Friday, July 21, 2017

Excessive heat slowly gives way to increased rain chances

** UPDATED AT 3:00PM FOR EXTENSION OF HEAT WARNING THROUGH SATURDAY **

We'll start this blog with a bit of "hopeful" news as we bake in the Mid-South sauna...

This map by Brian Brettschneider shows the normal midpoint of summer for a given location. Here in Memphis, it's around July 17 according to the data. We're slowly making progress towards fall!
What this means is that the average "peak" of summer heat here in the Memphis area is now in the rearview mirror. We're on the long downhill slide towards autumn. But summer is certainly not over yet!

A sprawling high pressure system at the mid and upper levels of the atmosphere is responsible for bringing the heat the past few days, while surface high pressure just to our east has allowed Gulf moisture to pool over the region, creating a very humid airmass that has exacerbated the hot conditions.

High pressure at the mid-levels of the atmosphere (500mb or 18,000', shown above) sits directly over the region, resulting in very hot air in the Mid-South under this "heat dome." It will slowly weaken as shift east this weekend. (PivotalWx)
UPDATED 3:00PM: An Excessive Heat Warning is in effect for much of the metro through Saturday evening and Heat Advisories remain in effect through Sunday as temperatures rise well into the mid (and for today, perhaps upper) 90s. Heat indices are averaging near 110° at mid-afternoon as the humidity has cranked up as well, evident in dewpoint readings in the upper 70s to near 80.


Like yesterday, there is only a slight chance of a cooling shower today, and it certainly does very little for the high humidity values. The general trend continues Saturday, though the upper level high pressure system that has brought the "heat dome" to the middle part of the country the past few days will start to move east, allowing perhaps a few more clouds and widely scattered showers, which could work to keep the heat index below 110° and temperatures in the mid 90s instead of creeping towards the upper 90s. If you have to be outside the next couple days, please take precautions against the heat and listen to your body for these signs of heat stress:


As high pressure aloft weakens this weekend, the heat will abate just a bit, as well as allowing rain chances to increase a bit, especially during the afternoon hours. Humidity will remain high, but with temperatures still in the mid 90s through Sunday, heat indices will remain above the 105° danger level. A few afternoon t'storms are possible Saturday, then scattered thunderstorms are expected on Sunday into Sunday night.

By early next week, our high shifts further east, a trough of low pressure develops in the Great Lakes region, and another high forms in the western U.S. The overall impact on our weather is that we'll be in a "northwest flow" pattern, meaning the wind aloft will blow from northwest to southeast. This is a pattern that favors upper level disturbances to move across the region from the northwest.

A loop of the mid-level (18,000') pressure and wind pattern, every 12 hours from Friday morning through next Wednesday morning, shows the high pressure ridge over our region breaking down by early next week as a trough forms to our north, then rebuilding from the west by the end of the loop (middle of next week). (PivotalWx)

In addition, a cold front will sink into the Mid-South by Tuesday, but stall out. This combination means the likelihood of scattered showers and thunderstorms to start the week, holding high temperatures down closer to 90°. Humidity remains of course, making for a muggy forecast.

By mid-week, high pressure to the west begins building back into the region, the front lifts back to the north, and temperatures warm back up into the 90s. We will likely still see a few daily thunderstorms typical of summertime but the storm track should shift back a bit north of the metro by Wednesday or Thursday.

But as I said at the top of the post, we're slowly getting closer to autumn than we are moving into the heart of summer! Schools start in a few weeks, which hopefully means the warmest part of the year will soon be behind us!

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

Thursday, July 13, 2017

The dog days have arrived! Rain chances heading into the weekend

Summer has definitely arrived in the Mid-South as temperatures are now consistently rising into the 90s each day. We've also seen dewpoints rise to mid-summer levels, pushing the heat index above 100 degrees each afternoon. Be sure you are taking precautions against the heat - drinking water, checking on the young and old, and avoiding it if possible!

