Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 172329

629 PM CDT Sun May 17 2015

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Monday)
Issued at 404 PM CDT SUN MAY 17 2015

Water vapor imagery at 20Z shows the closed upper low lifting
northeast over the northern plains, while very weak embedded pv
anomalies rotate southward over western and southern Nebraska.
Strong southwesterly winds through the column today continue to
advect high clouds into the CWA for this evening. Otherwise the cold
front currently over northwest Kansas and southern Nebraska is
expected to shift southeast through the area tonight. Short term
guidance tries to develop isolated thunderstorms north and west
across southern Nebraska. Noting that the data is not similar with
the current or previous hours lead me to discredit the coverage of
showers this far south. Will need to monitor, but believe they
should remain north of the CWA.

Cold air advection increases during the day Monday as northwesterly
winds pickup between 10 and 20 mph sustained. Skies remain mostly
sunny with temperatures much cooler in the upper 60s to lower 70s.

.LONG TERM...(Monday Night through Sunday)
Issued at 404 PM CDT SUN MAY 17 2015

More chances of rain and some isolated storms set up over the next
week over the region.  Tuesday through most of Tuesday evening
should still be mostly dry as northeastern KS is still under the
influence of an area of Canadian high pressure at the surface with
weak ridging through the mid levels of the atmosphere.  Early
Wednesday morning is when the next measurable rain chance will work
into the region as weak shortwave energy gets ejected from the
Central and Southern Rockies.  Still not looking for any major severe
weather but some isolated thunder is possible for a brief period in
the morning as the shortwave creates some weak forcing working over the
region and better isentropic lift sets up.  This all looks to be
quick moving through the day as the pattern de-amplifies into a more
zonal flow set up.  Fairly good confidence in 6Z-18Z being the best
window of opportunity for precip, so have kept POPS high during
these times.  Highs remain lower with the precip and clouds in the
upper 50s and low 60s, with Wednesday the cooler of the mid-term
period.  Lows will dip into the upper 40s.

Heading into Memorial Day weekend appears to set up similar to the
recent pattern that has been in place.  That being one of a deeper
trough setting up over the Western CONUS.  Weak ridging sets up for
Thursday and most of Friday.  A shortwave brings chances for rain
yet again on Saturday, but instability still looks minimal, so only
a small chance for isolated thunder forecast at this point.  Sunday
does appear to be another potentially interesting set up similar to
what has been taking place as the upper trough moves out of the
Rockies.  However, the GFS and EC solutions differ quit a bit.  The
GFS tries to deepen the low and thus create more of a potential
severe setup.  The EC actually projects that the upper trough will
remain and open wave and continue to weaken as it lifts up into the
Central and Northern Plains.  At this point, it is far out and will
need to be refined in subsequent forecast periods.


.AVIATION...(For the 00Z TAFs through 00Z Monday Evening)
Issued at 629 PM CDT SUN MAY 17 2015

For the 00z TAFs, VFR conditions are expected through the period.
Winds will shift from southwest to north by Monday morning as
surface high pressure moves into the region.




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