Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 271948
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
248 PM CDT SAT AUG 27 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 248 PM CDT Sat Aug 27 2016

Despite decent low level moisture and instability over forecast
area, there are no distinct focusing mechanisms. So no definite
location for where storms will pop up through the early evening
hours since they will be diurnally driven. Will keep isolated/
scattered wording through the evening, then kept slight chance pops
for areas along and north of I-70 after 06z Sunday as this area is
closer to boundary that is north of forecast area. Otherwise, lows
will be mild, in the upper 60s to low 70s, just a bit above normal
for this time of year.

Byrd

.LONG TERM...  (Sunday through Next Saturday)
Issued at 248 PM CDT Sat Aug 27 2016

The synoptic pattern at the start of the long term period Sunday
morning will feature slowly rising heights aloft as an upper-level
ridge builds into the Central CONUS.  This ridge will amplify
through the beginning of next week, before a trough diving into the
Northwest begins to break down the ridge by the middle of next week.

Not really much synoptically to hang our hats on through early next
week.  Despite the weak height rises, it doesn`t appear the warming
temps aloft will be quite strong enough to completely limit diurnally
driven thunderstorms.  Therefore, will continue with the forecast of
isolated to scattered thunderstorms Sunday into Monday.  Best
chances will reside on the fringe of the ridge across north-central
MO, with smaller chances closer to the ridge over southeast MO/west-
central IL.  Have bumped up temperatures a bit from the previous
forecast across the southeastern FA due to less expected convection
leading to higher prospects for prolonged solar insolation.

The latest guidance continues to suggest a weak front will drop
south near the region by midweek.  Timing differences remain, but
the GFS/ECMWF and GEFS solutions all show fropa through the bulk of
the area by early Thursday (slower than previously advertised).
Precipitation chances will be a bit higher Tuesday into Wednesday
ahead of the front, but will go ahead and trend the forecast drier
for Thursday into Friday in the wake of the front. Fronts this time
of year can often struggle to get as far south as guidance suggests,
so that is a trend we will continue to monitor in the coming
forecasts. Temperatures will remain warm and humid ahead of the
front with temps in the upper 80s/low 90s and heat indices in the
mid/upper 90s Sunday into Monday, but cooler conditions will arrive
by Thursday with temps back in the low/mid 80s.

KD

&&

.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1257 PM CDT Sat Aug 27 2016

Location and coverage of storms hard to pin down, so kept tafs dry
for now except KUIN since frontal boundary is closer to that site.
Otherwise, VFR conditions with light southwest to south winds.
Winds to become light and variable after 01z Sunday, then pick
back up a bit by mid morning on Sunday from the southeast. Some patchy
fog is possible towards daybreak on Sunday, so kept mention in
metro area tafs.

SPECIFICS FOR KSTL:
Location and coverage of storms hard to pin down, so kept taf dry
for now. Otherwise, VFR conditions with light southwest winds.
Winds to become light and variable after 01z Sunday, then pick
back up a bit by 14z Sunday from the southeast. Some patchy fog is
possible towards daybreak on Sunday, so kept mention in taf.

Byrd

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX


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