Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 240059

759 PM CDT Sat May 23 2015

...Update to aviation forecast discussion...

Issued at 713 PM CDT SAT MAY 23 2015

Short term trends and some of the latest model runs show back edge
of precipitation likely staying out of north central KS for
awhile, so have decreased POPs in that area. Thunder will also be
most likely isolated, and mostly concentrated in the far east.
There will be a sustained period of at least moderate rain in the
east, mainly east of a line from Herington to Manhattan to
Marysville. Precipitation efficiency is high, and rainfall rates
up to an inch an hour have been observed from some of the heavier
cores. Another shortwave appears to be enhancing convection in
west TX and that could come up later tonight with another bout of
moderate to heavy rain.


.SHORT TERM...(This Evening through Sunday)
Issued at 357 PM CDT SAT MAY 23 2015

Flooding concerns remain front and center for the next 36 hours.
Although mesoscale influences will dictate who receives the
greatest amounts of rainfall it still appears that areas roughly
along and southeast of a Emporia to Topeka line will see
widespread 2 to 4 inches with locally higher amounts possible
tonight through Sunday as moisture transport is maximized tonight
throughout the area within a environment characterized by PWATs of
1.5 to 1.75". 850mb winds of 40-50kts will be rather uniform
across the region with no obvious signs of a boundary at this time
however there are signals that a weak wave/meso element across OK
could enhance convection and rainfall rates along/east of the
turnpike tonight. The more obvious waves will arrive Sunday which
should act to back winds and support another round of heavy rains
across the eastern third of the area or roughly along and east of
highway 75. MUCAPE is fcst to remain modest AOB 500j/kg tonight however
given warm rain process and moisture transport rain will still be
locally heavy with training expected.

Have expanded the flood watch area to include Geary, Riley,
Pottawatomie and Nemaha counties given ongoing convection and
continued trend of short range models to shift axis of heavy rains
a bit further NW.

.LONG TERM...(Sunday Night through Saturday)
Issued at 357 PM CDT SAT MAY 23 2015

Have increased precip chances/amounts somewhat Sunday evening with
somewhat slower trend of ECMWF and GFS Ensembles, though at this
point amounts look low, but by this time small amounts could keep
flooding going and keeping the Watch through Sunday night. Differences in
the handling of the stronger/larger scale upper waves continue in
the latest models. The strongest feature still remains well south of
the area as it rotates northeast, with more spread in the weaker
wave passing through Nebraska Memorial Day and Monday night. Better
both lower and upper level forcing appears to stay to the northwest,
but in the weak overall flow and mean trough axis in place, will
keep chance PoPs going. Instability continues to look rather
impressive by mid afternoon with modest shear, giving rise to at
least some severe weather potential if storms can form.

Precip chances continue for much of the remainder of the week
continues. A weak surface trough sags in from the northwest for at
least small thunder chances again Tuesday afternoon and evening.
Though likely weak, isentropic upglide develops behind the
boundary  Wednesday into Wednesday night before the next slow moving
longwave trough approaches from the west. Moisture turn to the west
keeps chances going Thursday night with trough nearing and some
potential for a front to sag in around Friday night. Have the
highest chances in the latter periods with better overall forcing.
Overall weak flow should keep severe weather potential
climatologically low, and if repeated convection does occur the main
focus could again be flooding.


.AVIATION...(For the 00Z TAFs through 00Z Sunday Evening)
Issued at 713 PM CDT SAT MAY 23 2015

Periods of rain, occasionally moderate to heavy will continue at
TOP and FOE throughout the night. This should keep things in the
MVFR range with IFR visibilities in heavier rain. At MHK, precip
should be lighter for the most part and it will likely be VFR
until low-level stratus comes in later tonight. MHK could also
have gusty east winds on the west side of precip area. On Sunday,
there may be a break late morning to mid afternoon before another
chance of rain and thunderstorms come in later in the day.


FLASH FLOOD WATCH through Monday morning FOR KSZ011-012-022>024-



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