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

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FXUS63 KEAX 011547
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1047 AM CDT Wed Oct 1 2014

.MESOSCALE DISCUSSION...
Issued at 1047 AM CDT WED OCT 1 2014

Busy weather period shaping up for the next 36 hrs or so as strong
Pacific storm system continues to work into the central Plains
region. Regional radars showing plenty of ongoing convection across
the lwr Missouri Vly this morning with latest trends highlighting
renewed development from east-central KS northeast through the
greater KC metro and beyond. Latest water vapor imagery showing
responsible lead shortwave rapidly lifting northeast away from the
region. Considering this...and the fact the much of the fcst region
will be in the wrong quadrant of an upper jetstreak today...overall
thinking is that convection will begin to wane through the late
morning and early afternoon hrs. Beyond this...major questions remain
as incoming 12z guidance suggests another round of late
afternoon/evening storms as the next in a series of weak embedded
shortwaves ahead of the main upper trough now digging through the
Intermountain West approaches. Its this activity that has us worried
as model trends continue to support the possibilities of locally
heavy rainfall as a low-level jet of nearly 45 kts impinges directly
on the fcst region. From this vantage point...main areas for heavy
rain will likely be along and south of the I-70 corridor due to the
position of a weak warm front that should remain to our south today.
May have to consider a flash flood watch with this afternoon/s
package...however area of concern has been very dry in recent weeks
which will hopefully negate widespread flash flood concerns. In any
event...late afternoon/early evening convection will definately have
th potential of becoming severe as 0-6 km bulk shear vectors quickly
approach 40-45 kts. Good directional turning in the lowest 3 km will
should support isolated supercell development as conditions continue
to destabilize through the mid/late afternoon hrs. Best tornado threat
may in fact remain west of the CWA as current model trends suggest
better 0-1 km bulk shear will be delayed until well after sunset
across our area. That said...will continue to monitor and adjust as
needed.

&&

.DISCUSSION...
Issued at 351 AM CDT WED OCT 1 2014

Short Term (Today through Tomorrow Night):

The main weather concerns for this forecast package will be the
potential for a couple rounds of severe storms. The first of these
potential rounds of severe storms is expected to affect the western
CWA this evening/tonight. A second round of severe weather will
again be possible for most of the CWA on Thursday.

Showers and thunderstorms are ongoing across northeastern Kansas and
northwestern Missouri this morning with a few showers further east.
Showers have been training over those areas for several hours and
radar estimates about 1.00"-1.50" of precip has already fallen across
these areas. Luckily, flash flood guidance for these areas is high,
around 3.5"-4.0" for 6 hours. Nonetheless this will be an area that
will have to be monitored with several rounds of showers and
thunderstorms likely over the next 48 hours. These storms will
continue to move slowly eastward over the CWA through the morning
hours. Cloud cover and showers through the morning hours will cause
instability to be slow to recover across the area this afternoon
however, thunderstorms will be possible this afternoon across eastern
Kansas where skies may clear out earlier. This evening looks to be
the best chance for severe thunderstorms to develop as a lead
shortwave ejects out from an upper level trough across the eastern
Rockies. This will occur as a 40-50kt 850mb southwesterly LLJ get
ramped up across eastern Kansas. Models are depicting a weak surface
boundary bisecting the CWA. Good instability and lift will make large
hail and damaging winds the main threats this evening/tonight across
eastern Kansas and western Missouri. However with the weak surface
boundary in the area there is some potential for tornadic
development. 0-6km shear will be good with the swly LLJ at 850mb and
a 80-90kt mid level jet impinging on the area. However, 0-1km shear
is not as strong as winds near the surface will be light...what is of
more concern is that they are backed to the SSE. So, the most likely
scenario is that initial convection develops as supercells across
eastern Kansas with the initial threats being large hail/damaging
winds with a possible tornado or two. Supercells should eventually
merge into a more linear structure with damaging winds and perhaps an
isolated tornado being the main threat as storms move into western
Missouri.

Storms will continue through the early morning hours Thursday across
the CWA weakening toward daybreak as the LLJ weakens. We will then
again turn our attention to the west as the aforementioned upper
level trough digs as it moves out into Plains and forces a strong
cold front into the area. Thunderstorms are expected to develop west
of the area early Thursday along the front forming a line of storms.
These storms will push into the area on Thursday with the main
threat being damaging winds. The front should finally push east of
the area by Thursday evening. The upper level trough will move
through Thursday night. Some models try to develop instability
showers as the upper trough rotates through but dry air and
subsidence behind the front should undercut any chance for showers.
Two day rain totals could be on the order of 2.5"-3.5" however as
mentioned previously, flash flood guidance is not expected to be
exceeded over any locale.

Long Term (Friday - Tuesday):

The extended period looks much more benign then the short term
providing cold and dry conditions with a gradual warm up through the
period. On Friday, a reinforcing upper level trough will move
through the upper Midwest putting the local area under cool NW flow
aloft. Highs Friday and Saturday will only be in the mid 50s to
lower 60s with frost being a concern for Saturday morning as lows
drop into the mid to upper 30s. Northwest flow begins to relax
across the area by the second half of the weekend in to beginning of
next week. By Tuesday, highs will return to near normal with highs
in the low to mid 70s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
Issued at 630 AM CDT WED OCT 1 2014

Very challenging aviation forecast this go around as several rounds
of convection will be possible at the terminals this afternoon and
evening. Morning convection is pushing east of the terminals this
morning however there could be a few showers in the VC of the
terminals for the remainder of the morning hours with cigs around
8kft, This afternoon expect bkn cu around 5kft. The first challenge
is the potential for scattered thunderstorms this afternoon. With
bkn-ovc skies throughout most of the day it may be difficult for
thunderstorms to develop however, models indicate the potential for
scattered storms across the area so have a VCTS mention at the
terminals for the afternoon. The better chance for thunderstorms will
come tonight as a low level jet will spark convection across eastern
Kansas and western Missouri after 03Z. There is the potential for
some very strong storms reducing vsbys/cigs to IFR conds however,
have just tried to nail down trends and timing at this time. Winds
will be out of the south today btn 10-15kts. Tonight winds will
diminish while backing to the SE.


&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

$$

MESOSCALE...32
DISCUSSION...73
AVIATION...73





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