Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 062341
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
541 PM CST Tue Dec 6 2016
Issued at 354 PM CST TUE DEC 6 2016
Tonight - Wednesday...
A large area of cold high pressure over the Central Plains will
migrate eastward overnight but lose its identity as frontogenesis
within the 800-700mb layer begins to unfold across KS and MO. This
will be in response to an advancing stream of energy aloft in the
form of an elongated region of vorticity streaking eastward through
the Central Rockies. While moderate uvv will be generated within the
favorable dendritic snow growth region the top-down saturation will
have to overcome a very dry sub-cloud region. This is best scene on
vertical cross sections. Moderately high liquid snow ratios around
17:1 will help compensate for this initially dry airmass until it
saturates. For this reason have held on to the 1/2" to 1" snow forecast
for west central MO south of the MO River. Not thinking much more
than some flurries north of a MCI to Moberly line and dry across far
Think the light snow could start a bit earlier over east central KS
and extreme west central MO as soon as 15z but should better
accumulate in the 17z-20z time frame. The snow should be exiting
the far southern counties by around 00z.
Will hold off on headlines for now. Should later model runs indicate
more snow and/or arriving closer to the morning rush hour later
shifts will need to consider whether to issue a Winter Weather
Advisory. Concern being the first snow of the season for west central
MO and motorists not acclimated to winter time driving conditions.
Wednesday night - Friday...
A reinforcing surge of very cold air will follow in the wake of
Wednesday`s system as a 1048mb area of high pressure wedges
southward through the plains Thursday through Friday. Am expecting
temperatures 15-20F degrees below average with very dry conditions.
Saturday - Tuesday...
Strong warm air advection briefly returns for the start of the
weekend ahead of our next system. Latest ECMWF is coming more in
line with the GFS as the latter tracks a fast moving shortwave
southeast from the Northern Rockies through the Northern/Central
Plains and Mid MO Valley. Should see a bit more precipitation with
this system as southerly boundary layer winds draw in moisture from
the south while increasing warm air advection provides additional
ascent to wring out the precipitation. Main questions are
precipitation type and timing. Will run with a mixed case of
rain/snow for now and fine tune as we get closer in time.
.Aviation...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 533 PM CST TUE DEC 6 2016
Fair conditions are expected for the next several hours, including
the overnight period, as clouds eventually work their way into the
area by early Wed morning. Light snow will begin at the terminals,
except perhaps KSTJ, which might be too far north to see more than
just a few flurries, around mid morning and could last through the
late afternoon to early evening. Not expecting much accumulation, but
visibility could drop for brief periods into MVFR range. CIGs at the
moment don`t appear to dip below VFR thresholds, but there could be
some MVFR CIGs for brief periods. Light snow moves out of the area by
late Wed evening.