Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 130354

Area Forecast Discussion
National Weather Service Topeka KS
954 PM CST Sun Nov 12 2017

Issued at 950 PM CST Sun Nov 12 2017

The combination of GOES-16 data and surface observations is
showing a region of dense fog developing on the backside of the
now stalled stratus shield in east central Kansas. This fog will
be the most dense in low-lying regions and river valleys. The
aforementioned low stratus will begin lifting northward as return
southerly flow begins to set in. The slight increase in winds,
combined with the stratus and higher level cirrus, will aid in
degrading the fog coverage in the hours before sunrise. Therefore,
expect that the dense fog advisory will be trimmed from south to
north after roughly 3 to 4 am.


.SHORT TERM...(This evening through Monday)
Issued at 254 PM CST Sun Nov 12 2017

As of 20Z Sunday afternoon a mid-level trough across the Great Lakes
region continues to progress eastward. Westward, a mid-level ridge
continues to build across the central Plains. Weak CAA continues to
intrude on the area and the stubborn low-level stratus. As of 20Z
the back edge of the stratus field stretched from near Minneapolis,
KS to Manhattan to Holton to St. Joesph. It`s southward progression
near 20kts will allow to majority of the area to see clear skies
before sunset. The big question marks arise overnight, regarding
cloud cover and fog.

Overnight -- Given the brief window for surface heating experienced
across much of the area today, little boundary layer mixing has
occurred. A surface ridge axis is expected to traverse the CWA
overnight, decreasing winds to below 5 kts. With the light winds,
mostly clear skies and remnant boundary layer moisture in place,
expect fog to develop after sunset. The potential exists for some of
the fog to become dense in local areas. Low temperatures are
expected to remain in the middle to upper 30s across the area. The
potential for any freezing fog is minimal as road and surface
temperatures remain in the low 40s. As the aforementioned surface
ridge moves east of the area, weak southerly flow will return to
CWA. With the pre-existing boundary layer moisture displaced across
the southern portion of the CWA and southwesterly H85 winds near 15-
20kts, low-level stratus could advect northward overnight.

Monday -- The axis of best moisture transport associated with a 30kt
LLJ will shift eastward throughout the day on Monday. As a result
any areas remaining cloud free tonight will see increasing cloud
cover through the day. The best saturation depth and isentropic lift
looks to hold off until after 00Z Tuesday. Therefore, have no
mention of drizzle within the short term period. High temperatures
look to reach the low to middle 50s Monday afternoon.

.LONG TERM...(Monday night through Sunday)
Issued at 254 PM CST Sun Nov 12 2017

Warm advection and weak isentropic lift continue over the eastern
two thirds of the forecast area Monday night into Tuesday, and
with moisture relegated generally below 10kft and not much lift,
will carry drizzle as the primary precipitation type. By late in
the evening, some meager instability makes it over the area, ahead
of the frontal boundary as it moves southeastward, before clearing
the forecast area by mid Wednesday morning. Could see a few
thunderstorms across the east in the early morning hours. Lows
are in the 40s with daytime highs around 60 on Tuesday and a few
degrees colder on Wednesday as the cooler surface high moves in.

Another round of moisture/warm air advection returns on Thursday
and could be enough for some showers by Thursday evening. As the
next upper trof moves over the Rockies, plume of higher
instability comes over the southern plains, most of which is
shunted to the east of here before the next front comes in.
Between the two lies a drier and windier transition for Friday
morning, which could bring fire weather concerns, however the
front is currently progged to come southeastward quickly and would
bring a fast end to the dry wind threat. Models still about 12
hours different on the timing of this front, and a slower EC
solution would make for increased fire weather concerns and will
continue to monitor.

Saturday and Saturday night remain dry and possibly breezy early,
with highs in the 50s and lows in the 40s, and looks to be a few
degrees warmer on Sunday as southerly surface winds return.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 600 PM CST Sun Nov 12 2017

The back edge of a southward propagating MVFR stratus deck across
east central Kansas will slow down and begin lifting northward
late tonight. Fog may form across portions of northeast KS before
the clouds return, with visibilities falling to IFR or possibly
lower. Confidence in the timing of the clouds and fog is on the
lower side. Ceilings will lower to IFR under the stratus during
the morning hours and gradually lift to low MVFR by the afternoon.
Light winds tonight will increase out of the SSE on Monday at
around 10 kts.


Dense Fog Advisory until 7 AM CST Monday for KSZ010>012-022>024-



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