(A side note: today is the 37th anniversary of the hottest day on record in Memphis! July 13, 1980 saw the mercury rise to 108 degrees and was smack in the middle of the longest stretch of 100-degree days the city has ever seen, reaching 15 days!)



With the increased heat and humidity came a few popcorn showers the past couple of days. Unfortunately (if you want dry weather a little longer), rain chances will increase even further heading into the weekend as a front sags south. An upper level trough develops over the eastern U.S. in response to a building ridge of high pressure to the west, placing the region in northwest flow that promotes the passage of upper level disturbances. All of this adds up to: 1) slightly cooler temps due to increased cloud cover, 2) continuing high humidity, 3) higher rain chances, but 4) "marginal" severe weather chances.

The surface map for Friday evening shows high pressure over the Midwest and a front separating that airmass from warm, humid air to the south. The front will move south this weekend then wash out over the area by Sunday. (NOAA/NWS)


The upper level weather pattern this weekend features a strong ridge of high pressure over the western U.S. and a trough over the east, which places the Mid-South in northwest flow (wind following the arrows from northwest to southeast), meaning increased rain chances. (NOAA/NWS)

A Marginal Risk of a few severe storms exists on Friday across west TN and northern AR, according to the Storm Prediction Center. A few storms late in the day could contain strong wind gusts. (NOAA/SPC)

For those trying to plan outdoor events, I believe the best chance of thunderstorms, when a few could contain gusty wind as represented by the level 1 "Marginal Risk" of severe weather donated above, will be late Friday afternoon into the evening, and mainly north of the city. As shown by the afternoon run of the high-resolution NAM model below, an area of storms may fire up to our north and head towards the Memphis area late in the afternoon, but this model believes it could quickly fall apart heading into the evening.

The afternoon run of the NAM3 model from 1pm Friday to 1am Saturday shows a potential line of storms dropping towards the metro but falling apart as it gets close. Have a backup plan for any outdoor activities during the PM hours Friday.
Saturday could also see scattered showers and thunderstorms, but the highest likelihood will be during peak heating roughly south of I-40, or mainly north MS. Don't plan any outdoor activities the next couple of days without a "plan B" however. By Sunday, we should see a more northerly component to the wind as the front washes out just to our south, resulting in a low chance of precipitation and perhaps SLIGHTLY lower dewpoints. Temperatures this weekend will likely peak near 90 degrees each day.


As we head into next week, indications are that the ridge to our west shown in the upper level map above will build east, suppressing precipitation chances and causing temperatures to rise once again, back into the lower to mid 90s. More summertime weather as we work our way through the "dog days!" For the routinely updated, human-generated MWN Forecast, check out our mobile apps linked below or click here.


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

Monday, July 10, 2017

June 2017 Climate Data for Memphis, TN

June Climate Recap

For the first time in recent memory, Memphis International Airport experienced consecutive months of below average temperatures in May and June. May 2017 was the first month that was cooler than average in a calendar year and this month was the first June that was cooler than average in 13 years, according to the National Weather Service. In fact, Memphis usually sees its first 90° reading on May 24 on average, but this year didn't reach that mark until June 6. Only eight days recorded temperatures of 90 degrees or higher, which was six below normal for the month and now eight below average for the year. However, for the year, the average temperature is still 3.5 degrees above normal.

Radar animation as Tropical Depression Cindy moved across Shelby County on the morning of June 23, 2017.

Precipitation-wise, June was a bit wetter than average. Sporadic thunderstorms associated with diurnal thunderstorms provided some rainfall, but the remnants of Tropical Storm Cindy moving directly over the metro on the 23rd provided record-setting precipitation on that day, as well as strong southerly wind gusts. Outside of Cindy, there were a few other severe weather episodes. Hail just below severe criteria fell on the 1st in south Memphis. Wind damage occurred in multiple locations across the metro, mainly in the form of downed trees, on the 18th. Leading up to the arrival of Cindy, a brief tornado touchdown occurred near Red Banks in Marshall County on the 22nd. Finally, on June 30th, lightning resulted in a fatality, a female who was at home in Cordova when lightning struck her home.


