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

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FXUS63 KEAX 241117
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
617 AM CDT Fri Apr 24 2015

.SHORT TERM...(Today and Tonight)
Issued at 353 AM CDT FRI APR 24 2015

Still monitoring the potential for some severe weather across the
area on Friday afternoon and evening, but due to some model shifting
the general trend has been for the bulk of the severe weather to
occur off to the west of the forecast area. That being said, parts
of eastern Kansas and far western Missouri should still be preparing
for the potential of severe weather on Friday...

Surface analysis done earlier this morning has the warm front
associated with a developing surface cyclone well south of the
forecast area. Behind this warm front temperatures are generally in
the lower to middle 60s, with dewpoints in the upper 50s to lower
60s. Through the day today the surface cyclone, currently situated
over the Rocky Mountain region will deepen as it moves east, and
eventually bottom out around 990 to 995 mb in western Kansas. This
will help transport the warm and moist air northward into the area,
but not without some struggles. Ahead of the surface warm front
elevated showers will form through the early morning hours on
Friday. Antecedent instability is not extreme by any stretch, as
MUCAPE values are currently running in the 200 to 400 J/kg range.
There is also quite a bit of dry air to overcome, so the
isentropically lifted warm air advection showers will likely not
take on the form of widespread convection, rather in the form of
scattered showers with perhaps some isolated thunder embedded. No
severe weather is anticipated with this early morning showery
activity.

The main complication with the afternoon round of convection resides
with the extensive cloud cover, which is anticipated to be around
for quite a while. As far as surface features are concerned for
today, much will depend on whether or not the sun can find a way
through the cloud cover and warm up surface temperatures. The other
factor is whether the better/richer moisture can make it into the
forecast area, and if so how far north the moisture and warm air
will push this afternoon. As was mentioned earlier the anticipated
location surface triple point has shifted well west of the forecast
area, and will probably set up in central Kansas. This will be the
most likely initiation point for the most severe convection in this
region, needless to say quite a distance from this particular area.
However, given the very strong southwest flow aloft and an eventual
ejecting negatively tilted mid level trough, enough ascent could be
working its way into the area to break out some isolated to
scattered convection in the warm sector across SE/EC Kansas and into
WC Missouri. That being said, the most likely area for convection
through the evening hours will be along the better convergence zone
associated with the warm front, where surface winds back to around
120 to 150 degrees. The final destination of this feature is
somewhat uncertain, but at this point in time it appears the warm
front, along with the good surface convergence will end up somewhere
between Interstate-70 and HWY 36, thus putting the far northern
parts of the CWA in the cross hairs for a good push of thunderstorm
activity and heavy rain through the evening and overnight hours. The
bulk of this activity will likely be elevated, as storms would
initiate along the front and push northward into the cool side of
the boundary.

South of the boundary: As was mentioned before, the location of the
surface warm front is in some question, and that will depend on how
morning convection behaves, and whether or not the sun can make an
appearance. Short range hi-res models indicate that the warm front
could make it as far north as the KSTJ area, with temperatures as
warm as the middle to upper 60s, and dew points in the upper 50s to
lower 60s. However, even in that scenario the warm sector would be
incredibly narrow, with temperatures and dewpoints generally
dropping off toward the east of the CWA (central Missouri). So,
bottom line with the warm front probably sagging off to the
southeast the warm sector over the CWA likely only encompasses a
KFNB to KDMO line and areas west of that line. Any storms that can
go up west of that aforementioned line this afternoon should have
enough in the way of CAPE/Shear to become severe, however a capped
off environment deep in the warm sector without much in the way of a
triggering mechanism should limit the convection to isolated to
scattered in coverage. Short range models, such as the Hi-Res NMM
hints at some convection well within the warm sector; so while
having likely storms in the warm sector isn`t likely, there is a
chance that a storm or two could find a weakness in the cap or given
enough mid level ascent could get going in the warm sector.

Parameters:  There is still some question as to how ramped up the
ingredients for this system will be as we go into the
afternoon/evening hours. If recent hi-res models are to be believed,
by 00z, along and west of the aforementioned KFNB/KDMO line, ML CAPE
values could approach 1000-1500 J/Kg. These values would be easier
to attain with some breaks in the clouds, leading to warmer
temperatures. No cloud breaks --> no CAPE. Wind shear will be
incredibly ample to support severe weather. Deep layer shear (0-6km)
will be on the order of approximately 40 to 50 kts, so if the CAPE
does increase through the afternoon, it will have plenty of shear to
support severe storms. Forecast hodographs through the day are also
very impressive, and with a setup more conducive to storm activity
would likely result in several strong tornadoes. But as it stands
with perhaps only isolated development the widespread nature of
tornadic activity will be minimal. That being said, a strongly
clockwise looping of the hodograph, characterized by a veering wind
profile and increasing speeds with height 0-1 SRH values this
afternoon within the warm sector will be between 200 and 300 m2/s2.

Heavy rain potential: PWAT values in the 1 to 1.5 inch range is
slightly high on the anomaly scale, but not high enough to warrant
much of a threat for widespread flash flooding. Areas along and
north of Interstate 70 could see perhaps a couple inches of rain
with the heavier activity, as it moves out of northeast Kansas, into
northwest and northern Missouri. But with the boundary likely
oriented NW/SE and shear vectors pointing W/E there is more of a
normal component to the shear vectors with respect to the
orientation of the warm front, so widespread and long-lasting
training storms will not be a huge concern through the night. That
being said, typical heavy rains associated with deep convection will
likely still occur across northern Missouri and could bring some
isolated to scattered flooding/flash flooding.

So, to summarize... Morning showers will roll through the area
through the mid morning and should cease by early afternoon. Clouds
in the area will likely stymie the chances for severe weather by
limiting surface instability. The most likely area for severe
weather today will be west of a line from KFNB to KDMO. Should the
clouds break up, and a storm is able to go up in the warm sector
west of that line, it will likely be severe, with all hazards (hail,
wind, tornado) possible. Areas north of Interstate 70 will likely
see some heavy rain, which could result in some isolated to
scattered flooding/flash flooding.

Once the upper low moves east of the area, precipitation chances
decrease from west to east through the day on Saturday. Expect a dry
forecast for the rest of the weekend, leading into early next week,
with highs on Sunday in the lower 60s.

.LONG TERM...(Monday through Thursday)
Issued at 353 AM CDT FRI APR 24 2015

Should the current long-term models prove to be correct, next week
appears to be relatively benign across much of the forecast area.
The weather system to watch will be a cut-off low that develops in
the vicinity of the Grand Canyon late in the weekend, traversing
through OK-TX and into the Lower Mississippi Valley by the middle of
next week before continuing its eastward trek and phasing back in
with the overall upper-level pattern. The GFS and ECMWF handle the
low fairly similarly for it being this far out, keeping the system
well to our south with no agreement from the GEM from Tuesday
onward. Therefore, the only PoPs in this forecast period exist
across the far southern tier of counties overnight Monday into
Tuesday as the low passes to the south. Any northern shift in the
track will consequently bring PoP chances further north.

Normal temps for this time of year are generally in the upper 60s
for highs and upper 40s for lows. Comparing this to the forecast for
next week, highs on Monday are currently looking to be a few degrees
below normal, in the lower to middle 60s but will be dependent again
on where the aforementioned low ends up tracking. More cloud cover
would yield lower temps, clearer skies could bump up the temps a few
degrees. Upon the low`s departure, ridging looks to build in on the
backside, warming temps into the 70s in the latter half of the week.
Lower to mid 40s in the forecast for lows overnight Monday,
responding accordingly to the warming trend throughout the week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 614 AM CDT FRI APR 24 2015

Scattered showers with isolated thunderstorms will move through the
terminals through the mid morning hours, and should clear the area by
or shortly after 15z. MVFR CIGs remain in place through the day, then
another round of more widespread thunderstorms move in later tonight.
KSTJ should see T-storms first, followed by the KC Metro terminals.
Expect the heaviest rain to pass through fairly quickly, but
lingering light rain with embedded thunder could persist through most
of the night on Friday night.

&&

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

$$

SHORT TERM...Leighton
LONG TERM...lg
AVIATION...Leighton






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