Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 072310

Area Forecast Discussion
National Weather Service Topeka KS
510 PM CST Thu Dec 7 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday)
Issued at 312 PM CST Thu Dec 7 2017

Longwave upper trough was from the Great Lakes into the southern
Rockies with surface high pressure centered over western Oklahoma
early this afternoon. A very cool (and dry) airmass in place has
kept temperatures from rising much past the upper 20s for most of
the area despite plenty of insolation. Observations and satellite
imagery showing higher cloud spilling south over the western Conus
ridge into the northern Plains with surface obs showing a higher
theta-e airmass to the northwest.

Evening into Friday forecast challenges are temperatures and small
potential for very light precipitation. Dry air and clear skies
should allow for a fast fall in temperatures, but northwest winds
off the surface bring in a warmer and more humid airmass, with the
stronger winds aloft and increasing clouds likely keeping overnight
temperatures fairly steady. Models are fairly similar in lower cloud
working through the area late tonight into Friday morning though
near-surface parcels remain rather dry. Cloud depths do get into
the -10 to -14C range, though ascent and depth of moisture is
rather limited. Will go ahead with a mention of flurries but not
expecting any thing heavy or persistent enough for accumulations.
Overnight warm air advection over the cold boundary layer should
allow for highs in the low to mid 40s.

.LONG TERM...(Friday night through Thursday)
Issued at 312 PM CST Thu Dec 7 2017

A stronger shortwave rotates south through the longwave into the
Ohio Valley Friday night into Saturday, with a colder airmass
following. Most of this cold air stays to the east, but models do
vary somewhat with how much of this cold air reaches eastern
Kansas. Will have northeastern areas a bit cooler than Friday at
this time.

Upper flow de-amplifies somewhat for Sunday with warmer air
pushing east off the High Plains. Have continued to trend warmer
Sunday with west winds allow for rather low RH values. Cold front
with the next wave reinforcing the upper flow comes through around
Monday though model differences become notable in timing and thus
winds and temperatures, though west to northwest winds will
keep dewpoints low. There is some potential for fire weather
concerns this day as well.

Northwest flow aloft persists into late next week with
deep moisture continuing to be lacking for any reasonable chance for
measurable precip. Will keep temperatures near to slightly above


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 509 PM CST Thu Dec 7 2017

VFR conditions are expected through the period. Some clouds at
roughly 5kft will pass over terminals in the morning and early
afternoon, but no restrictions are anticipated. There is a small
chance for some flurries overnight mainly at MHK, but chances are
low enough to keep this mention out the TAF. LLWS also continues
to look marginal and is not included in this TAF issuance.




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