Memphis International Airport, Memphis, TN


Temperature
Average temperature: 78.4 degrees (1.2 degrees below average)
Average high temperature: 87.4 degrees (1.5 degrees below average)
Average low temperature: 69.5 degrees (0.8 degrees below average)
Warmest temperature: 92 degrees (14th, 20th)
Coolest temperature: 59 degrees (9th)
Heating Degrees Days: 0 (0 above average)
Cooling Degree Days: 410 (28 below average)
Records set or tied: None
Comments: Year to date, the average temperature of 62.7° is 3.5° above normal and second warmest on record (2012).

Precipitation
Monthly total: 4.61" (0.98" above average)
Days with measurable precipitation: 10 (1.0 days above average)
Wettest 24-hour period: 1.63" (23rd)
Snowfall: None
Records set or tied: Daily precipitation record set - 23rd (1.63")
Comments: Year to date, precipitation has totaled 23.46" or 84% of normal.

Miscellaneous
Peak wind: South/47 mph (23rd)
Average wind: 7.5 mph
Average relative humidity: 72%
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: 77.1 degrees
Average high temperature: 87.4 degrees
Average low temperature: 67.2 degrees
Warmest temperature: 92.7 degrees (14th)
Coolest temperature: 54.7 degrees (9th)
Comments: None

Precipitation
Monthly total: 4.43"(automated rain gauge), 4.58" (manual CoCoRaHS rain gauge)
Days with measurable precipitation: 12
Wettest date: 1.98" (23rd) (via automated gauge)
Snowfall: None
Comments: Precipitation on the 23rd was associated with the remnants of Tropical Storm Cindy.

Miscellaneous
Peak wind: South/31 mph (23rd)
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: 1.66 degrees
MWN forecast temperatures within 2 degrees of actual: 80%
MWN average dewpoint error: 2.20 degrees
MWN forecast dewpoints within 2 degrees of actual: 64%

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

Thursday, July 6, 2017

When will the wet weather end? Soon!

It's been a wet and stormy holiday week around the metro, with plenty of showers and storms that have rolled through Memphis, interrupting some fireworks shows while sparing others. Grass is lush (and tall if mowing has been difficult due to the daily rainfall) and the ground is soggy in some places. But could we see a break in the unsettled pattern coming in the near future? Mother Nature may have some relief for the Mid-South on her mind.

Areas along and north of I-40 in TN and much of AR have received as much as 200-400% of normal rainfall in the past 2 weeks. Surprisingly, Memphis International Airport is still over 4" below normal rainfall for the year. (Image credit: NOAA/NWS)

But First, More Storms!

Before the rain can stop, a few more scattered storms are rolling through the Memphis area today. With the potential for showers and thunderstorms out ahead of a cold front digging south, expect to dodge some raindrops this evening when heading out. Once the sun sets, however, expect skies to dry out with mostly cloudy conditions remaining in place overnight with lows in the mid-70s.

Friday into early Saturday is the period for this cold front to push through the Mid-South, with a change in the pattern in sight. Your final day of the work week starts out dry and hot, with highs in the low 90s. Then expect increasing clouds into the evening hours before some rain showers roll in for Friday overnight and into Saturday morning. Lows on Friday will be in the mid-70s.

Here comes the cold front! By Saturday morning, we expect a change in the weather pattern across the Mid-South.

Ah, Relief...

The wet conditions will finally subside on Saturday morning as the showers clear the metro. Left in its wake will be partly cloudy skies and highs near 90 once again. The wind shift from west to north should help usher in slightly less humid conditions, but still plenty of heat to go around. The heat will continue into the next week, with Sunday getting up to near 90 once again.

