Sunday, March 18, 2018

Volatile weather may miss Memphis, but Monday storms still expected

A potent low pressure system will pass just north of Memphis on Monday, but the timing and track of the system will likely result in muted effects for the area as compared to places to our east and south.

Sunday / Sunday night

Before that though, a cold front that slid south through the metro last evening has pushed our beautiful weather from Saturday southward, with a healthy mixture of clouds and sun dominating your Sunday and temperatures remaining about 15 degrees cooler than yesterday. As the aforementioned low pressure starts to energize in the southern plains, a "scout" upper level disturbance ahead of it, combined with yesterday's cold front returning north as a warm front, will result in evening showers tonight and a chance of rain overnight.

A strong upper level low pressure center will move from the KS/OK border at midnight tonight eastward to near Louisville by midnight Monday night. That low, and an accompanying surface low, will generate favorable conditions for severe weather along its southern flank. (NAM model, PivotalWeather)

Monday storms

By Monday morning, wind will shift to the south, a sure sign that the warm front will have moved to our north - but just barely. The low pressure to our west will be moving into the Ozarks, riding the fast train towards Nashville, and triggering scattered thunderstorms ahead of it. Accompanying the low, very strong upper level wind will result in high amounts of wind shear - one ingredient necessary in the production of severe storms. Another key ingredient, instability, will be less than ideal though, given the timing of the storms during the morning to mid-day hours, before the warm sector of the storm has a chance to really boil over. Thus, the lift generated by the approaching low will result in scattered thunderstorms, but the lack of appreciable instability (the main "fuel" for storms) will likely be insufficient to take advantage of the high amounts of shear over the area.

The result: scattered storms for the Memphis area during the post-morning rush hour through lunchtime period (about 9am-2pm) on Monday that could contain a few strong wind gusts and small hail, but likely not producers of damaging wind or hail, nor tornadoes. We are in a Marginal Risk of severe weather (level 1 on the 5-point scale) for Monday, with areas not far to our east a level higher and under a Slight Risk.

An Enhanced Risk of severe weather exists Monday for middle TN and north MS. The Memphis metro is on the edge of a Marginal Risk, category 1 on the 5-point scale. (SPC)

Meanwhile, to our east...

As the low moves east however, it will encounter an even warmer airmass with strong wind shear that could be capable of very large hail, damaging wind gusts, and even a few tornadoes. The most likely area for that to occur is from southern middle TN into north AL and northwest GA during the afternoon and evening hours, where an Enhanced Risk of severe weather is currently forecast (level 3 on the scale). In other words, the nearby track of the low earlier in the day will likely keep the Memphis metro from being under as volatile an airmass as areas to our east.

The Supercell Composite index, a measure of the capability of the atmosphere to produce supercells capable of severe storms, is maximized near the TN/AL border at mid-afternoon (4pm) according to the high-resolution NAM3 model. This index remains very low, mainly south of I-40, during the morning hours when we are most likely to see thunderstorms. (PivotalWeather)
As those areas to our east remain weather-aware, we're likely to see some afternoon sunshine that allows temperatures to rise into the mid 70s again. Gusty southwest wind is also expected as the low passes just to our north.

Remainder of the week

Behind this system, clouds wrap around back into the Mid-South as much cooler air filters back in on northerly wind. An embedded upper level system wrapping around the departed low will bring scattered showers on Tuesday with temperatures about 20° cooler than Monday, or in the mid 50s. A couple of cool mornings are expected with lows in the upper 30s Wednesday and Thursday mornings, but highs will slowly climb back into the mid 60s by week's end. Southerly flow re-establishes itself by Friday with more rain chances arriving in time for the weekend.

Stay in touch with our weather updates tomorrow via our social media feeds and mobile app and prepare for a few more chilly days to interrupt the blossoming of spring in Memphis!

Erik Proseus
MWN Meteorologist

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Sunday, March 11, 2018

February 2018 Climate Data for Memphis, TN

February Climate Recap

With a wet pattern dominating the weather in February, temperatures also were well above average due to increased moisture content in the atmosphere. For the month, the average temperature was 4.3 degrees above average, which ranks in the 88th percentile for warmth or 17th warmest February on record. High and low temperatures both averaged 4.3 degrees above average, so neither contributed more to the daily anomaly than the other.Three daily records were set or tied during the latter half of the month. Only six days saw average temperatures more than 2 degrees below the climatological average.

