Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 242327
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
627 PM CDT Tue Apr 24 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Wednesday)
Issued at 319 PM CDT Tue Apr 24 2018

A subtle midlevel shortwave is currently moving over southern NE and
providing the lift for an area of light rain now moving into north
central KS. This rainfall will gradually move eastward through the
late afternoon and evening. The lower troposphere is rather dry
therefore it may take some time for precipitation to reach the
surface. The high resolution guidance is suggesting isolated higher
precipitation rates that could saturate low enough for efficient
rain to reach the ground. The better chances appear to be locations
along and north of I-70 through the evening. Late this evening and
through the overnight the closed midlevel low pressure progresses
southward over central NE. During this time frame the differential
cyclonic vorticity advection will become maximized over eastern KS
causing more widespread rainfall. Isentropic ascent out ahead of the
wave will increase over portions of southern KS around midnight.
This lift will attempt to spread into east central KS enhancing the
rainfall rates in that area. Tomorrow morning midlevel low pressure
center tracks over central KS supporting another area of rain that
moves southward out of NE. This area of precipitation should track
across portions of northeast and east central KS until tomorrow
evening. The models have been trending slightly higher with the
rainfall amounts, which are now expected to range from 0.25-0.50 of
an inch. Some models are suggesting that locally higher amounts
closer to one inch are possible. Given the relatively lower
precipitation rates expected with this event and the dry spring
flooding is not of concern. Also, there is very limited instability
associated with this system therefore thunder appears unlikely.
Dewpoints should wet-bulb into the lower to mid 40s tonight, which
will dictate the low temperatures. Tomorrow the expansive cloud
cover and precipitation along with the post frontal air mass keeps
highs in the mid to upper 50s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 319 PM CDT Tue Apr 24 2018

The upper level trough initially over southeast and east central
Kansas early Wednesday evening, will move southeast into Arkansas by
late evening. Expect some precipitation chances through the evening
hours in the deformation zone. After midnight skies will clear in
the north central and northeast before increasing once again on
Thursday with the approach of the next upper trough. Some patchy
frost will be possible toward sunrise on Thursday mainly west of a
Marysville to Bennington line as temperatures dip into the mid 30s
with light to calm winds expected in these areas. Models continue to
differ slightly with the upper trough with timing on Thursday with
the NAM the slower of the solutions. Will continue to go with blend
of solutions with a lean toward the ECMWF/CMC and GFS. That said, a
cold front is forecast to move southeast across the cwa through the
day with gusty northwest winds behind it. QPF varies with the
models, but low level moisture with dew points approaching 50
degrees across east central Kansas, will increase thunder potential
in the afternoon. Soundings suggest around 600 J/kg and there
appears to be sufficient shear for a few storms in the afternoon.
The trough quickly moves through thursday night with a ridge
building in for the weekend with a transition to a southwest flow
early next week as a trough deepens in the western states. A warm
and dry weekend is expected with highs in the 70s continuing through
next Tuesday. Energy ejecting out of the western trough and waa may
bring a chance for showers and a few storms next Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 625 PM CDT Tue Apr 24 2018

Forecast similar to previous but sped up the cigs and lower visby
a few hours. Also added a wind shift and additional reduced IFR cigs
and visby for Wednesday afternoon as the upper low continues to
move through the state. Conditions should start to improve after
this TAF period.

&&

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

$$

SHORT TERM...Sanders
LONG TERM...53
AVIATION...67


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