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

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FXUS63 KEAX 301715
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1215 PM CDT Tue Sep 30 2014

.DISCUSSION...
Issued at 355 AM CDT TUE SEP 30 2014

Short Term (Today through Thursday night):

The short term will provide several rounds of showers and
thunderstorms Tuesday night through Thursday night with the
potential for severe storms on Wednesday night and again Thursday.
However, today will bring one more warm and (mostly)dry day. This
morning, a back door cold front is sinking southwestward from the
Upper Mississippi River Valley. This front is expected to sink into
the northeastern CWA backing winds to the ENE. It is across the
northeastern CWA where high temperatures will only reach the mid 70s
where most other locales across the rest of the forecast area will
reach into the low to mid 80s. Our first weather maker, in what will
be a one-two punch, is an upper level trough which is evident on
water vapor imagery this morning centered near the western NE/SD
border. This upper level trough will continue to move NNE through
the northern Plains today. This will send a weak cold front into the
Plains. Thunderstorms will develop this afternoon out ahead of the
cold front from eastern NE to central KS. A few of these showers may
clip extreme northwestern Missouri late this afternoon however the
bulk of the thunderstorm activity is expected to hold off until
tonight when a southwesterly 30-40KT LLJ is expected to increase
across eastern Kansas nosing into southeastern Nebraska. This will
fuel thunderstorms out ahead of the cold front however they are not
expected to be severe. These showers and thunderstorms will
overspread the area late Tuesday night into Wednesday morning.

Wednesday afternoon the nearly stationary cold front across central
Nebraska and Kansas will be the focus for afternoon thunderstorms
west of the area but will move eastward into eastern Kansas in the
evening. Also, Wednesday evening the second system, in the form of a
upper shortwave, will dig as it moves into the eastern Rockies. This
upper level system will force the cold front into eastern Kansas as
a 40-50KT LLJ develops. Steep mid-level lapse rate and 1500-2000J/Kg
of CAPE will support the potential for large hail and damaging winds
Wednesday night.

There will be another chance for severe weather Thursday but this
threat becomes more conditional as 1) early morning convection may
limit instability 2) and strength and speed of the upper level
trough will also play a role. The trend amongst models has been to
slow the upper level shortwave down as it digs into the western
Plains Wednesday night into Thursday. This would keep the associated
cold front across the northwestern CWA by Thursday afternoon. If
skies can clear out from early morning convection and instability
depicted by the NAM of 1500-2500J/Kg CAPE can be realized then
severe weather would again be possible with the main mode of
convection being a squall line with damaging winds and large hail
possible. The front will exit the area Thursday night with showers
continuing as the upper level trough shifts through the region.

Long term (Friday through Monday):

The extended time frame will be quiet with a cool start before
moderating into the latter half of the weekend into early next week.
As the upper level trough moves east of the area it will continue to
dig. Upper level ridging will build across the western CONUS. This
will leave the local area under northwest cool NW flow aloft.
Friday`s and Saturday`s highs will be in the low to mid 60s. The
upper level flow then shifts to a more zonal pattern by Monday with
seasonable highs in the upper 60s to mid 70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1209 PM CDT TUE SEP 30 2014

VFR conditions should prevail through at least the first half of the
period. Increasing clouds are expected later this evening, with
chances for showers and perhaps an isolated thunderstorm to impact
terminals after 06Z. How widespread and duration of the precipitation
remains a little uncertain at this time. Currently, ceilings should
remain low-end VFR for the majority of the time with the
precipitation, but will need to watch potential for a scattered MVFR
deck to sneak into the area, especially with the more robust
activity.

&&

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

$$

DISCUSSION...73
AVIATION...Blair





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