While the overly wet pattern for this time of year will mostly dry out by the end of this week, this will not totally eliminate the chances of rain and storms. With the summertime heat, pop up showers and storms will continue to be possible Sunday and into the next work week as well, especially across northern Mississippi, but they will be much less widespread than the past several days. In any case, expect improvement for the coming weekend from Saturday afternoon on through Sunday.

As the wet weather rolls through to end the week, be sure to follow us on Twitter and Facebook for the latest updates to our MWN forecast. You can also always check our human-powered forecast on our mobile apps. But it doesn't end there, as you can take MWN with you on the go and check that human-powered forecast on our mobile apps!

Hang in there folks, a change in the weather is coming!



Alex Herbst
MWN Meteorologist/Intern

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Visit MemphisWeather.net on the web or m.memphisweather.net 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, June 30, 2017

It's Independence Day weekend - who's bringing the fireworks?

It's overused, but apropos for the 4th of July. "Mother Nature's fireworks" could be a concern for the next few days as a frontal system nears our humid region. Upper level flow will favor the passage of disturbances - flies in the ointment, if you will - that will spark scattered showers and thunderstorms as we head into a long holiday weekend. We'll take this a day at a time...

Friday

A narrow line of heavy rain and thunder is moving through the metro as I type. The fortunate side to this is that it appears that should mark an end to most precipitation for the day as it pushes the instability east of the area and temperatures sit in the mid 70s behind the line, coincident with normal peak heating hours. Evening activities look to be in decent shape, though the next round of showers and thunderstorms is poised to enter the metro overnight. It'll be humid out, but temperatures should be a bit cooler than the past few evenings, likely in the upper 70s.

A Marginal (level 1/5) Risk of severe weather is forecast through 7am Saturday. This is mainly for storms that are expected overnight tonight and should occur after most evening activities are done. The main threat is isolated strong wind gusts and hailstones. (SPC)

Saturday

A cold front will slip into the northern portions of the Mid-South tonight as an upper level disturbance sparks a complex of thunderstorms in OK and western AR. Some of that activity is expected to move east into the Mid-South overnight into Saturday morning. Once again, this could be decent timing for afternoon and evening activities as the morning rain could help stabilize the atmosphere a bit. There still is come question on timing of the early day rain and its exact influence on the rest of the day, so at this point, we can't rule out the re-energizing of the atmosphere and some pop-up showers and thunderstorms during the PM hours of the day, so make sure you still have alternate arrangements for any outdoor activities. We're hopeful that fireworks shows Saturday evening will be provided by those paid to put them on!

The surface map for Saturday evening shows a front draped to our north and just a low chance of precipitation in the airmass south of the front. (NWS)

The Marginal Risk of severe weather for Saturday is now southeast of the metro as storms late tonight are expected to stabilize the atmosphere locally. A few thunderstorms are still expected, mainly in the morning, as indicated by the light green ("thunder") area. (SPC)

Sunday

As we get further out, the forecast becomes a bit murkier. There are no clear signs right now of any formidable systems moving through Sunday, but with the front remaining just to our north, any subtle upper level energy, combined with what is expected to be increasing heat again (approaching 90 degrees) could be enough to result in scattered showers and thunderstorms. At this point, we would expect those to be more heat-of-the-day storms which should wane during the evening in the absence of forcing to keep them going. Rain chances therefore are currently near 30% with heat indices in the mid 90s.

Monday

A work day for some, a vacation day for others... models have been leaning on the possibility of a little more organized chance of storms, particularly in west TN, during the day. Again, the situation is a little murky, but we've included a 40% chance of daytime precipitation, with things quickly diminishing in the evening. Being July 3, I know there are multiple choices for evening fireworks and outdoor events. We're crossing our fingers for a dry evening.


