Wednesday, September30, 2020
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Marine Weather and Tides
Winchester, MO

Version 3.4
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8/26/2020 The 7 day forecast is taking about 5 seconds to load but it will eventually load. NOAA is still working on it.
8/18/2020 NOAA continues to have trouble. Wind guest will occasionally be left off graphs. I am working with NOAA to resolve the issue.
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 6:56AMSunset 6:47PM Wednesday September 30, 2020 10:41 AM CDT (15:41 UTC) Moonrise 5:41PMMoonset 4:35AM Illumination 97% Phase: Waxing Gibbous; Moon at 13 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
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7 Day Forecast for Marine Location Near Winchester, MO
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location: 38.58, -90.53     debug


Area Discussion for - St. Louis, MO
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FXUS63 KLSX 301149 AFDLSX

Area Forecast Discussion . Updated Aviation National Weather Service Saint Louis MO 649 AM CDT Wed Sep 30 2020

SHORT TERM. (Through Late Thursday Afternoon) Issued at 358 AM CDT Wed Sep 30 2020

The main story today will be the milder conditions and gusty winds. Much cooler air will advect in late today into Thursday.

Regional analysis shows mainly clear skies over the area with southwesterly surface flow and surface temperatures largely in the 50s. Slightly milder temperatures and higher winds have mitigated the concern for any potential valley/river fog that was observed yesterday morning over southeast Missouri.

Satellite imagery shows a bank of clouds pressing from northwest to southeast around the Missouri/Iowa border. This is associated with a cold front, mid-level ascent and shallow layer of moisture. Skies are largely void of cloud cover ahead of the front, which will start the the mostly sunny. Diurnal heating processes will allow for ample mixing from late morning through the afternoon, pulling down some of the higher winds aloft. Gusts of 20-25 mph will become fairly common through peak heating. Some locations north of I-70 may even occasionally hit 30 mph. As the front sinks south, it will likely be accompanied by an increase in mid-level clouds, especially along and east of the Mississippi River. Otherwise the front passes through passes through dry with plenty of dry air through the lowest 5-7k feet.

There will be a fair spread in temperatures from north to south with more cloud cover and earlier frontal passage through the northern sections of the CWA (northeast MO/west central IL). Along and south I-70, there seems to be ample time for heating ahead of the front, giving rise to mid to upper 70s. Areas of southeast Missouri and southwest Illinois have the best potential to touch 80 degrees as peak diurnal heating likely occurs ahead of the cold air advection. General timing of front is from about 16z across the north, 19z near I-70 and 21z across the southern sections of the forecast area.

The remainder of the short term is characterized by cooler temperatures behind the front and the potential for gusty winds Thursday afternoon. Clear skies and light winds will allow temperatures to drop well into the 40s tonight. Highs will largely be in the 60s, but it will feel a bit cooler given that we mix winds down to result in 20-25 mph gusts Thursday afternoon.

Maples

LONG TERM. (Thursday Night through Tuesday) Issued at 358 AM CDT Wed Sep 30 2020

The extended period will be characterized by cooler than normal temperatures and what are likely to be low end impacts. These impacts will stem from patchy frost potential Friday morning and rainfall potential over a portion of the weekend.

At the start of the period, a longwave trough continues to consume the eastern half of the U.S., while the axis of an amplified ridge extends south to north over the west coastline through the southern provinces of Canada. Surface high pressure, centered over the Canadian-U.S. border, will continue to build south and parallel the Mississippi River Valley late Thursday into Friday. This will place the area under northwesterly flow aloft, clear skies, and light and variable winds. This pattern is conducive for efficient radiational cooling. Forecast lows range from the mid-30s to the low-40s with most locations clustered around the 50th percentile of guidance. Patchy frost still seems plausible in the coolest locations, mainly over northeast Missouri and outlying valleys/low elevations. Highs will not rebound far, ranging from the mid-50s to near low-60s. The key here is to point out that much of the day will be spent in the 50s with most locations struggling to get over 60.

