Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 232057

357 PM CDT Sat May 23 2015

.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 18Z TAFs through 18Z Sunday Afternoon)
Issued at 1227 PM CDT SAT MAY 23 2015

The next 24 hours is a very tricky forecast period. Bottom line is
all terminals will experience IFR GIGS at times generally
beginning mid-afternoon today. IFR VIS is not out of the question
as precipitation picks up later tonight. Don`t think an extended
period of rainfall is out of the question, which is why showers
stay in the forecast. The possibility of a period of thunderstorms
in the local areas does set up this evening with the better window
for instability. Very late in the forecast period, the conditions
should begin to show some improvement, but have chosen to not add
another line in for now as this will be the very tail end of the
forecast period and will need further evaluation at the next
forecast update.


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



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