Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 260837
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
337 AM CDT Fri Sep 26 2014

.SHORT TERM...(Today and Tonight)
Issued at 337 AM CDT FRI SEP 26 2014

Upper ridge remains in place from the southern Rockies to the
Northern Plains downstream of deep upper trough off the Pacific
Northwest coast. Water vapor imagery shows a weak upper low over
northern Missouri making slow southwest progress toward Kansas with
scattered mid cloud over various portions of the local area through
the night. Modes south flow continues in the lower levels east of
lee trough.

Only significant feature to monitor through tonight is the upper
low, which looks to meander west and north, nearest to northeast
Kansas. Decent forcing aloft occurs with this wave with deep but
rather weak isentropic ascent, but outside the layer from 5000-8000
feet AGL, moisture levels remain rather meager, and decrease tonight
as the 30-50 700mb dewpoint depression airmass measured on 0Z OUN
and FWD soundings comes north. Many recent runs of the short-range
models produce light propitiation in their first few hours of
output, but given lack of development and the overnight drying, have
little reason to add precip mention. Slightly cooler lower levels
keep highs in the lower to middle 80s with lows near persistence.

.LONG TERM...(Saturday through Thursday)
Issued at 337 AM CDT FRI SEP 26 2014

An upper level trough will continue over the mid Missouri Valley
Saturday and Sunday before weakening and moving southeast. A ridge
will build across the Plains ahead of an approaching upper trough in
the western states Sunday night and Monday. Models hint at a small
chance of precipitation Saturday night and Sunday morning across
parts of the western CWA in response to weak isentropic lift and on
the nose of the low level jet. Condensation pressure deficits are on
the order of 50 to 100mb for much of the area and soundings are also
rather dry below and above 700 mb so will continue with a dry
forecast for now, but continue to monitor later model runs. Highs
Saturday and Sunday will warm into the lower 80s with lows in the
upper 50s to lower 60s.

The next chance of precipitation arrives late Monday night through
Tuesday as the negative tilt upper trough moves across the Central
Plains. A cold front will stall from a low over the Western High
Plains into the Dakotas Wednesday in advance of the next upstream
upper trough approaching from the west. The front will slowly move
eastward Thursday and Thursday night as the upper trough moves
across the Plains. This will bring a chance of thunderstorms to the
area Thursday and Thursday night. Models differ on the Speed of the
front and upper trough progressing across the Plains late in the
period with the GFS more progressive than the ECMWF. Continued with
a model blend and kept precipitation through Thursday night. Highs
in the 80s will cool down into the 70s by Thursday with lows in the
60s.An upper level trough will continue over the mid Missouri Valley
Saturday and Sunday before weakening and moving southeast. A ridge
will build across the Plains ahead of an approaching upper trough in
the western states Sunday night and Monday. Models hint at a small
chance of precipitation Saturday night and Sunday morning across
parts of the western CWA in response to weak isentropic lift and on
the nose of the low level jet. Condensation pressure deficits are on
the order of 50 to 100mb for much of the area and soundings are also
rather dry below and above 700 mb so will continue with a dry
forecast for now, but continue to monitor later model runs. Highs
Saturday and Sunday will warm into the lower 80s with lows in the
upper 50s to lower 60s.

&&

.AVIATION...(For the 06Z TAFs through 06Z Friday Night)
Issued at 1118 PM CDT THU SEP 25 2014

Think models continue to struggle with the low level moisture
profile as many progs have CIGS that are not occurring. Because of
this think the isolated QPF forecasts may be overdone and will
maintain a VFR forecast based on persistence. If clouds do
increase, they should be well above 3 KFT.


&&

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

$$

SHORT TERM...65
LONG TERM...53
AVIATION...Wolters





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