Saturday, April 30, 2016

"Wake low" causes wind damage across the metro Saturday morning

For the second day in a row, a line of thunderstorms dissipated over the metro region. Both times a 'wake low' formed over the area. Saturday morning's was much stronger and produced the most impact. It made its appearance known in the form of high wind that occurred between about 10am and noon, starting in far eastern AR and making its way slowly east across the city and into the eastern suburbs.

So what is a wake low? According to the American Meteorological Society, a wake low is defined as:
"A surface low pressure area or mesolow (or the envelope of several low pressure areas) to the rear of a squall line; most commonly found in squall lines with trailing stratiform precipitation regions, in which case the axis of the low is positioned near the back edge of the stratiform rain area."
In other words, sometimes trailing a squall line a mesoscale (small scale) low pressure system will form. Typically it will trail a mesoscale high pressure system than forms immediately behind the squall line. In many instances, the meso, or wake, low will be aligned along the back edge of stratiform (steady rain) precipitation trailing the line of storms as air sinks, thus warming and also drying the back edge of precipitation. The pressure gradient between the meso high and meso low creates a scenario in which a localized area of high wind can develop. (Weather geeks will recall that wind increases when the gradient between two pressure systems increases. A strong high pressure system in close proximity to a strong low pressure system produces very strong wind.)

A wake low can form on the back edge of an area of precipitation due to sinking air that warms as it sinks. The pressure gradient between the meso high (shown as the 'cold pool' above) and the trailing low can contribute to increased wind speeds between the high and low.
In today's case, there was about a 3 millibar pressure difference between Memphis International Airport and West Memphis airport, a fairly large difference over such a short distance. The result was peak wind in the 50-55 mph range in many areas around the metro, including Tom Lee Park, where Beale Street Music Festival infrastructure was setup (though patrons were not in the park). Damage at Tom Lee Park included tents, trash cans, and many other loose objects overturned and blown apart and debris scattered throughout the park, which caused a 2 1/2 hour delay in opening the festival and 4 cancelled musical acts. There were also many reports of trees and power lines down throughout the Bluff City and into DeSoto County with over 22,000 customers without power on the MLG&W grid at one point.

Below are some pictures submitted to us on Twitter, as well as a 6 hour radar loop from 5-11am showing the decay of the squall line. The wake low formed in the last hour of the loop on the back side of the light precipitation.

Erik Proseus
MWN Meteorologist

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Thursday, April 28, 2016

Memphis in May starts this weekend - so of course it's going to rain!

Last year, the first weekend in May, and by association the Beale Street Music Festival, was blessed with amazing weather. But as you might expect from "Memphis in Mud," consecutive years would be taking it a bit too far! So, get those galoshes, rain boots, and ponchos ready (because umbrellas aren't allowed), and let's dig into the details of what to expect this weekend, whether you're headed downtown, to Arlington in April, or just having a spring garage sale!

Though the general pattern from Friday through Sunday is a wet one, there will definitely be some "lulls" as it won't rain the entire weekend. Hopefully this will provide some idea of when those might occur. A couple of "up-front" notes: severe weather chances are very low, so we don't expect any large hail, high wind, or tornadoes to strike a crowded outdoor event. However, rain will be heavy at times and lightning is also expected. We recommend you have a plan for what to do if you start hearing thunder - and standing under a lone tall tree ain't it.


The pleasant spring weather we've had today quickly gets inundated by Friday's lunch hour as low pressure forms over west TX, pulling a warm front north from the Deep South into the Mid-South. While the morning hours will be mainly dry, the afternoon will be mainly wet with periods of heavy rain possible, but minimal lightning.

The surface map for mid-day Friday shows a stationary front to our south as it gets ready to move north. Dark green is where highest rain chances are and the area to our west will expand east during the afternoon hours.
As the warm front approaches in the evening, some thunderstorms will also be likely and rain could continue deep into the overnight hours. Rainfall amounts Friday afternoon through early Saturday will likely be pretty close to an inch with much heavier amounts to our west. Again, severe weather is not expected. Temperatures Friday will top out in the upper 70s and remain mild (near 70) in the evening hours.

