Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 212302

602 PM CDT Thu May 21 2015

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Friday)
Issued at 335 PM CDT THU MAY 21 2015

Surface high pressure was located over much of Kansas this
afternoon. Return flow on the back side of the high was relegated to
the western high plains. Shortwave energy rotating around the base
of the eastern Pacific trough this afternoon will move northeast
into the Central Plains later tonight and Friday morning. Models are
in fairly good agreement with the energy lifting across eastern
Kansas in the morning and afternoon hours. Forecast soundings show
increasing mid level moisture late tonight and into Friday west to
east. Showers will be rather light and go into saturating the lower
layers through the day. The surface and 850mb high will move off to
the east allowing for a return of moisture into Oklahoma and
southern Kansas in the morning then increasing northward through the
afternoon hours, especially across north central Kansas. Have
maintained the focus for precipitation across north central into
east central Kansas through the day with lower slight chances across
far northeast Kansas. Rainfall amounts will be light through the day
and am not expecting any runoff issues. Thunderstorm chances look
small with little or no CAPE through the afternoon hours expected,
although shear will be marginal, so will stay with showers attm.
Lows tonight in the mid and upper 40s with light winds and gradually
increasing cloud cover. Highs Friday in the 60s with clouds and
scattered precipitation.

.LONG TERM...(Friday Night through Thursday)
Issued at 335 PM CDT THU MAY 21 2015

Weak to moderate but fairly deep isentropic upglide sets up Friday
night. This allows for a steadily moistening column and a decent
setup for precip, with increasing trends through the night. Have
kept mid-range PoPs area-wide with no obvious area of focus. The
isentropic lift diminishes Saturday but increasing moisture with PWs
nearing 1.5" keeps moderate PoPs going. Instability continues to
look difficult to come by well into Saturday but enough for thunder
mention to ramp up with time. Main precip event looks to come
Saturday night into Sunday evening as the upper trough to the west
slides east. There is rather good agreement in a mesoscale
convective system maintaining itself as it comes northeast from west
Texas Saturday afternoon, aided by south 850mb winds around 30kt in
a rather wet atmosphere. There is also good agreement in the trough
producing another to a few rounds of convection Sunday into Sunday
evening with some training as well as and skinny and modest CAPE
potential. Have continued to raise PoPs for these periods. At this
point it appears the eastern half of the area will see the highest
precip in deeper moisture. With wet ground and elevated river
levels, flooding continues to be the main concern, perhaps more so
for rivers than flash flooding, but both types remain possible.

Medium range guidance agrees on west to southwest flow persisting
well into next week, but differ on how modest waves from the western
trough make their way east. There could be a weak boundary sinking
in around around Memorial Day for an increased and more focused
precip chance per the latest GFS, but overall scenario keeps chance
PoPs (only slightly above normal) going through the forecast with at
least lower levels remaining moist and little if any capping
occuring. Severe weather concern remains muted with low values of
both shear and instability parameters. Temps should continue to warm
however with more breaks in precip expected.


.AVIATION...(For the 00Z TAFs through 00Z Friday Evening)
Issued at 555 PM CDT THU MAY 21 2015

VFR conditions are likely through the TAF period. Scattered
showers will approach MHK around 16Z...and TOP/FOE closer to 19Z.
Likelihood of widespread or persistent rain at any site is low,
but scattered showers could continue through the afternoon.




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