Area Forecast Discussion
Issued by NWS Topeka, KS

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551
FXUS63 KTOP 242334
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
634 PM CDT Fri Mar 24 2017

...AVIATION UPDATE...

.SHORT TERM...(This evening through Saturday)
Issued at 257 PM CDT Fri Mar 24 2017

Increasing isentropic lift within the warm sector this afternoon has
produced scattered showers and thunderstorms in the early
afternoon. Current position of the upper low was rotating through
the OK panhandle with the sfc low directly beneath. Frontal boundary
positioned from southwest to northeast over north central KS through
IA coincides with an additional dryline/front extending south of the
sfc low across central KS. Cloud cover and morning thunderstorms
have hindered sfc heating and instability across the CWA, leading to
further uncertainty with how severe storms will be later in the
afternoon and evening. Current analysis shows around 500 J/KG of sfc
based cape across central KS, in vicinity of the triple point with 0-
6 km bulk shear in excess of 40 kts. As the main system shifts east
southeast, bulk shear on the RAP increases towards 60 kts,
supportive of updrafts, however dependent on how much instability is
realized for supercells.

Current thinking is that scattered convection initializes along and
ahead of the southeast moving front after 3 PM (centered near the I
70 corridor), capable of producing large hail and damaging winds
near and south of the boundary. As convection lifts north of the
front, they should weaken. Latest runs of the HRRR and RAP depict a
few supercells developing east of Wichita, lifting north and east
into east central KS through 00Z. These storms may also produce
large hail and damaging wind gusts, especially if higher instability
is realized. As the upper low shifts over OK during the evening and
overnight periods, showers and scattered thunderstorms gradually
weaken and quickly lift off towards the north and east. Expect to
see off on and showers with embedded thunder overnight as weak mid
level frontogenesis wraps around the backside of the system.

On Saturday, model guidance is trending  towards a slower
progression with the upper low exiting the CWA. Increased pops
in the morning through early afternoon hours with the scattered
showers gradually clearing east by the evening. Northerly winds
overnight and Saturday gust up to 25 mph under overcast skies,
resulting in a much cooler afternoon with highs in the 60s.

.LONG TERM...(Saturday night through Friday)
Issued at 257 PM CDT Fri Mar 24 2017

The unsettled weather pattern will continue at least through the
next 10 days with 4 storm systems very likely to impact the
central plains during that time frame. The first system over the
area today will exit with precipitation ending by late Saturday.

By late Sunday afternoon, a quick-hitting short wave trough will
cross Kansas, taking on a negative tilt and pulling a quick return
of modified gulf moisture into eastern Oklahoma...and to a lesser
extent eastern Kansas. Locally, instability will likely be limited
by unimpressive lapse rates and boundary layer moisture. However,
widespread vertical motion on the north quadrants of the system
suggests a high likelihood for precipitation especially along and
south of I-70. Temperatures will be warm enough to support an all
rain forecast. This system will exit quickly with fairly pleasant
conditions for Monday and Tuesday.

A stronger, deeper upper trough is forecast with good model
agreement to enter the plains Tuesday night and slowly progress
east before taking on a negative tilt and accelerating out of the
area late Thursday. The current storm track would take the heart
of this trough south of the forecast area, so while it should be
quite effective in northward transport of gulf moisture, the best
dynamics, shear, and instability will likely remain well south of
the forecast area. However, the strong mid and upper level forcing
in the northern quadrants of the trough will once again give a
good chance for widespread rain across the area. This is one of
those storms that would have been a great snow storm if it had
happened 2 months ago and 20 degrees colder...but in this scenario
looks to likely fall as all rain.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday)
Issued at 633 PM CDT Fri Mar 24 2017

Models continue to show conditions deteriorating through the
evening as wrap around moisture brings MVFR and IFR CIGS to the
terminals. Think that once the frontal boundary moves through the
area, chances for thunderstorms will wane with the lose of
surface instability. There does not appear to be much improvement
for Saturday with low levels remaining saturated as the low
pressure system slowly moves east.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Prieto
LONG TERM...Barjenbruch
AVIATION...Wolters



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