Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 231745
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1245 PM CDT Tue Sep 23 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 328 AM CDT TUE SEP 23 2014

Upper trough making its way east out of the Central Rockies into
upper ridge over the Mississippi Valley. A rather sharp moisture
gradient existed ahead of the trough and south to southwest low
level trajectories were only allowing a slow modification to the dry
airmass and upstream precipitation from northwest Kansas into
northeast Nebraska early this morning had made slow east to
northeast progress since 0Z.

As the system comes east to just north of east today, isentropic
upglide and 700-850mb moisture convergence with the upper trough
weakens a bit today, likely at least in part due to diurnal
weakening of the low level jet, and short-range guidance is quite
similar with a slow drying trend to the precipitation. Still appears
western locations will see good coverage of precipitation early this
morning with what appears to be a weak MCV enter north central
Kansas at this writing. Should see a slow increase in intensity and
coverage tonight as upper trough axis sharpens bringing deeper
moisture on east in reinforced isentropic ascent. Far southeastern
locations will continue to be dominated by the dry low level
anticyclone and may well stay dry through tonight. Isolated to
scattered thunder still possible with modest elevated CAPE values
today and tonight. Bumped up temps a bit today with some late-day
clearing anticipated west and early day dry conditions east and
south.

.LONG TERM...(Wednesday through Monday)
Issued at 328 AM CDT TUE SEP 23 2014

Upper trof remains over the Central Plains on Wednesday as it
slowly weakens with time. Scattered precipitation chances diminish
to just slight chances by the evening hours as lift wanes and
temperatures aloft warm. Kept slightly cooler highs for Wednesday
with clouds and precipitation in the area. As rain ends, clouds
diminish and southerly winds return for Thursday, have highs near
80 and a dry forecast.

For Friday through Monday, a blocking pattern with coastal
longwave trofs and a 590dm high over the Northern Plains will
bring a dry forecast with high temperatures remaining around 80.
By late in the forecast, the pattern begins to break down, but how
it does so differs in long range models. Either case sensible
weather should remain similar as the weekend and will keep the
forecast as such.

&&

.AVIATION...(For the 18Z TAFs through 18Z Wednesday Afternoon)
Issued at 1244 PM CDT TUE SEP 23 2014

MAIN AVIATION CONCERN WILL BE SHOWER AND STORM CHANCES THROUGH
MUCH OF THE TAF PERIOD.

WATER VAPOR IMAGERY SHOWS A SHORTWAVE TRACKING OVER EASTERN
NEBRASKA. A BROAD AREA OF ISENTROPIC LIFT ALONG THE 310K SURFACE
REMAINS OVER NORTHERN KS AND WILL HELP TO KEEP SOME ISO-SCT SHOWER
AND STORM ACTIVITY TODAY. SEVERE STORMS ARE NOT EXPECTED. THERE
MAYBE AN INCREASE IN CONVECTIVE COVERAGE AFTER 06Z AS A MID/UPPER
TROUGH MOVES INTO THE AREA. THIS WILL RESULT IN MOISTURE TRANSPORT
INCREASING IN THE 850MB LAYER. AT THIS POINT CONFIDENCE IN
COVERAGE IS NOT HIGH ENOUGH TO RUN WITH A PREVAILING GROUP AND FOR
NOW WILL JUST USE A VCTS/VCSH TONIGHT. CLOUD HEIGHTS AND
VISIBILITIES ARE EXPECTED TO REMAIN ABOVE IFR LEVELS AND LIKELY
ABOVE MVFR LEVELS THROUGH THIS TAF PERIOD.

LAWSON

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...65
LONG TERM...67
AVIATION...LAWSON





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