Thursday, June 25, 2020

Saharan dust to visit the Mid-South

The next in a string of unusual events in 2020 may be the arrival of Saharan dust in the United States, and more specifically, the southeast U.S. and Mid-South!

Before you start fearing the worst... though this seems to be a fairly noteworthy event as Saharan dust storms go, it actually is likely to have minimal harmful effects on Mid-South weather for the majority of people. But it could indeed be noticeable if you are paying attention!

Background

Saharan dust storms (or more accurately, the "Saharan Air Layer [SAL]") are not uncommon and occur every year, mainly in the summer months, when large storms that generate a great deal of wind in the equatorial regions of Africa pick up dust from the Sahara desert and spew it into the atmosphere. The easterly trade wind then transports that dust over the Atlantic Ocean and westward. It is not uncommon either for dust to make it as far as the Caribbean and more tropical regions of the U.S. (think Florida for example). What makes this storm different seems to be its intensity - the amount of dust it contains and the lengthy path it is taking, following the prevailing wind right into the southeast U.S., with enough dust still suspended to be noticeable.

The image below was taken by one of the astronauts that just rode the SpaceX vehicle to the International Space Station a couple of weeks ago, showing the extent of the dust coverage over the central Atlantic.



Forecast

The current dust cloud has moved across the Atlantic and is arriving in the far southeastern U.S. now. The forecast loop below shows the path the dust is likely to take over the coming days, specifically from Thursday evening through Saturday evening. We could see some of the dust over the Mid-South Friday and Saturday.


While we aren't likely to see as poor of conditions as were observed in San Juan, Puerto Rico a couple of days ago, here's what was observed there this week:



Effects of the SAL

As you can see from the image above, the density of the dust in the Caribbean was quite high. However, after a couple thousand more miles of travel, it isn't likely to be as noticeable to the naked eye here. That doesn't mean it won't be noticed at all though! The most common effects of Saharan dust in the sky are:

  • More brilliant sunrises/sunsets - particularly in the orange/red realm if dust remains suspended high in the atmosphere
  • Hazy sky - if the dust settles out a bit lower, than our typical blue skies may be more muted or even a bit "hazy" with a tinge of brown.
  • Higher air pollution levels - especially if you notice a haze in the sky that seems to start near the ground. This would indicate that the dust is more prevalent in our little section of the atmosphere (the lowest 6 or so feet), which could be a mild irritant to those who suffer from allergies, asthma, or other breathing difficulties. Keep this in mind if it appears hazy out and take precautions if you are in a sensitive group.
  • Reduced visibility - in the most severe cases, and not likely here in the Mid-South, visibility can be reduced, almost like a smog scenario
  • Suppression of tropical activity - one of the side effects of Saharan dust is it also suppresses tropical storm formation in the Atlantic as the atmosphere is filled with a drying agent that keeps these systems from tapping into the moisture necessary to survive, as well as reflecting heat back into the atmosphere.

So be on the lookout (when it is not cloudy or raining) the next couple of days for signs of the Saharan dust!



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
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Tuesday, June 23, 2020

Cold front brings some relief tomorrow, but the summertime pattern is not far off!

Tuesday night into Wednesday 

While we have had a rather active afternoon across western Tennessee today, things have finally started to calm down. The remainder of the light rain has left the metro area and the skies are starting the clear up as we continue into Tuesday night as the cold front finally moves through. This will also shift our winds from southerly to more west-northwesterly but Wednesday morning and drop our overnight low into the upper 60s. Thankfully drier air will also usher in behind the cold front allowing for a very pleasant late June Hump Day with partly sunny skies and afternoon highs only in the mid 80s!  


Thursday through Saturday

These pleasant conditions stick around for most of Thursday with morning temperatures starting off near 70 under a mostly sunny sky, but by the afternoon a warm front will approach the area from the south. This will bring highs in the upper 80s and humid conditions with pop up showers. Much of the same continues into Friday the warm front moves further north and high pressure situates over eastern Tennessee. This will lessen our chances for widespread rainfall but scattered showers and thunderstorms will be possible for much of Friday and into Saturday. This will set us up for a much more seasonable pattern with overnight lows in the lower 70s and afternoon highs near 90 returning Friday and Saturday. 

