Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 010430
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1030 PM CST Sat Jan 31 2015
Issued at 1002 PM CST SAT JAN 31 2015
Snow has been falling and accumulating this evening across
northern Missouri with observations of 2 to 3 inches being
reported from Maysville to Kirksville. In St. Joseph and locations
north of MCI, accumulations of up to about an inch of snow has
been reported so far with the snow continuing to fall there. The
rain/snow mix line has set up across the Kansas City area,
reaching as far south as Pleasant Hill as surface temperatures
hover right around the freezing mark. Given the latest trends and
observations, have adjusted snow amounts slightly upwards this
evening along the southern extent of where the rain/snow line has
set up, leading to adding in a few counties to the previously
posted advisory, which now includes St. Joseph.
Latest NAMBufr soundings still show a low-level warm nose digging
in as far north as MCI by around dawn Sunday. However, the models
seem to be struggling to get a good grasp on the evolving system
so have not made any major changes to the forecast other than the
aforementioned changes. Will continue to monitor and update as necessary.
.SHORT TERM...(This Evening through Sunday Night)
Issued at 321 PM CST SAT JAN 31 2015
Forecast still on track for significant snow accumulations across
far northern Missouri tonight into Sunday. Have expanded the winter
storm warning into Nodaway and Gentry counties, and expanded the
winter weather advisory into Doniphan county KS.
For this afternoon and evening, precipitation type will be complex
with surface temperatures hovering in the 30s and the observed
freezing level varying between 500 and 1000 ft AGL near KEAX.
Slightly cooler surface temperatures across far northwest MO have
supported a mix with or transition to snow this afternoon, and do
not expect profiles to change significantly during the remainder of
the afternoon or the evening. However, an advancing warm nose between
1-2 km is evident in dual-pol over Topeka, and will help keep p-type
all rain or a rain/brief light sleet mix along and southeast of a
line St. Joseph to Kirksville this evening and into the early
overnight hours. Therefore, the main change to the forecast was to
bump up snowfall totals in northwest MO where the duration of
snowfall will be longer than expected, and little to no change was
necessary elsewhere where rain or a rain/ snow mix was expected
during the evening and early overnight hours.
Still some uncertainty in exactly where the snowfall gradient will
set up and how tight it will be, since areas that stay rain or a
rain/snow mix for the majority of the night will miss out on the
heaviest QPF, and the exact location of that snow vs. rain/snow line
is difficult to pinpoint. In general, 4 to perhaps 8 inches of snow
is expected by mid-morning Sunday across far northern Missouri, and
little to no snow is expected along and south of the MO river.
However, precipitation is still expected to switch to all snow
throughout the CWA between 09z and 15z Sunday as the system begins
to exit the region, so expect at least some light snowfall in most
locations. Model trends this morning deepened/amplified the system
and increased the amount of wrap-around moisture, so have just
slightly raised snow totals for this wrap-around period during the
late morning and afternoon hours -- additional amounts may be up to
an inch from far northeast KS through the KC metro to Macon, with
lesser amounts to the SW and slightly higher amounts to the NE.
Much colder temperatures and strong north northwest winds
will push into the CWA on Sunday, thus have added in a period of
blowing snow for areas that are expected to receive more than a few
inches of snow and wind speeds in excess of 20 mph.
.LONG TERM...(Monday through Saturday)
Issued at 321 PM CST SAT JAN 31 2015
Broad northwest upper flow continues for much of next week. Will see
a brief warming trend into the 40s on Tuesday, maybe even lower 50s
south of KC, before another cold front moves into the area Tuesday
night. GFS still wants to bring a weak clipper and brief shot of
minor snow accumulations into the area Weds and Weds night behind
the front, but the drier ECMWF is the more preferred solution at
this point given the magnitude of the surface high across the
Plains. Otherwise dry and seasonably cold conditions will prevail
for the remainder of the week.
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 531 PM CST SAT JAN 31 2015
Precipitation continues to fall at all four terminals this evening
with some snow beginning to be reportedly mixing in around the STJ
area. Given the falling surface temperatures at MCI and STJ, along
with the latest incoming model data and observations, have started
the rain/snow mix mention in this TAF issuance from the start of
the period through the overnight hours. A low-level warm nose
should be pushing northward across MKC and IXD and most likely MCI
as well, not allowing for much snow to fall at these three
terminals overnight. However, the question is how far north this
warmer air will reach and at this time, STJ looks to be switching
over to all snow after midnight. With these borderline
temperatures at the surface and aloft forcing complications to the
forecast, will continue to monitor closely and amend as necessary.
Behind the outgoing low pressure system responsible for this
weather, much colder air will rush in on Sunday with gusty NW
winds, potentially causing some snow to blow around but will hold
off on mentioning blowing snow in the TAFs for this issuance.
KS...WINTER WEATHER ADVISORY until 9 PM CST Sunday FOR KSZ025-102.
MO...WINTER WEATHER ADVISORY until 9 PM CST Sunday FOR MOZ001-011>015-
WINTER STORM WARNING until 9 PM CST Sunday FOR MOZ002>008-016-