Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 221750

Area Forecast Discussion
National Weather Service Topeka KS
1250 PM CDT Thu Mar 22 2018

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 257 AM CDT Thu Mar 22 2018

Early this morning the region was under northwesterly flow aloft due
to a broad mid-level trough stretched across the eastern U.S. and a
mid-level ridge over the Rockies gradually advancing eastward into
the central U.S. today into tonight.  A weak embedded wave was noted
within this mid-level flow over Nebraska, causing some mid-level
clouds to stream southward into northeast Kansas early this morning.
 At the surface, the center of high pressure was east of the CWA
with the advancing mid-level ridge helping to push surface low
pressure over the Rockies into western Kansas.  With this surface
low gradually advancing into Kansas today and tonight, models show
the pressure gradient increasing some over the CWA. As a result,
have increased the southerly winds some today, especially across
east central Kansas where wind gusts of 20-25mph will be possible
late morning into this afternoon.  Model soundings show the mid-
level cloud cover dissipating by early this afternoon as the
embedded wave near the area early this morning progresses further to
the east.  With mostly sunny skies and increasing southerly winds by
this afternoon, expect decent mixing with WAA boosting highs into
the upper 60s to low 70s from east to west across the CWA.  While
this southerly flow will advect some moisture into the area, minimum
RH values will likely drop to around 30% this afternoon over central
to east central Kansas.  With these dry conditions being co-located
with the breezy southerly winds, some areas of very high fire danger
are likely across portions of central to east central Kansas.

As the surface low advances further east tonight, model soundings
show some low/mid clouds building into the area through Friday
morning.  The combination of increasing cloud cover with southeast
winds overnight will cause lows to only drop into the 40s.

.LONG TERM...(Friday through Wednesday)
Issued at 257 AM CDT Thu Mar 22 2018

On Friday morning an upper-level jet streak and midlevel shortwave
trough will eject out over the Central Plains. Across eastern KS
pre-existing moisture and isentropic lift around the 295 K
surface beneath an EML could result in drizzle. Model soundings
show some steep lapse rates above the warm air advection that
could support some light rain showers. As the midlevel shortwave
progresses eastward during the day a surface cyclone deepens and
moves into central KS. It appears that the stout EML should keep
surface-based convection capped. During the evening areas near the
NE/KS state line will be closer to the trough and the associated
forcing as the wave tracks over NE. Therefore chances increase for
the cap to weaken and allow for elevated instability into the
overnight. It is still uncertain if there will be enough
instability for the threat of hail with these thunderstorms. With
PWATs over an inch a period of heavy rain may be possible. The
rain is expected to exit the area by sunrise Saturday morning.

Saturday will be mostly dry as mid/upper-level ridging builds over
the region. The post frontal air mass remains across the forecast
area Saturday and into Sunday, which means highs only reach the mid
50s to lower 60s. Return flow becomes better established late Sunday
as a mid/upper-level low pressure approaches the central Rockies.
The ECMWF is suggesting isentropic lift may result in some rain
showers Sunday afternoon and into the overnight while the GFS is
depicting an EML that would prevent convection until Monday
morning. Perhaps slightly better moisture advection could result
in elevated instability. During the day Monday a frontal boundary
enters the area. With the main longwave trough over the Rockies
there will be substantial northward mass flux over the plains. The
increased moisture will encounter the baroclinic zone and steep
midlevel lapse rates that could result in strong convection and
or heavy rain into Tuesday. The heavy rain may develop in the warm
sector south of the front or in the frontogenesis circulation
north of the front. A slight variation in the overall synoptic
set up could change the frontal position so confidence in the
details is low at this point.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1235 PM CDT Thu Mar 22 2018

Expect VFR conditions through Friday morning. A 30 KT southerly
low-level at 1200 feet will overspread the terminals Tonight
causing moderate low-level windshear of 25 to 30 KTS in the lowest
1500 feet. Stratus will move northward across the terminals after
15Z. The stratus will start out with ceilings of 3500 feet then
may lower towards 18Z.




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