The "most likely" precipitation total map through midnight Friday night indicates 3/4" or more of rain is expected with the initial wave of precipitation Friday.  2-3" may fall across  parts of Arkansas.


The daytime hours Saturday will probably see a break from the steady rain with just scattered showers or thunderstorms possible. Honestly, I wouldn't be surprised to see some fairly lengthy dry periods from morning through mid-afternoon. With the warm front to our north and the next cold front well to the west, there won't be a lot to trigger storm initiation outside of a weak passing upper level disturbance. With gusty southerly wind pushing temperatures to near 80 and very humid air in place, it won't take much to pop off a few thunderstorm cells though, so I'm not willing to call it a dry day.

By Saturday night, the low pressure center will be moving across the Missouri River Valley, dragging the cold front closer and rain and thunderstorm chances increase. If it stays fairly dry during the day, perhaps even with a peek of sunshine, instability will be pretty high, so lightning and thunder appears likely by evening. Severe weather chances should remain minimal with the main threats being a strong gust of wind or small hail, besides heavy rainfall. Evening temperatures will again be in the 70 degree range. Total rainfall Saturday and Saturday night could be another inch or so.

The surface map for Saturday early evening shows precipitation chances increasing again as a cold front approaches from the west. By Sunday morning, that front will be along the Mississippi River, marking an end to steady precipitation. Thunderstorms will also be possible as the front approaches Saturday night.

The "most likely" precipitation totals map for the period Saturday morning through the overnight hours Saturday night shows another 3/4" or so of rain will fall. 


The cold front moves through Sunday morning. It's passage should end just about all rain chances, though a post-frontal trough could wrap around the low to our north and bring a shower or two. Overall, we believe chances are low and by noon we should start seeing some sunshine. The rest of the day looks downright pleasant with highs in the upper 70s to near 80 and a breeze with a northerly component whisking the humidity to the south.

Total precipitation forecast by the NWS through Sunday afternoon indicates at least 2" of rain is expected in the Memphis metro this weekend.
Overall, we advise keeping rain gear handy and remaining weather aware throughout the weekend. We'll be nowcasting for the entire metro throughout the weekend on our social media channels below with an emphasis on Music Fest. You'll also be able to find radar, live tweets, and more through our mobile apps for Android and iOS (links below). Stay safe and stay dry (if possible!).

Erik Proseus
MWN Meteorologist

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Tuesday, April 26, 2016

Tuesday PM update - storm chances through Wednesday

UPDATED - 6:50pm CDT:
This evening's threat is waning as storms are having trouble departing MO and are weakening as they do, thanks to a cap of stable air they are attempting to sink south into. Our overnight chance of rain is now just 20%. The rest of the blog regarding tomorrow is still on track, including weakening of morning storms before they get here.

A warm and muggy day today has resulted in cloud cover over the area most of today, a sign that humidity is increasing as we head into a stormy pattern. The regional radar loop (shown below - always current) as of mid-afternoon shows a complex of storms extending from the St. Louis area west across MO.

Current regional radar loop. As of mid-afternoon storms are just coming into the picture in central MO as they drop southeast towards the Mid-South.
This complex will continue move southeast and is our first "fly in the ointment." As it moves south, it will encounter very moist air that is also unstable and will remain that way well after dark. Most models think it will either fall apart or move by to our northeast after dark. However, one of the more reliable short-term high-res models says "not so fast." If it's right, we could see some lightning and thunder between 10pm-2am. Severe weather is not expected locally, but a few strong storms are possible as the line moves into northwest TN early in the evening.

Once that passes, we turn our eyes to the west, where an outbreak of severe storms will be ongoing in the eastern and southern Plains. A line of storms is expected to cross AR by the wee hours Wednesday and will likely affect the metro after rush hour Wednesday morning. Once again, I expect we'll see a weakening line that will be in a state somewhere between scattered showers and a broken line of non-severe storms, depending on which model you believe. Either way, no morning severe weather is expected at this point.

