Area Forecast Discussion
Issued by NWS Springfield, MO
FXUS63 KSGF 170324 AAB
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SPRINGFIELD MO
1024 PM CDT Sat Aug 16 2014
Issued at 1024 PM CDT SAT AUG 16 2014
Forecast further refined to account for recent radar and
Weak cold front continues to move southward into the area. Aloft a
shortwave/shear axis is moving west to east across the region.
Convection over the past few hours has been confined to a narrow
region 20 miles (or so) either side of a line from Bolivar to
Rolla. Training cells have led to locally heavy rainfall and will
continue to monitor for any potential hydro issues. Broad
isentropic upglide and weak elevated instability will continue to
shift to the eastern half of the outlook area in the next couple
of hours and this will be the region of better rain chances.
Have cut PoPs across western portions of the outlook area as lift
is now focusing on areas east of the Highway 65 corridor. While
additional development is possible along the front/upper wave as
it moves into the region, it will likely be sparse in coverage.
.SHORT TERM...(This Evening through Tonight)
Issued at 306 PM CDT SAT AUG 16 2014
Main forecast concern will be with storm development and trends
for this afternoon through tonight. The cold front is making
slower than expected southward progress and currently extends from
Kirksville to Sedalia to Emporia Kansas. The airmass ahead of the
front has gotten very unstable with LAPS showing lifted indices
around -7 and CAPE over 3000 j/kg. Dewpoint temps in the lower to
mid 70s were pooling just ahead of the front. The latest radar
images shows storms beginning to develop just to the northwest of
the forecast area.
Storm coverage will increase ahead of the front through the rest
of the afternoon as the lower levels continue to destabilize and a
subtle 700mb trough moves across the area. Freezing levels will
remain high limiting hail growth potential. However unusually tall
CAPE profile on NAM Bufr soundings show that cloud heights may be
sufficient for at least some marginally severe hailstones. Steep mixed
layer below cloud height may also allow a few storms to produce
wind gusts to 60 mph. Am getting concerned about higher
precipitable water values showing up on forecast soundings so may
need to add limited flood potential to our HWO.
Storm development will gradually shift southeast through tonight
as the front makes its way toward the I-44 corridor...so will keep
pops going through the night. Severe threat should diminish with
loss of afternoon destabilization.
.LONG TERM...(Sunday through Saturday)
Issued at 306 PM CDT SAT AUG 16 2014
Short wave to exit eastward and approach LSX by 12z Sunday. On
going storms should be exiting region as well as front passes
through as well.
Weak ripples currently topping the upper ridge and then descending
into the plains to then be key for redevelopment of thunderstorms over
the eastern CWA on Sunday and then again on Monday. While POPS are
in the forecast...confidence in any organized rain is somewhat
limited after tonight into early next week.
Models then advertise a series of shortwaves to travel across the
northern tier of the nation...with variation in how they are
handling a split flow. Of particular interest is a stronger wave
that both the GFS/ECM advect across the northern tier to reach the
Great Lakes on Wednesday. There is the potential that this wave
will push a weakening front into the Central Plains that will
focus convergence as weak ripples top the ridge. At this time
though...will downplay rain chances while noting that some of the
warmest conditions of the summer will occur as the ridge builds
into the Central Plains.
Toward the end of the week...temperatures rise to above normal as
an upper ridge builds into the central U.S. Heat indices will
likely reach near triple digits Thursday and Friday afternoon.
We will need to address potential impacts on residents in our area
who have become acclimated to below normal temperatures so far
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 632 PM CDT SAT AUG 16 2014
Scattered storms developed a couple of hours ago and currently
extend from Warsaw to Lamar to Baxter Springs. Storms and
associated trough are making fairly steady eastward progress so will
be carrying tempo thunder early in the forecast for Joplin and lag
a couple of hours for Springfield and Branson.
The front is expected to stall near the Arkansas border Sunday
morning and will likely focus additional convection after 18z.
Will wait and let later runs get a better handle on storm
development location...but would expect some addition of TSRA in