Area Forecast Discussion
Issued by NWS Springfield, MO

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FXUS63 KSGF 161722
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
1222 PM CDT Tue May 16 2017

...18Z Aviation Update...

.SYNOPSIS...
Issued at 228 AM CDT Tue May 16 2017

Mild conditions were occurring early this morning with readings in
the 60s to low 70s as of 2 AM. Upper level ridge axis was
beginning to shift east of the area with southerly low level warm
advection. Main forecast points today will be with warm
temperatures again and with the surface winds starting to
increase.

A bit of unsettled weather will begin late tonight with another
system late in the week into the weekend.

&&

.SHORT TERM...(Today and tonight)
Issued at 228 AM CDT Tue May 16 2017

For today, upper level ridge axis will continue to exit to the
east as a trough swings eastward over the Rockies and an upper
level jet begins to round the base of the trough into the high
plains. The area from the Texas panhandle into western Kansas will
have the potential for some severe storms later today in advance
of this feature. Surface low will be well to the west of us, but
we will see the pressure gradient increase across the area today
allowing for some gusty winds to develop this morning through the
afternoon. Some gusts over 30 mph will be possible over the
western CWA. Temperatures will once again top out in the 80s
across the area.

By this evening, thunderstorms will be ongoing in the plains,
with the remnants of which may move into the western CWA after 06z
in a decaying phase. The severe risk will remain to our west with
the better instability and heavy rain is not expected to become
widespread.

.LONG TERM...(Wednesday through Monday)
Issued at 228 AM CDT Tue May 16 2017

The convection which could move in after midnight tonight will
linger to the east across the CWA but will continue to fall apart
the further east it gets on Wednesday, away from the best
instability and synoptic scale lifting.

The main upper system will lift northeast into the upper
Mississippi valley region by late in the day Wednesday. Pressure
gradient remains fairly tight across the area on Wednesday and we
will have windy conditions across the area, but especially over
the western CWA which may flirt with wind advisory criteria during
the afternoon hours. While there will be an axis of instability
over the eastern CWA late in the day and evening, best source of
lift will be closer to the upper low and surface low across Iowa
and northern MO. So while there will remain a risk of storms, we
are not expecting severe weather at this time.

The next system will make its way into the Rockies on Thursday
with a surface front stretched out to the north of our CWA.
Afternoon instability increases across the area during the
afternoon with ML CAPES from 1500-3000 j/kg. However there doesn`t
appear to be a focusing mechanism for organized convection during
the day. On Thursday night, the low level jet will set up to our
west and we should see some organized convection develop and push
into our CWA.

Our severe risk from Friday into Saturday will depend on how much
instability can develop in the wake of any convection that
develops during the nighttime Thursday night. GFS is the most
progressive with this system, ending things by Sunday morning,
with ECMWF slightly later on Sunday. There will be the potential
for heavy rain with this system as it moves through from Thursday
night into Sunday morning with PW values of around 1.6 in. at its
max Friday night. Given the recent heavy rains and flooding
earlier in the month, additional heavy rain may lead to some more
flooding, although it should be nowhere near what we had earlier
this month. At present, we are going with around 2 to 3 inches
across the area.

After a break later in the day Sunday into Monday, the next
shortwave energy will arrive on Monday into Tuesday of next week
with the next chance of showers and thunderstorms.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1222 PM CDT Tue May 16 2017

Southerly winds will remain gusty through the afternoon at all
three sites. As the sun begins to set, expect winds to become less
gusty at JLN and BBG; this will also result in the development of
LLWS at these sites. At SGF, local terrain effects are expected to
result in continued gustiness from the southeast through the
night, with a few gusts around 30 KT possible.

In addition to the wind/LLWS threat, decaying thunderstorms are
expected to move into far eastern Kansas and western Missouri
overnight, perhaps making it as far as the JLN terminal before
dissipating entirely. For now, will continue with VCTS mention at
JLN until the progression of the thunderstorms becomes more clear.

Expect southerly winds to remain quite gusty through the day
tomorrow.

&&

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

$$

SYNOPSIS...Lindenberg
SHORT TERM...Lindenberg
LONG TERM...Lindenberg
AVIATION...Boxell



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