Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 160841
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
341 AM CDT Sat Mar 16 2024

.KEY MESSAGES...

-Elevated fire danger conditions are expected this afternoon
 across parts of central and southeast Missouri.

-The forecast remains dry until next Wednesday night.

-It will be warmer and breezy today ahead of a cold front.
 Temperatures will tumble tonight behind the front and below
 normal temperatures are expected for Sunday through Tuesday
 morning. Sub- freezing temperatures are expected on both Monday
 and Tuesday morning.


&&

.SHORT TERM...  (Through Late Tonight)
Issued at 334 AM CDT Sat Mar 16 2024

High pressure centered over eastern Kansas this morning will be
squeezed southeast by an approaching cold front which is currently
digging southeast through the Upper Midwest.  The pressure gradient
between the high to our south and the approaching front will tighten
up across Missouri and central/southern Illinois today, causing
breezing conditions in the 15-25 mph range with gusts as high as 35
mph across parts of northeast Missouri and west central/south
central Illinois.  Satellite pics show some mid-high clouds over
Kansas, and I expect some of these clouds to spread east ahead of
the wave which is pushing the front south.  That being said, there
should be plenty of sunshine, and the strong west-southwest flow
ahead of the front should push temperatures well up into the mid and
upper 60s today and even some low 70s highs are likely in parts of
central, east central, and southeast Missouri into southwest
Illinois.  Short range guidance still shows the front moving into
northern portions of our forecast area late this afternoon, and
continuing southeast tonight.  RAP and GFS are in good agreement on
timing with the front moving through our farthest southern and
southeast counties by 04-06Z tonight.  With very dry low level air
in place, we`re still expecting a dry FROPA.

Carney

&&

.LONG TERM...  (Sunday through Friday)
Issued at 334 AM CDT Sat Mar 16 2024

he short wave trough that initially pushes the front south of our
area takes on a neutral tilt and moves rapidly east late tonight
along the southern periphery of a deepening long wave over southeast
Canada and the Great Lakes.  The flow aloft over the Mid-Mississippi
Valley becomes almost zonal briefly on Sunday which slows the low
level cold advection.  While Sunday will certainly be cold than
today (almost 20 degrees in most of our area), the real cold air
won`t arrive until Sunday night/Monday morning as another, much
sharper positively tilted trough digs through the Midwest into the
Lower Mississippi Valley by early Monday morning.  This trough will
usher a 1030mb Canadian high through the northern Plains into the
Midwest and bring sub-freezing temperatures mostly in the low to mid
20s to Missouri and Illinois on Monday morning.  It`ll feel
downright chilly on Monday with temperatures struggling into the
40s, particularly since we haven`t seen daytime highs that low since
late February.  Monday night`s low temperatures look a bit warmer,
although still below freezing, and it`s likely temps will bottom out
in the evening or just after midnight, and then remain steady or
slowly rise as winds turn back to the southwest.  Temperatures
should ramp up back into the 60s again on Tuesday due to the
southwest flow ahead of the trough.

Guidance members are in good agreement up to Tuesday
afternoon/evening, but then begin to diverge.  The pattern aloft
shifts from high amplitude with a trough to our east and a ridge to
our west to a more zonal pattern for Wednesday through Friday.  The
deterministic GFS and ECMWF both do this to a degree, but the EC
stay a little more amplified than the GFS.  Regardless, both models
pick up the closed low which is currently spinning over the
southwest U.S. and move it east.  This will bring a chance for rain
back to the area late Wednesday night through Friday as the wave
moves into the eastern Plains and through the Mississippi Valley.
While there does seem to be a decent chance for rain late in the
week, as the trough moves by, temperatures are still quite uncertain
due to the amplitude differences in the guidance members.  The LREF
25th-75th percentile spreads for temperatures increase from 2-3
degrees for today through Monday to 5 degrees on Tuesday, and then
to 10+ degrees for Wednesday through Friday.  That being said, the
temperatures don`t look extreme one way or another with the
quartiles showing temperatures near to around 5-7 degrees above
normal.

Carney

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1052 PM CDT Fri Mar 15 2024

VFR flight conditions are expected through the forecast period.
Surface winds will remain light overnight while slowly backing to
the southwest. The wind will then increase and become quite gusty
from the west by mid-late Saturday morning, veering to more
northwesterly early on Saturday evening with the passage of a weak
dry cold front.

Glass

&&

.FIRE WEATHER...
Issued at 334 AM CDT Sat Mar 16 2024

Temperatures will warm into the upper 60s and low 70s this
afternoon across parts of central and southeast Missouri.
Additionally, the wind will increase from the west-southwest
today. Sustained winds in excess of 12 mph along with higher gusts
are expected. There will be deep mixing today due to the warm
temperatures and breezy conditions and dew point temperatures are
expected to be in the mid 30s, causing relative humidity levels
to drop below 30 percent. RAWS observations from Ashland, Sinkin,
and Farmington Missouri show fuel moisture levels dropped to
between 8 and 11 percent on Friday, and similar if not lower fuel
moisture is expected today. Elevated fire danger conditions are
therefore expected for parts of central and southeast Missouri
this afternoon.

Carney

&&

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

$$

WFO LSX


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