Loop showing forecasted precipitation rates across the southeast for Thursday through Saturday at midnight from the European Model (EURO). This loop shows moisture moving through the region before a high pressure situates over eastern Tennessee on Friday.  (PivotalWeather.com)

Sunday through Tuesday

Sunday morning will start off with temperatures in the low 70s but afternoon highs will quickly warm into the low 90s. Higher humidity levels will return and lead to the possibility for scattered pop up thunderstorms or showers. Monday will bring much of the same with pop up thunderstorms and afternoon highs in the low 90s. Notice a pattern? 



Thanks to a typical summer time ridge, our weather will be stuck on repeat through mid-week. We will have mild mornings but hot and humid afternoons with scattered showers and thunderstorms especially after 2:00pm. Thankfully this pattern will limit widespread rain activity and severe storms but an isolated strong thunderstorm is never out of the question on a humid summer afternoon! 

Loop showing forecasted precipitation rates across the southeast for Sunday through Tuesday at midnight from the European Model (EURO). This loop highlights that we will see very little widespread rain over western Tennessee early next week with limited local pop up showers possible. (PivotalWeather.com)

An early look at the first week of July

While a typical summer pattern is likely through mid-week next week to end June, the Climate Prediction Center suggests that an slight shift is in store for the first week of July. Thankfully this pattern shift will not include a heat wave but is more indicative of near average temperatures continuing. It also suggests that July will start off rather soggy with an above average precipitation pattern through the 7th. Hopefully we can squeeze out a drier day on next Saturday for Independence Day! 

Climate Prediction Center's 8-14 Day Precipitation Probability highlighting that the southeast will likely see an above average pattern through the first week of July. (PivotalWeather.com)

Climate Prediction Center's 8-14 Day Temperature Probability highlighting that the southeast will likely see near to slightly above average temperatures through the first week of July. (PivotalWeather.com)

Allison Paige
MWN Meteorologist Intern

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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder
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Tuesday, June 16, 2020

How long will the sun last? Will it always be this hot and steamy?

Over the last week we saw relatively nice conditions outside, but over the weekend it was quite steamy. It looks like sun and warm temperatures will continue throughout this week. Our next decent chance of rain is going to be late this weekend and into the next. 

Weather through this week

After topping out in the mid 80s Tuesday, Tuesday night temperatures will drop to the mid 60s under clear skies. Wednesday will start out rather sunny before some cloud cover moves in making for a partly cloudy day. During Wednesday temperatures will top out in the mid to upper 80s, while Wednesday night will have clear skies and temperatures dropping to the mid 60s. Thursday will most likely be partly cloudy with steamy temperatures, as we will top out near 90. Overnight heading into Friday temperatures will drop to the upper 60s. 

Unfortunately, Friday will start a little heat wave as temperatures are going to top out in the low 90s. Friday night and heading into Saturday temperatures will only drop to around 70. During Saturday temperatures will reach a hot and steamy mid 90s temperature, thankfully there will be some cloud cover so hopefully that helps. Saturday night and into Sunday temperatures will only drop to the low 70s under some overnight cloud cover. 



What's the cause of our dry and hot weather?

We will be under the influence of the Bermuda High this week and heading into the early part of the weekend. A high pressure system usually brings warm, dry, and rather sunny conditions...which is what we'll be seeing!


Surface pressure map showing that there is a high pressure system off of the east coast of the United States, that is centered over Bermuda. 

Surface temperature anomaly late on Friday. An anomaly is a difference from average or normal, and temperatures will be 5-7 degrees above normal that evening.  

Sunday, Monday, and Tuesday

Sunday will be another steamy one as temperatures are expected to top out in the lower 90s, under partly sunny skies. Thankfully there is a slight chance of showers and thunderstorms on Sunday, so hopefully that comes in the evening and cools us off. Overnight heading into Monday, temperatures will again only drop to the lower 70s. Monday will again be pretty warm as temps are expected to top out near 90. Thankfully, there is again a chance of showers and thunderstorms on Monday, so hopefully it'll cool us off. Heading into Tuesday overnight temperatures will drop to the low 70s. Tuesday we will top out into the upper 80s, with scattered showers and thunderstorms possible.  
 
Looking at Week 2

The Climate Prediction Center (CPC) is predicting that From June 23rd - June 29th we will see near normal temperatures in our area and a chance of above average precipitation amounts for that week. 

