Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 080526

1225 AM CDT Tue Jul 8 2014

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Tuesday)
Issued at 259 PM CDT MON JUL 7 2014

Currently monitoring visible satellite this afternoon where multiple
boundaries are positioned across the region. A weak boundary was
tracking southeast through the CWA while a stronger area of outflow
winds was pushing southward into southern NE and far northern KS. A
weak warm front resided near the KS/NE border while the stronger
cold front was located over southern SD. Remnant cloud cover from
this morning`s showers were finally exiting east central KS,
allowing temps to quickly rise into the 90s, as heat indices
approach the low 100s. Dewpoints continue to mix down into the low
and middle 60s. On the water vapor in the mid levels, two vorticity
maxima were noted over northern NE and a stronger wave dropping southeast
from North Dakota.

Late this afternoon, surface CAPE near 3000 J/KG while effective
shear increases between 30 and 50 kts is supportive of strong to severe
convection. Main limiting factor for surface based convection is the
capping inversion holding across much of the area as seen on the 19Z
KTOP RAOB. Latest 4-KM WRF, HRRR, and RUC keep convection at bay
until after 00Z but could not entirely rule out a few updrafts
developing along the leading outflow boundary or warm front in
vicinity of KS/NE border. If a storm develops, it will be capable of
large hail and damaging winds.

Highest chances for severe convection reside after 00Z as scattered
storms along the reinforcing cold front and upper trough shift south
and east across Nebraska, northeast Kansas, and northern Missouri. the
progressive nature of the system, in addition to stout forward
propagating Corfidi vectors approaching 55 to 60 kts signal damaging
winds to be the primary hazards with this evening`s storms. Large
hail is also possible. Locally heavy rainfall will depend on the
speed of the line and any training convection that occurs towards
central KS along the boundary. Tornado potential is low in far
northern KS where the frontal boundary and weak low level shear
maximizes near 15 kts. Likely precip chances were focused over
northern, northeast, and east central areas based on the position of
the upper trough axis as the main line of storms quickly shifts
southeast overnight.

Guidance is on track to clear precip through by Tuesday mid morning
as skies become mostly sunny during the afternoon. A cooler and stable
airmass in the system`s wake will only bring temps to the 80s for
highs. Northerly winds increase between 10 and 15 mph sustained.

.LONG TERM...(Tuesday Night through Monday)
Issued at 259 PM CDT MON JUL 7 2014

Wed/Thurs...Should have a cool night Tuesday night as skies clear
and cooler airmass with lower dewpoints slides southward into the
forecast area. Strong sunshine and deeper mixing on Wednesday
should return high temperatures back into the middle 80s east to
upper 80s west. Still some consensus that front retreats back
northeast overnight Wednesday night into Thursday and brings a
chance for storms as it does so, although coverage may be shut
down quickly as warm temps and cap return aloft by the late
afternoon Thursday. Eastern counties may be able to stay a few
degrees cooler depending on how fast clouds and precip chances

As upper flow becomes slightly northwest into Thursday night,
passing wave still progged to generate an MCS mainly north of our
area then sliding east. Kept slight chances as some models slide
this boundary into our forecast area. Some discrepancies in the
extended as EC lays this boundary over the area through the
weekend while GFS is farther north and a warmer drier solution.
The GFS ensembles favor the warmer pattern and have left the
extended as such.


.AVIATION...(For the 06Z TAFs through 06Z Tuesday Night)
Issued at 1225 AM CDT TUE JUL 8 2014

TSRA still likely to affect the terminals through 09Z. Not
expecting strong wind gusts with these storms. Winds will be
variable then become north. VFR cigs expected with MVFR vsbys with
the TSRA. Clouds scatter out after 12Z and north winds around
10 kts are expected after 14Z, then decrease after 02Z Wednesday.




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