Plan a flight · Sun 9:11 pm CDT (02:11 UTC)

St. Louis Downtown Airport to Seattle-Tacoma International CPS → SEA

1,496 nautical miles (1,722 statute miles) northwest on a straight line, true course 301°, about 301° magnetic at the departure end (variation 0E). At 120 knots that is 11 h 52 min at the quickest height in today's winds (4,500 ft, a 6-knot tailwind), arriving about 7:03 am PDT (14:03 UTC), after sunset at the destination. Right now CPS is VFR, wind from the south (170°) at 4 knots; SEA is VFR, wind from the north (360°) at 7 knots. For planning, not a briefing: the legal preflight briefing comes from Flight Service (1-800-WX-BRIEF) or the FAA's own tools. Airlines fly this pair: 6 flights in the DOT's last twelve reported months, the route's page.

The route the straight line, the warnings crossed, restrictions, pilot reports and the airports along the way · click a mark for its words

Green, blue, red and purple airport dots are the flying conditions reported there now (VFR, marginal VFR, IFR, low IFR); grey means no report. Red areas are SIGMETs, orange areas AIRMETs, hatched red areas temporary flight restrictions. Map tiles: OpenFreeMap, data © OpenStreetMap contributors.

Warnings the route crosses SIGMETs and AIRMETs whose area the line passes through or comes within 25 nm of

SIGMET 8W: thunderstorms (a convective SIGMET) up to 35,000 ft, moving from the southwest at 40 knots, until 10:55 pm CDT (03:55 UTC). Over the route from 718 to 858 nm out.

as issued

WSUS33 KKCI 120155
MKCW WST 120155
CONVECTIVE SIGMET 8W
VALID UNTIL 0355Z
CO MT WY
FROM 40N SHR-60WNW RAP-20ENE CYS-30SW CYS-10NW BOY-40N SHR
AREA TS MOV FROM 22040KT. TOPS TO FL350.

AIRMET TANGO 3W: low-level wind shear (due to air speed loss or gain of 20 knots or more below 2,000 ft above the ground). Over the route from 190 to 379 nm out.
AIRMET TANGO 4W: moderate turbulence above 18,000 ft from 18,000 ft to 36,000 ft. Over the route from 628 to 1227 nm out.
AIRMET TANGO 4W: moderate turbulence below 18,000 ft up to 18,000 ft. Over the route from 768 to 987 nm out.
AIRMET SIERRA 4E: low cloud or poor visibility (IFR conditions) (due to ceilings below 1,000 ft, visibility below 3 miles, precipitation, mist). Over the route from 798 to 1197 nm out.
AIRMET TANGO 1W: low-level wind shear (due to air speed loss or gain of 20 knots or more below 2,000 ft above the ground). Near the route, 798 nm along the route.
AIRMET SIERRA 1E: mountains obscured by cloud (due to mountains obscured by clouds, precipitation, mist). Over the route from 838 to 1297 nm out.
AIRMET ZULU 3C: moderate icing up to 22,000 ft. Over the route from 848 to 967 nm out.
AIRMET ZULU 2C: moderate icing up to 16,000 ft. Over the route from 1057 to 1396 nm out.
AIRMET TANGO 1W: moderate turbulence above 18,000 ft from 18,000 ft to 39,000 ft. Over the last 140 nm of the route.

A SIGMET warns of weather hazardous to all aircraft; an AIRMET of weather that matters to small aircraft and to flying without instruments. "From 60 to 180 nm out" is measured along the route from CPS.

Pilot reports along the route within 50 nm of the line, last three hours, the serious ones first

E75L at 14,000 ft, 17 nm northeast, 6:22 pm CDT (23:22 UTC): moderate turbulence from 14,000 ft to 21,000 ft, remarks: during the climb zlc. 1157 nm along the route, 17 nm northeast of the line.
as filed, and in English
```
MSO UA /OV 32S/TM 2322/FL140/TP E75L/TB MOD 140-210/RM DURC /ZLC
```
Report
a routine report filed through MSO
Where
over 32S
Time
23:22 UTC
Height
at 14,000 ft
Aircraft
E75L
Turbulence
moderate from 14,000 ft to 21,000 ft
Remarks
during the climb zlc
B763 at 32,000 ft, 46 nm northeast, 8:29 pm CDT (01:29 UTC): light to moderate clear-air turbulence, remarks: zdvwc. 588 nm along the route, 46 nm northeast of the line.
as filed, and in English
```
RAP UA /OV RAP084081/TM 0129/FL320/TP B763/TB OCNL LGT-MOD CAT/RM ZDVWC
```
Report
a routine report filed through RAP
Where
81 nm east (084°) of RAP
Time
01:29 UTC
Height
at 32,000 ft
Aircraft
B763
Turbulence
occasional light to moderate clear-air turbulence
Remarks
zdvwc
A306 at 4,700 ft, 41 nm north, 7:51 pm CDT (00:51 UTC): a routine report with nothing remarked on. 928 nm along the route, 41 nm north of the line.
as filed, and in English
```
BIL UA /OV BIL280001/TM 0051/FL047/TP A306/SK BASE 047
```
Report
a routine report filed through BIL
Where
1 nm west (280°) of BIL
Time
00:51 UTC
Height
at 4,700 ft
Aircraft
A306
Sky
base 4,700 ft
E75L descending, 7 nm northeast, 8:04 pm CDT (01:04 UTC): remarks: had the airport in sight at 400-500FT above ground. 1027 nm along the route, 7 nm northeast of the line.
as filed, and in English
```
BZN UA /OV BZN/TM 0104/FLDURD/TP E75L/RM HAD THE AIRPORT IN SIGHT AT 400-500FT AGL
```
Report
a routine report filed through BZN
Where
over BZN
Time
01:04 UTC
Height
during the descent
Aircraft
E75L
Remarks
had the airport in sight at 400-500FT above ground
B737 descending, 7 nm northeast, 7:28 pm CDT (00:28 UTC): scattered clouds above 8,000 ft, fog, snow, remarks: broke out about 100FT above mins. 1027 nm along the route, 7 nm northeast of the line.
as filed, and in English
```
BZN UA /OV BZN/TM 0028/FLDURD/TP B737/SK SCT080/WX 1/2SM SN FG/RM BROKE OUT ABOUT 100FT ABOVE MINS
```
Report
a routine report filed through BZN
Where
over BZN
Time
00:28 UTC
Height
during the descent
Aircraft
B737
Sky
scattered clouds from 8,000 ft
Weather
1/2SM, snow, fog
Remarks
broke out about 100FT above mins
B738 at 24,000 ft, 8 nm northeast, 6:13 pm CDT (23:13 UTC): remarks: snow top flight level at 24,000 ft zlc. 1057 nm along the route, 8 nm northeast of the line.
as filed, and in English
```
BZN UA /OV BZN270030/TM 2313/FL240/TP B738/RM SN TOP FL 240 /ZLC
```
Report
a routine report filed through BZN
Where
30 nm west (270°) of BZN
Time
23:13 UTC
Height
at 24,000 ft
Aircraft
B738
Remarks
snow top flight level at 24,000 ft zlc
BCS1 at 3,700 ft, 38 nm north, 8:47 pm CDT (01:47 UTC): snow, rain, remarks: during the descent ils runway 12. 1157 nm along the route, 38 nm north of the line.
as filed, and in English
```
MSO UA /OV MSO/TM 0147/FL037/TP BCS1/SK 037/WX SN RA/RM DURD ILS RY 12
```
Report
a routine report filed through MSO
Where
over MSO
Time
01:47 UTC
Height
at 3,700 ft
Aircraft
BCS1
Sky
at 3,700 ft
Weather
snow, rain
Remarks
during the descent ils runway 12
C25B at 4,100 ft, 38 nm north, 7:36 pm CDT (00:36 UTC): no icing, overcast above 4,100 ft, remarks: during the descent ils runway 12. 1157 nm along the route, 38 nm north of the line.
as filed, and in English
```
MSO UA /OV MSO/TM 0036/FL041/TP C25B/SK OVC041/IC NEG/RM DURD ILS RY 12
```
Report
a routine report filed through MSO
Where
over MSO
Time
00:36 UTC
Height
at 4,100 ft
Aircraft
C25B
Sky
overcast from 4,100 ft
Icing
none
Remarks
during the descent ils runway 12
PC12 at 13,500 ft, 22 nm south, 8:08 pm CDT (01:08 UTC): no turbulence, a trace of icing, overcast from 9,000 ft to 13,500 ft, -10 °C. 1356 nm along the route, 22 nm south of the line.
as filed, and in English
```
PSC UA /OV PSC360025/TM 0108/FL135/TP PC12/SK OVC090-TOP135/TA M10/TB NEG /IC TRACE RM 135-090
```
Report
a routine report filed through PSC
Where
25 nm north (360°) of PSC
Time
01:08 UTC
Height
at 13,500 ft
Aircraft
PC12
Sky
overcast from 9,000 ft, tops 13,500 ft
Temperature
−10 °C
Turbulence
none
Icing
trace remarks from 13,500 ft to 9,000 ft
SB20 at 16,000 ft, 31 nm north, 8:52 pm CDT (01:52 UTC): remarks: zse. At the destination end, 31 nm north of the line.
as filed, and in English
```
PAE UA /OV PAE075045/TM 0152/FL160/TP SB20/SK TOP120/RM ZSE
```
Report
a routine report filed through PAE
Where
45 nm east (075°) of PAE
Time
01:52 UTC
Height
at 16,000 ft
Aircraft
SB20
Sky
TOP120
Remarks
zse
PC12 at 15,000 ft, 30 nm south, 7:42 pm CDT (00:42 UTC): remarks: zse. At the destination end, 30 nm south of the line.
as filed, and in English
```
YKM UA /OV YKM270050/TM 0042/FL150/TP PC12/SK TOP130/RM -ZSE
```
Report
a routine report filed through YKM
Where
50 nm west (270°) of YKM
Time
00:42 UTC
Height
at 15,000 ft
Aircraft
PC12
Sky
TOP130
Remarks
zse
PC12 at 13,000 ft, 30 nm south, 7:42 pm CDT (00:42 UTC): remarks: zse. At the destination end, 30 nm south of the line.
as filed, and in English
```
YKM UA /OV YKM270050/TM 0042/FL130/TP PC12/SK TOP130/RM -ZSE
```
Report
a routine report filed through YKM
Where
50 nm west (270°) of YKM
Time
00:42 UTC
Height
at 13,000 ft
Aircraft
PC12
Sky
TOP130
Remarks
zse
A321 at 13,500 ft, 30 nm south, 8:54 pm CDT (01:54 UTC): remarks: zse. At the destination end, 30 nm south of the line.
as filed, and in English
```
SEA UA /OV SEA120045/TM 0154/FL135/TP A321/SK TOP130/RM ZSE
```
Report
a routine report filed through SEA
Where
45 nm southeast (120°) of SEA
Time
01:54 UTC
Height
at 13,500 ft
Aircraft
A321
Sky
TOP130
Remarks
zse