Temperature outlook from the CPC showing temperatures will be near normal for the week of June 23rd to June 29th. 

Precipitation outlook from the CPC showing precipitation amounts could be above normal for the week of June 23rd to June 29th.

Max Magness
MWN Meteorologist Intern

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Complete MWN Forecast: MemphisWeather.net on the mobile web or via the MWN mobile app
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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder
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Tuesday, June 9, 2020

May 2020 Climate Data for Memphis, TN

May Climate Recap

After cooler than normal temperatures in April, May continued the trend, featuring only one day with a high that reached 90 degrees and an average temperature that was more than two degrees below normal. The coolest portion of the month, relative to normal, was a week-long spell from the 6th-12th that averaged 12.5 degrees below normal with highs in the 60s and a few lows in the low 40s. The first quarter of the year was wet, but drier weather from April continued in May with only 2" of rain recorded for the month. Nearly half of that fell on the 8th. 

Severe weather was limited in May. There were two events that resulted in severe weather reports. A thunderstorm on May 3 produced penny size hail in northeast Shelby County. A much more destructive event, on the afternoon of May 22, produced widespread damaging wind across Crittenden and Shelby Counties. Tress and power lines were downed from a wind storm that tracked across the area from AR. Over 52,000 Memphis Light, Gas and Water customers in Shelby County lost power in the storm as the Memorial Day weekend started.

Memphis International Airport, Memphis, TN


Temperature
Average temperature: 69.4 degrees (2.3 degrees below average)
Average high temperature: 78.7 degrees (2.5 degrees below average)
Average low temperature: 60.0 degrees (2.2 degrees below average)
Warmest temperature: 91 degrees (25th)
Coolest temperature: 43 degrees (9th, 10th)
Heating Degrees Days: 54  (35 above average)
Cooling Degree Days: 198 (28 below average)
Records set or tied: None
Comments: The month of May featured only one day that rose above 90 degrees, or one day less than average.

Precipitation
Monthly total: 2.00" (3.25" below average)
Days with measurable precipitation: 8 (2.3 days below average)
Wettest 24-hour period: 0.84" (8th)
Snowfall: None
Records set or tied: None
Comments: Only one day recorded more than one-half inch of rain, versus a May average of 3.7 days.

Miscellaneous
Peak wind: Northwest/46 mph (22nd)
Average wind: 8.5 mph
Average relative humidity: 67%
Average sky cover: 50%

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

Cirrus Weather Solutions / MemphisWeather.net, Bartlett, TN


Temperature
Average temperature: 68.5 degrees
Average high temperature: 79.2 degrees
Average low temperature: 58.3 degrees
Warmest temperature: 90.9 degrees (25th)
Coolest temperature: 40.1 degrees (9th)
Comments: None

Precipitation
Monthly total: 2.20" (automated rain gauge), 2.18" (manual CoCoRaHS rain gauge)
Days with measurable precipitation: 12
Wettest date: 0.93" (8th) (via automated gauge)
Snowfall: None
Comments: None

 Miscellaneous
Peak wind: West/52 mph (22nd)
Average relative humidity: 76%
Average barometric pressure: 29.96 in. Hg
Comments: None

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

MWN Forecast Accuracy

MWN average temperature error: 1.97 degrees
MWN forecast temperatures within 2 degrees of actual: 73%
MWN average dewpoint error: 2.31 degrees
MWN forecast dewpoints within 2 degrees of actual: 66%

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

Climate Outlook - June 2020

The June climate outlook for the United States from the Climate Prediction Center is shown below. Above average temperatures are forecast for the vast majority of the nation, with highest odds centered over the Great Plains. Odds favor above average temperatures for Memphis (50%) versus only a 17% chance of below average temperatures. Memphis' average temperatures for May is 79.6 degrees.




Wetter than normal weather is expected along the Gulf Coast and in the Pacific Northwest. Drier than average weather is forecast over the center of the country and in the I-95 corridor from the Mid-Atlantic to southern New England. For Memphis, odds favor average rainfall, which historically is 3.63 inches in June.

