Freezing drizzle developed during the evening hours of the 12th. By late evening into the early morning hours of the 13th, an area of light freezing rain spread northeast over the area lasting through around 5-6 am followed by continued freezing drizzle and mist.
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The episode as NWS HUN wrote it up.
Freezing drizzle developed during the evening hours of the 12th. By late evening into the early morning hours of the 13th, an area of light freezing rain spread northeast over the area lasting through around 5-6 am followed by continued freezing drizzle and mist. Ice accumulations ranged from 0.01-0.05 at most locations, but 0.10-0.21 inch accumulations was reported atop the Cumberland Plateau in Franklin County. Icy bridges, overpasses and a few roads were reported.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Huntsville, AL wrote its last area forecast discussion before the first event at Feb 12, 9:57 PM CST, 3 minutes earlier.
Area Forecast Discussion National Weather Service Huntsville AL 957 PM CST Fri Feb 12 2021 .NEAR TERM...(Rest of tonight) Issued at 957 PM CST Fri Feb 12 2021 Southwesterly flow aloft and elevated WAA will continue to strengthen overnight, as the northern portion of a broad mid-level trough over eastern Mexico begins to eject northeastward across South TX. A modest increase in synoptic scale ascent, coupled with strongly veering flow above the frontal inversion, will allow light rain to expand northward into southern portions of the forecast area between 4-6Z, and into the remainder of the region shortly after Midnight. Unfortunately, with air temperatures already at or below freezing for many locations, this will translate to freezing rain, and a Winter Weather Advisory has been issued for all counties in the forecast area (with the exception of Dekalb AL) through 14Z. A glaze of ice between 0.10-0.15 inch thick could accumulate on exposed/elevated surfaces along an axis extending from the Bankhead Forest/Cullman areas northeastward through Huntsville and Winchester, as this is the favorable zone where the northern edge of the most widespread precip will overlap with subfreezing temperatures in the boundary layer. To the west of this axis, chances for measurable precipitation drop off rather substantially across northwest AL, although freezing drizzle and patchy light freezing rain (in a few spots) could lead to a glaze ranging from a trace up to one tenth of an inch. And, finally, to the east of this axis, it appears as if temperatures will remain above freezing across Dekalb County, with no threat from freezing rain. .SHORT TERM...(Saturday through Sunday night) Issued at 312 PM CST Fri Feb 12 2021 Rain associated with the above noted system traversing the NE Gulf region will end from west to east during Sat. High temperatures should range from the upper 30s NW AL to upper 40s NE AL. The models have come around to an idea of the cold air pushing southward more, but remaining west of this area. This will spare the Valley more frigid conditions locations to our west have been experiencing. Lows Sat night should be a tad cooler, from the mid/upper 20s NW AL to mid 30s NE AL. Moisture seeping northward from the Gulf will bring lower end rain chances on Sunday. Given temperatures could be at or below freezing Sun morning, another chance of icing remains a possibility. The precip should become all liquid by the late morning. Highs to start the week will trend a bit cooler than on Sat as the cold airmass becomes more entrenched, ranging from the mid 30s NW AL to mid 40s NE AL. Yet another system moving to the NE from the Gulf, combining with stronger upper level support moving in from the west will bring more precipitation to the region Sun night. The rain will change to freezing rain during the course of the evening and overnight. The freezing precip will start impacting NW AL first, then slowly spread eastward during the night time. More accumulations of ice are likely, especially on elevated surfaces. Ice accumulations in the night should range upwards of 1/10 of an inch over parts of NW AL and adjacent middle TN before daybreak Mon. This could become a more significant weather maker given more wintry precip will continue in the early part of the extended. .LONG TERM...(Sunday night through Thursday) Issued at 312 PM CST Fri Feb 12 2021 Confidence continues to increase that a significant winter/ice event will impact the area on Monday, as a well amplified trough swings through the area and even colder air becomes anchored across much of the Central US. Isentropic lift will increase ahead of this upper trough axis, and chances for precip will increase Monday morning. What remains to be seen is how far southeast the freezing line makes it, as this will make all the difference when it comes to rain vs. freezing rain. Have fairly good reason based on both ensemble and deterministic trends that subfreezing air will be anchored across northwest AL by this time, and any precip that falls will likely be liquid until it reaches the surface. A stout warm nose around 1km AGL will be the reason we see freezing rain or sleet opposed to snow. With limited moisture in the snow growth zone and 850mb temps in the +4-6C range during the day Monday, think freezing rain will be the more dominant p-type for the northwestern portion of the HUN forecast area. Areas east of I-65 will likely see a cold but non-freezing rain throughout the day on Monday with temperatures just above freezing, but again this could change depending on the southeastern extent of the freezing line... something we are less confident on for now. The trough axis will swing across the area Monday night, and a stout punch of subfreezing air will make it all the way through the forecast area. We believe this will be where impacts are maximized, as subfreezing temperatures will outpace the colder air aloft, creating a rather messy winter weather situation. Believe most of the forecast area will be dealing with ice by this point, especially areas along and west of I-65. As the colder air begins to arrive aloft, could see a