Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

204
FXUS63 KLSX 202315
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
515 PM CST Fri Feb 20 2026

.KEY MESSAGES...

- There is a low chance (10-20%) for a brief period of light
  snow/light rain exists Saturday morning. With the current warm ground
  temperatures and no accumulation forecasted, no impacts are
  anticipated.

- Cooler temperatures continue through Monday before rebounding on
  Tuesday.


&&

.SHORT TERM...  (Through Late Saturday Night)
Issued at 246 PM CST Fri Feb 20 2026

Latest surface analysis unveils a strong occluded surface low over
the Great Lakes Region with a north-south elongated area of high
pressure across the Plains. This setup has led to a tightened
surface pressure gradient which has resulted in strong and gusty
westerly winds today. The result has been continued reinforcement of
a much cooler post-frontal airmass today that has kept afternoon
temperatures in the 30s and 40s across the area. As the surface low
continues to depart to the northwest and the high slides in from the
west, surface winds will relax this evening becoming much lighter as
they veer northerly overnight.

A mid-level shortwave, that is currently traversing over Colorado
under west-southwesterly flow, will move into the region tonight.
The most noticeable affect this system will have on our sensible
weather will be an increase of mid-level cloud cover leading to a
mostly cloudy sky on Saturday. With solar insolation limited,
temperatures will struggle to warm from the morning lows in the
20s/30s, with afternoon highs peaking in the 30s for areas north of
I-70 and the low 40s for areas south.

This mid-level shortwave will lack low-level support as it treks
into the Plains with only a few deterministic members developing a
feeble low-level system around the Ark-La-Tex Region. Around 50% of
the hi-res guidance resolves a field of light precipitation that
will move into the area tomorrow morning collocated with a region of
frontogenesis at 850-925mb. The greatest uncertainty and question
remains how much of this precipitation will reach the ground with
the dry low-level air in place. Most deterministic forecast
soundings limit saturation to a narrow column ranging from 5-15kft
AGL that would result in scattered sprinkles or flurries. The RAP is
currently the most bullish, depicting a 2-3 hr window where the
column would be saturated enough for precipitation to reach the
surface, with the best chance generally along and south of I-70.
Temperatures will be near freezing during this time with the most
likely precipitation type expected to be light snow where rates are
great enough for precip to reach the surface. Regardless, with the
progressive nature of the 850-925mb frontogenesis and lack of ample
low-level moisture, precipitation amounts are expected to be light.
Current HREF probabilities for rain amounts >0.01" and snow amounts
>0.1" is less than 20% with those chances limited to to central and
southern Missouri.

Peine/Maples

&&

.LONG TERM...  (Sunday through Next Friday)
Issued at 246 PM CST Fri Feb 20 2026

At the start of the extended, the region will be placed under deep
northwesterly flow with mid/upper level ridging over the
Intermountain West and robust troughing over the eastern CONUS. As a
result, cold air advection will be reinforced keeping areawide
temperatures 5-15 degrees below normal through Monday. Confidence is
high in below normal temperatures as all LREF ensemble members have
850mb temperatures near the 10th climatological percentile Sunday
into Monday night. The current expectation is that this will be the
coldest air the region has experienced since the first few days of
the month.

Monday morning appears to be the coldest time during this stretch as
an Arctic high drops southward out of the Northern Plains placing us
under light northerly surface flow that will aid in morning lows
reaching the teens across the region. As the Arctic high slides
eastward across the region Monday night, return flow ramps up
Tuesday, resulting in the beginning of another stretch of above
normal temperatures that is expected to last into next weekend.
Temperatures on Tuesday will rebound nicely under the increased low-
level southerly flow, potentially reaching afternoon values that are
15-25 degrees warmer than Monday. With no mid/upper level
disturbances under the northwesterly flow until Thursday, conditions
are forecasted to remain dry for the entire area.

Even with the above normal temperatures expected Tuesday into next
weekend, the mid/upper level flow regime next week will remain west-
northwesterly. Within this flow pattern, long-range ensemble
guidance is keying in on a shortwave moving into the region on
Thursday. The latest LREF and NBM both have only a 10-20% chance of
6hr QPF >0.01" with 24hr probabilities jumping up to 30-50% for
Thursday into Friday, due to discrepancies regarding timing of the
mid-level shortwave. Given this system is nearly a week away, there
are a lot of details that will need refined to hone in on the
precise timing of the greatest precipitation chances. Regardless,
guidance is in good consensus that the best precip chances will be
east of the Mississippi River. The passage and departure of the mid-
level disturbance on Thursday will briefly bring deep northwesterly
flow in its wake resulting in slightly cooler temperatures. However,
brief is the key word here, as the LREF and NBM temperature IQR`s
indicate that there is good agreement a steady warming trend will
continue into next weekend.

Peine/Maples

&&

.AVIATION...  (For the 00z TAFs through 00z Saturday Evening)
Issued at 510 PM CST Fri Feb 20 2026

VFR flight conditions will continue through the remainder of the
TAF period. There is a 30% chance for sprinkles/flurries tomorrow
morning from roughly 09-17Z along and south of I-70, including the
mid-Missouri (KCOU, KJEF) and St. Louis metro (KSTL, KSUS, KCPS)
terminals. Otherwise conditions will be dry.

Winds will remain from the northwest to north through the period,
increasing in speed again to around 10 kts tomorrow afternoon.

Delia

&&

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

$$

WFO LSX