Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 291148
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
648 AM CDT Wed Mar 29 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 332 AM CDT Wed Mar 29 2017

Early this morning the surface and mid-level lows were vertically
stacked over the Texas panhandle, with southerly flow ahead of this
system supporting moisture advection northward into the region. A
surface trough extending from the surface low was stretched across
east central KS, which was providing sufficient forcing to produce
widespread showers and storms with moderate to heavy rainfall.
Overcast skies from this widespread precipitation will keep early
morning temperatures nearly steady in the mid 40s to low 50s.

The moderate/heavy rainfall will continue along the surface trough
axis over east central to northeast KS into mid-morning.  Short-
range models show the potential for more scattered precipitation
over east central to northeast KS by late morning into the afternoon
hours, with the better focus for moisture and lift shifting to over
north central KS where the deformation zone within the wrap-around
precipitation is expected to set-up.  As a result, periods of
moderate to heavy rainfall will be possible over north central KS
into early this afternoon.  For this morning`s precipitation, model
soundings show some weak elevated instability present but do not
anticipate any strong or severe storms with the morning storms.

There is still uncertainty in the potential and coverage of any
strong to severe thunderstorms mid/late afternoon into this evening
across east central KS.  This uncertainty is largely due to
uncertainty in whether or not there will be any brief breaks in the
cloud cover this afternoon to support increased destabilization.
Models show MUCAPE values increasing to around 1000 J/kg by mid/late
afternoon with very low LCLs and 0-6km bulk shear values quickly
increasing to 60-80kts. As the surface low begins to move into far
southeast KS late this afternoon, the associated surface trough is
expected to extend northward into far east central KS.  This surface
trough, in combination with the increasing instability and shear
this afternoon, should provide enough forcing to support additional
scattered thunderstorm develop with some strong to perhaps severe
storms possible.  This potential for stronger storms will be focused
southeast of an Abilene to Holton line, with the best potential
being southeast of I-35. The main hazards with any strong storms
will be large hail and possibly some strong wind gusts. There is an
increasing threat for isolated tornadoes across the Ozarks and
possibly extending into west central MO. The threat for strong to
severe storms will diminish by mid evening as storms become more
elevated and instability quickly weakens.  Even though the
thunderstorm threat will diminish in the evening, another batch of
rain with scattered storms will develop across the CWA as the mid-
level low lifts into the area through Thursday morning.  So while
some breaks in precipitation are expected today and tonight, the
periods of moderate to heavy rainfall will likely result in QPF
amounts of 1.5 to 2.5 inches across much of the CWA, with locally
higher amounts possible.  The prolonged nature of the rainfall
should limit flooding concerns, but will need to keep an eye on
locations that receive locally higher amounts.

As for temperatures, overcast skies today will greatly limit any
daytime heating, keeping high temperatures in the upper 40s to low
60s from northwest to southeast across the CWA.  For tonight,
persistent cloud cover will keep lows in the 40s.

.LONG TERM...(Thursday through Tuesday)
Issued at 332 AM CDT Wed Mar 29 2017

The medium to extended period will continue a series of upper level
troughs/lows to move across the Plains. On Thursday the upper low
will be over eastern Kansas and gradually move east into Missouri by
evening before moving off into the Ohio Valley. Most of eastern
Kansas remains in the trowal through the day with periods of rain
continuing through the day, gradually diminishing toward the evening
hours. Areas of east central Kansas could see an additional half
inch of rain with lesser amounts elsewhere. A ridge builds in aloft
across the Southern and Central Plains Friday allowing the area to
dry out some. However the next in the series of upper troughs is
expected to be over the Four Corners on Saturday then begin to move
eastward slowly into early next week across the Southern Plains.
Precipitation chances will be on the increase for the weekend and
then continue through Monday night as the upper trough moves
eastward across the Southern Plains then into the Ohio Valley by
Tuesday. Models do diverge with the speed and location of the closed
upper low with the ECMWF being faster than the other operational
models and ensemble mean. Either way the wet pattern will continue
with periodic chances of showers and a few storms. High temperatures
through the period will be in the 50s and 60s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 640 AM CDT Wed Mar 29 2017

For the 12z TAFs, periods of showers and thunderstorms are
expected through a majority of the TAF period, which will result
in reduced cigs/vis. Expect cigs to lower to IFR conditions this
morning with the potential for a brief improvement in conditions
during the afternoon as scattered thunderstorms begin to develop
near the TAF sites. Scattered storms that develop late afternoon
into this evening should diminish by mid evening with scattered
showers expected into Thursday morning. Northeasterly winds will
remain gusty today before diminishing early this evening as they
shift to the north.

&&

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

$$

SHORT TERM...Hennecke
LONG TERM...53
AVIATION...Hennecke



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