Tuesday-Friday

July 4th and the following days all look to see a fairly typical summertime patter emerge with plenty of heat and humidity with a chance of afternoon/early evening showers and thunderstorms. No major frontal systems are expected, though a weak front could move close late in the week. The overall pattern favors the potential for widely scattered to scattered diurnal thunderstorms each day. Unfortunately for those who have enjoyed our below normal temperatures in June, summer looks to make a comeback next week with highs in the lower 90s, dewpoints in the lower 70s, and heat indices pushing 100. Time to find a pool.



Erik Proseus
MWN Meteorologist

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Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net 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

Sunday, June 25, 2017

The Summer Swing Begins in Memphis This Week

Are you ready for the summer? Are you ready for the sunshine? We've got warmth and sunshine for much of our week ahead, but some storms could rain on our parade heading into later this week. Let's dig into the details.


A Sunny Start
Sunday has brought abundant sunshine throughout the afternoon for the Memphis area and temperatures running mostly in the mid-80s. Lower humidity helps too, and that pattern is likely to continue into the beginning of the work week. Temps will slide into the mid-60s on Sunday night with partly cloudy skies, before jumping back up to the mid-80s on Monday.

The next chance of showers and storms comes on Monday night as a "reinforcing" cool front pushes through, though any precipitation should be isolated in nature and mostly remain to our north. There will be a likely increase in clouds on Monday ahead of any rain, but overall should be a good day.

Tuesday will see any early clouds decreasing with continued low humidity and warm temperatures. Wednesday continues the pattern of warmth, albeit with slowly rising humidity. It could become a bit more sticky, but temperatures remain in the mid to upper 80s for highs the middle of the week. The sun will remain a prominent feature in the forecast those days, while overnight will see mostly clear skies and lows in the upper 60s to near 70. Be sure to keep yourself and your pets cool in the heat of the summer coming up.

Here are some smart tips on how to keep your pets safe and cool this summer.

Summer Storms Are Coming

As the latter part of the week approaches, there is an increasing chance of pop-up showers and thunderstorms around the metro area. With the heating of the day where temperatures could approach 90 degrees, along with increased humidity, it would not be surprising to see some storms fire up late in the afternoon and into the early evening hours.

Temperatures continue to remain warm through the rest of the week with highs in the upper 80s to near 90. Lows will be on the rise too, with most nights dropping into the lower 70s.

Heading into the weekend, we will be watching an approaching cold front from the west that could bring more widespread rain and thunderstorms just in time for the weekend. Fortunately, this messy weather should clear just ahead of the July 4th holiday coming up.



Be sure to follow along with us on social media for all the latest weather for the Mid-South. Follow @memphisweather1 on Twitter or like us on Facebook. You can also download the MWN app from the Apple or Google Play stores, featuring pinpoint severe weather alerts from StormWatch+.

And one last request - the Commercial Appeal's #MemphisMost contest ends Monday morning at 9am, and we've been nominated for "Most Accurate Forecast" for the first time ever! Please consider casting a vote at www.MemphisMost.com tonight or early Monday. You can even vote once an hour! Thanks much and have a great week!

Alex Herbst, Meteorologist
MWN Social Media Intern

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Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net 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

Saturday, June 24, 2017

2017 Solar Eclipse: A Viewing Guide for Memphis and the Mid-South

On August 21, the first total solar eclipse to make an appearance over the continental United States since 1979 will pass within 150 miles of Memphis. The last time a total solar eclipse spanned the contiguous U.S. (as this one does) was 1918, nearly a century ago, and the first total solar eclipse visible anywhere in the CONUS in 38 years. Despite the area of totality missing Memphis by a short drive, most of North America, including the Memphis metro, will experience a partial eclipse. In the case of Memphis, the sun's obscuration will be 93%, so nearly total!

What is a solar eclipse?

