Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 080532
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1132 PM CST Sat Dec 7 2013
.SHORT TERM...(This Evening through Sunday)
Issued at 341 PM CST SAT DEC 7 2013
Weak shortwave over the Rockies will track into the Plains tonight
and Sunday sending a wave of light snow our way late tonight and
Sunday morning. General model trend has been to back off on snow
amounts slightly, with the higher amounts shifting north of the
MO/IA border in closer proximity to the strong upper level jet.
Still, isentropic lift alone should be enough to produce a broad
area of 0.05" to 0.15" QPF amounts, roughly translating to 1 to 2
inches of snow given liquid/snow ratios around 15:1. Higher end of
this range will be across far northern MO. Given slow snowfall
rates, relatively light wind and the powdery nature of the snow,
impacts should be relatively minimal south of the MO/IA border so a
winter weather advisory will not be issued at this time.
Snowfall will taper off through the late morning and afternoon as
drier air builds down from aloft. However, this drier air may
provide an airmass somewhat favorable for patchy freezing drizzle
Sunday afternoon and evening as a weak low-level trough swings
through. Thermal profiles look borderline between drizzle/flurries,
but regardless of precip type any additional amounts Sunday
afternoon and evening should be very light with little to no snow or
.LONG TERM...(Sunday Night through Saturday)
Issued at 341 PM CST SAT DEC 7 2013
Will still be under the influence of the positive tilted upper trough
to start next week before the upper pattern transitions to northwest
flow. 12z GFS/ECMWF are in very good agreement through the entire
Past couple of runs of NAM/GFS have been generating weak and layered
frontogenesis as a strung out vorticity lobe ejects northeast
through KS and MO Monday/Monday night. Juxtaposition of near
saturated layer with the frontogenesis is mainly south of the CWA
but GFS is far enough north to warrant slight chance PoPs across the
extreme southern counties Monday night. Any snow still on the ground
Monday will limit any warming despite sunshine.
Expect some moderation in temperatures on Tuesday as moderate warm
air advection tries to scour out at least some of the arctic air.
Even with this warming temperatures will only reach the 30s or at
least 10 degrees below average. Another surge of colder air will
force its way into the region on Wednesday with the passage of a dry
cold front. High pressure which follows will quickly move out and
southerly return flow should allow temperatures to climb back into
the 30s for the rest of the forecast period.
.AVIATION...(For the 06Z TAFS through 06Z Sunday Night)
Issued at 1128 PM CST SAT DEC 7 2013
Snow continues to expand over central Kansas late this evening. The
latest guidance continues to indicate rapid saturation as we approach
3am, with increasing snow rates by 12z. The good news is that snow
will only last through the morning, and should remain light in nature
but visibilities dropping to 1-2 miles will be possible along with IFR
We`ll see diminishing snowfall after 10am with the potential for a
couple hours of light freezing drizzle at all TAF sites. Soundings
suggest dry conditions in the afternoon, before freezing drizzle
probabilities increase again in the evening. Very low confidence on
chances of FZDL in the evening and will not include at this time.
Ceilings should remain MVFR after the snow finishes.
Snow totals should average around an inch for the KC terminals with
slightly higher amounts in STJ.