transition from freezing rain to sleet late Monday, especially over NW AL and SM TN. There could be a brief window for some snow accumulation over far NW AL late Monday night, but this really depends on how quickly the colder air arrives aloft, and if this happens before the dry air sinks in. Any impacts will likely linger through Tuesday night, as high temps struggle to make it above freezing until Wednesday. The main focus with this event will be on impacts. It is too early to mention specific ice accumulations, but even just a few hundreths could create slick spots on area roadways, especially bridges and overpasses. It remains to be seen how quickly road temperatures will respond, but we continue to grow more confident that widespread travel impacts will occur, especially over northwest Alabama and southern middle Tennessee. Unfortunately, ice is a lot harder to mitigate when it comes to travel, and roads can become hazardous quickly. Depending on ice accretion, some power outages could be possible. If this happens, it could take a while for power to be restored in some areas. Temperatures will remain below freezing across much of the area until Wednesday morning, even dropping into the teens in northwestern AL Monday night. This will be especially hazardous for those who are without power. It is important to monitor this situation over the holiday weekend and begin prepping for these potential impacts now. Temperatures will begin to recover on Wednesday, with highs in the 40s, but the next system will bring yet another chance for rain and wintry weather by the second half of the work week. More details to come with this system in future updates. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 606 PM CST Fri Feb 12 2021 Trends in sfc observations at both terminals (as well as upstream obs in Middle TN) suggest that cigs/vsbys will settle into the MVFR range early this evening as light BR/HZ develops in the fairly moist low-level airmass. However, light precipitation should spread northward late this evening, as an approaching upper-lvl disturbance induces strengthening SW flow above a shallow frontal inversion. We have introduced -RA beginning arnd 04Z/HSV with -DZ noted at MSL, where chances for measurable precipitation appear to be quite a bit lower. The base of the stratus layer will descend to IFR-levels as precip begins, with lower MVFR vsby indicated as well. A brief period of light FZRA/FZDZ may also occur, mainly btwn 10-14Z, and this has been indicated with a PROB30 group. Any lingering lgt rain will end at MSL/16Z and HSV/18Z, with cig/vsby both predicted to improve to MVFR- levels by 20Z. Sfc winds will remain from the NNE at 5-10 knots for much of the period, although they may back to NNW beginning late tomorrow morning. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...Winter Weather Advisory until 8 AM CST Saturday for ALZ001>009-016. TN...Winter Weather Advisory until 8 AM CST Saturday for TNZ076-096-097. && NEAR TERM...70/DD SHORT TERM...RSB LONG TERM...25 AVIATION...70/DD For more information please visit our website at weather.gov/huntsville.
Hazardous Weather Outlook...UPDATED National Weather Service Huntsville AL 356 PM CST Fri Feb 12 2021 ALZ001>010-016-TNZ076-096-097-131130- Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan- Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN- 356 PM CST Fri Feb 12 2021 This Hazardous Weather Outlook is for north Alabama and portions of southern middle Tennessee. .DAY ONE...Tonight... Light rain will spread northward into the outlook area this evening, ahead of a storm system to our southwest. Temperatures across the northwestern half of the area are expected to fall to or slightly below freezing after Midnight, with light rain transitioning to light freezing rain. Ice accumulations ranging from a trace up to 0.05 inch will be possible, mainly to the west of a line extending from Moulton to Harvest and Tullahoma. .DAYS TWO THROUGH SEVEN...Saturday through Thursday... The potential for patchy, light freezing rain will persist across the northwestern half of the area through around Noon on Saturday. However, a similar situation will unfold once again during the morning hours on Sunday, with light freezing rain possible to the west of a line from Smith Lake to Huntsville and Winchester. A strong winter storm is expected to impact the Tennessee Valley during the period from Sunday evening through Tuesday morning. Locations across the northwestern half of the outlook area will begin to experience freezing rain on Sunday night, with a mixture of freezing rain, sleet and snow possible for much of the day on Monday. The wintry mixture of precipitation will shift eastward Monday evening, before ending early Tuesday morning. This system has the potential to produce significant accumulations of both freezing and frozen precipitation, which will likely have an impact on travel. After a brief break on Tuesday, another storm system will bring a mixture of rain and snow to the region on Wednesday and Thursday. .SPOTTER CALL TO ACTION STATEMENT... Activation of storm spotters and emergency management personnel is not anticipated at this time. 70/DD
The national radar mosaic for the moment the first event began.
3 winter weather. Local standard time, as filed.
Freezing rain and drizzle fell during this period with ice accumulation of 0.01-0.05 inches in northwest Franklin County, with 0.10-0.21 inches in southeast Franklin County atop the Cumberland Plateau. Freezing mist and fog were reported before and after this time period as well.
Freezing rain and drizzle fell during this period with ice accumulation of 0.01-0.05 inches. Freezing mist and fog were reported before and after this time period as well.
Freezing rain and drizzle fell during this period with ice accumulation of 0.01-0.05 inches. Freezing mist and fog were reported before and after this time period as well.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Tennessee in 2021Every state in 2021This day in weather historyWarnings in Tennessee, February 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 939015, 939016, 939017.