Precipitation was the big story for the month with three days recording near or more than two inches of rain, including 1.99" on the 10th, 2.82" on the 21st, and 3.12" on the 28th. Overall, two-thirds of the days in February had measurable rain with an average cloud cover for the month of 80%. With all of the rain came some periods of minor flash flooding, although river flooding at the end of the month into the first few days of June was the bigger impact as the Mississippi River climbed above flood stage and local tributaries such as the Loosahatchie and Wolf Rivers also overflowed their banks.
February 2018 was the in the top 3 wettest on record for ten states that drain into the Ohio or Mississippi Rivers, resulting in flooding late in the month into early March in both basins, including the Mississippi River at Memphis. (NOAA/CPC)

For the months comprising meteorological winter (November 2017-January 2018), the average temperature was 43.0 degrees, which is 0.4 degrees below the long-term average. Precipitation totaled 24.95", which was 10.84" above average and ranks seventh wettest on record.

Memphis International Airport, Memphis, TN

Average temperature: 49.8 degrees (4.3 degrees above average)
Average high temperature: 59.0 degrees (4.3 degrees above average)
Average low temperature: 40.6 degrees (4.3 degrees above average)
Warmest temperature: 77 degrees (19th, 20th)
Coolest temperature: 24 degrees (2nd, 5th)
Heating Degrees Days: 433 (115 below average)
Cooling Degree Days: 14 (12 above average)
Records set or tied: February 19th: 77° (tied record high); February 15th: 65° (record warmest low); February 20th: 66° (record warmest low)
Comments: February 2018 was the 17th warmest on record.

Monthly total: 13.43" (9.04" above average)
Days with measurable precipitation: 19
Wettest 24-hour period: 3.12" (28th)
Snowfall: 0.0" (1.3" below average)
Records set or tied: February 28th: 3.12" (daily record set); February 1-28: 13.43" (monthly record set)
Comments: Precipitation for the month set the all-time February record. Nine days recorded more than 0.5" and 2 days saw more than an inch fall.

Peak wind: West/41 mph (24th)
Average wind: 9.5 mph
Average relative humidity: 75%
Average sky cover: 80%

Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions /, Bartlett, TN

Average temperature: 48.7 degrees
Average high temperature: 58.8 degrees
Average low temperature: 38.9 degrees
Warmest temperature: 78.6 degrees (19th)
Coolest temperature: 21.7 degrees (8th)
Comments: None

Monthly total: 11.79" (automated rain gauge), 13.75" (manual CoCoRaHS rain gauge)
Days with measurable precipitation: 19
Wettest date: 2.56" (28th) (via automated gauge)
Snowfall: None
Comments: Four days recorded more than 1" of rain, while two days have more than 2" of rain.

Peak wind: Northwest/29 mph (4th)
Average relative humidity: 80%
Average barometric pressure: 30.20 in. Hg

Click here for a daily statistical recap for Bartlett, TN.

MWN Forecast Accuracy

MWN average temperature error: 2.84 degrees
MWN forecast temperatures within 2 degrees of actual: 56%
MWN average dewpoint error: 3.01 degrees
MWN forecast dewpoints within 2 degrees of actual: 49%

MWN's forecasts extend out five periods (2.5 days, or roughly 60 hours). Historical accuracy statistics can be found here.

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Friday, March 9, 2018

Spring break arrives - wish the weather were better!

The past couple of days have been cold relatively speaking - compared to both early March averages and recent history - but that trend ends for a few days as the pattern turns wet once again.

As high pressure shifts east, wind has turned around to the south and will be quite breezy today with afternoon gusts to 25 mph. However, that will help to push the mercury back into the 60s despite more cloud cover than previous days. Heading into the overnight, the next system to our west starts to organize and the southerly flow (resulting in increased moisture from the Gulf) brings a chance of showers before dawn Saturday morning.

