Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 010446
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1146 PM CDT Sun Apr 30 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Monday)
Issued at 325 PM CDT Sun Apr 30 2017

The 500 mb upper low was over south central Kansas at 18z. The low
had become vertically stacked with the surface low in the same
general area. The radar mosiac was showing showers near the low
center expanding diurnally early this afternoon. This shower
activity should move through northeast Kansas late this and evening
along with the upper low. The coverage should decrease some this
evening but will keep pops going. The brunt of the deformation zone
precipitation should miss our area to the northwest, but a
diminishing band of precipitation is forecast to traverse northeast
Kansas tonight. Cloud ice will be marginal for sn and since the
boundary layer temperatures remain warm enough to keep the
precipitation rain, will not mention sn in the forecast.  It would
not be surprising to see a little wet snow mix in up along the
Nebraska border where surface temps are in the upper 30s. Once the
front moves through as the surface low moves out, the pressure
gradient tightens which supports increasing westerly winds. Dry
weather on Monday with decreasing clouds. The airmass should mix
well allowing gusty winds in the mixed layer of around 30KT to mix
to the surface. Temperatures on Monday will still be around 10
degrees F below normal for May 1.

.LONG TERM...(Monday night through Sunday)
Issued at 325 PM CDT Sun Apr 30 2017

By Monday night, the surface and mid-level lows will be moving into
the Great Lakes region with west-northwesterly flow in place across
the central U.S.  These light westerly winds combined with generally
clear skies will keep low temperatures Monday night in the low/mid
40s.  Expect dry conditions Monday night through Tuesday before the
next system approaches the region.  Despite increasing cloud cover
through the day, highs should rise into the mid/upper 60s.

There will be two areas of focus that will contribute to
precipitation chances during the Tuesday night through Wednesday
night period.  At the surface, low pressure will be tracking into TX
with an associated warm front stretching northeastward across OK and
should hover near the KS/MO/AR/OK borders.  Models show scattered
precipitation developing along and north of this boundary, with
showers extending northward into central and east central KS Tuesday
night into Wednesday.  Do not anticipate thunderstorms with this
precipitation due to little to no instability present that far north
of the boundary.  The second area of focus is with an embedded
shortwave that models show developing over Montana Tuesday morning
and deepening into a mid-level trough as it dives southeast into the
High Plains and Central Plains Tuesday night into Wednesday. This
advancing mid-level trough will provide enough forcing to bring
additional precipitation chances into north central KS on Wednesday,
with precipitation shifting eastward across the CWA by Wednesday
evening. Model soundings show some weak instability aloft over north
central KS as this trough passes overhead, so have added a slight
chance of thunderstorms to that region Wednesday afternoon.  Much of
this scattered precipitation will end Wednesday night as the mid-
level trough progresses east of the CWA and develops a closed-low.
Models are now showing the potential for some light isolated
precipitation to develop on the back side of this exiting low on
Thursday across far northeast and east central KS, so have some
slight-chance PoPs in place.  As this deep mid-level trough advances
across the eastern U.S., a broad mid-level ridge will slide into the
central U.S.  Models continue to show a blocking pattern setting up,
with this ridge remaining anchored over the central U.S. late week
through next week, with the next closed mid-level low remaining over
the western U.S.

As for temperatures, the mid-week precipitation will keep highs
cooler in the 60s, but expect a moderating trend once the ridge
builds in, with high temperatures rising into the low 70s by Friday
and into the mid/upper 70s over the weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1144 PM CDT Sun Apr 30 2017

Kept similar track as previous TAF with cigs coming down and winds
picking up overnight. Do have some low MVFR/IFR cigs for much of
the morning hours, then clearing late afternoon. Added a line to
bring down winds in the evening.

&&

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

$$

SHORT TERM...Johnson
LONG TERM...Hennecke
AVIATION...67


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