HRRR (high-res model) "simulated radar" though 3am shows the MO storm complex grazing the metro and the Wednesday morning system approaching from the west. Graphic courtesy WxBell. 
However, the morning system will have a direct impact on what happens the rest of the day. The best bet is that we'll see a few peeks of sun by mid-day and the atmosphere will "re-energize" as the day goes on and as a cold front approaches from the west. The entire Mid-South is in a Slight Risk (category 2 of 5) for the potential for strong to severe storms to develop and move through the metro.

The primary risks will be large hail and damaging wind, though a tornado is possible. I also expect we'll see some refinement to the severe weather outlook tomorrow once the effects of morning rain on the overall state of the atmosphere are better understood. An Enhanced Risk (category 3/5) outlook is entirely possible somewhere in the Mid-South. The most likely timing for PM strong storms will be from mid-afternoon through about midnight, with additional refinement also expected as we head into tomorrow. If you have evening activities outdoors, we strongly recommend a plan B and to stay weather aware. (Yes, I know it has rained for about 1,512 Wednesdays in a row...)

After Wednesday, Thursday looks warm and dry with storms possibly returning by Friday evening and lasting off and on throughout the weekend.

Below are some tips to review prior to our severe weather threat - know them and share them! In addition, we highly recommend you have multiple ways of receiving severe weather warnings, no matter if you are at work, home, or asleep. Pros and cons of multiple ways are shown below as well.  One of those ways, if you have a smartphone, is to have StormWatch+ severe weather notifications set up via the mobile app. Links to more information and downloads are at the bottom of this post. Stay tuned to our social media accounts also listed below for the latest information!

Stay safe!

Erik Proseus
MWN Meteorologist

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

Sunday, April 24, 2016

Time for the A/C, but how about our storm chances this week?

A beautiful spring weekend is about in the books; hope you got a chance to get out and enjoy it! A little warmth crept into the area as high pressure shifted to our east, allowing warm southerly air to move in. With almost no cloud cover, highs reached 80°+ each day this weekend, but humidity levels were still comfortable and morning lows were very pleasant (in the 50s).

The surface map for Sunday night shows high pressure on the east coast bringing warm, southerly flow into the Mid-South, while a storm system organizes in the Plains.

Monday and Tuesday

As we head into the last week of April and towards the first weekend of Memphis in May, the warming trend will continue with a few chances of thunderstorms from the middle of the week into next weekend. Starting early in the week, dry weather continues as the focus for strong to severe thunderstorm activity focuses on the central and southern Plains. With increasing humidity, expect cloud cover to also be more prevalent than the weekend, though partly cloudy will suffice for Monday and partly sunny for Tuesday. Look for highs to reach the lower to mid 80s with lows in the 60s and warm southerly wind throughout. A shower or thunderstorm is possible Tuesday, but most areas will remain dry.

By Tuesday evening, a few showers or thunderstorms will be possible in the area, while severe storms are expected in the Plains. The cold front to our west will move into the region Wednesday bringing high chances of thunderstorms and perhaps a chance of severe weather.


The central U.S. storm system will make a push east on Wednesday which is our next best chance for thunderstorms. The Storm Prediction Center has a 15% chance of severe weather (equivalent to a Slight Risk, or category 2/5) for areas west of the Mississippi River on Wednesday. However, that could easily change as both the American GFS and European models indicate storms could roll into the Memphis metro late Wednesday afternoon and evening, which is when instability is maximized due to being during peak heating hours. The PM hours Wednesday will be worth monitoring, with storms possibly continuing into the overnight hours. It's too early to define exact storm threats and timing, so stay tuned.

The Storm Prediction Center's severe weather outlook for Wednesday indicates possible severe weather from MO/IL south across the western Mid-South into northeast TX.  This scenario will bear watching as the outlook are will be adjusted daily as the system draws near. Severe weather threats are TBD at this time.

