Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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000
FXUS63 KEAX 272109
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
409 PM CDT Wed Aug 27 2014

.SHORT TERM...(This Evening through Saturday Afternoon)
Issued at 408 PM CDT WED AUG 27 2014

Turned out to be a fairly busy day as heavy rains impacted portions
of northwest Missouri overnight into the daylight hours. In
fact...gage and local COOP reports indicted close to 5" of new rain
across Atchison County, MO...with even higher amounts likely due to
continued rainfall through early afternoon. Concerns continue to rise
this afternoon for another heavy rainfall event tonight...but we/ll
address those concerns a little later.

Local radar showing weak convection across southeastern portions of
the fcst area this afternoon...as redeveloping southerly flow begins to
ascend the convectively reinforced stalled front to our south. Though
severe is not expected at this time...a strong wind gust to two
cannot be ruled out before activity decreases with loss of daytime
heating early tonight.

Moving on to the overnight...concerns quickly shift to possible heavy
rainfall event as large scale trough drops from the central Rockies
into the high Plains. As this occurs...fcst models in excellent
agreement that a leeside low will track northeast through the central
Plains which will result in gradual northward movement of the
stalled front as a southerly LLJ of 30-35 kts strengthens over time.
Models in recent days have had a difficult time in determining where
the heaviest QPF axis would occur...and today/s model suite is no
different as the GFS and high-res ARW and NMM members maintain the
furthest southward position /i.e. over NW MO/. Considering this
morning/s outflow essentially kept the front in place much of the day
today...forecaster consensus amongst WPC and several surrounding WFOs
has been to follow the further southward position. As a
result...portions of our area will be under the gun once again for
renewed convection and heavy rainfall as we progress through the
overnight period tonight into Thursday morning.

As a possible clue...Blended TPW and Percent of Normal satellite
products showing PWAT values close to 2" across the area today /2-3
standard deviations above normal/. Meanwhile...experimental layered
RH satellite fields showing upper-level moisture actually being
advected our way from Hurricane Marie over the western Pacific as
southerly flow intensifies ahead of approaching upper trough axis. As
a result...have elected to go with a flash flood watch which will be
in effect from 3z through 15z Thursday. Would not be surprised to see
a few 2-3 inch reports up north and considering 1 and 3 hr flash flood
guidance is extremely low due to earlier heavy rainfall...see no
reason not to have a watch in place.

Shwrs/storms should gradually begin to die down Thursday morning as
front retreats north into Iowa and Nebraska. With area residing in
the warm sector once again...afternoon high temps on Thursday should
rebound back into the upper 80s and low 90s across much of the
region. Shwrs/storms to begin redeveloping once again on Friday as
main upper trough axis begins to approach the west. Will have to watch
how things transpire Thursday morning to see if any additional hydro
headlines will be needed through late week. Main trough and associated
cold front to pass through the area on Friday night into Saturday.
Have offered likely pops across much of the area Friday night before
showing a gradual drying trend through the day on Saturday.

.LONG TERM...(Saturday Evening through Wednesday)
Issued at 408 PM CDT WED AUG 27 2014

Upper troughing still in place over the region for the second half
of the weekend. This will result in additional chances of
precipitation Saturday night into Sunday. Both ECMWF and GFS
indicate the nocturnal jet strongest over west central Kansas...but
the GFS favors precipitation developing on the nose of the jet and
towards the east and the ECMWF prefers the Dakotas during the night
on Saturday.

By Sunday...Upper level jet digging into the northern or central
Rockies helps induce lee side cyclogenesis. This along with a
thermal ridge axis out ahead of surface feature will turn surface
flow more southerly ushering in additional moisture. Too early to
say how much capping we will have during the day...so keeping PoPs
at slight chance through the day on Sunday is reasonable. In
addition...temperatures will creep back up into the upper
80s...especially if we have decent sunshine.

Sunday night into Monday...finally will see surface front into
northwest of CWA and better chances of rain once again in northern
half of Missouri and Kansas. Decent temperature gradient with lower
80s north of the Missouri River and around 90F in the southern zones
for Monday and Tuesday. Depending on where the front stalls on
Tuesday...we may see additional heavy precipitation in the area
through mid week.  Models diverge some with GFS bringing the front
back as a warm front during the day on Wednesday...while the ECMWF
pushes the precipitation down into Arkansas.  Either way...most of
the extended forecast will have better chances of precipitation than
we have seen south of the Missouri River over the last couple of
weeks. Temperatures should be down from the last several days as
well.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1224 PM CDT WED AUG 27 2014

Ongoing shwr/storm activity now lifting northeast of area terminals
as southerly flow reestablishes itself aloft. Overall...current fcst
calls for dry conditions this afternoon as main outflow boundary
from this morning/s convection remains south.
Overnight...shwrs/storms expected to redevelop after 3z as low-level
strengthening and stalled front to our south begins lifting north. For
now...have offered a VCTS mention at all terminals starting between
2/3z...with a tempo TSRA mention at STJ...which stands the best
chance at realizing impacts from developing overnight convection.
Conditions should improve after sunrise as front retreats north.
Weak easterly winds between 5-10 kts expected through the period.


&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...FLASH FLOOD WATCH from 10 PM CDT this evening through Thursday
     morning FOR MOZ001>006-011>015.

     FLASH FLOOD WATCH from Thursday evening through Friday morning
     FOR MOZ001>006-011>015.

&&

$$

SHORT TERM...32
LONG TERM...Adolphson
AVIATION...32





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