Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

926
FXUS63 KLSX 280741
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
241 AM CDT Sat Mar 28 2026

.KEY MESSAGES...

- A widespread freeze will occur this morning, but warmer
  temperatures are forecast next week.

- Elevated fire danger conditions are expected across central and
  eastern Missouri this afternoon.

- A cold front late Tuesday or early Wednesday brings our next
  chance of thunderstorms followed by a cool down.

&&

.SHORT TERM...  (Through Late Tonight)
Issued at 233 AM CDT Sat Mar 28 2026

Mostly clear skies across the region this morning (only some
passing cirrus) with surface high pressure centered over southern
Iowa. At 250mb, the longwave trough from yesterday has started to
amplify which will further push the surface high pressure
southeast over eastern Missouri. As the pressure gradient weakens,
winds will start to go calm. Sheltered areas have already gone
calm with temperatures rapidly falling were the PBL has decoupled.
The warmest location at this time is the City of St. Louis thanks
to the urban heat island. A widespread freeze will occur for
almost the entire region, with the exception being St. Louis City.
Given this, the freeze warning and frost advisory remain in
effect with no changes at this time.

During the day today, the 250mb longwave trough axis will
continue to accelerate east taking the aforementioned surface high
pressure east with it. This means the calm winds from this
morning will start to slowly come up in speed and veer around from
the southeast. Sustained winds will be strongest across northeast
Missouri (~10 to 15 mph) and weakest over south-central Missouri
(< 5 mph). The air mass today remains plenty dry as PWATs looks to
bottom out around 0.15" (or below the 10th percentile for this
time of year). This also means dewpoints will likely fall off into
the teens this afternoon (especially over east-central Missouri).
High temperatures will be in the mid to upper 50s over the region
(maybe reaching 60 degrees over central and south-central
Missouri). This will push relative humidity values down into the
teens for central and south-central Missouri. For northeast
Missouri, relative humidity values will bottom out in the low to
mid 20s. There was some areas that observed over 1" of rainfall
yesterday, with most of the region receiving less than 0.5". Even
with this rainfall, latest fuel moistures have fallen off back to
the single digits this evening with some recovery expected this
morning. As such, an Elevated Fire Danger risk exists across
eastern Missouri this afternoon.

Tonight into Sunday morning, temperatures will be warmer compared
to this morning due to the persistent southerly winds across
Missouri and Illinois. Expect low temperatures in upper 30s to
lower 40s. A few sheltered locations could reach the mid 30s, but
confidence in this occurring is low at this time.

BAH

&&

.LONG TERM...  (Sunday through Friday)
Issued at 233 AM CDT Sat Mar 28 2026

Surface high pressure will be centered over the Mid-Atlantic
states Sunday morning and continue to move east over the Atlantic
Ocean by Sunday afternoon. This will allow surface winds over
Missouri and Illinois to continue to veer from the south and then
southwest while also increasing in speed (10 to 15 mph). The other
consequence of the return flow is a warming in temperatures.
850mb temperatures warm to 6- 8 degrees C by Sunday afternoon with
1000/ 850mb thicknesses recovering to 1350m. High temperatures
Sunday will likely warm into the upper 60s east of the Mississippi
River, with low 70s generally west of the Mississippi River.
Dewpoints will start to recover on Sunday into the 40s, but
another round of Elevated Fire Danger is possible Sunday
afternoon.

Monday, a shortwave will move onshore across western British
Columbia and progress east over southern Canada. This shortwave is
the feature that has been causing the model discrepancy for later
in the work week which will be discussed more below. For Monday,
temperatures will warm into the 80s across most locations as
southerly winds persist. Most of the area will likely be dry with
substantial low level capping in place on forecast soundings.

Tuesday into Wednesday, models have seemed to come into much
better agreement that a cold front will cross the zones late
Tuesday into early Wednesday with the latest run of the NBM
showing IQRs around 10 degrees or less (compared to this time
yesterday where the IQR was 25 degrees). Out ahead of the cold
front, temperatures will be warm with the southwest flow off of
the Ozarks allowing highs to surge into the upper 80s across
south-central Missouri. If the frontal passage is slower
temperatures will likely be warmer, where as if the cold front is
slower high temperatures will be lower Tuesday. It should be noted
that the wave over British Columbia still isn`t being sampled by
upper air releases and this solution could still change.

For the second half of the work week, a potentially active
pattern will continue as multiple mid-level waves progress
overhead. This means showers and thunderstorms will be possible
starting Tuesday and persisting through the work week.

BAH

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1050 PM CDT Fri Mar 27 2026

Dry, VFR conditions will prevail through the TAF period across the
region as weak northerly winds turn out of the south by Saturday
afternoon.

MRB

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Freeze Warning until 9 AM CDT this morning for Audrain MO-Boone
     MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
     Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln MO-Madison MO-
     Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike
     MO-Ralls MO-Reynolds MO-Saint Charles MO-Saint Francois MO-
     Sainte Genevieve MO-Shelby MO-Warren MO-Washington MO.

     Frost Advisory until 9 AM CDT this morning for Saint Louis City
     MO-Saint Louis MO.

IL...Freeze Warning until 9 AM CDT this morning for Adams IL-Bond IL-
     Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey
     IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL-
     Pike IL-Randolph IL-Saint Clair IL-Washington IL.

&&

$$

WFO LSX