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Complete MWN Forecast: MemphisWeather.net on the mobile web or via the MWN mobile app
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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder
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Saturday, June 6, 2020

Tropical Storm Cristobal takes aim at the Gulf Coast, and Mid-South

As we just finish the end of the first official week of the 2020 Atlantic hurricane season, the THIRD named storm of the year will become the SECOND U.S. landfall in what is expected to be an active season overall. Previously, Tropical Storm Arthur made a close approach to the North Carolina Outer Banks on Monday, May 18. That was followed by Tropical Storm Bertha, which formed and gained tropical storm strength an hour before making landfall on the South Carolina coast on May 27.

Tropical Storm Cristobal moves towards the Gulf Coast

Now, all eyes turn toward the Gulf Coast as Tropical Storm Cristobal churns towards the Louisiana coastline with a Sunday evening landfall projected. Due to recent interaction with the Yucatan peninsula and dry air wrapping around the system, rapid strengthening is not forecast and the system likely won't have time to gain hurricane strength before making landfall.

Saturday morning visible satellite imagery of T.S. Cristobal as it heads for the LA coastline (COD)

Primary threats from the central Louisiana coastline eastward through the MS, AL, and FL panhandle coastal areas this weekend into Monday are torrential rain that is likely to cause freshwater flooding, wind gusts to near hurricane force, up to 5 feet of storm surge, churning waters with high waves and rip currents, and isolated tornadoes.

The official track for T.S. Cristobal as of Saturday morning, via the National Hurricane Center.

Once Cristobal makes landfall, it will move north-northwest across Louisiana into Arkansas on Monday, then accelerate north and northeast into Missouri Tuesday morning and across the Corn Belt into the western Great Lakes by Wednesday morning. The main impacts in the Lower Mississippi Valley and north as far as the Mid-South are likely to be gusty wind shifting from east to south, heavy rainfall, and isolated tornadoes.

Forecast tracks from multiple models are in fairly good consensus Saturday morning, as shown by this "spaghetti plot" of model solutions. (Tropical Tidbits)

Remnants of Cristobal to impact the Mid-South

While we won't notice anything out of the ordinary this weekend (mostly sunny with highs in the 90s), initial impacts in the Memphis area will begin Monday as clouds thicken, rain arrives around lunchtime into the afternoon and breezes pick up from the southeast.

Forecast rain amounts from the NOAA Weather Prediction Center show up to 3" in the Memphis metro, while higher amounts will occur just to the east of the center's path with lesser amounts further away. (WeatherBell)

The period of heaviest rainfall in the metro is likely to be Monday evening through Tuesday morning when 2-3" of rain could fall (heaviest in east AR) as the center of Tropical Depression Cristobal is likely to move through central AR. A few embedded thunderstorms are possible overnight and the tornado threat will bear watching (though they are typically more common in these scenarios during the daytime hours when the sun's rays provide a little more instability). In addition, wind will pick up out of the southeast to 25-30 mph with gusts reaching 30-40 mph Monday evening and overnight.

According to the early Saturday run of the European model, maximum wind gusts through Tuesday evening will be in the 50-60 mph range just to the east of the storm's path, while we could see 40+ mph peak wind. (WeatherBell)

By Tuesday morning, with the center of the storm into central Missouri, steady rain should taper off but showers and a few thunderstorms remain possible, especially in the morning hours. Wind will likely remain gusty from the south Tuesday, in the 30-35 mph range. By Tuesday night, a cold front will push through, bringing the potential for another round of showers and thunderstorms, but also escorting a drier and less humid airmass for the remainder of the week.


Preparation and cleanup weather

We recommend using this weekend to prepare for heavy rain and prolonged strong wind Monday PM into Tuesday. Make sure gutters and storm drains are clear and ready for a couple of inches of rain. Secure outdoor objects or bring them in. A few wind gusts Monday night will exceed 40 mph, but a lengthy period of 30-40 mph wind gusts is expected (up to 24 hours). Once it all passes, pleasant early summer weather with low humidity, highs in the mid 80s, and lows in the mid 60s for several days will make for ideal conditions for any cleanup that is necessary.



Erik Proseus
MWN Meteorologist

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Complete MWN Forecast: MemphisWeather.net on the mobile web or via the MWN mobile app
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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder
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Wednesday, June 3, 2020

How long will the heat last, and will Cristobal affect Mid-South weather?

For most of last week we had rather sunny skies, with bearable temperatures. Unfortunately, as I'm writing this blog it looks like it'll be hot and steamy over the next week...that is until a potential tropical disturbance. From the end of this week, over the weekend, and into the beginning of next week it looks like it'll be hot and steamy before the remnants of Cristobal brings tropical moisture and rain to the area (primarily on Tuesday). After the remnants of Cristobal leaves the area it looks like conditions for the middle of June could be cooler and dry.



Thursday and Friday

 Our chances of showers and thunderstorms will continue overnight into Thursday (50% chance). Temperatures will only drop to the lower 70s under mostly cloudy skies before our chance for showers and thunderstorms increase during the day and afternoon hours on Thursday (60% chance). Thursday will top out in the mid to upper 80s with winds coming from the southwest at about 10 mph. Luckily overnight into Friday chances for showers and thunderstorms will decrease slightly (to about 30%) as temperatures drop to the lower 70s again. During Friday, the shower and rain chances will stick with us (30% chance) as we reach a hot and humid high just below 90. Friday night into Saturday we will see temperatures drop into the lower 70s, under partly cloudy skies, and with a slight chance of rain (20% chance).

The reason we are seeing the shower and thunderstorm chances stick with us is due to a pesky upper level disturbance. This upper level disturbance brings with it some cyclonic vorticity (or counter-clockwise spin in the upper levels of the atmosphere), which leads to pressure falls, instability and sometimes active weather (such as showers and storms).

500mb (18,000 feet) heights and vorticity are shown in this graphic from ECMWF output. The little green and yellow blob of cyclonic vorticity over the Memphis area is what could help create showers and storms Friday. (Wxbell)  

Saturday, Sunday, and Monday

 Saturday and Sunday will mirror each other in almost every way. Both days look like they will top out in the lower 90s, with heat indices nearing 100 (HOT and HUMID!!!!). Sky conditions on both days will be partly cloudy to partly sunny, with very low rain chances. The overnight lows heading into Saturday and Sunday will drop to the lower 70s under some clouds. As we head into Monday temperatures will drop to the mid 70s under a mostly cloudy sky. Monday we have a chance of rain showers (30%) as we top out near 90 once again. 
Tuesday and Wednesday (Cristobal)

Tropical Storm Cristobal has formed in the Bay of Campeche near southern Mexico and will sit down there for a couple days before moving north towards the Gulf Coast. It'll likely make landfall somewhere along the LA coastline late Sunday then continue north towards the Mid-South. Looks like it could be wet if you're headed to the AL/FL beaches to start next week. On Tuesday we might see the remnants of Tropical Storm Cristobal reach Memphis bringing with it tropical moisture, some soaking rain, and temps in the mid 80s. As of right now the European Model is predicting around 1" of rain, with the Weather Prediction Center (WPC) predicting 1-2" of rain. Overnight temperatures heading into Wednesday will drop to the mid 70s before a pleasant Wednesday arrives in the area. On Wednesday we will likely top out in the mid 80s under mostly sunny skies.
European model output showing rain totals for early next week. The model gives us around one inch of rain in the metro area as it tracks Cristobal through AR. (WxBell)

This is how much rain is predicted to fall by the WPC late Monday into late Tuesday. Rain totals predicted by the WPC look to be between one and two inches. 

This is the ensemble "spaghetti" plots for the GFS, Euro, and UKMET models. Spaghetti plots are primarily used to show the numerous potential paths for Cristobal. They show some obvious spread in the paths but it looks like we'll still get something out of this (Weathernerds.org). 

How long will the heat last? 

 After the remnants of Cristobal pass during the first half of the week, the Climate Prediction Center (CPC) is predicting that temperatures will be more pleasant, possibly below normal. The CPC is also predicting that precipitation could be below normal, potentially making for a pleasant and dry period from June 11th-17th.

Temperature outlook provided by the CPC showing that temperatures in Memphis could be a little below normal from June 11th-17th.

Precipitation outlook provided by the CPC showing that precipitation in Memphis could be a little below normal from June 11th-17th.

Max Magness
MWN Meteorologist Intern
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Follow MWN on Facebook and Twitter for routine updates and the latest info!
Complete MWN Forecast: MemphisWeather.net on the mobile web or via the MWN mobile app
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
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