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

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070
FXUS63 KEAX 022326
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
526 PM CST Fri Dec 2 2016

.Discussion...
Issued at 328 PM CST FRI DEC 2 2016

Focus on forecast remains with two separate chances for
precipitation, followed by well below normal temperatures late next
week. For tonight, warm air advection will result in increasing
mid/upper level cloudiness to overspread the forecast area in
advance of an approaching upper trough. Temperatures will be several
degrees warmer than last night, with minimum readings in the upper
20s to middle 30s.

The southern stream portion of the trough will evolve into a cut-off
low, while several lead shortwave troughs will kick out in advance
of the deamplifying western US trough. The strongest of these waves
will approach the area Saturday night into Sunday morning, likewise
giving the CWA the highest probability of precipitation Sat night.
Based on forecast soundings across eastern Kansas into Missouri, the
thermal profile supports the large majority of this precipitation
will be in the form of rain, with a warm layer in the lowest 2-3kft,
and wet-bulb temperatures in the mid-30s. Any brief period of
precipitation with high enough rates that can retain snow to the
surface will fight surface temperatures in the middle 30s with
relatively warm ground. Therefore, may see a brief window of a rain-
snow mix across far northern Missouri -closest to the Iowa border-,
with any accumulations expected as a dusting on grassy/elevated
surfaces. Precip will quickly exit the area by late morning Sunday,
with clouds clearing shortly thereafter. With little cold air
associated with this system, temperatures will remain rather mild
behind the departing shortwave trough, with highs on Sunday in the
middle 40s to lower 50s.

Models are fairly consistent early next week before differences
result in notable implications for the forecast area. The area will
find itself under a weak ridge in advance of the next large western
trough on Monday, while the aforementioned cutoff low opens and
ejects into the TN Valley on Tuesday. Additionally, a cold front
moves through the CWA on Tuesday, filtering in the beginnings of a
much colder period. This is where several models diverge in handling
the next piece of energy upstream associated with the large upper
trough. The Euro has been consistent in evolving a stout shortwave
trough on the nose of a 120kt upper jet, with notable H85
frontogenesis laid across the area. This upper ascent likewise
produces a swath of precipitation across an already cold airmass
with a thermal profile supportive of snow. In comparison, the GFS
has the nose of this jet 24 hours faster, is slightly less
amplified, does not have a notable thermal boundary nearby, and
likewise fails to generate any QPF. The Canadian is closer to the
Euro, but not as pronounced. The takeaway is there is high
uncertainty with this mid-week system, so while there is some chance
for accumulating snowfall, confidence this far out remains
realistically low. What all models do show is a much colder airmass
to infiltrate into the CWA by mid/late week. Highs in the 20s and
lows in the teens seem reasonable, esp with H85 temps on the order
of -14 to -18C.

&&

.Aviation...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 524 PM CST FRI DEC 2 2016

VFR conditions are expected to prevail throughout the forecast
period. A shortwave trough will approach the area tomorrow afternoon
and ceilings will gradually drop from the southwest to northeast
throughout the day. Ceiling should be around 5000 ft by 00Z. In
addition, surface winds will gradually shift from the northeast to
the southeast but they will remain light. Finally, rain is expected
to move into the area tomorrow evening and while there is a slight
chance for light rain to arrive shortly before 00Z, the best chance
for light rain is after 00Z.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

$$

Discussion...Blair
Aviation...CDB/Grana



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