Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLSX 260911
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
311 AM CST Wed Nov 26 2014

.SHORT TERM: (Today and Tonight)
Issued at 310 AM CST Wed Nov 26 2014

Clipper system over Nebraska/Iowa border will continue to drop
southeast today, bringing the area some light snow/rain. Short
range guidance including the HRRR, RAP, NAM and GFS are in good
agreement that light precip will overspread the area through the
morning hours, reaching the Mississippi River between 16-18Z.
Primary lifting mechanisms continue to look like low level
moisture convergence, frontogenesis, and broad scale lift
generated by the parent shortwave. Precipitation will initially
have to fight some pretty dry low level air as it moves into the
area as dewpoints are in the upper teens and low 20s. Evaporative
cooling as well as favorable vertical profiles would indicate that
initially most if not all of the precipitation will fall as
snow...especially over central and northeast Missouri. Insolation
through later in the morning and afternoon, combined with
southerly flow along and east of the Mississippi river (which will
be east of the low track) will probably cause the snow to mix with
rain across a good portion of the area for at least part of the
afternoon. Between the mix, above freezing temperatures, and warm
ground conditions (2 inch soil temperatures range from 32 to 40
degrees across the area), expect only minor accumulations of and
inch or less today. The tail end of the clipper will continue to
affect the area this evening with additional minor accumulations
possible...generally along and east of the Mississippi in
southeast Missouri and southwest Illinois. The lingering
precipitation should end before 06Z this evening.

Carney

.LONG TERM:  (Wednesday through Next Tuesday)
Issued at 348 PM CST Tue Nov 25 2014

(Thursday and Friday)

Upper pattern will gradually flatten out and temperatures will begin
to warm back up during this period as the models are in good
agreement that surface high will pass through the area on Thursday
night.  By Friday, south to southwesterly winds will advect warmer
air into the area which bring temperatures back to normal.

(Saturday through next Tuesday)

GFS and ECMWF still agree that upper pattern will be zonal over the
weekend with a cold front moving south across the CWA on Saturday
night and Sunday. Still looks like chances for precipitation will
increase along the the front by late in the weekend as both models
show a shortwave wave trough moving through the area on Sunday
night. Then model solutions become more divergent by early next
week as the GFS is slightly more southwesterly aloft with an
approaching storm system whereas the ECMWF stays more zonal.
Temperatures ahead of the front on Saturday still look like they
will be about 10 degree above normal with 850mb temps around +10C.
Then temperatures will be closer to normal behind the front as
coldest air will not be able to come down because of the zonal
flow.

Britt

&&

.AVIATION:  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1125 PM CST Tue Nov 25 2014

VFR flight conditions and dry weather will persist overnight with
clouds increasing and thickening across the region. A northwest
flow storm system is still on track to impact the area on
Wednesday with precipitation spreading in KCOU around 14z and KUIN
and the St. Louis area terminals between 16-17z. Temperature
structure at the onset of the precipitation suggests all snow at
KCOU and KUIN with predominately MVFR flight conditions, while
there is more uncertainty in the ptype at and KSTL/KSUS/KCPS with
snow at the onset and then mixing with rain. Flight conditions
could lower into the IFR category during the precipitation.
Precipitation should taper to very light snow/flurries by mid-
afternoon to evening with a northwest wind shift as the system
passes.

Specifics for KSTL:

VFR flight conditions and dry weather will persist overnight through
mid morning on Wednesday with clouds increasing and thickening. A
northwest flow storm system will impact the area on Wednesday with
precipitation spreading into KSTL between 16-17z. There is some
uncertainty in the ptype, however the current thinking is that we
will see snow at the onset and then mixing with rain in the afternoon.
Flight conditions could lower into the IFR category during the
precipitation. Precipitation should taper to very light snow/flurries
by early evening with a northwest wind shift as the system passes.

Glass

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     39  28  34  27 /  70  60   0   0
Quincy          38  20  27  22 /  70  20   0   0
Columbia        39  23  34  27 /  70  20   0   0
Jefferson City  40  25  35  27 /  70  20   0   0
Salem           40  29  33  24 /  70  60   0   0
Farmington      40  28  36  26 /  70  60   0   0

&&

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

$$

WFO LSX





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.