Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

144
FXUS63 KLSX 061103
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
603 AM CDT Sun Oct 6 2024

.KEY MESSAGES...

- A cold front will move through the area today, resulting in
  steady cooling to near average temperatures by tomorrow
  afternoon. A gradual warming trend is expected Tuesday through
  the end of the week.

- Gusty winds and low humidity will lead to more widespread
  elevated fire danger this afternoon, mainly in open grasslands
  and agricultural fields. This will be highly dependent on local
  fuel conditions.

- There is very little potential for precipitation over the next
  week.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 306 AM CDT Sun Oct 6 2024

Quiet conditions prevail throughout the region early this morning as
we await the arrival of a cold front over the next few hours. This
boundary is currently located across northwest Missouri and eastern
Iowa, and will steadily march southeastward through the morning,
clearing our area by mid afternoon. Behind this front, winds will
switch to the northwest, and cold air advection will gradually
increase throughout the day. While this will keep temperatures a bit
cooler than yesterday, particularly north of I-70, the core of the
post-frontal airmass will not arrive until overnight and tomorrow,
and thus afternoon temperatures will likely remain above seasonal
averages save for a few counties in northeast Missouri and west-
central Illinois.

Instead, the greatest impact this front will have will be on fire
weather conditions, as the airmass behind it will be very dry.
Upstream dewpoints across Iowa have fallen well into the 30s and 40s
early this morning, and this will be the case during the afternoon
in our area as heating and deep mixing commences. Meanwhile, breezy
northwest winds are also expected in a few areas, and the
combination of these two factors will lead to elevated fire weather
conditions this afternoon. Please see the fire weather discussion
below for more details.

Overnight tonight, the surface pressure gradient will steadily
weaken as surface high pressure sinks further into the area, and
winds will weaken. Temperatures are likely to settle into the 40s to
low 50s as a result. By tomorrow, this surface high will move
further south, bringing with it the core of the post-frontal
airmass. Even still, this airmass will be competing with clear skies
and strong insolation, and temperatures are likely to climb to near
seasonal averages, which is very near 70 degrees for this time of
year. Even lighter winds and continued clear skies will result in
even cooler temperatures overnight Monday, likely in the 40s area-
wide with perhaps a few valleys dipping into the 30s.

BRC

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 306 AM CDT Sun Oct 6 2024

From Tuesday onward, a benign weather pattern is expected to
develop that will result in a gradual warming trend and little to no
opportunities for precipitation. Today`s cold front is expected to
sink all the way to the Gulf of Mexico and remain there for several
days and possibly longer, while surface high pressure remains draped
across the Mississippi Valley. Meanwhile, developing tropical
cyclone Milton is very likely to drift east across the central Gulf
and into Florida through mid-week, maintaining east-northeast low
level flow and further preventing rich moisture from returning
northward. This will make precipitation very difficult to produce,
and this is well represented in NBM/LREF ensemble members which are
almost completely dry through the end of the week.

Meanwhile, a large ridge of high pressure across the intermountain
west will slowly inch eastward through the week, allowing for steady
warming across the central plains and Mississippi Valley. Ensemble
mean 850mb temperature anomalies are forecast to very slowly inch
upwards throughout the week, reaching near the 90th percentile by
late in the work week and perhaps even warmer over the weekend.
Likewise, NBM surface temperatures are forecast to steadily climb
through the week, reaching near 80 degrees by mid-week and perhaps
slightly warmer by the weekend. With no obvious features like
shortwaves or cold fronts currently forecast, ensemble spreads are
also quite narrow all the way through Saturday. Late in the weekend,
model guidance does hint at another cold front finally sinking into
the region, but even this boundary does not currently produce a
significant signal for precipitation, as the preceding airmass
continues to be dry. However, we will need to keep an eye on fire
weather concerns late in the week and over the weekend, as there are
hints of developing southwest flow after what will very likely be
nearly two weeks without any meaningful precipitation.

BRC

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 601 AM CDT Sun Oct 6 2024

VFR flight conditions can be expected today, with almost entirely
clear skies. Northwest winds will be somewhat breezy throughout
the day, with the most persistent and strongest winds expected at
UIN. Winds will switch slightly to out of the north to northeast
during the evening and overnight, and weaken significantly.
Otherwise, no hazards are expected.

BRC

&&

.FIRE WEATHER...
Issued at 257 PM CDT Fri Oct 4 2024

A broad area will observe elevated fire weather conditions today,
although the actual threat of wildfires will be highly dependent
on the state of local fuels.

A cold front will steadily move through the area this morning, and
behind this front humidity is expected to quickly drop. By early
afternoon we will likely see humidity values falling to roughly 20
to 25 percent, with a few locations possibly touching 15 percent
as well. Winds are also expected to be breezy, likely between 10
and 15 mph sustained with gusts to near 20 mph. However, wind
speeds are not likely to reach much higher than this aside from
perhaps a few sporadic gusts. Deep mixing to near 5000 ft will
also promote efficient ventilation and smoke dispersion.

These conditions will support erratic fire behavior in areas
where fuels are receptive to burning, which remain highly
variable. However, areas north of I-70 have seen no meaningful
rainfall over the last week or more, and also have a high
percentage of land that is predominantly covered by finer fuels
like grasses, along with agricultural areas where the fall harvest
is well underway. Agricultural fields with significant cover of
cured crops or crop debris will be among the most vulnerable areas
considering how quickly this vegetation dries out.

BRC


&&

.CLIMATE...
Issued at 242 PM CDT Fri Oct 4 2024

Daily record highs for Saturday Oct 5

KSTL: 92 in 1938
KCOU: 94 in 1937
KUIN: 89 in 1938


&&

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

$$

WFO LSX