606 
FXUS63 KTOP 131154
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
654 AM CDT Sat Oct 13 2018

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 353 AM CDT Sat Oct 13 2018

Early this morning surface high pressure was centered east of the 
CWA with water vapor imagery showing the remnants of Sergio tracking 
across Texas.  An expansive area of low stratus was noted across 
Missouri and extending westward into far eastern Kansas. With 
yesterday's rainfall and light winds present, areas of dense fog 
were developing along the edge of the status and in nearby river 
valleys. With model guidance suggesting areas of 1/4 mile or less 
visibilities persisting through sunrise, have issued a Dense Fog 
Advisory for portions of far northeast/east central KS through 14z 
today. While the nearby stratus was keeping temperatures in far 
eastern KS a few degrees warmer in the low 40s, mostly clear skies 
elsewhere kept temperatures a bit cooler in the mid/upper 30s as the 
light southerly winds were not providing much advection of 'warmer' 
air into the region.  The combination of these cooler temperatures, 
light winds, and surface moisture should result in some patchy frost 
development this morning.  

For today, models are in decent agreement in keeping moisture 
associated with the remnants of Sergio south of the CWA, with focus 
instead shifting to another mid-level trough starting to dive 
southward from Canada into Montana and the Dakotas this morning and 
deepen across the High Plains through tonight.  This deepening 
trough will push a surface cold front southward into northwest/north 
central KS this afternoon and progress southeastward across the CWA 
tonight.  With model soundings showing ample low-level dry air in 
place through the day, expect much of northeast and east central KS 
to remain dry with some scattered light rain showers starting to 
develop across north central KS during the afternoon. With 
essentially no instability present, expect just rain showers as the 
front moves into the area.  As model soundings show the low-levels 
gradually saturating during the evening and overnight hours, have 
increasing PoPs from west to east across the CWA. As for 
temperatures, the combination of southerly winds and partly to 
mostly sunny skies across much of the CWA should allow temperatures 
to quickly rise this morning into early afternoon before cloud cover 
increases across north central KS with the approaching front.  As a 
result, expect highs to range from the upper 50s to low 60s from 
east to west.  As winds shift to the northwest tonight with the 
frontal passage, expect decent CAA to cause temperatures to quickly 
drop (especially across north central KS), with lows ranging from 
the mid 30s to mid 40s from northwest to southeast across the CWA. 

.LONG TERM...(Sunday through Friday)
Issued at 353 AM CDT Sat Oct 13 2018

Focus for these periods remains in first few periods with a strong 
cold front surging south through Kansas under persistent strong 
southwest flow aloft. Mid-level saturation should be easy to come by 
though still have questions on ice crystals in the cloud in central 
and southern areas and this coinciding with winter precip-supporting 
temps in the lower levels. Also, the dominating source for lift 
appears to be the frontogenesis alone, and there are some 
indications of a slower frontal progression, so getting the best 
forcing aligned with the cold temps in northwest locations is again 
not certain. Model consensus still suggests portions of north-
central Kansas will receive enough precip in the deep cold air for 
accumulating snow amounts. Lapse rates aloft still suggest some CSI 
to near CI in place for periodic stronger precip rates and this 
could be enough for accumulations on all surfaces. Will go ahead 
with an Advisory where confidence in the above is the highest. 
Frontogenesis weakens with mid-level drying for decreasing precip 
trends Sunday night for less impactful precip in the southeast. 
Temperatures Sunday night will likely bring a hard freeze to a least 
northwestern locations so those with interests susceptible to temps 
in the mid to upper 20s may want to take action today. 

Surface ridge settles into the central Plains Monday for a little 
recovery in temps and another cold night Monday night with another 
potential hard freeze. Conditions improve into the mid week with 
moderating temperatures and modest winds. There remains some 
potential for some showers around Thursday night as southwest flow 
taps into some increasing moisture as an upper trough lifts 
northeast out of the desert Southwest.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 646 AM CDT Sat Oct 13 2018

For the 12z TAFs, LIFR conditions are expected this morning as
areas of dense fog were present near KTOP/KFOE with 1/4 mile or 
less visibilities at times. These conditions should improve by mid
to late morning with VFR conditions likely through the remainder 
of the day. Overnight, a cold front will track southeastward 
across the TAF sites, causing winds to shift to the north-
northeast and cloud ceilings to drop back to MVFR. However, there
is still some model uncertainty with when overnight to expect 
these MVFR cigs to develop over the TAF sites. Scattered rain 
showers may begin to develop near KMHK late overnight, with better
chances for rain showers near KTOP/KFOE beyond the end of the TAF
period.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM CDT this morning for KSZ011-012-
024-026-039-040-055-056.

Winter Weather Advisory from 7 AM to 10 PM CDT Sunday for KSZ008-
009-020.

&&

$$

SHORT TERM...Hennecke
LONG TERM...65
AVIATION...Hennecke