Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 140924
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
424 AM CDT Sat Apr 14 2018

.SHORT TERM...(Today and tonight)
Issued at 424 AM CDT Sat Apr 14 2018

A complicated winter weather event is unfolding across portions of
north central and northeast Kansas today and tonight with concerns
existing on precipitation type and the impacts of the concurrent
strong winds.

A large upper level cutoff low was centered along the north central
Kansas and south central Nebraska this morning. Over the course of
the next 24 hours, this low meanders ENE--reaching central Iowa by
12Z Sunday. A elongated deformation zone arced into north central
Kansas from central Nebraska. At the surface, a complex 997mb
barbell low was pivoting over northwestern Missouri with secondary
cold front/trough axis beginning to dip southward across the KS/NE
border. A very tight pressure gradient and strong CAA on the western
flank of the cyclone was bringing northwest winds of 25-35 kts with
gusts nearing 50 kts in central Nebraska. These winds and colder
temperatures will push into the CWA throughout the day today.

The biggest issue with the forecast today and tonight revolves
around precipitation type. A broad mid-level dry slot currently
visible on GOES-16 water vapor imagery has led to the loss of ice
introduction into the column on the east side of the deformation
zone, which has been confirmed by ground reports in south central
Nebraska. Based on this trends, leveraged a top-down approach to
model the behavior of the dry slot throughout the period--with
freezing drizzle or drizzle along the east flank of the deformation
zone and then higher chances of snow as the deeper moisture wraps
around the mid-level low. However, this forecast is walking a fine
line in trying to allocate various components of the QPF fields into
ice and snow amounts. Any deviations from this forecast will
substantially alter snow/ice amounts.

Overall forcing for ascent in the deformation zone is rather broad
and weak. Therefore, storm total snow amounts between now and
tonight are only expected to be 1-3 inches, with the highest amounts
in north central Kansas and little to no precip in southern portions
of the CWA. However, despite the relative lack of higher snow
amounts, the aforementioned strong winds will lead to blowing snow
concerns in north central Kansas. Forecast soundings still show 40
to 50 kts at the top of the mixed layer throughout the day and based
on upstream trends, these should be realized at the surface. The
question is, will blizzard conditions be met? For now, given the
possibility of p-types oscillating between snow and freezing drizzle
and lack of a pre-existing snow pack, have opted for a continuation
of the winter weather advisory with near blizzard conditions
mentioned in the body of the product and highlighted in other
mediums.

The overall precip shield should gradually shift east through the
day and slowly weaken, with most of the precipitation concluded
before 06Z. Near record to record cold then settles into the region
tonight with lows in the low 20s north to mid to upper 20s
southeast. These temperatures would pose a serious threat to any
sensitive vegetation that has bloomed in the recent stretch of warm
weather.

.LONG TERM...(Sunday through Friday)
Issued at 424 AM CDT Sat Apr 14 2018

Deep surface low will continue to move off to the northeast into
northern Indiana and Ohio on Sunday as high pressure builds into
central and eastern Kansas. The surface pressure gradient will
gradually decrease through the day and expect gusty northwest winds
to continue through the mid afternoon. Morning wind chill
temperatures will start out in the single digits and teens Sunday
morning making for a frigid start to the day. Highs on Sunday are
expected to range from the upper 30s to mid 40s, which is some 20
degrees below normal for mid April. Lows drop into the teens and 20s
Monday morning along with light winds and clear skies will allow for
good radiational cooling to take place. Warm advection and rising
heights on Monday will yield highs in the 50s to near 60.

Moisture will increase on Tuesday as a warm front lifts northward in
response to an approaching upper trough from the surface through 850
mb. Veering winds to the southwest will keep the deeper moisture
across east central and southeast Kansas. Forecast soundings show
much of the area will remain capped to surface based convection save
areas southeast of I-35 in east central Kansas where it weakens by
late afternoon or early evening. Highs Tuesday will warm back into
the 70s across the area. As the upper trough moves across the Plains
a surface front and dry line will move eastward across northeast
Kansas Tuesday evening. There is a small chance for thunderstorms to
develop in east central Kansas Tuesday evening along the front as
the cap weakens. 45 kts of 0-6 Km shear and around 800 J/kg of Cape
may be sufficient for an isolated storm or two to develop along the
front.

Temperatures cool back to near normal for latter half of the week
with highs mainly in the 60s and lows in the 30s and 40s. There is a
chance for showers at the end of the week and into next weekend with
as another upper low is forecast to move across the Plains.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday)
Issued at 1200 AM CDT Sat Apr 14 2018

Models are in agreement for deteriorating conditions through the next
24 hours. The more uncertain aspect to the forecast is timing when
lower CIGS move into the terminals and there may be some tweaks to
the forecast as I could be a little conservative on bringing the
lower CIGS in. Think the more likely window for precip will be
during the afternoon hours as the deformation zone moves overhead.


&&

.FIRE WEATHER...
Issued at 424 AM CDT Sat Apr 14 2018

Gusty winds along with afternoon minimum relative humidity in the 22
to 35 percent range on Tuesday and Wednesday will bring very high
fire danger to the area. Southerly winds Tuesday will shift to the
west and northwest behind a frontal boundary/dryline Tuesday night
with gusty northwest winds expected on Wednesday.


&&

.CLIMATE...
Issued at 340 PM CDT Thu Apr 12 2018

Record temperature information for Saturday, April 14:

Location  Record Lowest Minimum (Year)  Record Lowest Maximum (Year)
--------------------------------------------------------------------
Topeka         21F (1950)                    39F (1928)
Concordia      23F (1928)                    42F (1983)

Record temperature information for Sunday, April 15:

Location  Record Lowest Minimum (Year)   Record Lowest Maximum (Year)
---------------------------------------------------------------------
Topeka         25F (1928)                     45F (1993)
Concordia      22F (2014)                     42F (1945)

Record temperature information for Monday, April 16:

Location  Record Lowest Minimum (Year)
--------------------------------------
Topeka         26F (1953)
Concordia      25F (1953)

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 7 PM CDT this evening for
KSZ008-009-020-021-034-035.

Wind Advisory until 7 PM CDT this evening for
KSZ008-009-020-021-034-035.

Winter Weather Advisory from 10 AM this morning to 7 PM CDT this
evening for KSZ010-022-023-036-037.

Wind Advisory from 10 AM this morning to 7 PM CDT this evening
for KSZ010-022-023-036-037.

&&

$$

SHORT TERM...Skow
LONG TERM...53
AVIATION...Wolters
FIRE WEATHER...53
CLIMATE...Wolters



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