Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 260838
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
338 AM CDT Thu Apr 26 2018

.SHORT TERM...(Today and tonight)
Issued at 338 AM CDT Thu Apr 26 2018

Early this morning, surface high pressure was tracking over the
outlook area behind the exiting system that brought yesterday`s
rain. Skies had cleared out early this morning, but satellite
imagery showed scattered cirrus clouds streaming southward into
the area ahead of the next cold front that will track across the
CWA this afternoon. With the center of the surface high over south
central KS, winds were generally light across the area, however
occasional wind speeds of 5-10mph were noted in some observations.
The combination of clear skies, light winds, and moisture from
yesterday`s rain showers supported the development of some fog
early this morning, however the occasional higher wind speeds
along with scattered high clouds was generally keeping this fog
development patchy and predominantly focused in low-lying areas
and near bodies of water. Cannot rule out some localized areas of
dense fog with brief visibility reductions of near 1/4 mile at
times. Due to the highly variable observations with visibilities
from this patchy fog, do not feel a dense fog advisory is needed
at this time. These early morning conditions also supported enough
radiational cooling to drop temperatures into the mid/upper 30s
to around 40 degrees from west to east over the CWA, resulting in
concerns for frost development. The streaming high clouds may
impact just how low temperatures drop in some locations, so frost
development may very well be patchy. Will continue to monitor
temp/dewpoint trends this morning, and a Frost Advisory remains in
effect for portions of north central KS.

As another mid-level trough dives southward across the Northern
Plains, it will help to push a cold front southward across the CWA
this afternoon.  With limited available moisture, expect just
increasing mid-level clouds with nothing more than some scattered
sprinkles possible along the front. Short-range guidance shows
temperatures likely rising into the mid/upper 60s by this afternoon,
however the coverage and depth of the advancing cloud cover over
eastern KS and then how quickly cloud cover scatters out behind the
front late this afternoon across north central KS could certainly
impact this temperature forecast.  As surface high pressure moves
into the area tonight behind the front, expect light winds and
clearing skies to support another night of radiational cooling to
drop temperatures possibly into the upper 30s across north central
KS. As a result, will need to monitor the potential for patchy frost
once again tonight in that region.

.LONG TERM...(Friday through Wednesday)
Issued at 338 AM CDT Thu Apr 26 2018

Temperatures are the main forecast challenge Friday into Saturday.
West to northwest low-level winds bring decent warm-air advection
with plenty of sun and should bring highs back into the lower to
middle 70s Friday. A "back door" front sinks south across the
area Friday night as a shortwave rounds the base of the upper
trough over the Great Lakes. Models do vary somewhat on strength
of cold- air advection, but with good insolation again expected,
only have temps a category or two cooler than Friday.

Upper ridge axis pushes east across the central Plains Saturday
night into Sunday with modest mid-level isentropic upglide
resulting in its wake. Enough of a consistent signal exists for
small precip chances in the northwest Sunday morning though could
only see sprinkles in dry air below 10k feet. Lee cyclogenesis
brings gusty south winds by early Sunday afternoon and supports
highs back in the 70s. GFS and ECMWF are in fairly good agreement
with a lead wave passing over northern areas Sunday night into
early Monday for another small chance for precip.

Deepening lee cyclone and surface ridge into the southeast CONUS
brings a windier day Monday, with continued suggestions of
Advisory-level speeds. Handling of energy in the mean western
CONUS upper trough differs from model-to-model and run-to-run in
continued split flow, and confidence in when and where the greater
precipitation chances and severe weather potential will be is not
high. A modified cold front may push southeast into the area
Tuesday and become nearly parallel to the upper flow suggesting a
heavy rain setup, with the front potentially lingering or
refocusing in the area for Wednesday. At this point, chance PoPs
are in order for most of the area Tuesday through Wednesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1136 PM CDT Wed Apr 25 2018

Fog potential is the primary overnight concern, with recent
rainfall and clearing skies. High cirrus not likely to do much to
prevent development, although a light west wind develops over the
next few hours. Will carry shallow fog and lower visbys late
tonight into early morning for TOP/MHK given proximity to low
spots and rivers.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM CDT this morning for KSZ008>010-
020>022-034>036.

&&

$$

SHORT TERM...Hennecke
LONG TERM...65
AVIATION...67



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