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Old Jamestown, Missouri 7 Day Weather Forecast
Wx Forecast - Wx Discussion - Wx Aviation
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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: 9:56 pm CDT Jul 20, 2026 |
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Overnight
 Mostly Cloudy
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Tuesday
 Chance T-storms then Sunny
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Tuesday Night
 Mostly Clear
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Wednesday
 Mostly Sunny
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Wednesday Night
 Partly Cloudy
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Thursday
 Mostly Sunny
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Thursday Night
 Partly Cloudy
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Friday
 Chance Showers
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Friday Night
 Slight Chance T-storms
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| Lo 80 °F |
Hi 94 °F |
Lo 69 °F |
Hi 83 °F |
Lo 64 °F |
Hi 81 °F |
Lo 65 °F |
Hi 79 °F |
Lo 67 °F |
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Heat Advisory
Overnight
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Mostly cloudy, with a low around 80. Southwest wind 5 to 7 mph. |
Tuesday
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A 30 percent chance of showers and thunderstorms, mainly before 7am. Mostly cloudy, then gradually becoming sunny, with a high near 94. Heat index values as high as 102. Northwest wind 8 to 14 mph, with gusts as high as 21 mph. |
Tuesday Night
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Mostly clear, with a low around 69. North wind 8 to 13 mph, with gusts as high as 20 mph. |
Wednesday
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Mostly sunny, with a high near 83. North wind 8 to 10 mph. |
Wednesday Night
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Partly cloudy, with a low around 64. North wind 5 to 9 mph becoming light northeast. |
Thursday
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Mostly sunny, with a high near 81. |
Thursday Night
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Partly cloudy, with a low around 65. |
Friday
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A chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 79. Chance of precipitation is 30%. |
Friday Night
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A slight chance of showers and thunderstorms. Mostly cloudy, with a low around 67. Chance of precipitation is 20%. |
Saturday
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Mostly sunny, with a high near 86. |
Saturday Night
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Mostly clear, with a low around 71. |
Sunday
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Sunny, with a high near 94. |
Sunday Night
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Mostly clear, with a low around 76. |
Monday
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Mostly sunny, with a high near 95. |
Forecast from NOAA-NWS
for 3 Miles NNW Black Jack MO.
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Weather Forecast Discussion
097
FXUS63 KLSX 210354
AFDLSX
Area Forecast Discussion
National Weather Service St Louis MO
1054 PM CDT Mon Jul 20 2026
.KEY MESSAGES...
- Widely scattered showers and thunderstorms this afternoon will
diminish this evening after sunset. Another round of scattered
thunderstorms is possible tonight. A few storms may produce
wind gusts of 50-60 mph across parts of northeast Missouri and
west central Illinois.
- A cold front will move through the area on Tuesday. There is a
chance for thunderstorms with the front, mainly in the
afternoon across southeast Missouri and southern Illinois.
- Cooler and less humid air will move into the area behind the
front, with highs only in the low to mid 80s on Wednesday and
Thursday.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 338 PM CDT Mon Jul 20 2026
Warm and humid conditions continue across the area this afternoon
across much of the area. A weak cold front moved across much of
Illinois and stalled near the Mississippi River last night. This
front is now moving slowly back to the northeast, and the warm moist
airmass is building back into Illinois behind it. Scattered
thunderstorms over the eastern Ozarks will dissipate this evening as
daytime heating wanes. Storms arent showing much organization and
deep layer shear is only around 20kts. However the RAP is showing
MLCAPE values in excess of 3000 J/Kg so an isolated strong wind gust
cant be ruled out.
Another much stronger cold front will move from the Upper Midwest
through the Mid Mississippi Valley on Tuesday, and this will break
our most recent stretch of hot weather. Additional thunderstorm
development is expected ahead of the front tonight across Iowa,
though it is unclear how widespread and how strong the storms will
be by the time they reach our forecast area. Forecast soundings are
showing a fairly deep dry layer in the low levels, and subsequently
a great deal of CINH. Both the RAP and GFS therefore show very
little QPF with this front, and even the HRRR only shows widely
scattered convection as the front moves through. However, CAPE
values will continue in the 2500-3000 J/Kg range ahead of the front
early Tuesday morning, with around 40kts of deep layer shear, so any
storms that can punch through that CINH could become severe, most
likely in far southeast Missouri into south central Illinois Tuesday
afternoon.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 338 PM CDT Mon Jul 20 2026
A deep long wave trough over the eastern U.S. will allow a much
cooler Canadian high pressure system to dig into the Mississippi
Valley Tuesday night and Wednesday. Temperatures are expected to be
much cooler in the low to mid 80s in most locations Wednesday and
Thursday as high pressure moves from the Midwest into the Ohio
Valley. Medium range guidance is moving a short wave trough from
the Great Plains into the Mid Mississippi Valley Thursday into
Friday. There are some timing and amplitude differences with this
wave, however guidance suggests the low level reflection of the wave
will generate a low level jet Thursday night into Friday which will
produce precip that persists through much of Friday into Friday
night. Clouds and precip on Friday look to suppress temperatures ,
and highs may not even reach 80s. Warmer weather spreads east from
the Great Plains through the weekend into early next week as the
long wave pattern shifts east and the upper ridge builds back into
the Mississippi Valley.
&&
.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1054 PM CDT Mon Jul 20 2026
Strong to severe thunderstorms continue to slide southeast from Iowa
with the leading edge currently approaching northern Missouri. These
storms are expected to percolate in intensity as they continue to
slide southeast into northeast Missouri within the next few hours.
As of now, there is still about a 30-50% chance for thunderstorm
impacts at KUIN with the most likely timeframe from 06-10z. A lot of
uncertainty remains on the evolution of these thunderstorm clusters
overnight with about a 30% chance that remnant activity makes it
into the St. Louis Metro area around the 09-12z timeframe.
Confidence in impacts at the central Missouri terminals remains too
low at this time to be added to the TAF but will continue to be
monitored. All of this activity is out ahead of a cold front that
will pass from north to south late tonight into the day tomorrow.
Along and behind this cold front, once the surface wind shifts from
westerly to northerly, MVFR visibilities from smoke/haze are
possible at all terminals. Northerly surface winds become gusty
tomorrow with gusts up to 20-25kts before weakening after sunset
tomorrow night.
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Heat Advisory until 7 PM CDT Tuesday for MOZ041-047>051-
059>065-072>075-084-085-099.
IL...Air Quality Alert until midnight CDT tonight for ILZ058>060-
064-065-069-070-074-079-095>102.
Heat Advisory until 7 PM CDT Tuesday for ILZ069-074-079-
100>102.
&&
$$
SHORT TERM...Carney
LONG TERM...Carney
AVIATION...Peine
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