Thursday and Friday

Though the medium-range models disagreed a bit the past few days, they are now converging on a solution that would keep Thursday and perhaps most of Friday dry as weak high pressure builds in behind Wednesday's system. Expect some sun, but likely not "sunny" days with continued warm temperatures, probably in the 80s for highs and 60s for lows.

Next weekend

As we head towards next weekend and Beale Street Music Fest, the crystal ball gets a little fuzzy. Long-range solutions from the computer models offer various solutions, but it appears that scattered thunderstorms will be possible again late in the week as a warm front pull back north across the region. Then, things get even more murky as to when the next cold front moves through, ranging from Saturday PM (European model) to Sunday PM (GFS/Canadian models). For now, we'll call next weekend "unsettled" with daily chances of thunderstorms. The one thing we are fairly certain of is that it won't be as cool as last year's Music Fest. Hopefully it just won't turn in to another Memphis in Mud!

As many of you know, MWN is the Official Weather Partner of Memphis in May, so we'll be keeping a close eye on the weekend and will also keep you abreast of changing conditions, including updates from Tom Lee Park during Music Fest. Stay up to date with our latest thoughts on storm chances via the human-powered MWN Forecast on our mobile apps or on the web.

Speaking of which, the Android app has a new update out (with iPhone releasing in the upcoming week) which adds a couple of features, including the ability to read these blog posts within the app and adding Drummonds, TN to our current conditions providers. We also updated some "under the hood" stuff that will keep StormWatch+ on top of its game. With severe weather season upon us, we strongly recommend you consider having a smartphone option for severe weather alerting and our StormWatch+ service is one of the best! Download links can be found below.

Erik Proseus
MWN Meteorologist

Follow MWN on Facebook, Twitter, and Google+ Visit on the web or on your mobile phone. Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Friday, April 15, 2016

Weather 102: The Omega Block and its effects on our upcoming weather

It's been a dreary and cool couple of days as an upper level low pressure system has moved SLOWLY over the region. As we head into the weekend, we have one thing to say to Mr. Upper Low:

As of Friday morning, an upper level low pressure system was over the region with it's counter-clockwise flow and unsettled weather, resulting in clouds and showers that moved little.
Yep, we're kicking the upper low to the curb and setting up a fairly interesting and "weather nerdy" pattern as we head into the weekend and early next week. Today, I introduce you to the "Omega Block." No, it's not something the anesthesiologist gives to numb a section of the body. An Omega Block is a weather pattern in the upper levels that, when plotted on a map, resembles the Greek letter omega, or an upside down horseshoe. The "block" term comes from the fact that the pattern tends to persist for a while and blocks the forward progression of air masses. Here's the mid level (18,000 foot) map for mid-day Saturday:

By mid-day Saturday, the Omega Block will set up over the eastern U.S., with its distinct inverted horseshoe shape at the mid levels, which will keep weather systems at bay to the west.
The black line with arrows represents the flow of air at 18,000'. Notice it's shape - like an omega symbol. The atmospheric setup is basically strong low pressure over the Four Corner (which is resulting in a major snow storm for the Denver area and Rockies east of the Continental Divide), low pressure over the west-central Atlantic, and a large area of high pressure covering the eastern half of the country between the lows. Air flows counterclockwise around the lows and clockwise around the high, resulting in the huge ridge between the lows.

Because the ridge forces the jet stream up and around it, air doesn't flow from west to east like normal, but has large bends north and south. Warm and dry air is found under the high, while cool and stormy weather is found on either side of the block. This is fairly obvious in the surface map valid Saturday at 1pm that shows a lot of precipitation, particularly on the west side of the high, with a large dome of dryness under the ridge.

The surface map and 12-hour accumulated precipitation for mid-day Saturday shows the effects of the Omega Block quite well. Stormy weather around the periphery of the block and dry and warmer weather under it.
For the Mid-South, we'll still have lingering clouds tomorrow, despite the ridge taking over at the upper levels, as flow in the low levels will be from the southeast, pulling moisture around the south side of the surface high pressure area. However, we will start to warm up a bit and by Sunday we'll see a lot more sun and temperatures that reach the mid to upper 70s.

