Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 231121

621 AM CDT Wed Jul 23 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 328 AM CDT WED JUL 23 2014

As of early this morning, the cold front had tracked just south of
the forecast area, with surface high pressure centered over the
Northern Plains spilling southward into the region behind this
front. While temperatures have cooled down some with the shift to
northerly winds from the frontal passage, moisture has pooled behind
the front, resulting in dewpoint temperatures rising into the low/mid
70s. These dewpoints combined with temperatures in the 70s to near
80 degrees was keeping overnight heat index values in the mid/upper
80s for much of east central Kansas. This pooling moisture had
shifted south of far northern Kansas so dewpoint temperatures had
dropped into the upper 60s/near 70 degrees. Water vapor imagery
showed the fairly-unchanged mid-level ridge centered over the
central and southern Rockies with a few weak embedded shortwaves
developing along the northeastern edge of the ridge axis. These
shortwaves, with the help of some weak isentropic lift, have been
able to produce some scattered showers and thunderstorms early this
morning across southwest South Dakota and over southwest/south
central Nebraska. These storms were tracking southeast and if they
are able to sustain themselves, there is a chance that a few storms
may skim near the southwest part of the forecast area, so have
slight chance PoPs in for that area through around sunrise.

For today, surface high pressure will continue to spread across the
region with light northeasterly winds keeping temperatures
near-normal in the mid 80s northeast to the low 90s southwest.
Cooler dewpoints in the mid 60s to near 70 degrees are expected
today, so heat indices should only reach into the low/mid 90s this
afternoon. The mid-level ridge should shift a bit further east into
the Central Plains today and tonight. Most models are showing the
potential for additional embedded shortwaves to develop along the
northeastern edge of the ridge today and tonight, however there is
still some uncertainty with regards to the exact location and
tracking of these waves. In general, these shortwaves should stay
north of the forecast area, however the NAM and GFS both suggest
that storms from these waves may track into far northern Kansas
overnight into Thursday morning. Due to the uncertainty in any
storms from these shortwaves actually tracking into the forecast
area overnight, have kept a dry forecast at this time for today and
tonight but will need to continue to monitor the trends with these
shortwaves through the day. The surface high pressure will start
shifting east of the area tonight with winds gradually veering to
the southeast. Models are trending a bit cooler with temperatures
tonight, so have lows ranging from the mid 60s east to the upper 60s

.LONG TERM...(Thursday through Tuesday)
Issued at 328 AM CDT WED JUL 23 2014

Lift over a warm frontal boundary along with weak upper level wave
may bring some isolated to scattered thunderstorms across northeast
Kansas Thursday morning. Models also show some weak isentropic lift
in the 305K-310K layer as well early Thursday morning. By afternoon
the upper support will come to an end as the wave moves off into
Missouri in the northwest flow aloft. The warm front will move from
west to east across the cwa on Thursday and expect highs in the mid
90s in north central Kansas with lower 80s in the far northeast

An upper level high will push east through Thursday night through
Friday. Models suggest another wave will move southeast and bring a
chance of thunderstorms back into the forecast mainly across
northeast Kansas. On Friday a boundary will move into the northern
counties by the evening hours. Thermal gradient increases across the
cwa with temperatures once again reaching around the century mark
and with humidity will yield heat indices around 105 degrees Friday
afternoon and will likely need a heat advisory.

An upper level trough is forecast to move across the Northern Plains
on Saturday and slowly move a cold front southward across the
Central Plains. The upper trough will shove the upper high back to
the west over the Rockies with northwest flow reestablishing over
much of the Central Plains. Little in the way of upper support or
forcing until Saturday night and Sunday and have kept a chance of
showers and thunderstorms for these periods. Beyond Sunday the ridge
builds in the western states as the upper trough deepens over the
eastern CONUS. This will bring cooler temperatures back for the
start of the week and continue into midweek with below normal
temperatures for late July.


.AVIATION...(For the 12Z TAFs through 12Z Thursday Morning)
Issued at 620 AM CDT WED JUL 23 2014

For the 12z TAFs, cigs should remain VFR through the period. Winds
will prevail out of the northeast today before veering to the
southeast overnight with the eastward shift of the surface high




SHORT TERM...Hennecke
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