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Old Jamestown, Missouri 7 Day Weather Forecast
Wx Forecast - Wx Discussion - Wx Aviation
NWS Forecast for 3 Miles NNW Black Jack MO
National Weather Service Forecast for: 3 Miles NNW Black Jack MO
Issued by: National Weather Service Saint Louis, MO
Updated: 6:01 pm CDT Aug 26, 2026
 
Tonight

Tonight: Mostly clear, with a low around 68. Northwest wind 5 to 7 mph becoming calm  in the evening.
Mostly Clear
Thursday

Thursday: Sunny, with a high near 88. North wind 3 to 8 mph.
Sunny
Thursday
Night
Thursday Night: Mostly clear, with a low around 62. North wind 5 to 7 mph becoming calm  in the evening.
Mostly Clear
Friday

Friday: Patchy fog before 8am.  Otherwise, sunny, with a high near 86. Calm wind becoming northeast around 5 mph in the afternoon.
Patchy Fog
then Sunny
Friday
Night
Friday Night: Mostly clear, with a low around 62. Northeast wind around 5 mph becoming light and variable  in the evening.
Mostly Clear
Saturday

Saturday: Mostly sunny, with a high near 90.
Mostly Sunny
Saturday
Night
Saturday Night: Partly cloudy, with a low around 69.
Partly Cloudy
Sunday

Sunday: Mostly sunny, with a high near 96.
Mostly Sunny
Sunday
Night
Sunday Night: Mostly clear, with a low around 74.
Mostly Clear
Lo 68 °F Hi 88 °F Lo 62 °F Hi 86 °F Lo 62 °F Hi 90 °F Lo 69 °F Hi 96 °F Lo 74 °F

 

Tonight
 
Mostly clear, with a low around 68. Northwest wind 5 to 7 mph becoming calm in the evening.
Thursday
 
Sunny, with a high near 88. North wind 3 to 8 mph.
Thursday Night
 
Mostly clear, with a low around 62. North wind 5 to 7 mph becoming calm in the evening.
Friday
 
Patchy fog before 8am. Otherwise, sunny, with a high near 86. Calm wind becoming northeast around 5 mph in the afternoon.
Friday Night
 
Mostly clear, with a low around 62. Northeast wind around 5 mph becoming light and variable in the evening.
Saturday
 
Mostly sunny, with a high near 90.
Saturday Night
 
Partly cloudy, with a low around 69.
Sunday
 
Mostly sunny, with a high near 96.
Sunday Night
 
Mostly clear, with a low around 74.
Monday
 
Mostly sunny and hot, with a high near 98.
Monday Night
 
Mostly clear, with a low around 77.
Tuesday
 
Sunny and hot, with a high near 98.
Tuesday Night
 
Partly cloudy, with a low around 77.
Wednesday
 
Mostly sunny and hot, with a high near 97.

 

Forecast from NOAA-NWS for 3 Miles NNW Black Jack MO.

Weather Forecast Discussion
080
FXUS63 KLSX 262343
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
643 PM CDT Wed Aug 26 2026

.KEY MESSAGES...

- An isolated thunderstorm or two is possible (20 percent
  chance) through this evening, mainly in south-central/
  southwestern IL and southeastern MO. A thunderstorm could be
  strong to severe with damaging winds.

- Behind a cold front today, temperatures will be near to
  slightly below average before a heatwave build Sunday into
  next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 232 PM CDT Wed Aug 26 2026

Confidence continues to decrease in initiation of thunderstorms
across the CWA this afternoon and evening with some of the latest
CAMs have thunderstorms remain outside of the CWA and others showing
sparse coverage. This factor is mainly owing to the CWA being
between areas of large-scale ascent (upper-level trough to the north
and an MCV to the south), weak low-level convergence/forcing, and a
weak capping inversion that may not be overcome. That being said, an
isolated thunderstorm or two is still possible across south-
central/southwestern IL and southeastern MO this evening as a weak
cold front consolidates with a pre-frontal trough across that area,
providing a window of greater low-level convergence. With 20 to 25
kt of deep-layer wind shear, high DCAPE/"inverted-V" sounding
signatures, and 1500 to 3000 J/kg MLCAPE; one of these thunderstorms
could briefly become strong to severe with damaging winds.

&&

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
Issued at 232 PM CDT Wed Aug 26 2026

Behind the front, a surface anticyclone will expand into the Mid-
Mississippi River Valley Thursday and then arrive on Friday,
accompanied by a seasonably cool and dry airmass (850-hPa
temperatures and PW around the 25th climatological percentile)
infiltrating the CWA. This airmass will translate to high
temperatures in the low to mid-80s F, low temperatures in the upper
50s to mid-60s F, and lower humidity through Saturday morning.
Efficient nighttime radiational cooling will also promote fog
development each night/morning, predominantly in river valleys as a
combination of radiation and steam fog.

The surface anticyclone will quickly depart to the Great Lakes on
Saturday as it follows the most vigorous subsidence leading an upper-
level ridge amplifying and shifting into the Mid-Mississippi River
Valley. This process will facilitate southwesterly low-level
flow/WAA with 850-hPa temperatures surging to around 21 to 23 C
(above 95th climatological percentile) by Sunday, persisting into
next week. With full sunshine, these 850-hPa temperatures would
likely yield widespread high temperatures in the 90s F, including
favorable southwesterly flow and downslope warming off the Ozark
Plateau potentially resulting in values even approaching 100 F in
central MO and the St. Louis metro. Fortunately, dewpoints/humidity
will at least initially be lower than previous heatwaves we have
seen so far this summer but probabilities of 100+ F heat index
values do increase each day in response to a slow increase in
humidity/dewpoints. The details of the upper-level wave pattern next
week are still not uncertain but there has been an underlying trend
toward a stronger, more persistent ridge across the Mid-Mississippi
River Valley. As such, confidence is increasing in a longer duration
of heat through mid-next week. It is worth noting that there is a
still a preferred corridor for episodic showers and thunderstorms
around the periphery of the ridge, but if this trend holds there is
less concern for the CWA to be impacted by showers and thunderstorms
aside from far northern parts of northeastern MO and west-central IL
through Wednesday.

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 643 PM CDT Wed Aug 26 2026

Scattered showers/storms have stayed east of the St. Louis metro
with a 15% chance for an isolated shower or weak thunderstorm near
the STL metro terminals within the next hour. Northerly surface
winds now encompass all local terminals as the cold front has
cleared from north to south this evening. Light and variable winds
are expected tonight, favoring the development of fog particularly
in river valley locations. As a result, mention of MVFR/IFR
visibilities from fog has been included at KSUS/KCPS/KJEF for a
period early Thursday morning before clearing after sunrise. Light
northerly winds continue through the day tomorrow before going light
and variable again for the region tomorrow night.


&&

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

&&

$$

SHORT TERM...Pfahler
LONG TERM...Pfahler
AVIATION...Peine
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Forecast Discussion from: NOAA-NWS Script developed by: El Dorado Weather






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