As we head into next week, the Omega Block breaks down after a 3-4 day run and the low over the Four Corners fills, or weakens, as it moves northeast into the Plains. This will shift the stormy weather east, bringing rain and thunderstorm chances into the Mid-South from the west. The upper level pattern becomes more "zonal," or west-to-east, which will allow the low to progressively move closer and bring clouds and rain chances. However, temperatures will still likely be in the mid 70s most of next week as lows remain mild, or near 60.

By mid-week, the block will break down and the upper level low on the west side of it will move into the Plains. Flow across the southern U.S. will be "zonal," allowing weather systems to move a little more freely. However, the overall flow will be rather weak as the primary jet stream is well north in Canada, resulting in the Plains low being fairly slow moving.
The surface map for the same time as above shows the surface low and frontal systems across the mid-section of the country, which will increase our rain chances again heading into the middle of the week. 

So the next several days break down something like this...

And looking even further ahead, the Climate Prediction Center indicates that much of the CONUS, and especially the eastern half, will have high probabilities of above normal temperatures for the last week in April. Who's ready for some 80s??

NOAA Climate Prediction Center outlook for the last week of March indicates a 70% chance of above normal temperatures. Perhaps our first string of highs in the 80s as we approach May?

Erik Proseus
MWN Meteorologist

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

Sunday, April 10, 2016

Possible severe storms Monday, then cool... then warm!

A chill to start the weekend turned very windy and much warmer today as a developing weather system in the Plains begins to exert its influence on the region. In fact, with the dry, tilled ground in the Mississippi Delta and southerly wind gusts of 40-50 mph, blowing dust has resulted in very low visibility in areas of northeast AR and the National Weather Service took the unusual step of issuing an Arizona-like Dust Storm Warning for far northeast AR!

At least a couple of accidents are blamed on visibility that dropped below 1/2 mile in that region. Here in the immediate metro, the dust is not a serious issue, but looking through the haze to the west might mean a nice sunset to an 80-degree day!

Turning our attention to the week ahead, most of the action will be early in the week (Monday in fact) followed by another cool spell, then gradual warming with temperatures well above average to end the week. After Monday, rain chances are slim to none the rest of the week, except perhaps on Thursday when showers or a thunderstorm could affect mainly north MS.

On Monday, we will start the day with mild temperatures as lows remain in the 60s overnight due to increasing moisture and clouds and continued (but not quite as strong - gusting 25-30 mph) south wind. Chances of showers increase during the morning as temperatures climb towards 70° and south wind remains gusty. By afternoon, thunderstorms will develop to our west and begin moving into the metro ahead of a developing area of low pressure in the southern Plains. A few factors will combine to create an atmosphere capable of strong storms and heavy rain over the metro.

The nearly two days of strong southerly wind that precedes the system will result in dewpoints (a measure of humidity in the air) that reach the lower to mid 60s (plenty to feed any storms - see graphic below). The combination of available moisture and surface temperatures that reach the lower 70s will create instability in the atmosphere as a cold front approaches from the north. The instability, measured by an index called CAPE (Convective Available Potential Energy - or energy available to create convection/storms), will likely rise to near 1000 by late afternoon, especially along and south of I-40. The highest CAPE values, where instability is strongest, will be across southern AR (see second graphic below).

Forecast dewpoints at 4pm Monday from the Global Forecast System (American/GFS) model. Mid 60s is plenty of "juice" for the formation of thunderstorms. The drier air (lower dewpoints) to the north will be moving south by evening behind a cold front that marks the edge of the drier air. Graphic courtesy Pivotal Weather.

Forecast CAPE (instability) from the GFS model at 7pm Monday shows the best "fuel" for storms well to the southwest, but sufficient instability to promote thunderstorms in the metro. As the front approaches from the north, instability is shut off. Graphic courtesy WxBell.