With high pressure along the southeast coast, southerly flow over the Mid-South means increasing moisture and chances of rain. Low pressure over west TX will move east, grazing just south of the metro Saturday night. Surface map valid midnight tonight. (NWS)

Our computer models that are normally pretty reliable within 3-4 days have been struggling with the pattern for the first weekend of Spring Break. There are still some differences, but all now forecast a weak low pressure system to move by just south of Memphis Saturday night. The differences lie in the strength of the low and placement of heavier rainfall. While Saturday looks to feature scattered showers (likely not all-day rain), overnight Saturday night likely will be the wettest period of the weekend. The axis of heaviest precipitation will likely be across north MS/AL, where over 2" of rain could fall this weekend. In the Memphis area, an inch would not be unexpected and also would not result in additional flooding issues given the recent dry days of late, allowing the ground to dry some and the smaller rivers/creeks to return to normal levels. With the track of the low just to our south, we can't rule out a few thunderstorms, but most will be to our south and southwest, as will any chances of severe weather. Temperatures should also remain mild with highs Saturday in the lower 60s.

The severe weather outlook for Saturday and Saturday night shows that a few thunderstorms will be possible in the metro (lightest green), but the severe weather chances (darker green to yellow) will remain south of the area. (SPC)
As the low departs Sunday, "backlash" cloudiness and scattered showers will be possible as an upper level low pushes the system to the east, but brings those rain chances as well. Temperatures will also remain in the 50s all day and a north wind will kick up quite a bit by afternoon. Overall, not a real promising way to start an extended break for most of the school kids in the area!

Total precipitation through Sunday evening as forecast by the NWS. It shows an inch or a little more in the Memphis area, while I believe we could trend down a bit more and end up with a little less than that. Saturday night appears to be the wettest part of the weekend, but neither Saturday or Sunday will likely be completely dry. (WxBell)

If you don't like the rain on Spring Break, then there is good news - the rest of the week looks to be dry. However... cooler air arrives again, lasting much of the week. Lows will be back down into the 30s with highs only in the 50s from Monday through Thursday. We should start to see a warming trend heading into the final weekend of the break, though it could also become wet again. Sunny and 70° just isn't in the forecast quite yet - but we'll be there soon enough! Early March weather always tends to feature a few surprises as the seasons really start to change.

Erik Proseus
MWN Meteorologist

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Sunday, March 4, 2018

Typical early spring week ahead - warm rain, cold sun, then warm rain again!

The past few days have reminded of how beautiful early spring can be in the Mid-South! Crisp mornings have given way to mild afternoons as highs have reached the 60s. Outside of some afternoon clouds today, sunny skies were a welcome sight after deluges to end the month of February.

The week starts wet

Unfortunately, a beautiful weekend leads to a rainy Sunday night and Monday, but at least rainfall amounts will be "tolerable" as compared to, well, seemingly every time it rained last month, but especially earlier this week! With 4.64" of rain in less than 48 hours - from Tuesday evening through Thursday late morning - February rainfall shot into the record books with an official total of 13.43" - more than 2" higher than the previous record set in the late 19th century!

Total amounts over the next 24 hours should be in the 1/2" range with the steadiest rainfall occurring from around midnight tonight through rush hour Monday morning. Scattered showers, and a possible afternoon thunderstorm, are expected Monday until a front arrives in the early evening to bring the rain to an end.

Forecast rainfall amounts through 6pm Monday from the high-resolution ensemble forecast (HREF) model. Memphis is forecast to receive about 1/2" according to this, and most other, model data. (NOAA/SPC)

Mid-Week Forecast

Behind the departing system, Tuesday looks decent with mostly sunny skies and highs in the lower 60s, though a brisk northwest wind is a harbinger of things to come in the temperature department. Reminding us that cold spells in early March are not rare, the mid-week period will feature highs barely above 50° and lows dropping close to freezing in the city and likely below freezing in rural areas. Hopefully not much damage is done to budding plants and flowers that have flourished on the above average temperatures and abundant rainfall in February!

Be watching for national weather news to feature another significant storm for the northeastern U.S. during the mid-week period, which will help to drive that colder air on its western flank down into our region!

As another Nor'Easter rocks the major metros in the northeastern U.S. with wind and snow later this week, cold air on its backside will dive south into the south-central U.S. courtesy of building high pressure of Canadian origin. (PivotalWx)

Early look at Spring Break weekend

As we get towards the first weekend of Spring Break for many, the thermometer starts to climb again, but so do the rain chances. Early indications are that next weekend could be a wet one once again. Yes, another potentially wet Saturday that have come far too often this year! I hope you enjoyed this weekend!

River flooding

While significant land-based flooding was avoided during this past week's heavy rain, the rivers are high, and climbing. On the Mississippi River at Memphis, where flood stage is 34', the river is at 38' as of 4pm and peaking near 39' over the next few days. It is projected to remain above flood stage for at least the next couple of weeks. For comparison, this crest would be just short of the 39.6' crest reached in 2016, but well short of the 48' it reached in 2011 when national media "waded" in the river at the foot of Beale Street. However, if the river rises a few inches above the projected crest, which is possible, this year's spring flood would rank in the top 10 historically at Memphis. Water levels on tributaries like the Looshatchie and Wolf Rivers will remain high the next couple weeks as high water levels on the main stem don't allow these feeder rivers to empty.

A hydrograph (past/forecast river levels) of the Mississippi River at Memphis shows a rapid climb of nearly 10 feet over the past week (blue) and a forecast crest (purple dots) near 39' in the coming days. Currently, the river is not expected to drop back below flood stage until March 18. (NWS)

Overall, the week ahead doesn't look too bad, book-ended by rain chances and with a dip in temperatures mid-week. It looks a lot like an early spring forecast! Follow us all week on social media as we provide updates every day on Facebook and Twitter. Also be sure to download the mobile app for the latest conditions, radar, and most recent update to the human-powered MWN Forecast. All links are below.

Erik Proseus
MWN Meteorologist

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Friday, March 2, 2018

Severe Weather Awareness 2018: Weather Radio and Mobile Alert Apps

Today's Severe Weather Awareness Week topic covers a couple of ways of receiving warning information - NOAA Weather Radio and mobile alert apps. We have always advocated for having multiple ways to receive warnings, as no one solution is fool-proof or immune from dissemination issues.

Weather radio is the voice of the National Weather Service. It provides continuous weather information 24 hours a day, every day of the year. The nationwide network of weather radio stations provides the public with the fastest most reliable source of up-to-date weather information directly from the National Weather Service. You need a special radio to receive weather radio broadcasts, a radio that is capable of receiving signals in the very high frequency public service band.

Broadcasts may vary, but generally include area forecasts, present weather conditions, short-term forecasts, climatic data, river and lake stage forecasts, and other specialized information. The broadcasts are updated continuously. Weather radio is useful anytime, but it is most important when severe weather threatens. During periods of severe weather, routine programming is interrupted, and the focus shifted to the local severe weather threat. In an emergency, a warning alarm tone is broadcast that activates specially designed receivers to turn on automatically, or to produce a visual or audible alarm.

A typical NOAA Weather Radio console setup in an NWS office. strongly encourages every home to have a NOAA Weather Radio.  These devices are as important as smoke detectors and possess the same capability to save your life in the middle of the night.  Specifically, our favorites are from Midland and include the basic desktop version (WR-120, pictured at top).  It can be purchased at retailers such as Walgreen's, Kroger, and other discount stores, as well as online retailers like Amazon for about $30-40. Learn more about NOAA Weather Radio on MWN's Weather Radio page.

Alternative to Weather Radio - Mobile Apps

One problem with Weather Radio and warnings sirens for that matter is that they alert on a COUNTY-wide basis, even if the warning issued by the National Weather Service is for only a small portion of the county. To know if YOUR LOCATION is in the warned area, we highly recommend our personalized weather warning service, StormWatch+, which can be added to our MWN mobile apps for iPhone and Android.  StormWatch+ pairs the NWS polygons (or warning boxes that are drawn irrespective of county borders) with your GPS-provided location to send push notifications in the event that YOU are in harm's way. No more alerts when the storm is 20-30 miles away and not a threat to your area! Learn more about StormWatch+ at and get personalized weather alerts in the palm of your hand!

