Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 241136

636 AM CDT Thu Jul 24 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 349 AM CDT THU JUL 24 2014

Water vapor imagery this morning showed the broad mid-level ridge
still anchored across the Rockies, resulting in northwesterly aloft
across the forecast area. A few weak embedded shortwaves were noted
along the northern edge of the ridge axis over South Dakota. While
these waves should progress southeastward along the ridge axis, most
models show any precipitation that develops from these waves to
remain north of the forecast area. It`s worth noting though that
recent early morning runs of the HRRR and RAP have started to show
precipitation from these shortwaves diving further south along the
Nebraska/Iowa border and skimming near far northeast Kansas by this
afternoon. However, due to the agreement of the synoptic models in
keeping precipitation north of the area and with the fairly poor
performance of these short-range models over the last few days, have
gone with a dry forecast for today but will continue to monitor
these shortwaves through the day.

Surface high pressure was situated over the region early this
morning, resulting in light winds, mostly clear skies, and cooler
conditions as temperatures dropped into the 60s. This surface high
gradually will shift eastward toward the Ohio River Valley, with
winds shifting to the southeast today and further to the south
overnight. These southeasterly winds today will keep temperatures
near or slightly below the seasonal normals as afternoon highs
should reach into the mid 80s east to low 90s west.

Water vapor imagery showed a mid-level trough and closed-off low
moving onshore in the Pacific Northwest, and models show this low
progressing eastward along the U.S./Canadian border over the next
few days. This advancing low will help to flatten the mid-level
ridge currently in place, resulting in the area of surface low
pressure currently over the northern Rockies being pushed southward
into the High Plains tonight. Model soundings show high clouds
building in over the region tonight, so this cloud cover combined
with southerly winds will result in better insolation and keep low
temperatures tonight a few degrees warmer in the upper 60s to mid

.LONG TERM...(Friday through Wednesday)
Issued at 349 AM CDT THU JUL 24 2014

Friday, the upper level ridge builds into northeast Kansas with the
edge of the westerlies over Missouri and Iowa. Thermal axis will
develop across the Central Plains ahead of a surface trough/front
that is expected to slowly move across Nebraska and into north
central Kansas by Friday evening. Dew point temperatures in the
middle 60s in north central Kansas and near 70 in northeast Kansas
will combine with afternoon temperatures from the upper 90s in far
eastern counties to around 105 toward central Kansas to produce
afternoon heat indices of 104 to 109 and will likely need a heat
advisory for the day on Friday.

The frontal boundary will slowly move south Saturday and Saturday
night settling in southern Kansas by Sunday morning as the upper
level ridge is suppressed westward as an upper level trough moves
across southern Canada and the Northern Plains. A unstable airmass
develops across northern Kansas Saturday with CAPE of 2500-5000 J/kg
and moderate shear. Soundings show inverted V cap eroding by late
afternoon and could see some isolated thunderstorms developing. If
they do develop then damaging wind gusts will be the main hazard.
Saturday will be a little cooler than Friday due to the presence of
mid and upper level clouds. However temperatures will range from
the  lower 90s along the Nebraska border to around 101 near central
Kansas. Dew points in the upper 60s to around 70 will combine with
the temperatures to produce heat indices of 99 to 104.

Cooler temperatures and dry weather are expected on Sunday in the
wake of the front and this should continue into mid week with
northwest flow aloft and high pressure over much of the Central
Plains. The next chance of precipitation comes Tuesday night and
Wednesday with the western counties having the best chances. Both
the GFS and ECMWF indicate mid level waves moving through the
northwest flow.


.AVIATION...(For the 12Z TAFs through 12Z Friday Morning)
Issued at 636 AM CDT THU JUL 24 2014

For the 12z TAFs, VFR conditions are expected through the period.
Calm winds this morning will increase out of the southeast today and
persist at roughly 8-10kts through the afternoon and evening hours.
Expect the wind direction to begin shifting more to the south by
Friday morning as the next system approaches the region.




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.