Because of the high instability values, strong wind fields, an approaching low pressure system over southwest AR into the ArkLaTex region, an Enhanced Risk (category 3/5) of severe weather is present in that region. However, a Slight Risk (category 2/5) is present eastward up to the southwest corner of the metro, while a Marginal Risk (category 1/5) covers the metro (see graphic below). In other words, the highest probability of severe weather is well to our south and west (see second graphic below), but a few strong to borderline severe storms are possible in our area. The main risks will be large hail and damaging wind from late afternoon through the evening. The tornado threat is very low.

The Storm Prediction Center severe weather outlook for Monday shows the highest probability of severe weather where the greatest instability is - southwest AR. A Marginal Risk (category 1/5) exists for the metro with a few strong storms possible from mid-afternoon through early evening.

The probability of severe weather within 25 miles of a point on Monday is shown in this graphic from SPC. The metro is within a 5% risk area, which is relatively low, though not far from the 15% area. This could change on Monday.

A factor that limits our chance of severe weather includes the front pushing into the area before the main dynamics of the storm arrive from the west. Once the front arrives and wind shifts to the north early in the evening, the instability is shut off and the strong storm environment ceases to exist. Should the front slow up a little bit or afternoon rain fail to materialize, then instability could be stronger and our severe weather risk could climb. This forecast is the best educated guess based on the predicted state of the atmosphere about 24 hours out.

Besides severe weather, the atmosphere will have plenty of available moisture to work with as the system arrives, so heavy rain is also a good possibility (which will also end the blowing dust and, temporarily, the pollen, problem). Forecast rainfall amounts vary fairly widely between models due to placement of storms, but widespread 1.5-2" readings are expected from afternoon into the evening with some areas well above 2" if storms train over any particular area. In addition, rain will continue once the front passes tomorrow evening, so some heavy rain will be possible through perhaps midnight.

The National Weather Service forecast for rainfall amounts through Tuesday morning shows the heaviest over north MS closer to the track of a low pressure system, though models differ on exact amounts, ranging from just over an inch to well over 2". Graphic courtesy WxBell.

Following Monday night's rain ending, we appear headed for a mostly dry, but cooler, spell as we head into mid-week. Highs will be back down in the 60s with lows in the 40s. A disturbance passing by to the south will bring clouds and perhaps a few showers or a thunderstorm Thursday, mainly over north Mississippi, before we begin a warming trend that takes us into next weekend. I don't think we'll need the clothing layers next weekend that we started this weekend with! the GFS model forecast highs and lows for the next 10 days are shown below and are provided for planning and guidance only. Average highs/lows for this time of year are in the lower 70s and lower 50s, respectfully.

GFS Ensemble forecast temps for the next 10 days, courtesy WxBell. Temps are not exact and are to be used for trend analysis.

Stay tuned to our social media feeds and mobile apps tomorrow for the latest on severe weather trends and any severe weather watches or warnings that may be issued. Links to download the app or monitor our social media feeds are provided below.

Erik Proseus
MWN Meteorologist

Follow MWN on Facebook, Twitter, and Google+ Visit on the web or on your mobile phone. Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

UPDATED: Weather to plan your week around for the first week of April

I decided to give something new a try on this blog post written Sunday night. I'm going to let you know each day how I did and provide meaningful updates as necessary to the next day's forecast. Yep, total transparency! Something no one running for office can promise AND deliver... You'll see the daily updates in red below. Read on...

ORIGINAL POST - Sunday, April 3, 8:23pm

It's been a very busy few days on top of nursing a sore back, so this blog will be brief and to the point. Fortunately, there's not a lot "out of the ordinary" to talk about relative to this week's weather. It's early April when temps average 70/50 (high/low) but large swings are not at all uncommon. Thankfully, we really aren't expecting any severe weather in the next week, despite three cold frontal passages. We also aren't forecasting any heavy rainfall like those that contributed to the wettest month of March on record! Let's take the week day-by-day.


Tomorrow will be a warm sector day ahead of an approaching cold front that will only deliver a glancing blow to the Mid-South as the parent low pressure system moves by well to the north. Only a few clouds are expected as moisture remains very limited with the front that arrives late Monday. Highs will be well into the 70s after lows remain near or above 50. With mostly sunny skies, a nice day to do something outside, unless you're working, then we recommend a long patio lunch.