From NASA's total eclipse page, eclipses occur when the sun, moon, and Earth periodically align. Solar eclipses happen when the moon moves between Earth and the sun. When the moon eclipses the sun, it produces two types of shadows on Earth. The umbral shadow is the relatively small area on Earth where an observer would see a total eclipse. The penumbral shadow is the much larger area where an observer will see a partial eclipse. Here, the sun is not completely covered by the moon.


During a total solar eclipse, there is as noticeable drop in light level (like twilight) and, subsequently, air temperature. The brightest stars and the planets become visible. Animals act like it is nighttime with birds and squirrels nesting and crickets chirping. In other words, there is nothing quite like it during the middle of the day!

Solar eclipse of July 22, 2009 taken by Lutfar Rahman Nirjhar from Bangladesh.

Mid-South Path

The Memphis metro will not be in the path of totality of this year's solar eclipse, but will be well within the area of a partial eclipse. In fact, for the Memphis area specifically, the sun achieves 93% obscuration, or very near totality. The nearest areas which will have a total eclipse are about 150 miles northeast of Memphis as shown in the map below.

The path of the total eclipse is shown above in the map generated by NASA. Times of maximum eclipse at various points are provided as well as the duration of the total eclipse (which is higher the closer to the center of the shadow you are).

As for the timing of the partial eclipse event here in the Memphis area, here are the pertinent details:


If you are considering a trip to see the total eclipse, the closest large cities within the path of totality are Nashville and Paducah, although anywhere along the path shown in the map above will do!

Eclipse details for Nashville:

Start of partial eclipse: 11:58am CDT
Start of total eclipse: 1:27:26pm CDT
Point of maximum eclipse: 1:28:25pm CDT
End of total eclipse: 1:29:23pm CDT
End of partial eclipse: 2:54pm CDT

Eclipse details for Paducah:

Start of partial eclipse: 11:54am CDT
Start of total eclipse: 1:22:17pm CDT
Point of maximum eclipse: 1:23:28pm CDT
End of total eclipse: 1:24:39pm CDT
End of partial eclipse: 2:49pm CDT

You can look up these same details for any location in the United States from this site.

Will weather cooperate?

Of course the other major consideration on an eclipse day is cloud cover. If it is overcast, it won't matter whether an eclipse is occurring because you won't be able to see it! NOAA's National Centers for Environmental Information (NCEI, formerly NCDC) has done research on local climate data (cloud cover specifically) to determine the "viewability" of many locations within the eclipse area. Shown below is a map of eclipse viewability in the region of interest for Memphians. Each dot is shaded according to how likely that location is to produce good viewing conditions based on historical record (of course anything could happen on August 21, 2017!).

Here in Memphis, the climatological record says there is a 51% chance that the eclipse is viewable, with cloud cover being scattered or less 61.6% of the time historically. In Nashville, the "viewable ratio" is just 44%. The closest locations with the best potential for good viewing conditions within the path of totality are Paducah and Cape Girardeau, MO (both 77% "viewable").

The area of total eclipse is shown in dark red and at least 90% obscuration is in orange. The surrounding lighter orange color will have more than 75% obscuration. The shaded dots represent the historical "viewability" for indicated areas with a whiter dotter indicating a better chance of less cloud cover, or greater "viewability." For an interactive version of this map, click here.  (NOAA/NCEI)


Viewing tips

Looking directly at the sun is unsafe except during the totality phase of an eclipse, when the moon entirely blocks the sun’s bright face, which will happen only within the narrow path of totality as described above. That will NOT occur in the Memphis area, as we'll experience only a partial eclipse (even though only 7% of the solar disk will be visible locally, it's enough to burn your retinas if you look directly at it).

The only safe way to directly view a partial eclipse sun is through special solar filters, such as “eclipse glasses” or hand-held solar viewers. Homemade filters or ordinary sunglasses, even very dark ones, are not safe for looking at the sun. Four manufacturers have certified that their eclipse glasses and handheld solar viewers meet the international standard for such products. One of those manufactures eclipse and 3-D glasses for worldwide use right here in the Memphis area - American Paper Optics of Bartlett!


