Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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FXUS63 KEAX 240535

1135 PM CST Sun Nov 23 2014

Issued at 944 PM CST SUN NOV 23 2014

Back edge of rain shield has accelerated eastward over the past hour
in line with the 00Z NAM and latest HRRR output. Will end the rain
faster from west to east. In addition, will limit any mention of snow
to the n central and northeastern counties where temperatures in the
upper 30s are advecting southeast out of central/south central IA.
Will leave in mention of minor snow accumulations for these areas.


.SHORT TERM...(This Evening through Wednesday Afternoon)
Issued at 307 PM CST SUN NOV 23 2014

Rain showers will continue to fill in this afternoon and evening,
impacting the forecast area along and ahead of a southeastward-
moving cold front. Rainfall totals for this evening should be mainly
less than a half of an inch in most locations.

Main focus in the short term will be the potential for rain changing
over to snow overnight as a cold front pushes through the area and a
band of post-frontal precipitation pushes eastward over the falling
temperatures. Soundings begin to support snow in our far northwest
around 03z to 06z, but initially the surface warm layer will be too
thick for snow to make it to the surface. As the near-surface layer
cools, rain will begin to mix with and then eventually change over
to snow mainly between 06z and 12z tonight. Precipitation amounts
during this time are anywhere from trace to 0.20", but with the warm
temperatures ahead of the front and warm/wet surface conditions, it
will take a pretty aggressive snow rate to accumulate any snow. Have
painted an area of 0.5-0.75" snow across northeast MO where the
coldest post-frontal temperatures and highest snowfall rates are
expected as the band moves through, then have tapered snow amounts
to zero elsewhere. The post-frontal band is expected to exit the
region by 12z, then perhaps just a dusting of light snow could wrap
back into northeast MO during the late morning/afternoon hours.

Lows tonight should not drop far below freezing with the bulk of the
cold air waiting until after 12z to push into the region, but little
to no temperature rise is expected across northern MO on Monday as
cold air continues to filter in. Elsewhere, highs may recover a bit
into the lower 40s by mid afternoon.

The next system will be a quick clipper that dives from Alberta into
northeast Missouri on Tuesday night into Wednesday morning. Light
snow is possible across the northeastern half of the CWA with this
feature, but low moisture availability will limit potential snow
accumulations to just a few tenths of an inch.

.LONG TERM...(Wednesday Evening through Sunday)
Issued at 307 PM CST SUN NOV 23 2014

Much of the long-term (particularly into next weekend) is plagued
spatially and temporally with model discrepancies with the GFS,
ECMWF, and the GEM struggling to agree, although the 12Z ECMWF has
come into a bit of a better agreement with the 12Z GFS as compared
to the 00Z ECMWF run. Low amplitude ridging at the 500mb level
appears to dominate much of the center of the country behind an
exiting sharp trough, according to the latest GFS and ECMWF runs
whereas the GEM brings a shortwave trough racing down from Canada
into MT/ND before phasing into a larger wave dominating over
Ontario. Regardless of which solution ends up playing out, they do
all generally agree on zonal flow aloft with ripples riding through
behind the NW flow on the backside of the aforementioned exiting

Between the GFS and the ECMWF, the GFS appears to be much more
progressive aloft and at the surface as compared to the ECMWF. High
pressure sinking south behind an exiting surface low takes hold of
the forecast area on Thursday, then quickly scoots across the Ohio
Valley, leaving the door open for a frontal boundary to sweep
through behind the high, according to the GFS. The ECMWF solution is
messier and slower and diverges significantly from the GFS at the
surface by next weekend. Taking all of this into account, have kept
the forecast area dry for this forecast period given a lack of a
clear precip-generating signal, except for the GFS that brings the
front through on Saturday, but again is low confidence given the
vastly different solutions.

With respect to temperatures, they look to remain on the cooler side
of normal through the end of the week, but again, the forecast for
the temps from late Friday onward has low confidence given the
discussed model discrepancies.


.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1133 PM CST SUN NOV 23 2014

Back edge of rain shield will exit northeast and central MO by pre-
dawn hours of Monday morning. Could see a rain/snow mix or brief
change over to snow over far northeast MO but little if any accumulation.

Otherwise, main concern will be from gusty northwesterly winds. Tight
pressure gradient will gradually weaken from west to east on Monday
but boundary layer mixing could see winds ramp up higher during the
late morning and early afternoon hours. VFR cigs at all four
terminals but MVFR cigs possible Monday across northern MO. Also
can`t rule out widely scattered flurries over northern MO. Will see
winds diminish from west to east early Monday evening with clearing
from west to east.




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