Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 220823
AFDTOP

AREA FORECAST DISCUSSION
National Weather Service Topeka KS
323 AM CDT THU SEP 22 2016

.SHORT TERM...(Today and tonight)
Issued at 319 AM CDT Thu Sep 22 2016

Current water vapor shows several weak mid level shortwaves moving
out over the plains this morning. The associated weak isentropic
lift is expected between now and late morning mainly over north
central and far northern KS. This is where isolated to scattered
showers and possibly some thunder may occur. The GFS seems quite
bullish with the amount of QPF especially given the fact no other
models agree with these amounts. Also, there is a small complex of
decaying storms over southwest KS. Any remnant MCV could reach north
central KS later this morning and bring a slight chance for showers
as well. Only the HRRR is showing this activity will reach the
forecast area. After late morning the chances should diminish. High
clouds associated with the tropical moisture fetch will stick around
until at least the evening. Highs today look to reach the upper 80s
to lower 90s with dew points in the upper 60s. Winds will become
gusty out of the south again today mainly during the late morning
and early afternoon. Quiet weather continues tonight with partly
cloudy skies and lows in the mid 60s.

.LONG TERM...(Friday through Wednesday)
Issued at 319 AM CDT Thu Sep 22 2016

Friday, the downstream ridge across the plains and mid MS river
valley will amplify as the upper trough across the western US
deepens. Friday will be another warm day with south-southeast winds
of 15 to 25 MPH. Highs will reach the upper 80s to lower 90s.
Thunderstorms that develop across western KS during the early
evening hours may reach the western counties of the CWA late Friday
night.

Saturday through Sunday night, An intense upper level trough across
the Western US on Friday will begin to shear apart as if moves east
across the plains. There will be stronger ascent ahead of the
positive tilt upper wave as it moves east across KS Saturday night
through Sunday night. There will be a good transport of deep gulf
moisture northeast across eastern KS at 850mb, ahead of the upper
trough Saturday night through Sunday. Both the GFS and ECMWF
forecast a widespread QPF of 1 to 3 inches across the CWA. If the
rain falls over a 24 to 36 hour period then there will probably only
be minor flooding possible. However, stronger thunderstorms may
train from southwest to northeast across portions of the CWA
Saturday evening into Sunday morning which may produce a greater
potential for flash flooding. The next few shifts will have to watch
the potential for flooding Saturday night into Sunday.

Since the upper trough begins to shear apart as it moves into the
plains, the 0-6 KM effective shear weakens during the afternoon
hours. Given MLCAPES of 1500-2500 there could be a few pulse severe
storms that develop along the surface front across west central KS,
then may move into the western counties of the CWA before the
stronger ascent moves east along the front and develops a line
of showers and thunderstorms during the evening hours of Sunday.

The GFS is more progressive moving the upper trough east across the
plains and the heavier rain may move southeast of the CWA during
the mid morning hours of Sunday. If the GFS were to verify the
surface front will move southeast across the CWA during the early
morning hours of Sunday and skies may clear from northwest to
southeast during the afternoon hours. The ECMWF is slower moving the
positive tilt H5 trough across the plains on Sunday and keeps
widespread showers and elevated thunderstorms across much of the CWA
through the day Sunday and into Sunday night as isentropic lift
continues north of the surface cold front.

Monday through Tuesday, Once again the ECMWF and GFS solutions
diverge as the ECMWF continues to amplify the southern section of
the upper level trough across southwest NM, then lifts the H5 trough
northeast across the plains by mid week. The GFS keeps the northern
branch of the H5 trough amplified as it shifts northeast across the
Great Lake States. If the ECMWF verifies there will be at least a
slight chances for showers and thunderstorms through the week. If the
GFS were to verify then expect dry conditions through the week.
Highs will be around 70 on Monday with temperatures warning into the
mid to upper 70s by Thursday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1154 PM CDT Wed Sep 21 2016

VFR conditions are likely through the TAF period with increased
wind speeds during the late morning through afternoon hours. 2000
foot AGL winds will be in the 30-35 kt range through 12Z, which
should be slightly less than LLWS criteria.

&&

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

$$

SHORT TERM...Sanders
LONG TERM...Gargan
AVIATION...Barjenbruch



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