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FXUS63 KTOP 252325
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
625 PM CDT Wed Apr 25 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Thursday)
Issued at 317 PM CDT Wed Apr 25 2018

The closed midlevel cyclone responsible for the widespread rain is
currently located over central KS and will continue to progress
southeastward this afternoon and evening. The northern periphery of
the rain shield is currently located in north central KS and
southeast NE and is expected to migrate southward with the forcing.
Given the modest forcing timing of these features has been fairly
consistent among the models. Most locations should begin to dry out
between now and 9 pm with the latest departure near the I-35
corridor. The associated cloud deck is also expected to clear out
this evening.

A surface ridge builds across the area tonight therefore wind speeds
become light especially in the valley regions. In fact, soundings
show that winds will be light through a deep layer in the lower
troposphere. Given most areas have received a 0.25-0.50" of rainfall
today the soil will be relatively saturated. As radiational cooling
commences tonight the main challenge is how low the dew points will
decrease. This will have implications for the potential for frost
and fog. The latest guidance is suggesting low temperatures could
reach the lower to mid 30s across portions of north central KS
tonight. The uncertainty is will the latent and sensible heat from
the rain soaked ground keep the temperatures from supporting frost.
Also, there is some high-level cirrus forecasted to spread across
the Central Plains from the northwest that could slightly inhibit
the radiational cooling. Fog will also be possible across most of
eastern KS once the clouds clear out and lasting until around
sunrise. There is a chance the fog could be dense especially in the
sheltered valleys. Tomorrow an elongated midlevel trough axis dives
southeastward over the upper Midwest and Central Plains, which
forces a weak cold front/differential moisture boundary through the
area in the afternoon and evening. It appears despite the relatively
deep mixing there is not enough upper forcing to remove the midlevel
cap in place for much convection besides potentially an isolated
high-based shower along the boundary in the evening. The highs
tomorrow trended down slightly, which could be due to the mid to
upper level clouds although generally in the 60s.

.LONG TERM...(Thursday night through Wednesday)
Issued at 317 PM CDT Wed Apr 25 2018

Surface high pressure builds in Thursday night behind the departing
upper trough into Kansas. Clearing skies are expected through the
evening hours with mostly clear skies expected after midnight. Winds
are expected to become light or calm Thursday night. Good radiational
cooling is expected and frost will be possible once again as
temperatures drop into the mid 30s across much of north central and
into northeast Kansas. Warmer temperatures in the low to mid 70s
Friday and Saturday with northwest flow aloft and a return of
southerly winds during the day on Saturday on the back side of the
retreating surface high. Northwest flow aloft transitions to a
southwest flow aloft late Sunday and continuing through mid week
next week.

Increasing southerly flow and tightening pressure gradient will
lead to gusty winds from Sunday through Tuesday. Temperatures are
expected to warm back into the upper 70s to lower 80s from Sunday
through Tuesday with 70s mainly on Wednesday. There is increasing
signal for showers and thunderstorms next Tuesday and Wednesday.
Shear and instability along with moisture will be sufficient for
some strong thunderstorms Tuesday and Wednesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 623 PM CDT Wed Apr 25 2018

Have another hour or two before MVFR cigs lift, but given todays
rainfall and clearing skies overnight, anticipate some BR at the
terminals overnight. Should break up not long after sunrise and
winds become west then northwest Thursday as the next system
approaches.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 8 AM CDT Thursday for KSZ008>010-
020>022-034>036.

&&

$$

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