Marine Weather and Tides
3/30/2021 -- ANZ330 has been split into ANZ331 and ANZ332. Click EDIT in Marine Forecast and select your new zone.
1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.
|Sunrise 5:57AM||Sunset 8:16PM||Thursday July 29, 2021 6:01 PM CDT (23:01 UTC)||Moonrise 10:39PM||Moonset 10:43AM||Illumination 70%|
7 Day Forecast for Marine Location Near Holiday Shores, ILHourly EDIT Help
Area Discussion for - St. Louis, MO  (on/off)  Help NOTE: mouseover dotted underlined text for definition
FXUS63 KLSX 292057 AFDLSX
Area Forecast Discussion National Weather Service Saint Louis MO 357 PM CDT Thu Jul 29 2021
SHORT TERM. (Through Late Friday Night) Issued at 354 PM CDT Thu Jul 29 2021
Currently, an upper-level trough is digging equatorward across the eastern United States as a ridge remains anchored over the western half of the country. A shortwave rounding the base of the trough is sending a cold front through the Midwest, and this front is currently along the Missouri-Iowa border extending into central Illinois. South of this front, the atmosphere has become quite unstable, as 5,000+ J/kg of SBCAPE is noted on SPC mesoanalysis. As the front pushes further south into this unstable airmass, convection is expected to form along the front. With better upper- level support further eastward, convection is expected to remain isolated to scattered. Effective bulk shear is around 20-25 kts, leading to storms that form to carry a threat of damaging wind gusts and hail mainly across northeastern Missouri and west-central Illinois. As we get into the overnight hours, instability will wane, leading to a decrease in strength and coverage of convection as the front pushes further south toward the I-70 corridor.
As for temperatures this afternoon and evening, despite convective debris and cirrus from convection in central Illinois, current temperatures and dew points have lead to heat index values area-wide 100-110. Therefore, the current heat advisory remains on track through this evening.
For tomorrow, the cold front is expected to be positioned northwest to southeast across portions of central and southeastern Missouri. During peak heating, MUCAPE of roughly 2,000-3,000 J/kg will reside along this boundary, with lesser amounts just behind the front thanks to residual boundary layer moisture. Subtle shortwaves in the flow may tap into this instability and form isolated convection along and just behind the front. With a lack of more robust forcing and 0-6 km bulk shear around 20 kts, convection is expected to be weak and short lived. If the front is able to push further southwestward, the focus for convection may be just outside of the CWA. Regardless, confidence is high that there will be plenty of dry time during the day tomorrow.
With guidance consensus having the front just on the edge of the CWA or further southwest during peak heating, I've bumped temperatures down a degree or two. Dew points will be lower behind the front as well, and heat index values at or above 100 are not likely, so we will not be extending the current heat advisory.
LONG TERM. (Saturday through Next Thursday) Issued at 354 PM CDT Thu Jul 29 2021
Friday evening, convection is expected to develop upstream of the CWA across Nebraska and Iowa at the nose of a low level jet and track southeastward along the front. Some model guidance has the front pivoting a little northward into western portions of our CWA ahead of this convection. Marginal instability and shear will be present south of this boundary as convection enters Missouri, posing a low risk of severe storms in central Missouri late Friday night/early Saturday morning. If the front remains a little further south, the severe threat will be mitigated in the CWA. Regardless of front's positioning, confidence is high in widespread rain along and behind the front early Saturday morning and through the day on Saturday as a shortwave traverses the Middle Mississippi Valley. High precipitable water and warm cloud depths will allow for efficient rain fall, potentially leading to a isolated flood threat if heavier rain is able to train over the same location. Confidence remains high that the initial shortwave and subsequent shortwaves through Sunday morning will push the front and rain southward, decreasing the chance of rain from north to south early Sunday.
Through the remainder of the period, ensembles have the eastern trough holding, keeping the CWA in northwest flow aloft and an area of high pressure anchored over the Midwest. This surface high will keep easterly/northeasterly flow across the CWA, which will hold relatively lower temperatures and humidity over the area. This cooler solution is supported by current ensemble means for surface temperatures, giving me confidence in break from the heat and a mostly dry forecast.
AVIATION. (For the 18z TAFs through 18z Friday Afternoon) Issued at 1224 PM CDT Thu Jul 29 2021
The main focus for impacts this period will be a southward moving cold front and associated storm potential. This front is currently across southern Iowa and northern Missouri, and is expected to move over the KUIN terminal later this afternoon. At that time, storms will form along the front, but coverage is expected to be isolated to scattered, so confidence is not high enough to have direct impact to the terminal mentioned in the TAF at the moment. As the front and associated storms move further south this evening, storm coverage is expected to lessen, decreasing confidence further in direct impacts to the remaining local terminals, including KSTL. For all local terminals, storms that do directly impact terminals will be capable of heavy rainfall and gusty winds, so sub-VFR flight conditions are possible. The front is anticipated to clear all local terminals by tomorrow morning except KCOU and KJEF where the front may linger, so I've left VCSH in the TAF for now. With the front's passage, winds will shift to out of the north and remain light.
PRELIMINARY POINT TEMPS/POPS. Saint Louis 75 87 67 78 / 40 10 30 70 Quincy 70 83 64 73 / 50 10 60 80 Columbia 74 88 70 81 / 20 20 30 60 Jefferson City 75 89 71 84 / 20 20 30 50 Salem 70 84 63 76 / 40 5 20 60 Farmington 72 88 66 85 / 20 20 10 40
LSX WATCHES/WARNINGS/ADVISORIES. MO . Heat Advisory until 9 PM CDT this evening for Audrain MO-Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO- Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln MO-Madison MO- Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike MO-Ralls MO-Reynolds MO-Saint Charles MO-Saint Francois MO- Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO- Shelby MO-Warren MO-Washington MO.
IL . Heat Advisory until 9 PM CDT this evening for Adams IL-Bond IL- Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL- Pike IL-Randolph IL-Saint Clair-Washington IL.
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|St. Louis Regional Airport, IL||3 mi||74 min||W 8||10.00 mi||Fair||91°F||73°F||56%||1014.6 hPa|
|St. Charles, St. Charles County Smartt Airport, MO||23 mi||67 min||WSW 7||10.00 mi||Fair||95°F||76°F||54%||1013.1 hPa|
|St. Louis Lambert International Airport, MO||23 mi||70 min||WSW 14||10.00 mi||Mostly Cloudy||95°F||76°F||54%||1013.1 hPa|
|Litchfield Municipal Airport, IL||23 mi||66 min||WSW 4||10.00 mi||Fair||88°F||80°F||77%||1014.6 hPa|
Link to 5 minute data for KALN
Wind History from ALN (wind in knots)
|1 day ago||Calm||Calm||S||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||S||S||Calm||Calm|
|2 days ago||NE||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||N||NE|
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