ACTUAL: Anyone see any clouds today? Right, just a few this evening trailing the cold front that moved through with stealth, as promised. Today's high was 80 (undershot that one by a few degrees) and the low was 52 (nailed it).


Limited moisture falls even further behind Monday's cold front and temperatures will be about 10° cooler, topping out in the mid 60s despite a sunny sky. Morning lows will be in the mid 40s. Wind quickly turns back around to the southeast by Tuesday afternoon, which will have a bearing on Wednesday's weather. (No changes as of Monday night. Right on track.)

ACTUAL: Temperatures overachieved again today (71) under sunny skies, but they were still about 10 degrees cooler than Monday as predicted. The morning low was 51 with outlying areas closer to the mid 40s. Wind was east to southeast this afternoon.


Yet another frontal system moves through late in the day. This one will have a little more moisture to work with, as well as a bit of unstable air ahead of it. Scattered showers are expected, especially in the afternoon, as well as a few thunderstorms. Compared to our cold fronts last week, this one will not have nearly the upper level energy so severe weather is currently not anticipated, nor is widespread heavy rainfall as the system will move through rather quickly. Highs will be near 70 with lows in the lower 50s. Rain will probably be gone by evening, but the upper level pattern shifts behind this front, leading to a change in the pattern for week's end... Very little change for Wednesday (as of Tuesday night). Rain and a few storms are still expected in the afternoon hours, but should not be severe. Temperatures will again run a couple degrees above this forecast.

ACTUAL: Pretty much spot on! Two distinct lines of showers and thunderstorms moved through during the afternoon,. No severe weather occurred, but wind was pretty strong! Rainfall was heavy, but brief with less than 1/2" area-wide. Rain was gone by evening as predicted. Highs were within 2 degrees (72) and lows were accurate for the outlying areas, but stayed warm in the city (near 60).


The upper level pattern becomes dominated by an eastern U.S. trough heading into the end of the week, which will mean northwest flow for the Mid-South (upper level wind blowing from northwest to southeast) and temperatures cooling to below April norms. Northwest flow will mean some clouds linger Thursday with a slight chance of a shower. Highs still reach the mid 60s after morning lows in the upper 40s, but a stiff north wind at the surface will make it feel cooler, especially if sunshine is limited. Wednesday night comments: Looks like I expected a slightly stronger trough than we'll end up seeing, with a little more sun and slightly warmer temperatures than predicted. Will be interested to see how this actually pans out.

ACTUAL: Well, I get to use my favorite slogan: "It seemed like a good forecast at the time!" The upper level trough is in position as expected, but more sunshine than expected and some dry air that heats  rather efficiently resulted in a beautiful day with highs in the mid 70s, or 10° above Sunday's prediction. In effect, the cooldown is simply delayed a bit more than expected. Morning lows in the upper 40s was perfect and the breezy northwest wind also materialized as expected. No rain.


The eastern U.S. upper level trough strengthens, which in turn drops cooler air into the Mid-South. Skies will average partly cloudy but look for highs only near 60, or about 10° below average for this time of year. North wind means a chilly day and the nighttime hours will be cold. Saturday morning lows could drop to near 40 in the city and some frost will be possible in outlying areas. Thursday night comments: Once again, the Sunday night forecast for Friday will be too cool, but probably not a lot - mid 60s versus near 60. Saturday night's temperatures will be as predicted - chilly!

ACTUAL: Mid 60s was the actual high, just a bit above the forecast from Sunday night. The wind was indeed brisk today and tonight's low is right on track with the forecast - lows in the 30s are expected outside the loop, though some wind will keep frost to a minimum.

As I mentioned on Facebook and Twitter Saturday, it's REALLLLY tempting to start planting outdoors, but unless you are planting something hearty, or easy to move to a warmer spot for a night, I strongly suggest waiting until at least next weekend after this cold spell moves through. A gardener told me that it's wise to wait until after Tax Day to plant. Not sure if that has more to do with the warming of the ground and end of potential cool snaps or the status of your bank account when you go to Lowe's or the local nursery, but either way it makes sense.

