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

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000
FXUS63 KEAX 302317
AFDEAX

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

.SHORT TERM...(This Evening through Thursday Night)
Issued at 333 PM CDT TUE SEP 30 2014

This Afternoon/Tonight: A slow-moving cold front currently stretches
from central Kansas into central Nebraska, with a warm front
situated over northern/northeast Missouri. Water vapor imagery and
observations show an occluding low pressure moving north through the
Dakotas in response to a deepening upper trough over the
Intermountain West. For the remainder of the afternoon and evening,
a low probability of showers will be possible along the warm front,
although this might amount to sprinkles at best. Otherwise, an
expansive area of showers over northern Kansas into eastern Nebraska
will continue to lift north-northeast as the primary upper forcing
lifts away from the region. Only far northwest Missouri will see a
chance of showers during the daylight hours with this activity.
Additional showers and thunderstorms will develop behind this
initial activity during the evening hours over eastern Kansas as a
35-40kt low level jet develops across the area. Chances for showers
and thunderstorms will increase overnight as upstream convection
expands and consolidates eastward. Initial rainfall for the KC Metro
area should arrive around or just after midnight. Instability will be
marginal, with MUCAPE AOB 1000 J/KG, so the overall severe weather
threat will be low tonight.

Wednesday/Thursday: A subtle shortwave trough will graze the
forecast area Wed morning, with the nose of an 80kt upper jet
entering central Kansas. This should maintain ongoing showers and
thunderstorms over much of the forecast area. Some of this activity
is expected to weaken by late morning, with convective debris
lingering into the afternoon. Likewise, this scenario paints some
uncertainty to the Wednesday afternoon forecast. Afternoon
temperatures should be kept in the middle 70s to lower 80s as
overall instability will be slow to increase. A different story is
expected to the west of the CWA, where stronger heating and upper
forcing will allow robust convection to develop over eastern Kansas
Wed afternoon. While severe weather is expected west of the forecast
area, the degree of instability provides more uncertainty for points
eastward. Current thoughts are for ongoing storms over eastern
Kansas to move east and gradually weaken upon encountering a less
favorable environment with eastward extent. However, the western
half of the CWA could see isolated severe weather, mainly during the
evening/overnight hours, with the greatest threat being large hail
and damaging winds. While shear profiles would support some threat
of tornadoes, the timing/convective mode of ongoing storms and some
decoupling of the boundary layer may prohibit such development. This
activity will work its way across the remainder of the CWA overnight
into Thu morning. One final round of thunderstorms is expected on
Thursday as the surface cold front and associated surface low move
through the CWA. While details are still challenging to resolve,
some form of linear or broken line of storms seems plausible with
strong forcing and the quick movement of the front. Deep layer shear
and instability should be sufficient for strong to severe storms with
this round of convection. Rainfall will move east of the forecast
area before late Thursday night, with cooler temperatures advecting
into the region. In addition to the strong/severe weather concerns
over the next two days, locally heavy rainfall will be possible
through the event. Average rainfall amounts may average 1.5 to 2.5
inches across the forecast area during the multi-day event.

.LONG TERM...(Friday through Tuesday)
Issued at 333 PM CDT TUE SEP 30 2014

Deep cold air advection behind Thursday night`s front will bring a
10 to 15 degree drop in temperatures on Friday with highs in the
upper 50s and lower 60s. Moisture will be quick to scour out so that
most of the day should be sunny, which will also allow northwest
winds to gust up to 30 mph.

Deep ridging will settle into the Plains Friday night with lows in
the upper 30s for much of the area. Flattening upper-level flow will
then bring a slight warm-up for the end of the weekend with highs in
the upper 60s and lower 70s. There`s a very slight chance for a few
showers on Sunday with system rotating into the Upper Midwest and
Great Lakes, but most energy and moisture with this system will stay
well to the northeast of the area. For now kept with an increase in
clouds on Sunday but otherwise mostly dry.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 616 PM CDT TUE SEP 30 2014

VFR conditions are expected for next six hours at least. From about
midnight through the remainder of the forecast though, uncertainty is
very high. Scattered showers and thunderstorms have developed over KS
and NE in association with a strong upper-level storm system. All of
this activity will eventually move eastward through the night and
spread across all of the terminals eventually. Timing of the onset
looks to be midnight in later for far northwestern MO and 06Z to 08Z
for east central KS and west central MO. From that point, the
uncertainty really increases. The slow moving nature of the system
suggest that the area will see high chances for showers and storms
through late Wednesday morning or afternoon. But the scattered nature
of the precipitation makes the timing of precipitation induced
reductions in visibility and ceiling a challenge. Have opted to keep
conditions low end VFR with scattered MVFR ceilings. If a stronger
shower or storm moves over a terminal, a reduction to IFR is likely.
But with the scattered nature the duration and timing is too
uncertain to depict a lower group at this time.

&&

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

$$

SHORT TERM...Blair
LONG TERM...Hawblitzel
AVIATION...CDB






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