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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Thursday, March 1, 2018

Severe Weather Awareness 2018: Severe Thunderstorms

There are approximately 2,000 thunderstorms in progress around the world at any given time. Most of these storms are beneficial and bring needed rain. Only a small fraction, less than one percent, are classified as severe. Severe thunderstorms are those thunderstorms that produce hail one inch in diameter or larger or strong wind gusts of 58 mph or greater. Hail that is one inch in diameter is about the size of a quarter. A small fraction of these thunderstorms produce tornadoes. All thunderstorms are capable of producing deadly lightning. The heavy rains or the lightning activity in a thunderstorm do not have anything to do with a thunderstorm being classified as severe. Some of the severe thunderstorms safety rules are as follows:
  • Find shelter immediately. Go to a sturdy building that will withstand high winds. Avoid electrical appliances and telephones.
  • It would be a good idea to bring your car inside a garage and to secure loose objects.

A Severe Thunderstorm Watch means that conditions are right for severe thunderstorms to develop, but none have been observed. People should keep an eye on the sky and listen to commercial broadcasts or NOAA Weather Radio for any subsequent warnings.

Severe Thunderstorm Warning means that a severe thunderstorm is occurring. The severe thunderstorm has been detected by Doppler radar, or reported to the National Weather Service by our Skywarn Spotter Network, or the local law enforcement agency in a particular county.

When a Severe Thunderstorm Warning is issued for your location, treat it the same as you would a Tornado Warning. Severe thunderstorms can produce damaging winds, large hail, and deadly lightning and will occasionally produce a tornado, particularly in very strong squall lines, where a brief tornado can occur with little notice.'s "Storm Center" is your one-stop shop for severe weather information. The MWN Storm Center includes Mid-South radar, a clickable watch/warning map that updates as new alerts are issued by the NWS, recent storm reports, maps outlining severe risk areas from the severe weather experts at the Storm Prediction Center, and severe weather safety tips. If you are looking for information on severe weather in the Mid-South, the MWN Storm Center is the place to start!

Also, don't forget our mobile severe weather alerting tool that capitalizes on the convenience of mobile app technology! StormWatch+ will alert you if you are in the path of the storm via mobile phone, even if you are asleep. In addition, the StormWatch+ EnRoute feature will alert you if you drive into a severe weather warning! StormWatch+ is available within the MWN mobile apps for Android and iOS devices. Learn more or download the app by visiting on your computer or mobile device.

Severe wind reports (58+ mph) in the Mid-South by month. Most high wind reports occur in spring and summer, though they can occur in any month. Courtesy NWS-Memphis.

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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Wednesday, February 28, 2018

Severe Weather Awareness 2018: Tornado Safety

The El Reno, OK EF-3 tornado of May 31, 2013, taken from about one mile away by storm chaser Nick Hellums.
Tornadoes are violent columns of rotating air that are produced by severe thunderstorms.  Weak tornadoes produce wind of  65-85 mph, while the strongest (such as the Moore, OK tornado of May 2013), produce wind well over 200 mph and can be a mile wide or larger (the El Reno, OK tornado of May 2013 is the widest on record at 2.6 miles!). Not all severe thunderstorms produce tornadoes, only a small fraction do, but people should be alert for the possibility if and when a Severe Thunderstorm Warning is issued and take action when a Tornado Warning is issued for their location.

Tornado safety rules include:
  • At home or in small buildings, go to the basement or storm shelter, or to a windowless interior room such as a closet or bathroom on the lowest level.  Get under something sturdy such as a table or heavy bed.
  • Abandon mobile homes and vehicles for a sturdy structure. If there is no such structure nearby, lie flat in a ditch, ravine, gully, culvert, or a low spot with your arms and hands shielding your head, staying mindful of possible flooding as well.
  • In large buildings such as at school, shopping centers, hospitals, or factories/warehouses, go to the predesignated shelter area. Interior hallways on the lowest floor are best. Stay out of areas with high roofs or large roof spans, as they typically offer little to no protection from tornadic wind due to weakly supported roofs.
  • At school, children should follow the safety procedures established by school officials. These should include avoidance of areas with high roof spans and glass exposed to the exterior of the school. Children should crouch down next to a wall or under desks or tables and cover the head and neck with their hands.
  • At all times, avoid windows or large panes of glass.
  • If outside and sturdy structures are not available, try to drive to the nearest sturdy structure for shelter.  If one is not available, lie down in an area that is lower than surrounding areas (ditch or ravine if possible) with arms/hands shielding your head (being mindful of potential flash flooding).
  • When taking cover, have shoes on, photo ID on your person, cell phone (preferably charged in advance) with you, and crouch down and protect the back of your neck with your arms and hands.