Saturday and Sunday

Highs rebound fairly well under full April sun with mid 60s expected for highs as wind shifts back towards the south. By Sunday, a developing weather system to our west will mean a slight chance of showers as Gulf moisture starts moving back into the region. Highs should be back near average or slightly above. It looks like early the following week will see out next chance of heavier spring rain and perhaps a few decent thunderstorms. Friday night comments: Saturday will actually be the coolest day of the day with highs in the upper 50s.

ACTUAL: Pretty much dead on for Saturday with sunshine and highs in the mid 60s after a low in the mid 40s. As for Sunday, the slight chance of showers forecast a week ago occurred early in the morning with highs well above average at 81°. The other notable weather event was the very strong south wind.  

For the week, the main points were well-forecast with temperatures averaging above forecast by a category or two for the most part, but with the trends well forecast. The "outlook" for early this coming week, forecast 8 days ago, is also dead on - "heavier spring rain and a few decent thunderstorms." Exactly what I'm expecting tomorrow!

Here's the official MWN Forecast, updated daily (or check it out in our mobile app).

Here's the week wrapped up with a nice little bow on it:

Erik Proseus
MWN Meteorologist

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

Tuesday, April 5, 2016

March 2016 Climate Data and Forecast Accuracy

March Recap

A very warm month with record precipitation marked the beginning of spring in the Mid-South. Multiple rounds of heavy precipitation occurred during the month with a particularly wet spell during the second week of the month when nearly twice the normal monthly average occurred. That was followed by another 4"+ storm total to end the month. Despite abundant precipitation and cloud cover, temperatures averaged 4.5 degrees above normal for the month. Severe weather occurred with storms that rolled through the metro on the 13th (Tornado Warning) and additional storms on the 31st (Severe Thunderstorm Warnings). Flash flooding also occurred on the 9th-10th.

Top 10 wettest months of March on record

Top 10 wettest months on record

Memphis International Airport, Memphis, TN

Average temperature: 58.5 degrees (4.5 degrees above average)
Average high temperature: 68.2 degrees (4.3 degrees above average)
Average low temperature: 48.8 degrees (4.7 degrees above average)
Warmest temperature: 82 degrees (15th)
Coolest temperature: 34 degrees (21st)
Records set or tied: None
Comments: None

Monthly total: 16.20" (11.04" above average)
Days with measurable precipitation: 13 (2.5 days above normal)
Wettest 24-hour period: 5.62" (9th-10th)
Total Snowfall: None
Records set or tied: Back-to-back daily precipitation records were set on the 9th (4.53") and 10th (3.43"), as well as on the 31st (2.42"). The monthly total marked the wettest March on record, besting the previous record by more than 3", and was the 4th wettest month ever recorded at Memphis International.
Comments: Five days recorded more than 1.00" of rain and three days recorded more than 2.00".

Peak wind: Southwest/39 mph (22nd)
Average wind: 9.3 mph
Average relative humidity: 62%
Average sky cover: 60%

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

Cirrus Weather Solutions /, Bartlett, TN

Average temperature: 57.2 degrees
Average high temperature: 68.3 degrees
Average low temperature: 46.1 degrees
Warmest temperature: 83.1 degrees (15th)
Coolest temperature: 29.9 degrees (21st)
Comments: None.

Monthly total: 12.66" (automated rain gauge), 13.03" (manual CoCoRaHS rain gauge)
Days with measurable precipitation: 13
Wettest date: 3.76" (9th) (via automated gauge)
Total Snowfall: None
Comments: None

Peak wind: 27 mph (23rd)
Average relative humidity: 73%

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

MWN Forecast Accuracy

MWN average temperature error: 2.48 degrees
MWN forecast temperatures within 2 degrees of actual: 64%
MWN average dewpoint error: 2.91 degrees
MWN forecast dewpoints within 2 degrees of actual: 59%

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

Follow MWN on Facebook, Twitter, and Google+ Visit on the web or on your mobile phone. Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder