Area Forecast Discussion
Issued by NWS Topeka, KS

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192
FXUS63 KTOP 201139
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
539 AM CST Fri Jan 20 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 232 AM CST Fri Jan 20 2017

Early this morning one mid-level trough was lifting northeast out of
the area with water vapor imagery showing the next disturbance
centered over eastern Colorado.  Models show this disturbance
deepening into a shortwave trough as it pivots northeastward across
Kansas today and tonight. With surface low pressure over the
Texas/Oklahoma panhandles early this morning, the advancing
shortwave trough will help to push this low pressure northeastward
across the CWA with an associated warm front lifting into east
central KS by late afternoon. Ahead of this warm front, plenty of
low-level moisture was present across the region with satellite
imagery showing the entire CWA blanketed under low stratus. As a
result, widespread areas of dense fog were noted this morning and a
Dense Fog Advisory remains in effect until 10 AM. While there is
still some model uncertainty with when exactly this low-level
moisture will diminish today, short-range model soundings have been
trending toward this moisture lingering over the area through much
of the day before the warm front begins to lift northward over the
area.  As a result of the expected lingering low cloud cover, have
lowered temperatures today by a few degrees with highs in the upper
40s to low/mid 50s from northwest to southeast.  With some lift
noted with the low-level moisture in model soundings, expect periods
of drizzle to persist through much of the day, particularly across
north central to northeast KS.  This drizzle should diminish by late
this evening, but persistent low cloud cover will keep temperatures
tonight above the seasonal normals with lows in the 30s.

.LONG TERM...(Saturday through Thursday)
Issued at 232 AM CST Fri Jan 20 2017

The active weather pattern will continue across the region through
the coming week as a series of upper level disturbances crosses
the CONUS. Saturday night into Sunday will feature a deepening
upper low becoming closed off over the Red River valley to our
south. While this system will be quite dynamic, much of the energy
will remain focused south of the forecast area with severe weather
in the southeast CONUS and some wrap-around precipitation north of
the low closer to home along the KS/OK border. Dry advection from
the north should prevent any precip from making it as far north as
the local forecast area. Temperatures are likely to remain warm
through this period with highs in the 40s and 50s through Tuesday.

Upper ridging will build over the region by Monday while another
strong vorticity maximum is well-forecast by model guidance to
surge across KS on Tuesday. The timing of this vort max and
associated jet streak appears conducive to a fairly rapid
deepening of the storm system as it crosses KS/NE. The current
storm track would take the surface low across northern parts of
the forecast area with some potential for warm advection rain/snow
in advance of the surface low with another round of precipitation
(most likely in the form of snow) possibly extending south into
KS on the back side of the low. Accumulating snow is likely to be
associated with this storm system, but given the current forecast
track would *likely be focused north of the local forecast area*.
The current ECMWF and Canadian models are at least suggestive of
some minor accumulation in far northern KS, but the snow gradient
looks likely to be tight with this storm and any shift in storm
track could make a substantial difference in the forecast. Do
expect colder air to build in as strong northerly winds develop as
the system passes.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 534 AM CST Fri Jan 20 2017

For the 12z TAFs, LIFR conditions will remain in place through
most of the morning with the areas of dense fog resulting in low
cigs and 1/4 to 1/2 mile visibilities. Conditions may be slow to
improve this afternoon, but short-range models show the potential
for KTOP/KFOE to improve to VFR conditions briefly late tonight
into the overnight hours before lower cigs return. However, for
KMHK, models suggest that conditions may only improve to MVFR
overnight with additional patchy fog development possible by
Saturday morning with the center of the surface low passing
directly over the area. With this approaching surface low, winds
will veer from southeast to west through the period.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM CST this morning for KSZ008>012-
020>024-026-034>040-054>056-058-059.

&&

$$

SHORT TERM...Hennecke
LONG TERM...Barjenbruch
AVIATION...Hennecke



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