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

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000
FXUS63 KEAX 261714
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1214 PM CDT Sat Jul 26 2014

.UPDATE...
Issued at 1033 AM CDT SAT JUL 26 2014

A MCV over northeastern Kansas is throwing a few wrinkles into the
going forecast. First, cloud cover is limiting how quickly we are
warming up so far this morning and with the bulk of the MCV yet to
track over the area it seems thicker cloud cover will persist through
much of today. This will continue to hold back temperatures through
at least early this afternoon. To account for this, have lowered
temperatures 2 to 3 degrees/ hr which resulted in about a 2 to 3
degree decrease in max temperatures. Dewpoints are tracking well but
with lower temperatures heat indices are now around 100 to as warm as
103.

The second concern is that this MCV will allow convection to
redevelop ahead of it. This is already occurring with isolated to
scattered showers and a few storms being triggered in the unstable
environment due to forcing from the MCV. Have increased or added
precipitation chances across mainly the northern two-thirds of the
forecast area to account for this. While there is ample instability
for this convection, shear is very weak at this point in time, so the
threat of severe weather is low.

The other item we`re watching is intense convection entering
northeastern Nebraska that is on a trajectory towards the forecast
area. This area seems to be mainly driven by a shortwave moving
around western ridge. It`s possible this area may move into northern
Missouri later this afternoon/early this evening. The question though
is if the stronger shear helping to sustain that convection can
build further south as well. The HRRR has started indicate this
system moving into the area but decreasing in strength. However
broader scale models and mesoanalysis show shear increasing across
northern Missouri so there appears to be some potential for either
the ongoing convection or new convection to develop across northern
Missouri and potentially become severe later this afternoon.

&&

.DISCUSSION...
Issued at 403 AM CDT SAT JUL 26 2014

The main weather concerns for this forecast package will reside in
the first 24 hours. The first of the concerns today will revolve
around the heat. The second concern will revolve around
precipitation chances late this afternoon into tonight and the
severe potential surrounding them.

Looking at 850mb temperature this morning and models continue to
range between 24C-28C. Providing we can mix up to that layer that
will yield highs in the 90s. However, there are a couple of caveats
(other than mixing) to this temperature forecast. The first is cloud
cover. There is a complex of thunderstorms currently heading east
across central Kansas. As this complex moves across central and into
eastern Kansas it is forecast to weaken as the LLJ veers. Of some
concern however is that some of the hi-res models such as the
HRRR/RAP hold it together long enough to move into our local area
providing from additional cloud cover. As such have lowered
temperatures a degree or two. However, heat indices should still
reside in the 102-107 range across the western CWA where a heat
advisory is in place from 1PM to 8PM. The second caveat will be the
potential for storms and what time they will initiate. The first
possibility is that one mentioned previously where thunderstorms
across Kansas move east and refire this afternoon. The second
scenario would be thunderstorms developing this evening along a cold
front which is currently extending from north central Iowa into
extreme northwestern Missouri and into northern Kansas. In either
scenario, strong instability will be in place with 2500-3500J/Kg of
CAPE will be available, along with steep mid level lapse rates, and
strong shear. As such storms that do develop will have the potential
to be severe with damaging winds and large hail being the primary
threats.

The cold front will be forced through the forecast area tonight as
an unseasonably strong upper trough moves from south central Canada
into the Upper Midwest. This will continue thunderstorm chances into
the night time hours.

By Sunday morning the front will shift south of the area. Northwest
flow aloft will bring cooler temperatures with highs in the 80s on
Sunday. A secondary cold front will move through the area on Sunday
night. This will bring another round of cooler July air to the area
Monday through Wednesday as the upper level flow remains out of the
northwest. Expect highs during this period to range from the upper
70s to lower 80s. Precipitation chances will increase on Thursday
and Friday as the medium range models depict the potential for upper
shortwaves moving through the area on continued northwest flow.
Precipitation during this timeframe as well as northwest flow will
keeps highs below normal in the low to mid 80s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1213 PM CDT SAT JUL 26 2014

The ongoing showers/storms in the area should move east of the
terminals within an hour or two of issuance. The focus then shifts to
what the storms in northeastern Nebraska will do. On their current
path, they should stay to the northeast of the terminals and possibly
move through northern/northeastern Missouri. Latest guidance suggest
this line will weaken/erode as it begins to build into the area
though. So there is quite a bit of uncertainty still but confidence
is higher that this developing complex will not impact the terminals.


&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...HEAT ADVISORY until 8 PM CDT this evening FOR KSZ025-057-060-
     102>105.

MO...HEAT ADVISORY until 8 PM CDT this evening FOR MOZ020-021-028-029-
     037-043-053.

&&

$$

UPDATE...CDB
DISCUSSION...73
AVIATION...CDB






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