Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 261719

1219 PM CDT Sun Apr 26 2015

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 335 AM CDT SUN APR 26 2015

East northeast flow around a high pressure centered in western
Ontario continues to keep an extensive area of cloud cover across
much of Missouri, Kansas and Nebraska. Clouds will hang on for much
of the morning hours before dissipating through the afternoon hours.
East northeast surface winds will continue through the day and
strengthen this afternoon as pressure gradient increases between the
high and a surface low over the western Texas Panhandle. Highs today
are expected to top out in the lower 60s.

Tonight, the surface high will build south into northern Kansas
through the night while the surface low moves east into north
central Texas. An upper level shortwave trough located over Arizona
this morning is forecast to move east into the Texas Panhandle.
While most of the north central and northeast Kansas will be clear
some increase in clouds is expected across parts of central and east
central Kansas. The lower boundary layer remains mixed overnight and
winds of 5 to 10 mph will be common with dry air advection and
should keep any fog formation at bay. Lows tonight should cool into
the upper 30s along the Nebraska border to the lower 40s elsewhere.

.LONG TERM...(Monday through Saturday)
Issued at 335 AM CDT SUN APR 26 2015

The chances for the nearly the entire forecast to remain dry are
rather high. Models are in good agreement with Rockies upper trough
becoming cut off from the northern branch and tracking east along
the Red River Monday through Tuesday night. The GFS continues to be
an outlier with a secondary wave rotating north into Oklahoma and
deeper moisture and even a weak elevated TROWAL into east central
Kansas. Even with this feature, lower level east flow from modified
Canadian high pressure keeps the lower 10k-15k feet layer dry and
difficult for anything more than very light precip to result. At
this point will leave a very small rain mention in far southwest and
southern locations Monday and Monday night but anything more than
trace amounts even here seem unlikely. Will keep highs in this area
slightly cooler with mid 60s elsewhere. Upper ridge pokes northeast
into south central Canada from the Great Basin for much of the
midweek. There remain some suggestions of a weak front passing south
into the area behind a weak wave downstream of this ridge but any
airmass change will be hardly noticeable the atmosphere still
stable. The 0Z ECMWF and GEM bring shortwave energy south behind the
old low around Wednesday but again expect a lack of moisture to keep
things dry even if this wave placement did verify. Models are
similar and consistent with earlier runs in the western ridge
breaking down as a trough works east across the northern Rockies,
with a modified cold front sliding into the area Friday night. Some
moisture return on south winds ahead of the front may be able to
destabilize conditions for some chance for convection along the
stalled boundary Saturday. Would normally be quite hesitant to go
with this scenario this far out, but given model consistency will go
along. Highs should rise rather steadily into the middle and upper
70s by the late week, possibly topping 80.


.AVIATION...(For the 18Z TAFs through 18Z Monday Afternoon)
Issued at 1209 PM CDT SUN APR 26 2015

MVFR ceilings at onset of TAF are expected to scatter from east to
west this afternoon, likely between 20Z and 21Z at TOP/FOE...and
between 21Z and 22Z at MHK. VFR conditions are likely through the
rest of the TAF, but if winds become very light overnight would
have a chance for shallow fog to develop especially at TOP/MHK.
Currently expect winds to stay strong enough to prevent fog.




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