All glasses or solar filters should be inspected before use. If scratched or damaged, discard them. To view the eclipse, stand still and cover your eyes with your eclipse glasses or solar viewer before looking up at the bright sun. After glancing at the sun, turn away and remove your filter — do not remove it while looking at the sun.


If you decide to travel to a location that experiences totality, you can safely remove your solar filter or glasses only when the moon completely covers the sun’s bright face and it suddenly gets quite dark. As soon as the bright sun begins to reappear, replace your solar viewer to glance at the remaining partial phases (see above tips).

An alternative method for safe viewing of the partially eclipsed sun is pinhole projection. You may remember doing this for previous partial eclipses in the past. Here are instructions to make a very simple projector out of cardboard.

Viewing an eclipse can be done with solar glasses or with a "pinhole camera," which is diagrammed above.

For more information on the eclipse, we recommend the following sites, which are full of great information:
Now we need to all cross our fingers for a sunny day on August 21!

Erik Proseus
MWN Meteorologist

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Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net 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

Wednesday, June 21, 2017

Remnants of Cindy to pass over the Mid-South Friday

We've been keeping a close eye on (potential, then actual) Tropical Storm Cindy in the Gulf of Mexico the past few days. For the first time in several years, the remnants of a former tropical system are set to pass directly over the Mid-South. First, here is the latest forecast track of Cindy (click any image on this page for a larger version):

Latest forecast track of Cindy from the National Hurricane Center.


Forecast Path

As you can see from the graphic above, as of early Wednesday evening, Cindy is expected to make landfall early Thursday morning near Beaumont, TX, or along the TX/LA border. It will be a moderate tropical storm with maximum sustained wind near 45-50 mph when it makes landfall. From there, it heads north up the TX/LA border then begins a right turn Thursday night, heading into southern AR, That right turn continues, moving what will likely be Tropical Depression Cindy, over the Mid-South, if not Memphis proper, on Friday around mid-day. There are some model discrepancies on the exact track of the center of the low and the timing, but it will be during the day Friday.

Effects on the Mid-South

The effects here in the Mid-South will primarily be those that were problems to our south today - some gusty wind, not-insignificant rainfall which could lead to some flash flooding, and as with any landfalling/remnant tropical system, a few strong storms that could produce brief tornadoes. We'll take them one at a time.

Wind

Wind has not been a major factor even while Cindy was a tropical storm today. Strongest wind of up to 40-50 mph was primarily right near the center and in convective bands well removed east and north of the storm. Cindy will weaken after landfall, but we'll see breezy conditions (10-20 mph, some higher gusts) through Thursday night. On Friday, as the low approaches and depending on its exact track, some areas could see sustained wind of 20-30 mph with a few gusts to 40+ mph, mainly in convective (thunderstorm) bands and near the path of the low. By Friday evening, any strong wind will subside back to the baseline of 10-20 mph. Widespread power outages are not anticipated, but with a slightly weakened grid due to remaining tree limbs on lines, etc. from recent storms, sporadic or scattered outages are possible, mainly Friday.

Heavy rain and flooding

The primary threat from Cindy is, and will continue to be, periods of heavy rain and the potential for flash flooding. Timing of any "bands" or "slugs" of moisture is very difficult more than several hours out, so trying to pinpoint exact times of when they will occur is borderline futile. Suffice it to say, rain chances will be high from late tonight until the system passes late Friday, however it is not expected to rain hard the entire 2-day period.