Winds aloft along the route, and the time en route the forecast for use 20:00–03:00 UTC · at 120 knots true airspeed

The westbound cruising heights for this course (VFR: even thousands plus 500 ft; above 18,000 ft the forecast levels), with the wind averaged along the line from the 15 forecast points nearest it (STL, COU, MKC, DSM, OMA, GRI, ONL, PIR, RAP, BIL, DLN, LWS, GEG, YKM, SEA). A plus sign is a headwind, a minus sign a tailwind.

Height	Average wind	Head- or tailwind	Temperature	Ground speed	Time en route	Arrival
4,500 ft	160° at 6 kt	−6 kt	13 °C	126 kt	11 h 52 min	7:03 am PDT (14:03 UTC)
6,500 ft	180° at 5 kt	−4 kt	10 °C	124 kt	12 h 04 min	7:15 am PDT (14:15 UTC)
8,500 ft	210° at 5 kt	−1 kt	6 °C	121 kt	12 h 22 min	7:33 am PDT (14:33 UTC)
10,500 ft	220° at 9 kt	+2 kt	2 °C	118 kt	12 h 41 min	7:52 am PDT (14:52 UTC)
12,500 ft	220° at 13 kt	+4 kt	-1 °C	116 kt	12 h 54 min	8:05 am PDT (15:05 UTC)
14,500 ft	230° at 15 kt	+6 kt	-5 °C	114 kt	13 h 07 min	8:18 am PDT (15:18 UTC)
16,500 ft	230° at 17 kt	+8 kt	-9 °C	112 kt	13 h 21 min	8:32 am PDT (15:32 UTC)
18,000 ft FL180	230° at 18 kt	+9 kt	-12 °C	111 kt	13 h 29 min	8:40 am PDT (15:40 UTC)
24,000 ft FL240	240° at 26 kt	+15 kt	-22 °C	105 kt	14 h 15 min	9:26 am PDT (16:26 UTC)
30,000 ft FL300	240° at 32 kt	+17 kt	-35 °C	103 kt	14 h 31 min	9:42 am PDT (16:42 UTC)
34,000 ft FL340	240° at 41 kt	+27 kt	-41 °C	93 kt	16 h 05 min	11:16 am PDT (18:16 UTC)
39,000 ft FL390	250° at 48 kt	+39 kt	-47 °C	81 kt	18 h 28 min	1:39 pm PDT (20:39 UTC)

Based on data from the 11th at 18:00 UTC; valid on the 12th at 00:00 UTC for use 20:00 to 03:00 UTC; temperatures above 24,000 ft are below zero. Heights are above sea level; a height is left out when the forecast has no wind for it over most of the line (the ground is higher). Ground speed is the airspeed less the headwind; the time en route is for the straight line and ignores climb, descent and routing around weather.

The forecast points as issued

Point	From	3,000	6,000	9,000	12,000	18,000	24,000	30,000	34,000	39,000
STL	used from 0 nm out; 12 nm from the line	210/13	260/16 17°	270/21 10°	280/24 5°	310/20 -7°	320/22 -18°	320/44 -33°	320/59 -43°	310/69 -51°
COU	used from 50 nm out; 40 nm from the line	210/16	220/19 15°	240/33 10°	250/29 7°	280/21 -6°	280/19 -18°	300/34 -31°	300/40 -42°	300/60 -52°
MKC	used from 150 nm out; 78 nm from the line	200/28	220/30 16°	270/20 11°	280/22 7°	260/27 -6°	270/27 -18°	280/38 -32°	270/38 -40°	280/50 -52°
DSM	used from 199 nm out; 73 nm from the line	200/32	240/27 17°	260/19 10°	260/16 5°	260/19 -7°	240/22 -19°	270/20 -32°	270/38 -42°	290/58 -53°
OMA	used from 249 nm out; 38 nm from the line	190/34	230/34 19°	250/25 12°	250/18 6°	250/22 -7°	250/28 -19°	260/34 -32°	260/39 -41°	280/56 -51°
GRI	used from 349 nm out; 60 nm from the line		210/31 19°	240/21 14°	240/17 6°	260/27 -7°	260/34 -18°	240/45 -32°	250/56 -40°	260/62 -51°
ONL	used from 399 nm out; 35 nm from the line		200/20 17°	230/26 14°	240/21 7°	250/27 -9°	260/32 -19°	240/44 -34°	240/56 -41°	250/62 -51°
PIR	used from 549 nm out; 94 nm from the line		L/V 17°	230/13 12°	220/22 6°	250/31 -9°	250/34 -21°	240/50 -35°	230/61 -43°	240/62 -51°
RAP	used from 598 nm out; 51 nm from the line		120/15 12°	180/22 11°	220/26 5°	230/35 -9°	240/40 -22°	240/50 -37°	240/51 -41°	240/47 -47°
BIL	used from 798 nm out; 108 nm from the line		080/24	130/14 -1°	180/33 0°	210/43 -10°	220/58 -21°	200/55 -36°	220/75 -44°	240/83 -48°
DLN	used from 997 nm out; 65 nm from the line			080/10 -3°	180/8 -3°	180/23 -14°	200/58 -22°	200/80 -36°	220/85 -41°	230/81 -45°
LWS	used from 1147 nm out; 101 nm from the line	010/5	050/14 -2°	040/12 -6°	160/7 -10°	190/30 -22°	200/54 -27°	200/48 -35°	210/40 -37°	230/32 -41°
GEG	used from 1297 nm out; 48 nm from the line		050/18 -2°	060/19 -8°	L/V -11°	160/11 -24°	190/17 -31°	200/19 -35°	220/14 -37°	250/11 -41°
YKM	used from 1347 nm out; 60 nm from the line	030/16	020/18 0°	030/30 -8°	030/23 -13°	020/40 -23°	010/73 -29°	010/54 -36°	360/29 -37°	330/16 -40°
SEA	used from 1446 nm out; 25 nm from the line	360/9	350/10 1°	010/10 -5°	030/20 -11°	020/60 -17°	010/86 -26°	360/90 -40°	010/68 -42°	360/31 -43°

