Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 190949

Area Forecast Discussion
National Weather Service Topeka KS
349 AM CST Sun Feb 19 2017

.SHORT TERM...(Today and tonight)
Issued at 349 AM CST Sun Feb 19 2017

Southerly low level flow bringing increased moisture into the area
overnight. Enough clearing and weaker winds above the boundary layer
in the southeast to allow some fog to form. Calls to law enforcement
in this area reveal fog is patchy and some variation of observation
visibilities supports this. Will watch trends but at this time will
hold off on Dense Fog Advisory. High cloud becoming more persist
into western and central Kansas ahead of southern stream upper low.

High cloud should continue on east this morning with low levels
continuing to saturate as well. With southerly flow also picking up,
this makes for a tough high temperature forecast. Models have been
consistently too cool in recent days, but even the RAP is keeping
diurnal rises in check in this more moist regime. Have stayed closer
to it for highs. Expect morning fog to slowly dissipate with the
stronger winds developing over the boundary layer but will keep some
mention into the late morning. Precip chances increase this evening
as the upper low weakens as it enters the Southern Plains. Models
continue to have a decent spread in where best forcing for ascent
will be as a northern branch wave enters the Northern Plains nearly
coincident with the southern wave. PW values that were already 50%
above normal Saturday evening nearly triple by 12Z Monday per every
GEFS ensemble member and will be near record high values. Expect at
least scattered showers and a few thunderstorms for eastern areas by
late in the night despite weak forcing but any significant amounts
look unlikely.

.LONG TERM...(Monday through Saturday)
Issued at 349 AM CST Sun Feb 19 2017

On Washingtons Birthday,Monday,the upper trough will move through
eastern by early evening. Associated cold front is forecast to move
through much of northeast Kansas by 00Z Tuesday. Models show a few
hundred jules of mucape in the morning in northeast and east central
Kansas and will continue to mention a slight chance of
thunderstorms. By afternoon, the deeper moisture will advect
eastward into Missouri as winds shift to the southwest and west
while the forcing for ascent shifts east as well. Continued trend of
drying out the cwa from west to east in the afternoon hours. Not
much in the way of cooler temperatures in the wake of the frontal
boundary. On Tuesday, westerly downslope winds will develop across
Kansas and Nebraska. Forecast soundings show mixing down from 900mb-
850mb in the afternoon with 850 MB temperatures averaging around 13
Celsius and should yield temperatures in the mid to upper 70s.
Tuesday through early Thursday is looking dry and mild with nearly
zonal flow aloft. Temperatures will continue to be above normal with
highs in the mid 70s on Wednesday. On Thursday an upper trough will
move across the Rockies and into the Western High Plains. Models are
beginning to come into a little more agreement with the new
operational GFS trending toward the ECMWF and the CMC solutions.
This system looks to bring a chance of rain and thunderstorms
initially Thursday afternoon and evening. Colder air on the north
side of the surface low will allow precipitation to change over to a
rain and snow mix then eventually over to all snow for much of north
central Kansas Thursday night. Thermal profiles show a change back
to all rain on Friday before the system moves out. Temperatures on
Friday will be much colder with highs in the upper 30s to lower 50s
with the colder temperatures in north central Kansas. Changes in
track and speed are likely yet, so keep abreast of later forecasts.
next Saturday will start out in the 20s for lows warming into the
40s in the afternoon. Dry weather is expected on Saturday in the
absence of any weather systems.


.AVIATION...(For the 06Z TAFS through 06Z Monday)
Issued at 1120 PM CST Sat Feb 18 2017

Not a lot of change from the prev forecast with the 00Z models
continuing to show moisture advection leading to some fog and
stratus towards daybreak. Have continued to base the forecast off
of the model consensus and there may be some adjustments to the
onset of the restricted conditions. NAM and RAP forecast soundings
now show the low level moisture scattering out by early afternoon.
So have VFR conditions for much of the afternoon. However the
strongest surge of moisture is expected Sunday night with a return
of at least MVFR conditions.




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