Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 241721
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1221 PM CDT SAT SEP 24 2016

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 302 AM CDT Sat Sep 24 2016

Upper low over CO/WY at this hour pushing a piece of energy
northeast in to Nebraska and western Kansas has generated a broken
line of showers and embedded thunder over the western parts of the
state.  Some of these may reach western counties toward sunrise.  As
the low approaches, precipitation patterns in the guidance indicate
several rounds of enhanced rain chances.  Stronger impulse progged
to lift NE out of central Oklahoma and bring another increase in
coverage for the afternoon hours.  This may act in concert with an
increase in instability to bring a strong storm to the area in the
afternoon hours.  NAM / HRRR are more generous with the instability
while GFS and RAP less so. As of the early morning hours of
Saturday, area remains in a marginal risk for severe storms with
primary concerns for wind gusts and locally heavy rain. Highs today
forecast in the low to middle 80s.

PW values from last evenings sounding near an inch climb to near 1.5
inches by this morning, and toward 2 inches by Saturday evening as
moisture plume streams northward ahead of the upper low, and initial
stronger storm development could bring some training storms and
locally heavy rainfall. As front moves in for the overnight hours
Saturday night, this plume pivots over the eastern counties and
brings the locally heavy rain threat east as it does so.  Total
forecast amounts are generally 2 inches or less, but would
anticipate some locally higher amounts as storms train from SW to NE
along the front as it slowly pushes SE. On the downside will be
decreasing instability which could help diminish precip efficiency.
Overnight lows with clouds and rain look to hold in the upper 50s
far northwest to middle 60s southeast.

.LONG TERM...(Sunday through Friday)
Issued at 302 AM CDT Sat Sep 24 2016

By Sunday morning the cold front will bisect the forecast area as it
continues to progress southeastward. At this time the northern
stream trough will be tracking over ND with the one axis extending
southward over central KS. A few of the models are showing an
increase in mid level frontogenesis at this time as well as energy
lifting out of the southern stream, which may enhance the precip
across the southeast half of the forecast area during the morning.
The NAM is most aggressive with this scenario therefore will have
watch the latest trends to see if the artifact is real, and if so
where it may come together. With the possibility of enhanced precip
rates an additional 0.5 to 1 inch of rainfall may be possible, but
confined to east central KS. This area will have to be monitored for
potential flash flooding, which will depend of how much rain falls
late Saturday and overnight. By mid day though the front should exit
the area and most locations will be drying out. North central KS
will pretty much remain dry after sunrise Sunday. In the evening
another mid level trough axis will swing out over the plains forcing
the moisture and lift southward. The Canadian air mass will quickly
move in behind the front supported by a surface high pressure, which
is forecasted to track through the high plains. The coolest low
temperatures will be on Monday and Tuesday mornings with mid to
upper 40s for most locations. While high temperatures stay in the
70s through Friday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1219 PM CDT Sat Sep 24 2016

Adjusted the timing of precipitation as storms continue to develop
just west of MHK.  Scattered storms are expected ahead of the main
band which is expected to reach MHK by 20Z and near TOP/FOE at 22Z.
Behind this, more showers and storms are expected through the
morning with heavy rain and lightning probable.  Conditions will
begin to clear later in the morning.

&&

.TOP Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...67
LONG TERM...Sanders
AVIATION...Heller


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