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

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FXUS63 KEAX 281117
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
617 AM 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 12Z TAFS through 12Z Saturday Morning)
Issued at 614 AM CDT FRI APR 28 2017

Current VFR conditions will likely be short-lived as both
widespread rainfall and upstream MVFR cigs follow in behind
departing precipitation. Generally, expect MVFR conditions by
mid-morning, persisting through much of the TAF period with cig
heights falling to IFR prior to daybreak Saturday as additional
rainfall moves into the area.

&&

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

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

&&

$$

Discussion...Blair
Aviation...Blair
Hydrology...lg


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