Between Friday and early Saturday we remain entrenched within the base of the upper longwave trough as the surface ridge begins to translate east into the Ohio Valley. Despite being behind the surface ridge, we never really escape the cooler airmass with single digit H8 air overhead. After starting out in the upper 30s to mid-40s, afternoon temperatures will range from the upper 50s to mid-60s.

The main focus will be on the incoming shortwave via northwest flow aloft. Ensemble guidance has been decently clustered around the late Saturday into mid-Sunday timeframe for precipitation. There are some deterministic difference between the ECM/GFS that may separate a decent, steady rainfall and scattered showers. The ECM is suggesting better organized surface low that rounds the base of the digging upper trough, while the GFS remains quite a bit more open and smeared is presence. This is likely lending a hand in grasping onto any definitive answers for just how wet is may be. Regardless, the overarching theme will be a cool, damp afternoon Saturday into at least the first part of Sunday as the axis of the upper trough and ample lift passes directly overhead. We are likely to see a smattering of lingering shower activity behind the system through early afternoon Sunday with gradually improving conditions.

The upper trough continues eastward with high pressure building in at the surface. Modest upper ridging to the west becomes more suppressed in time, resulting in zonal flow aloft. Drier conditions are expected with temperature gradually moderating closer to seasonal norms from Monday into Tuesday.

Maples

AVIATION. (For the 12z TAFs through 12z Thursday Morning) Issued at 617 AM CDT Wed Sep 30 2020

The main impact in the period will result from gusty winds beginning late this morning and extending through the afternoon.

A cold front that currently stretches east to west through Iowa will continue a southward track today. Ahead of the front, west and southwesterly winds will increase, becoming gusty as diurnal heating begins mix higher winds down from aloft. Gusts between 20 and 25 knots will be common at all terminals from 16z through 23z. I would not be surprised to see lower gusts creep into northeast Missouri and central Illinois a little earlier, but timing in the TAF captures the greatest potential. We may even briefly exceed 25 knots around KUIN through the afternoon.

The front will push through KUIN late this morning into the early afternoon. Though moisture will be limited, there may be a brief lowering in the few/scattered VFR cloud bases to around 5k feet. Winds then shift out of the northwest behind the front and remain gust through the evening before dying down near and after sunset. This will also be the theme along the front at terminals to the south from early to mid-afternoon. Expect slightly lower gust potential with the strongest stretching through northern Missouri and into west central Illinois.

Expect winds to lighten after sunset with VFR conditions through the end of the valid period.

SPECIFICS FOR KSTL:

West to southwesterly winds will increase through the morning and become gusty this afternoon. Westerly winds will continue up until the approach of a cold front early this afternoon, turning northwesterly behind the front. Moisture is limited along the boundary, but may result in a few clouds around 5k feet with frontal passage with nothing expected below VFR.

Winds will die down overnight before increasing again late morning Thursday. Aside from impacts as a result of wind, expect VFR through the period.

Maples

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

WFO LSX


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
St. Louis, Spirit Of St. Louis Airport, MO8 mi47 minWSW 14 G 2410.00 miFair68°F42°F39%1007.8 hPa
St. Louis Lambert International Airport, MO15 mi50 minWSW 13 G 2410.00 miA Few Clouds69°F42°F38%1008 hPa
St. Louis Downtown Airport, IL20 mi48 minVar 5 G 1810.00 miFair69°F41°F36%1008.4 hPa

Link to 5 minute data for KSUS

Wind History from SUS (wind in knots)
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Last 24hrW6NW12
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1 day agoNW14W9
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W5W7W5SW4SW4W4W5SW3W4W5W4W5CalmW6W7W6
2 days agoW9W5SW5NW9NW8NW7CalmNE4N10
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NW11NW9NW8N5CalmNW8W8NW6W7W4W5W9W8

Tide / Current Tables for
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Weather Map
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NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
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Other links: Northern Pacific     Contential US     Full GOES-East
Ground Weather Radar Station St. Louis, MO
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