A Tornado Watch, typically issued for a large area such as several counties, means that conditions are favorable for the development of severe thunderstorms that can produce tornadoes. Stay tuned to NOAA Weather Radio, commercial TV or radio, and other trusted sources for warnings and watch the sky for the possibility of developing severe weather.  Have your plan ready should a warning be issued and be ready to exercise that plan on a moment's notice.

A Tornado Warning, typically issued for a small area in the path of a storm, means that Doppler Radar has indicated the likelihood of a tornado or a tornado has been sighted by spotters or law enforcement.  If you are in the path of the storm (sometimes called "in the polygon" due to the shape of the warnings that are drawn by the NWS), immediately find shelter using the rules above.

A Tornado Emergency is not a warning type, but is issued (usually following the original Tornado Warning) when a large and destructive tornado has been confirmed and is moving into a populated area.  The risk of destruction and fatalities is high and an elevated call-to-action is required.  Everyone in the storm's path should immediately take action.

Storm Shelters

MWN recommends Take Cover Storm Shelters to keep Mid-South residents safe in the path of the storm. We have become very familiar with Take Cover's high-quality products, as well as their outstanding customer service, and have no reservations about endorsing this fantastic company. You can learn more about Take Cover Shelters and their in-ground shelters, which are installed in a concrete slab such as a garage floor, at their website or on Facebook. Be sure to mention when you contact Jessica!

StormWatch+ Alerts

In addition, a personal warning device that only alerts you if YOUR location is in the path of a dangerous storm is a MUST. We encourage you to add StormWatch+ to your app. It will wake you up at night for the most dangerous situations and allow you to customize exactly what locations you want to be alerted for and what types of alerts to receive, as well as when you don't want to be bothered.  The MWN mobile app is available for iPhone and Android devices.

For more information and interesting statistics on Mid-South tornadoes, see this recent study and this comprehensive overview produced by NWS-Memphis. Graphics below published in the second link listed.

Mid-South tornadoes by month. The primary season is spring, but a secondary season exists in the fall. Tornadoes can occur in any month however. Courtesy NWS-Memphis.

Mid-South tornadoes by hour of the day. Most tornadoes occur in the late afternoon to early evening, though they can occur at any time of day. In fact, 46% of Mid-South tornadoes occur at night, which contributes to a high death rate. Courtesy NWS-Memphis.

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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Tuesday, February 27, 2018

Severe Weather Awareness 2018: Lightning Safety

Severe Weather Awareness Week continues with a look at how to stay safe when lightning is nearby.

  • Any lightning safety plan should incorporate the 30/30 rule. The 30/30 rule states people should seek shelter if the flash to bang delay/length of time in seconds between a lightning flash and its subsequent thunder is 30 seconds or less and that they remain under cover until 30 minutes after the final clap of thunder.
  • Move inside a well constructed house, a large building, or an all metal vehicle. Stay away from electrical appliances and do not use a corded telephone (mobile and cordless phones are OK).
  • If you are in a boat, get off the water and into a substantial building, or at least into an enclosed and all-metal vehicle with the windows up. If you're caught in an open metal boat, lie down in the boat with cushions between you and the metal sides and bottom.
  • If you are caught outdoors, get down to avoid being the highest point for a lightning discharge. If you're caught in a flat open field or your feel your hail standing on end, crouch down and cover your head with your hands. That way, only your feet will touch the ground.
  • Move away from motorcycles, scooters, golf carts, bicycles, tractors, and other metal farm equipment. Avoid wire fences, clothes lines, metal pipes, drains, railroad tracks, and other metallic objects.
  • Avoid lone trees and the tallest trees. If caught in the woods, pick a small grove of trees as your shelter, and stand at least 5 feet from the trunk of the nearest tree to avoid flying bark if the tree is struck.
  • Avoid standing in a small isolated shed or other small ungrounded structure in other areas.
  • If in a group of people in an open area, spread out before you kneel down.

For most weather providers (especially the small fish like us), lightning data is one piece of weather information that can be hard to come by (especially in real-time). There are only a couple of providers of commercial lightning data in the U.S., which makes re-distributing the data cost-prohibitive for all but the largest commercial vendors. That is why you won't find lightning data on MWN.

