Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 261145

645 AM CDT Tue Aug 26 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 401 AM CDT TUE AUG 26 2014

Early this morning a broad mid-level ridge remained anchored over
the southeastern quadrant of the U.S. with a deepening mid-level
trough over the Great Basin area. With this pattern in place,
southwesterly flow aloft prevailed across the central U.S. with
water vapor imagery showing a few weak embedded shortwaves
developing across Kansas and Nebraska early this morning. At the
surface, low pressure was in place with a fairly stationary boundary
across south central Kansas and extending into northeast Kansas,
essentially bisecting the forecast area. With the support of a
stronger embedded shortwave, an MCS quickly developed across eastern
Nebraska early this morning and persisted through the overnight
hours as it was supported by the low-level jet and decent isentropic
lift. A weaker shortwave was noted across central Kansas, which
sparked a cluster of showers and thunderstorms overnight. However,
this activity was gradually weakening as outflow boundaries
continued to gust out ahead of the storms. As a result, local radar
showed several outflow boundaries situated across the region from
this activity. Mid-level clouds were in place over eastern Kansas,
providing better insolation and keeping temperatures more mild in
the mid/upper 70s. However, cooler conditions were noted over north
central Kansas as a result of the rain-cooled air, bringing
temperatures down into the mid 60s to low 70s.

The precipitation forecast continues to be a challenge in the short
term as we continue to deal with a stationary boundary over the
forecast area, passing weak embedded shortwaves, and lingering
outflow boundaries from overnight convection. The HRRR has been
handling the morning activity fairly well and shows the
precipitation lifting northward and becoming more focused near the
Kansas/Nebraska border before finally diminishing by mid to late
morning. However, there is uncertainty with whether or not any
additional convection will develop near the stationary boundary
and/or along any of the lingering outflow boundaries this afternoon. While a
few models are hinting at this redevelopment, they vary with regards
to the location of the precipitation. At this time, have increasing
PoPs during the afternoon hours into this evening across the
northern half of the forecast area. A stronger embedded shortwave
may once again track across north central Kansas into Nebraska late
tonight, supporting overnight convection primarily near the
Kansas/Nebraska border. While the potential for severe weather is
low, cannot rule out some strong wind gusts and locally heavy rain.

With this set-up in place, temperatures are also a challenge for
today as they will be greatly affected by any precipitation that
develops. In general, expect slightly cooler conditions across far
northern Kansas where precipitation may linger this morning and
potentially redevelop this afternoon. However, conditions may still
heat up across east central Kansas as this region may stay mostly
dry through the day. Afternoon highs in this area could reach into
the mid/upper 90s with heat indices reaching into the 100 to 103
degree range. This area may be close to heat advisory criteria, but
due to the uncertainty in the development of any afternoon
convection, have not issued one at this time but will need to
closely monitor through the day. Low temperatures tonight are
expected to drop into the upper 60s north to low 70s south.

.LONG TERM...(Wednesday through Monday)
Issued at 401 AM CDT TUE AUG 26 2014

Wednesday will likely see an ongoing MCS across Nebraska as models
focus on areas north of the Kansas border. Expect outflow boundaries
to be present across the northern CWA and possibly some ongoing
convection through the morning hours. Left over boundaries may also
be a focus for additional development in the afternoon as well.
Wednesday night into Thursday energy will eject out of the Rockies
trough across western Kansas and Nebraska this along with the low
level jet should fuel yet another MCS across the Plains mainly
across Nebraska. Western Kansas convection will move east into the
CWA Wednesday night and into Thursday morning. Additionally Nebraska
MCS could also clip the northern counties and have maintained
highest probabilities of showers and thunderstorms to the north of

The models slowly move the upper trough across the Rockies and
Plains as it is cut off from the westerlies. The 00Z GFS and the 00Z
ECMWF continue to be in agreement with the speed of the trough
through the end of the week while the GFS ensemble mean is just a
tad faster as is the GEM with the passage of the trough axis across
eastern Kansas and western Missouri. Front should move into central
Kansas Thursday night into Friday then progress slowly across
eastern Kansas through Saturday. The front will be a focus for
convection as well as locally heavy rainfall as precipitable water
values of 1.50 to 2.00 inches will be in place. Good moisture
transport will continue each night across the plains as the low
level jet increases and larger scale ascent increases with the
approach of the upper trough. Some convection may linger into Sunday
in the east with another chance of thunderstorms late Sunday night
and into Monday as a wave moves through the Zonal flow across the
Central Plains. Temperatures will gradually cool by the end of the
week with Wednesday being the warmest day especially south of I-70.
Near normal temperatures in the upper 80s to lower 90s are expected
from Thursday through Monday.


.AVIATION...(For the 12Z TAFs through 12Z Wednesday Morning)
Issued at 644 AM CDT TUE AUG 26 2014

For the 12z TAFs, winds have shifted to the north with the stalled
front positioned near the TAF sites. These winds should veer toward
the southeast through the day as the boundary shifts a bit further
north. Scattered showers and thunderstorms have developed north and
west of KMHK and expect this scattered pop-up activity to continue
to develop near KMHK through mid to late morning. There is the
potential for showers and thunderstorms to redevelop this afternoon
along lingering boundaries from the early morning convection,
however there is too much uncertainty with regards to location let
alone occurrence to warrant a mention in the TAFs at this time, but
this potential will need to be monitored closely in future updates.




SHORT TERM...Hennecke
AVIATION...Hennecke is the U.S. government's official web portal to all federal, state and local government web resources and services.