tilly

&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1128 PM CST Mon Jan 26 2015

Surface low continues to make slow progress southeast away from
forecast area. Winds behind system are from the northwest to
north. As for clouds, back edge remains along and east of
Mississippi River. Currently VFR cigs, but models and some sites
upstream are MVFR. For now have MVFR cigs moving into KUIN by 07z
and into metro area by 10z. Then as surface ridge builds in clouds
to scatter out from north to south. KUIN to scatter out by 15z
Tuesday while metro area will be around 01z Wednesday. In the
meantime, KCOU to remain clear with just a few sc through the
forecast period. By late afternoon/early evening, winds to veer
to the east.

Specifics for KSTL:
Surface low continues to make slow progress southeast away from
forecast area. Winds behind system are from the northwest to
north. As for clouds, back edge remains along and east of
Mississippi River. Currently VFR cigs, but models and some sites
upstream are MVFR. For now have MVFR cigs moving into metro area
by 10z. Then as surface ridge builds in clouds to scatter out around
01z Wednesday and winds veer to the east.

Byrd

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     42  28  54  39 /   0   0   5  10
Quincy          39  27  51  36 /   0   0   5  30
Columbia        47  30  59  38 /   0   0   5  10
Jefferson City  48  29  59  39 /   0   0   5   5
Salem           37  24  46  36 /   0   0   5  20
Farmington      44  26  51  39 /   0   0   5  10

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX





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