Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 160913

Area Forecast Discussion
National Weather Service Topeka KS
313 AM CST Sat Dec 16 2017

.SHORT TERM...(Today and tonight)
Issued at 301 AM CST Sat Dec 16 2017

An upper level trough moving onshore across the western US will kick
a cutoff upper level low across north central Mexico north-
northeastward across TX and into eastern KS by 12Z SUN. The closed
upper low will become an open upper level trough as it moves
northeast across western TX into west-central OK. The upper trough
will also fill as it lifts northeast across OK into eastern KS

Today will be nice and warm with southerly winds of 10 to 20 MPH and
higher gusts across east central KS. The low-level WAA and boundary
layer mixing to around 915MB should allow highs to reach the upper
50s to around 60 degrees. If the mixing is a bit deeper across east
central KS, then highs could reach the mid 60s.

Tonight, the upper level trough will approach from the southwest and
will spread light rain into the southeast counties after 8Z,
which will shift northward through the early morning hours of
Sunday. Most numerical models show good ascent, ahead of the PV
anomaly, across eastern KS, and there may be enough residual
moisture advection across east central KS for a few tenths of an
inch of rainfall along and southeast of I-35. There may be a few
hundredths of an inch of rainfall across the remainder of east
central and northeast KS during the early morning hours of Sunday.
It looks dry across central and north central KS as the better
ascent and residual moisture return will remain across the eastern
half of the CWA. Temperatures will remain above freezing Tonight,
so there should be no travel problems with only light rain across
the eastern half of the CWA.

.LONG TERM...(Sunday through Friday)
Issued at 301 AM CST Sat Dec 16 2017

Sunday daytime frame will result in at least a small amount of
rainfall for portions of the forecast area.  Best likelihood of
precip will be over east central KS and perhaps up into portions far
northeast KS as the southern open shortwave lifts into the region
from the Baja through the southern Plains region.  Dynamic forcing
with this wave do look fairly impressive at least initially but then
weakens through the day.  A general lack of deeper moisture over the
area will limit precip amounts added onto any previous amounts from
late Saturday/early Sunday morning. Most forecast soundings support
all p-type being liquid.  There is still a hint of a very small
window of some type of freezing drizzle over extreme northern
counties near the KS/NE border, but this is only with the NAM
solution.  Low level lift looks too weak for drizzle at this point,
so the end result may be in the form of low level stratus deck
overspreading the area. Regardless, have only gone with liquid rain
in the forecast as temps should fall on the higher side the
GFS/EC/Canadian solutions where precip does actually have a chance
at making it to the ground.   The wave departs the area into the
afternoon Sunday.  Weak cold front stalls over the area as a more
split flow regime remains in place with northeast KS in the
transition zone.

Into the work week, temps generally remain above normal and dry
conditions persist as the northern stream flow remains north of the
area and the southern stream of energy weakens as a positively
tilted lobe of energy over the Desert Southwest into the central
Rockies dampens out and sends any significant energy south of the
forecast area.

Into the Thursday time frame and late Wednesday, the next potential
weather system will approach the area as flow transitions to zonal
over the central Rockies activating the lee trough and increasing
southerly flow.  As a western Canadian upper trough digs into the
northern CONUS, most solutions show this feature amplifying.
Generally, there is some disagreement, but the EC tends to be the
slower solution with the GFS appearing to develop more CAA behind
the system into Friday which would lead to a very noticeable cool
down with high temps late in the week struggling to reach the lower
to mid 30s.  Precip amounts with this system are hard to know right
now. But, broad large scale ascent does develop ahead of this lobe
of energy and extends into the forecast area.  Right now mentioning
a diurnal transition of p-type from rain/snow to rain then back in
the evening before colder air can support more snow.  Again, amounts
are hard to pin down as this is near the end of the period.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1120 PM CST Fri Dec 15 2017

VFR conditions are expected through the period. Low level wind
shear is forecast to continue through 13Z at the terminals. Winds
will remain near 10 kts from the southwest backing to the south
and decreasing around 00Z Sunday.


Issued at 301 AM CST Sat Dec 16 2017

Today, there will be a very high fire danger across east central KS,
generally along and south of I-70. During the late morning hours and
through the afternoon hours south-southwesterly surface winds will
increase to 10 to 20 MPH with some gusts of 25 to 30 MPH. Deeper
boundary layer mixing will also cause minimum relative humidities to
drop to around 30 percent. The combination of gusty surface winds,
low relative humidity and dry fuels will cause a very high fire
danger to develop from the late morning hours through the afternoon
hours across much of east central KS.




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