Area Forecast Discussion
Issued by NWS Springfield, MO

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FXUS63 KSGF 182357 AAA
AFDSGF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SPRINGFIELD MO
657 PM CDT Mon Aug 18 2014

...Mesoscale Discussion and Update to Aviation Section...

.MESOSCALE DISCUSSION...
Issued at 657 PM CDT MON AUG 18 2014

Rather interesting and tricky forecast for overnight tonight into
the daylight hours of Tuesday morning.

QPF from the various models are all over the place, most with
nothing affecting the area, while some have remnants of activity
to our north moving in and dissipating. The recent track record of
model QPF has been less than stellar. Case in point, several short
range models have indicated that we should have had quite a bit of
QPF over our area all afternoon. So, confidence in such information
is low.

There are items that support rain chances for our region beginning
later tonight. Isentropic upglide in the 310-315K levels along
with greater than 1000 J/kg of uncapped, elevated CAPE will focus
on northeastern Kansas as the low level jet gets cranked up late
this evening. The tail end of a short wave moving through the
Upper Midwest will also provide some help lift-wise as well. This
area of initiation will be on the southwestern edge of 25-30kt
0-6km bulk shear, with the best shear further to the northeast.
This is enough shear and CAPE to suggest that initial development
should create an organized cold pool. The critical question
becomes, just how quickly does this happen.

Initial forward propagating system motion vectors point to the
south/southeast. However, the low level jet will veer pretty
quickly overnight and the forward propagating vectors shift to a
more east/southeast direction. As a result, much depends on exact
timing.

The bottom line is that we will need to watch for initiation over
northeast Kansas later this evening. Just how this activity
progresses from there is up to timing. Will go ahead and massage
PoPs for overnight tonight through Tuesday morning to account for
the latest thoughts. Further refinements are expected as the
atmosphere shows it cards.

&&

.SHORT TERM...(This Evening through Tuesday)
Issued at 250 PM CDT MON AUG 18 2014

An upper level ridge of high pressure is currently pushing east
across the southwestern U.S. This is leaving the region in an
upper level northwest flow pattern. A weak disturbance is expected
to move through this northwest flow tonight and trigger storms
across northeastern Kansas into northwestern Missouri late this
evening. This activity will then push to the southeast overnight
into Tuesday morning, mainly remaining north and east of the area
but may clip portions of central Missouri. Theta-E differences and
MUCAPE values over 2000 J/kg could support a few strong storms
wind gust in excess of 50 mph with any line segments that can
develop.

An outflow boundary from this activity will develop and push south
through the rest of the area tonight and Tuesday morning.
Additional storms will be possible along this boundary with the
best chances remaining along and north of the Highway 54 corridor,
with storms weakening as the approach Highway 60. This convection
should dissipate by the late morning hours Tuesday.

.LONG TERM...(Tuesday Night through Monday)
Issued at 250 PM CDT MON AUG 18 2014

The upper level high will move east and over the region by
Thursday. Storms are expected to develop across northern Missouri
again Tuesday night and push to the southeast again, but with the
upper level high pushing farther to the east this activity will
mainly occur north and east of the area, maybe just clipping the
far eastern Ozarks.

The upper level high will then remain over the region Thursday
into the weekend, ushering in a very warm air mass. Highs will
top up in the middle to upper 90s each afternoon Thursday into
this weekend, with heat index values generally in the 100 to 105
degree range. Afternoon mixing may help heat index values from
getting too out of hand but, never the less, hot conditions can
still be expected this week and weekend. Dry conditions are
also expected Wednesday into the weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 657 PM CDT MON AUG 18 2014

See the mesoscale discussion above for details on the evolution of
the weather pattern over the next 12 or so hours. Implications on
the TAFs are for thunder to be included in PROB30 groups at both
JLN and SGF later tonight. This will be refined with further
updates in the coming hours. Overall, VFR conditions will be
common, though brief periods of MVFR/IFR will be possible if
thunderstorms can make it to the JLN/SGF aerodromes. Any lingering
activity should exit by midday and gusty southwest winds will
develop over the region Tuesday afternoon as skies clear. At this
point, thunder has not been included for BBG, though this may
change with later updates.

&&

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

$$

MESOSCALE...Gagan
SHORT TERM...Wise
LONG TERM...Wise
AVIATION...Gagan





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