The colors of the echoes on radar indicate the relative severity of the storm. On StormView Radar, anything colored orange, red, or pink has a fairly high likelihood of containing lightning. As we nowcast on Facebook and Twitter, we'll also be sure to let you know if a storm is electrified so that you may adjust your plans as necessary to maintain your safety.

Photo credit: Brian Anderson

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Monday, February 26, 2018

Recap of Saturday's severe weather, and more rain??

Given the first Enhanced Risk outlook for Memphis since May 27 (you recall the Memorial Day weekend Tom Lee Storm right?), we fared pretty well. Some of our neighbors not far to the north were not so lucky.

Sequence of events

A Tornado Watch was issued at 3:20pm - our first since August 31, 2017 - as a line of storms moved across Arkansas towards the metro. The most potent airmass would end up being just north of our area where Tornado Warnings were issued from northeast AR across northwest TN. Locally, Severe Thunderstorm Warnings were issued as far south as the I-40 corridor with straight-line wind generally peaking in the 40-50 mph range as the line moved through between 7-8pm, resulting in some scattered power outages but no major damage. By 8:30pm, the majority of the metro was receiving just rain, as the line continued pushing east.

Unfortunately, severe storms dropped at least a couple of tornadoes in northeast AR, the Missouri Bootheel, and northwest TN, including an EF-1 that affected Keiser and Osceola, AR and an EF-2 that struck Malden, MO.

Judging the forecast

Below you can see the severe weather outlook issued at 8am Saturday morning by the Storm Prediction Center, overlaid by the preliminary severe weather reports for the day. Overall, this was an excellent forecast with nearly all of the reports within the Slight (yellow) or Enhanced (orange) Risk areas. You can make out a southwest-to-northeast "path" of the damaging storms across AR to areas just north of the I-40 corridor into central KY.

Our Friday morning forecast indicated the timing of the storms would be between 8pm-1am Saturday night. That was adjusted Saturday morning to between 6-10pm, indicating the primary threat would be damaging wind and flooding, followed by a low risk of tornadoes. Overall, I feel that worked out quite well.

Map showing the Saturday 8am severe weather outlook (color fill) overlaid by the severe weather reports received by Monday evening. (NOAA/SPC)

Looking ahead - more flooding?

While severe weather drew the most attention Saturday, precipitation that totaled 4-5" in the metro and nearly a foot in portions of central AR resulted in high rivers and tributaries and some instances of urban and flash flooding. River flood warnings continue across the region with the Mississippi River itself forecast to cross flood stage by this weekend and remain there for a couple of weeks, cresting about 2.5' above flood stage at Memphis.

Analysis of precipitation that occurred over the past week, ending Monday morning, February 26. Roughly 4-5" of rain fell in the metro in the past week. (NWS / WxBell)
The next system arrives Tuesday night and continues through Thursday morning and promises to be another soaker. There appear to be two periods of potentially heavy rainfall - one Tuesday overnight and another Wednesday evening into the overnight hours. During the day Wednesday, rain chances remain high but amounts should be more manageable. By mid-day Thursday, I'm expecting another 2-4" of rain, locally higher, to have fallen across the area, which should push us over the all-time February rainfall record of 11.14". We're currently about 1.5" shy of that record. Flood Watches are again posted for this time period and rivers will only continue to climb as water simply can't soak in anymore and will run off into drainage areas and then local creeks and streams that feed the rivers.

Once the system departs Thursday, sunny skies are on tap once again heading into the weekend. Could this be the first Saturday in nearly 2 months to be dry and sunny??

Severe Weather Awareness Week

This week is also Tennessee Severe Weather Awareness Week (SWAW), so be sure to check out our SWAW webpage with new weather topics being added daily, as well as our social media feeds where we are giving away free MWN apps and NOAA weather radios this week! In fact, find our pinned post on Facebook and enter to win one of those Midland radios on Tuesday night! We're also running a sale on StormWatch+ in the MWN mobile app - only $5.99! That's a ONE-TIME fee for peace of mind in the form of personalized notifications when hazardous weather threatens. Learn more by clicking here.

Erik Proseus
MWN Meteorologist

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