For now, it appears showers will begin to overspread the area tonight with the first main band moving through early Thursday morning. After this round, there could be a lull during the mid-day hours tomorrow, although given the unstable and very moist atmosphere that is in place, scattered showers and thunderstorms are probably a decent bet. Another round could affect the metro late tomorrow into the early overnight Thursday night, though that may set up just to our north. (Again, this is not set in stone.) Then, indications are that we'll see one more period of rain, probably the heaviest, associated with the approach, passage, and departure of the low itself during the day Friday, quite possibly lasting into Friday evening. Again, this is HIGHLY subject to change. (If you have tickets to Live at the Garden Friday night or plan to attend a Levitt Shell concert, watch for information from those entities on their plans and stay tuned to the forecast. Even if it isn't raining during the concert times, conditions may be too wet leading up to the events to get them properly setup.)

Overall, rainfall totals could vary quite a bit from one place to another but are expected to generally fall in the 2-3" range between tonight and Saturday morning with some areas seeing up to 5". Flash flooding and urban ponding/flooding are possible. Flash Flood Watches are not currently in effect but I put odds at better than even that they will be before Friday. Our area is under a Moderate Risk of flash flooding for the Thursday night/Friday period, as shown below.

Rainfall projections from the NWS through Saturday morning show a band of 2-3" of rain expected across the metro. A few locations could see more, and possibly less, as these numbers are approximates. Memphis is just northeast of the 2-3" annotation in the center of the image. (NWS/WPC)

The Weather Prediction Center forecasts a Moderate Risk (10-15% chance) of flash flooding on Friday for the metro. (NOAA/WPC)

Brief tornadoes

Thunderstorms associated with remnant tropical systems build in highly-sheared environments where wind at various levels of the atmosphere is blowing briskly, and in varying directions. This can lead to the threat of spin-up tornadoes in some of these storms, even those that may not contain lightning or be severe by any other definition. (Storms from tropical systems tend to have much less lightning than a "normal" summertime thunderstorm and are also not as tall, but they can still pack a punch.) The greatest threat for any tornadoes will be to the right of the track of the storm. On Thursday, that threat will mainly be to the south of the metro in LA, southeast AR, and western MS where there is a Slight Risk of severe storms. The Memphis area is in a Marginal Risk on Thursday, meaning a few storms could contain brief damaging wind gusts or a spin-up tornado. (Hail is generally not a threat with tropical systems as their "core" is warm, not cold like classic low pressure systems.)

The Storm Prediction Center severe weather outlook for Thursday, showing the Slight Risk (where a tornado is most likely) south of the metro. (NOAA/SPC)
On Friday as the low passes near the metro moving northeast, the most favorable position for brief tornadoes will be in the southeast quadrant of the storm. If the low passes to our north, Memphis could be in that quadrant. If it passes just to the south or overhead, the favored area will be to our south. Currently, the Storm Prediction Center, based on the Hurricane Center track, places the Slight Risk south of Memphis with the metro in a Marginal Risk once again. That could change and will bear monitoring. Overall, the probability of tornadoes also will go down a bit from Thursday to Friday as the system weakens in general. As a last comment, the tornadoes associated with weak remnant systems in general are not the monsters we see in the Plains or Dixie Alley associated with supercells. They are more akin to the brief spin-up's that are possible with a squall line moving through, but we still need to prepare for the possibility that they could occur, and probably with little notice.

The Storm Prediction Center severe weather outlook for Thursday, showing the Slight Risk (where a tornado is most likely) southeast of the metro. (NOAA/SPC)

After the storm

By Friday night, it appears the worst will be over with perhaps a lingering shower that lasts until Saturday morning. Most of Saturday looks like it could be dry (though precipitation may hold back a little longer than current thinking) and Sunday introduces another conundrum, as computer models have fought like pre-teen siblings over whether an upper level system brings additional rain chances. Right now those chances appear fairly low. Stay tuned.



In the meantime, be sure to follow us on social media for the absolute latest on this dynamic weather situation; download the MWN app for radar, currents, the MWN Forecast, and our social feeds as well as StormWatch+ optional severe weather alerts; and check out the MWN Tropical page (optimized for desktop browsing) with more information on the current status and future of Cindy! All social and app links are listed below.

Erik Proseus
MWN Meteorologist

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