Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 240441
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1141 PM CDT Mon Apr 23 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Tuesday)
Issued at 259 PM CDT Mon Apr 23 2018

Mid/upper level closed low pressure is still meandering over the mid
MS valley. The associated cloud cover has moved off to the southeast
allowing for ample heating. Temperatures have been warmer than a
majority of the guidance, but highs in the lower to mid 70s seem to
be on track. At the surface a ridge extends from central TX
northward into northern WI. Wind speeds should decrease this evening
as the pressure gradient relaxes allowing for a modest nocturnal
inversion. The lower tropospheric moisture has decreased since
yesterday and there has been deep afternoon mixing today, which
should limit any fog development late tonight. Tomorrow, a closed
midlevel low pressure progresses southeastward over the northern
High Plains. A cold front will extend southward and move into
portions of central KS in the afternoon. There should be some
upper-level diffluence and differential cyclonic vorticity
advection that should provide some large-scale lift. Models are
also showing isentropic lift on the 300-305 K theta layers, but
mainly confined over central and southwestern KS. Some of that
lift may move over east central KS Tuesday night.

.LONG TERM...(Tuesday night through Monday)
Issued at 259 PM CDT Mon Apr 23 2018

There may be a lull in the precipitation Wednesday before the
midlevel low tracks overhead another round of enhanced vertical
motion. The better instability looks to stay south of the forecast
area so expected mainly rain showers. Midlevel lapse rates will be
marginal on Wednesday, but the operational GFS and a few GEFS
ensemble members are suggesting 200-300 J/kg of MUCAPE. Perhaps if
there is some surface heating as the lift becomes juxtaposed over
east central KS there could be some isolated thunderstorms. This
seems unlikely given the expansive cloud cover that is forecasted
over the area. Rainfall amounts for this event are expected
around 0.25-0.35 inches across the entire area. The next midlevel
trough axis progresses southeastward over the upper Midwest and
Northern Plains Thursday afternoon, which will send a front into
the eastern KS. The main challenge will be the lower-level
moisture recovery in the wake of the previous system along with
the midlevel lapse rates. As of now it appears moisture will be
very limited and only supportive of maybe isolated storms. The
quick moving front exits the area on Thursday evening. A midlevel
ridge builds over the central US into next weekend, bringing dry
conditions and seasonable temperatures.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1134 PM CDT Mon Apr 23 2018

Forecast should hold for VFR CIG/VIS during the period. The
exception may come with a shower last portion of the period near
KMHK, but any precip is expected to be light. Therefore, VFR
conditions should still persist with mainly mid-level cloud cover.

&&

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

$$

SHORT TERM...Sanders
LONG TERM...Sanders
AVIATION...Drake



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