Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 022312
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
612 PM CDT Sat May 2 2015

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Sunday)
Issued at 404 PM CDT SAT MAY 2 2015

19Z water vapor imagery shows a shortwave moving across IA while
500MB profiler data suggests a more subtle wave has passed through
eastern KS. Meanwhile a weak mid level ridge has propagated east and
is centered over the TX big bend region with the mean westerlies
remain north along the Canadian boarder. At the surface, high
pressure over the southeast U.S. and low pressure in the northern
plains has favored continued moisture advection with southerly winds
bringing mid 50s dewpoints into the central plains.

For tonight and Sunday, large scale forcing continues to be absent
from the pattern. However models hint at the possibility for
sporadic shower activity as early as this evening. The HRRR and RAP
are the most optimistic in generating the shower activity. It
appears the evening QPF is driven by warm air advection and
isentropic upglide around 700MB. However RAP soundings suggest
moisture will be rather limited in this layer. Because of this and
the general subsidence behind the subtle wave, am not convinced
showers will redevelop across central KS this evening. There are
also signs that another subtle wave could come out of the CO Rockies
late tonight and Sunday morning with some elevated light shower
activity. There is a more organized signal in the isentropic
surfaces of a shallow layer of lift Sunday morning. With bases at 10
KFT and little if any instability above this layer, am not sure any
precip would amount to much and it end up being mainly virga. So
have maintained a dry forecast for now, but there could be some
light hit or miss precip with not much impact. Thanks for the
collaboration EAX and ICT.

Southerly winds and increased low level moisture should help keep
lows tonight around 60 degrees. Increasing clouds from the west
should also help keep overnight lows mild. With continued southerly
winds, models continue the warming trend at 850MB with good mixing.
Therefore have maintained highs in the lower and mid 80s. However if
there is elevated shower activity, the forecast may be to warm for
areas that remain cloudy.

.LONG TERM...(Sunday Night through Saturday)
Issued at 404 PM CDT SAT MAY 2 2015

Several opportunities for precipitation remain present through the
forecast, with challenges on where and when the higher chances will
be being the main challenge.

The main trend in the nearer periods is the trend for a farther
north settling of the cold front as it enters the area. Getting the
front much past the northwest counties could be difficult with
little/no additional frontogenesis from convection through Sunday
afternoon along it and west to southwest flow over it. Have
continued to taper precip chances, especially in the south into
Monday night. There continues to be at least minor potential for
severe weather and perhaps training storms near the boundary. NAM
continues to look overdone with low level moisture and thus CAPE,
but values near 2000 J/kg seem possible along the front with flow
aloft nearly parallel to the boundary with slow cell motions and PWs
near 1.5", more likely late Monday into Monday night.

The front/effective front remains on track to mix back north Tuesday
with some drier air moving in through the day, but attention then
turns to the southwest as an upper wave remains on track to push
slowly northeast through the Central Plains Tuesday night through
Wednesday night. Models are fairly consistent with better upper
forcing to the northwest and southeast, but also with widespread
convection developing to the south-southwest and translating through
late Tuesday night into Wednesday. Beyond Wednesday night, there
continues to be indications of a weak boundary near to just west of
the area with continued moisture availability into the area into
Saturday.

&&

.AVIATION...(For the 00Z TAFs through 00Z Sunday Evening)
Issued at 611 PM CDT SAT MAY 2 2015

VFR conditions expected through the taf period.

&&

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

$$

SHORT TERM...Wolters
LONG TERM...65
AVIATION...Sanders





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