The weather now: both ends and the airports along the way public airports with a weather report within 25 nm of the line, one for each stretch

Airport	Where	Conditions	Wind	Visibility	Ceiling	Elevation	Reported
CPS Cahokia/St Louis, IL	departure	VFR	from the south (170°) at 4 knots	10+ mi	none	412 ft	8:53 pm CDT (01:53 UTC)
SUS St Louis, MO	20 nm out, 8 nm southwest of the line, tower	VFR	calm	10+ mi	none	463 ft	01:54 UTC
ICL Clarinda, IA	259 nm out, 0 nm north of the line	VFR	from the south (180°) at 5 knots	10+ mi	none	995 ft	01:55 UTC
OMA Omaha, NE	309 nm out, 13 nm north of the line, tower	VFR Sky: a broken layer at 25,000 feet	from the south-southeast (160°) at 11 knots	10+ mi	25,000 ft	984 ft	01:52 UTC
ANW Ainsworth, NE	509 nm out, 0 nm northeast of the line	VFR	from the north (360°) at 7 knots	10+ mi	none	2,588 ft	01:55 UTC
CUT Custer, SD	678 nm out, 4 nm west of the line	VFR	from the north-northeast (030°) at 5 knots	10+ mi	none	5,619 ft	01:53 UTC
GCC Gillette, WY	768 nm out, 6 nm northwest of the line	IFR Sky: a broken layer at 600 feet, a broken layer at 4,700 feet, overcast at 8,000 feet	from the north (010°) at 7 knots	9 mi	600 ft	4,365 ft	02:04 UTC
BZN Bozeman, MT	1027 nm out, 7 nm northeast of the line, tower	IFR Sky: a few clouds at 600 feet, overcast at 1,500 feet Weather: light snow, mist	calm	1.25 mi	1,500 ft	4,473 ft	02:03 UTC
HRF Hamilton, MT	1157 nm out, 4 nm east of the line	low IFR Sky: overcast at 300 feet Weather: light snow, mist	from the north (350°) at 7 knots	1.5 mi	300 ft	3,635 ft	01:55 UTC
LWS Lewiston, ID	1267 nm out, 22 nm southwest of the line, tower	VFR Sky: overcast at 6,000 feet	from the west-northwest (300°) at 8 knots	10+ mi	6,000 ft	1,442 ft	01:56 UTC
MWH Moses Lake, WA	1376 nm out, 8 nm northeast of the line, tower	VFR Sky: a broken layer at 9,000 feet, overcast at 11,000 feet	from the east (080°) at 4 knots	10+ mi	9,000 ft	1,188 ft	01:52 UTC
SEA Seattle, WA	destination	VFR Sky: a few clouds at 3,000 feet	from the north (360°) at 7 knots	10+ mi	none	432 ft	6:53 pm PDT (01:53 UTC)

The highest airport on this list sits at 5,619 ft; the ground between airports is higher still. Check the sectional chart for the terrain and the minimum safe heights along the line.

