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

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FXUS63 KEAX 281728
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1228 PM CDT Fri Apr 28 2017

.Discussion...
Issued at 414 AM CDT FRI APR 28 2017

Overall forecast remains on track with the primary change owing to a
potential northward shift to the axis of heaviest rainfall through
the weekend.

Water vapor imagery and high resolution model guidance continues to
suggest isentropic ascent and saturation to generate scattered
showers through the remainder of the early/mid morning hours before
a dry slot ends precipitation from west to east. Highest rainfall
totals will reside along and north of Interstate 70. Should be a
notable break in rainfall this afternoon into the evening hours.

The most immediate concern will be heavy rainfall Saturday morning
into Sunday morning with notable synoptic setup. A slowly-
evolving longwave trough over the Plains states is bringing in a
healthy batch of mid/upper level Pacific moisture and low-level
Gulf moisture. The position of the surface front will help dictate
corridor of the heaviest rainfall over the weekend. Latest
thinking is this boundary will lift north and become quasi-
stationary on Saturday evening. How far north and whether ongoing
convection will limit its northward extent remains highly
uncertain. Confidence is increasing however that where this heavy
band of rain resides will lead to flash flooding concerns and
river flooding as several rounds of moderate to heavy
precipitation trains across the area. Currently, this zone is
expected along a line from Chanute, Kansas to Clinton/Sedalia,
Missouri. It`s worth noting that each subsequent model run has
shifted this corridor further north, with the 06Z NAM now the
farthest northwest approaching the KC Metro area. The takeaway is
that while the exact location of the heaviest rainfall remains
uncertain, the potential exists for a corridor of 3-4 inches of
rain with locally higher amounts to affect the southeast third of
the forecast area, resulting in the potential for flooding rains.
Likewise, a flash flood watch remains in place for these areas,
and future forecasts will closely monitor northwest expansion if
model trends continue.

Wrap-around TROWAL light precipitation is expected on Monday before
precipitation comes to an end Monday evening as the upper low
departs. While slight chances of rain will be possible mid-week,
overall amounts are anticipated to be low. As for temperatures, the
forecast area remains on the cool-side of the surface front/pattern,
resulting in maximum readings below climatological averages.

&&

.Aviation...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1228 PM CDT FRI APR 28 2017

Lingering rain showers will push out of all terminals prior to
18z, making much of the TAF period dry this evening and tonight.
Ceilings have been a bit jumpy this afternoon but are generally
settling in the middle of the MVFR category on the south side of
the warm front, and near the IFR/MVFR threshold along and north of
the front. This boundary will gradually sink southward during the
evening, bringing sites back to low MVFR and eventually IFR late
this evening. Winds will transition to the northeast as the front
passes, generally at speeds less than 12 kts through Saturday
morning. Rain will push back into the region Saturday morning, and
while the potential for a few embedded thunderstorms was too low
to warrant mention in any of the TAFs, cannot completely rule out
a stray thunderstorm especially at IXD after sunrise Saturday.
Once they begin Saturday morning, rain showers and IFR ceilings
will continue beyond the end of the forecast period.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Flash Flood Watch from 7 PM CDT this evening through Sunday
     evening for KSZ057-060.

MO...Flash Flood Watch from 7 PM CDT this evening through Sunday
     evening for MOZ039-040-043>046-053-054.

&&

$$

Discussion...Blair
Aviation...Laflin



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