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

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FXUS63 KEAX 212337

637 PM CDT Thu May 21 2015

Issued at 344 PM CDT THU MAY 21 2015

The main concern during the forecast period will be the potential
for additional rainfall through the period to cause localized flash
flooding and to exacerbate ongoing river flooding as well as cause
additional rivers to go into flood.

The short term looks to remain rather benign allowing flooding on
area rivers to abate. This is thanks to surface high pressure
residing over the area today. This area of high pressure will remain
over the forecast area tonight and into the day on Friday. Friday an
approaching leading shortwave ejecting out from an upper level
trough over Southern California will allow precipitation to spread
eastward across Kansas. However, as it approaches eastern Kansas and
western Missouri it will run into dry air in place. That being said
light, high based showers will be possible tomorrow afternoon and
night across eastern Kansas and western Missouri while the eastern
CWA remains dry. On Saturday, the upper level trough will slowly
move into the Great Basin area while a upper level ridge begins to
assert itself over the southern CONUS. The building of the sern
ridge will have two effects. The first being, it will slow the
progressive pattern across the CONUS and secondly, will allow the
Gulf moisture to stream into the area on the back side of the ridge.
Consequently, moisture will become more plentiful as we head into
Saturday and especially Saturday night through Sunday night. On the
day Saturday expect mainly just scattered showers and
thunderstorms...severe weather is not anticipated as instability is
extremely low. As we move into the Saturday night to Sunday night
period, PWAT values rise to 1.50"-1.75" which is 2 to 3 standard
deviations above normal. This will be the main period of concern as
storms could be very efficient rain producers. And, with 2 to 3
three rounds of heavy rainfall depicted by the models Saturday night
through Sunday night, this may cause localized flash flooding as
well as exacerbate ongoing river flooding, and cause additional
rivers to go into flood.

Beyond this period conditions improve somewhat although it will
continue to remain wet. By Monday, the upper level trough moves into
the northern and Central Plains with continued shortwaves moving
through the area. The good news is moisture flow out of the Gulf
becomes veered and PWAT values become more seasonable. As such,
scattered showers and thunderstorms will be possible Monday thru
Wednesday. Late in the period the slow moving pattern beings to
break down and we return to more zonal flow. However, conditions may
continue to remain wet as models indicate a upper shortwave moving
from the northern Plains into the Upper Midwest sending a front into
the area and stalling.


.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 637 PM CDT THU MAY 21 2015

VFR conditions are expected to persist through the forecast period.
Progressively thicker cirrus will build in from the southwest by early
Friday, but ceilings will remain at or above 10 kft. Light winds will
vary in direction from northwest to southwest, but at speeds around 5




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