At SEA when you get there the forecast at the estimated arrival, 7:03 am PDT (14:03 UTC)

Wind from the southeast at 4 knots, visibility more than 6 miles, patches of fog, clear skies VFR

The whole forecast for SEA

From Sun 5:00 pm PDT (00:00 UTC): wind from the north at 12 knots, gusting to 20, visibility more than 6 miles, a few clouds at 2,000 feet, a few clouds at 5,000 feet
From Sun 8:00 pm PDT (03:00 UTC): wind from the northeast at 6 knots, visibility more than 6 miles, clear skies
From Mon 3:00 am PDT (10:00 UTC): wind from the southeast at 4 knots, visibility more than 6 miles, patches of fog, clear skies
From Mon 9:00 am PDT (16:00 UTC): wind from the south-southeast at 4 knots, visibility more than 6 miles, clear skies
From Mon 11:00 am PDT (18:00 UTC): wind from the west at 6 knots, visibility more than 6 miles, clear skies
From Mon 8:00 pm PDT (03:00 UTC): wind from the northwest at 5 knots, visibility more than 6 miles, scattered clouds at 25,000 feet

The forecast for CPS, the departure

From Sun 7:00 pm CDT (00:00 UTC): wind light and variable, visibility more than 6 miles, clear skies
From Mon 3:00 am CDT (08:00 UTC): wind light and variable, visibility 3 miles, mist, a few clouds at 25,000 feet
At times between Mon 3:00 am CDT (08:00 UTC) and 6:00 am CDT (11:00 UTC): visibility 1 mile, mist
From Mon 6:00 am CDT (11:00 UTC): wind from the southwest at 10 knots, visibility more than 6 miles, a few clouds at 25,000 feet

Temporary flight restrictions on the line or within 25 nm of it

6/7634 CENTRALIA, MO, Monday, October 12, 2026 UTC 17 nm from the route, 100 nm along the route · a hazard on the ground (fire-fighting, a chemical spill, rescue work) · today · ZKC

Daylight

Sunset at CPS 6:27 pm CDT (23:27 UTC), at SEA 6:27 pm PDT (01:27 UTC) (civil twilight ends 6:58 pm PDT (01:58 UTC)). At 120 knots the arrival at SEA is before sunrise there (7:23 am PDT (14:23 UTC)).

Each restriction opens the FAA's own page with the exact area, heights and times. Ordinary notices to air missions (closed runways, lights out) are not shown: the FAA's notice search is not open to sites like this one at this time.

Radar and forecast charts for the regions crossed government pictures, the latest each time the page loads

Radar now, the upper Mississippi valley · loop National Weather Service

Radar now, the northern Rockies · loop National Weather Service

Radar now, the Pacific Northwest · loop National Weather Service

Radar, the whole country · loop National Weather Service

Surface analysis now Weather Prediction Center

Forecast chart, 12 hours ahead Weather Prediction Center

Forecast chart, 24 hours ahead Weather Prediction Center

Sources: the Aviation Weather Center's data service (SIGMETs, AIRMETs, graphical AIRMETs, pilot reports, winds and temperatures aloft, observations and terminal forecasts), the National Weather Service radar, the Weather Prediction Center's charts, the FAA's temporary flight restriction list and shapes, and the FAA's airport file for the positions, elevations and magnetic variation. Fetched when the page is viewed and kept a few minutes. Each leg is the straight line between its two airports; airways, terrain and airspace are not considered. The airports in detail: St. Louis Downtown Airport, Seattle-Tacoma International.