Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 011018
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
418 AM CST Sat Mar 1 2014
Issued at 417 AM CST SAT MAR 1 2014
Surface cold front has traversed through the area, with the area of
high pressure off to the north. This area of SFC high pressure is
associated with a frigid Canadian air mass, which will spread
rapidly into NW and WC Missouri through the day on Saturday. That
known, we can expect a general decline in temperatures through the
next several days. The cold air in place will set the stage for
a potentially significant winter storm, expected to commence late
day on Saturday. Good isentropic ascent through the early part
of the day, leading to perhaps an early onset of some light
freezing drizzle or perhaps some very light snow flurries
in the morning hours before the main event kicks in Saturday
Models are still a bit inconsistent regarding the exact placement of
the heaviest snow for Saturday night through Sunday. What we are
fairly certain of at this point is that the air at the surface and
in the immediate lowest levels near the surface will be extremely
cold. Given this low level temperature profile it`s fairly certain
that any precipitation that falls over the next 36 to 48 hours will
be in the form of either sleet or snow. All models are also in good
agreement regarding a weak warm nose in the 850 to 700 mb layer,
which will be strong enough to completely melt any snow which forms
in and above the preferred dendritic growth layer. As the
precipitation falls through the warm layer and melts it will reenter
the aforementioned extremely cold low level layer and be able to
refreeze back into sleet. Given how weak the warm nose aloft is as
well as how incredibly cold the low levels are there is little
concern for any freezing rain, except for perhaps the most southerly
row of counties in the CWA.
00z NAM seemed a little weak with the strength and northern extent
of the warm nose aloft. 00z upper air hand analysis indicated the 0C
850 mb isotherm about 30 to 60 km further north than the 00z NAM
initialized, with subsequent isotherms south of the 0C isotherm also
being located a little further south on the model than reality
indicated. The 700 mb isotherms in the model initialization seemed
pretty close to reality. Given perhaps the model underestimation of
the strength and northern extent of the warmer air aloft, opted to
forecast the snow/sleet mix line a little further north (KSTJ to
KIRK line) than the previous forecast. Also opted to hold on to the
sleet/snow mix a little longer in the southern zones, mainly along
and south of Interstate 70. The duration of sleet will definitely
cut into snow amounts the longer it persists. Conversely the faster
the warm air can retreat ahead of the advancing 850 cold front the
faster the transition from sleet to snow can occur.
Regarding the lifting mechanism for this event, it appears to be
largely driven by a combination of isentropic lift, mainly along the
275 to 295 K theta E surface, and very strong and deep
frontogenetical lift. The best frontogenetical lift will encompass
almost all of the area, for a long duration between late Saturday
evening through late Sunday afternoon. The combination of the
isentropic ascent and frontogenetical ascent will contribute to
omega values ranging between 10 and 20 -ubars/sec through Saturday
night into Sunday. While there does not appear to be much signal in
the way of convective development, cross section analysis indicates
some decreasing Theta E with height during the peak of the event,
manifesting in some negative EPV. The result will be at least some
periods of localized efficient snow production, and perhaps some
spotty and isolated convective development. While it does not appear
likely that thunderstorms will form, cannot rule out a few claps of
thunder within the more convective elements.
Light sleet and snow is expected to last over a long duration,
starting late Saturday evening, lasting through late Sunday night.
The heavier snow bands will be scattered across the area, producing
much briefer periods of moderate to heavy sleet/snow. The result of
nearly a day of steady sleet and snow is widespread 5 to 7 inch snow
amounts, with some areas reaching up to 9 inches. The exact areas
receiving the higher snow amounts will be largely dependent on where
the heavier snow bands set up, as well as how long the sleet falls.
As far as sleet totals go, expect areas along and south of
Interstate 70 to receive up to an inch of sleet, with perhaps the
far southern counties of the CWA reaching up to 2 inches of sleet.
After the sleet transitions to snow, perhaps an additional 3 to 7
inches of snow could fall. Expect snow to end across far norther
Missouri by Sunday afternoon, then across west central Missouri by
Sunday evening, then in central Missouri by early Monday morning.
With between 5 and 9 inches of sleet/snow expected, have issued a
winter storm warning for those areas expected to receive the highest
totals. Kept the winter weather advisory for the far northern
counties of MO, along the IA border for up to 4 to 6 inches of snow.
Extremely cold temperatures will already be in place while the storm
is ongoing, however expect that incredibly cold air to remain in
place, and even to an extent be reinforced as the early part of next
week begins. Expect highs on Sunday to remain in the single digits,
with overnight lows on Monday morning to drop between -2 and -10
degrees across the entire area. Light north winds between 10 and 15
mph will cause wind chill values to drop to -15 to -20 degrees
across the entire area, with perhaps -25 to -30 degree wind chills
along the far northern border of MO/IA.
Tuesday through next Saturday...
A general, and relatively dramatic warming trend is in store for the
remainder of the week. By Tuesday the surface high will move east of
the forecast area, allowing for some light southerly return flow to
bring in some warmer air. By mid week, expect temperatures to get
back into the middle to upper 30s, then by Friday we can expect
widespread upper 40s to middle 50s across the entire area. Another
cold front sweeps through the area by next weekend, which will
subdue the warm up a bit, as temps on Saturday may only reach the
upper 30s to middle 40s.
.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
Issued at 1131 PM CST FRI FEB 28 2014
Lower-end MVFR ceilings are beginning to fill in behind the cold
front, and should spread southeast through the morning hours. The
lowest ceilings may be a bit transient, but generally MVFR ceilings
are expected to fill in by 12z across most of the area.
Snow and sleet are expected to develop on late Saturday afternoon
into the evening hours, and should spread southward through the late
evening and overnight hours. The heaviest precipitation is generally
expected after 03z in far northwest Missouri and after 06z in the KC
metro and points southward. Ceilings should be initially MVFR, but
should gradually lower to IFR overnight.
Issued at 258 PM CST FRI FEB 28 2014
Record-breaking cold temperatures are possible for the start of
March. Listed are the record minimum high temperatures...
*NOTE: The all time record coldest high temperature for Kansas City
in March is 11 degrees, set on March 4th 1978. The current forecast
for Sunday indicates a potential that this all-time record may be
broken and potentially the first time a single digit high
temperature has even been observed in the month of March.
Kansas City St. Joseph
March 1st 19F/1980 19F/2009
March 2nd 14F/1943 14F/1960
March 3rd 17F/1978 17F/1960 and 1978
Listed are the record low temperatures...
Kansas City St. Joseph
March 2nd -7F/1980 -7F/1980
March 3rd -1F/1978 0F/1978
March 4th -10F/1978 -13F/1978
KS...WINTER STORM WARNING from 6 PM this evening to 6 AM CST Monday
WINTER STORM WARNING from 6 PM this evening to Midnight CST
Sunday Night FOR KSZ025-102>105.
MO...WINTER STORM WARNING from 6 PM this evening to 6 AM CST Monday
WINTER STORM WARNING from 6 PM this evening to Midnight CST
Sunday Night FOR MOZ012>017-020>025-028>033-037.
WINTER WEATHER ADVISORY from 6 PM this evening to 6 PM CST
Sunday FOR MOZ001>008-011.