Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 290900
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
300 AM CST Sat Nov 29 2014
Issued at 300 AM CST SAT NOV 29 2014
Above normal temperatures are expected to continue today, as a
midlevel ridge axis shifts over the forecast area and 925 hPa
temperatures increase to around +16 C throughout the CWA. Highs
today should reach the 60s in most locations, and slightly lighter
winds will also help temperatures feel warmer this afternoon.
The main focus in the short term will be the arrival of a strong
cold front on Sunday. The front has already begun plunging southeast
across Montana, and will arrive in our area on Sunday. Timing of the
frontal passage is just a touch slower than yesterday, which creates
a slightly higher potential of light rain showers in southeastern
portions of the CWA along/ahead of the front Sunday afternoon. Upper
40s to lower 50s dewpoints are expected to surge into the area ahead
of the front, and may combine with lift along the cold front to
support light precipitation in central MO where moisture is highest.
NAM and some SREF soundings indicate a lingering saturated layer
around ~900 hPa just behind the front which could support a brief
window of freezing drizzle or perhaps some very light sleet as a
result of quickly falling boundary layer temperatures, but have some
concerns that the saturated layer may be a bit overdone and may be
too shallow to support precipitation just behind the front, so have
not included any wintry precipitation in the forecast at this time.
Should more of the soundings become supportive, the most likely
locations for freezing drizzle transitioning to light sleet would be
in northwest MO on Sunday morning, and then in central MO late
Sunday afternoon or evening.
Sharply colder temperatures and brisk northwest winds are expected
immediately following frontal passage, allowing temperatures to tank
into the teens by daybreak Monday. A little recovery in temperatures
is possible Monday afternoon as clouds clear out, but highs are not
expected to surpass the freezing mark in the CWA. However, the cold
front`s parent trough will continue to sweep off to the east, and
will allow temperatures to moderate back into the 40s or low 50s for
Tuesday through the rest of the forecast period.
The next chance of precipitation is still expected Wednesday night
and Thursday as a shortwave trough drifts eastward across the
region. Soundings look mainly supportive of liquid precipitation,
but have included a chance of rain or snow to account for some
uncertainty in temperature profiles. In any case, the zonal flow
aloft and seasonable daytime temperatures should not support any
snow accumulations during this period.
.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
Issued at 1140 PM CST FRI NOV 28 2014
Feeling is that fog development will not be prevailing through the
entire early morning period, as dry air above the surface and mixed
out boundary layer should provide enough mitigating ingredients to
prevent the widespread, prevailing fog. That being said, moisture
will make its way into the area and temperature/dew point depression
will be rather low, so will go with a mention of MVFR fog, with
perhaps some brief IFR periods. HRRR guidance through the night
indicates some patchy IFR VIS near the terminals, so will hold on to
the mention of IFR. Otherwise VFR conditions prevail.