Thursday, November 30, 2017

5 Musings as November comes to an end

The month of November is wrapping up and we now head into the season in which people start asking (more) about important things (like snow). It's also the end of a couple of other seasons though. Here's more on that, as well as a look ahead to this weekend's beautiful weather, a major weather pattern shift on the horizon, and why a satellite that produces amazing imagery went dark today.

1. November 30 marks the end of what we in the business refer to as "meteorological fall." We all know that REAL (astronomical) winter doesn't start for a few weeks yet. But weather folks have to be different. So for us, winter starts tomorrow. That's mainly because when computing climate statistics and so forth it's much easier to break the seasons by in 3-month groupings at the start/end of a month. September-November was fall, and it ended warm. Check out these numbers: 63, 68, 66, 67, 68, 67, 68. Those are the high temperatures for the past week. Who says we don't get fall? For the meteorological season, our unofficial average temperature was 65.1°, or roughly 1 degree above the long-term average. Precipitation totaled 7.46", which is a bit over 5" below average, with only 1.81" of that falling in November. That results in conditions like this:
The U.S. Drought Monitor, zoomed into the Lower Mississippi Valley, shows "abnormally dry" conditions creeping into the metro from the south.
2. November 30 also marks the official end of the Atlantic hurricane season (and all the people say "Amen!"). There's no way else to slice it, it's been a brutal year. From Harvey in Texas, to Irma in Florida and the southeast, to Maria in Puerto Rico, this will be one for the record books. I don't necessarily believe in "we were due," but it had been 12 years since the last U.S. landfall of a major hurricane (if you don't count "non-tropical" Sandy). Here's a summation of the numbers:
17 named storms, ten hurricanes, six majors, and two category 5's. And a bunch of other records broken. Good riddance! (If you want to hear what The Weather Channel's Jim Cantore had to say about the season, check out the Carolina Weather Group episode that aired just last night, with yours truly on the panel!)

Preliminary storm tracks for the 2017 Atlantic hurricane season. Click for larger view. (NHC)
3. So when will this warm weather end? Not for several more days! With a fairly tranquil weather pattern nationwide for the next few days, no major fronts are expected through the weekend. We'll see mild weather with highs in the 60s continuing into early next week as high pressure aloft dominates.
The GFS model for the jetstream level of the atmosphere, valid Monday morning, shows a ridge of high pressure over our region (the large "hill" in the eastern U.S.). However, the first signs of a significant pattern shift can be seen in the western U.S. where a large trough (the "dip" in the jet stream) can be found. (PivotalWx)
Precipitation forecast through Sunday evening. The beginning of the next system to affect our area shows up in the Northwest U.S. (NOAA)
As for weekend activities, the forecast is grand! Here's a planner for Saturday, which features the St. Jude Memphis Marathon, a Tiger football watch party at the Liberty Bowl, and Christmas parades among other things. You can find the official MWN Forecast here or in our app.

4. What brings the warm weather to an end and how cold does it get? If you looks above again at the jetstream forecast for Monday morning, you'll see a huge dip over the western U.S. As that shifts east, it "dips" even further south, allowing cold air from Canada to spill south into the eastern U.S. Early signs are that this pattern - dominated by an eastern U.S. trough and western U.S. ridge - could last right into the middle of December. There will be ebbs and flows of course, but much colder air will be found in the eastern U.S., including the Mid-South, in this pattern.

As the pattern shifts, watch for the potential for some heavy rain and thunderstorms near a front that moves through sometime between next Monday night and Tuesday night. A relief from the dry weather, but also the end of fall most likely. Below is what this morning's GFS (American) model ensemble said about temperatures for the next 2 weeks. Note that these are not exactly right, but give you a good idea of the trend.

The GFS model is run multiple times with slightly different parameters to create an "ensemble" of potential solutions. Above is the average high and low temperatures for the next 2 weeks from this ensemble. (WxBell) 

5. Finally, November 30 also brought to an end (if everything goes well) the "preliminary, non-operational" phase of GOES-16, our new awesome-sauce meteorological satellite that was launched just about one year ago. It's been in testing phase for much of this year and has provided dramatic and beautiful imagery from 22,500 miles up. For the next 3 weeks, its propulsion systems are pushing it a bit further east from its test location, where it will become fully operational in mid-December as GOES-East. This day will be nearly as monumental in the meteorological community as the day it was launched and the day it sent back its first images. For more on GOES-16 (formerly GOES-R) see this blog post.

By this time next year, its sister satellite (GOES-S/17) will likely be operational over the west coast as GOES-West. A new chapter in satellite meteorology is being written! Below was the parting image, in natural color, from GOES-16 this morning at 7:32am CST.

Erik Proseus
MWN Meteorologist

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Tuesday, November 21, 2017

Time for Turkey! Thanksgiving treat in store for the Mid-South

As people all across the country prepare for the Thanksgiving holiday, millions will be hitting the road and traveling to friends and family to celebrate. But will Mother Nature cooperate with your plans for the extended holiday weekend?

The Mild Mid-South

If you're heading out on the road starting on Wednesday, be prepared to fight the traffic, but not the weather. A fairly dry cold front is helping to knock down temperatures the day before your Thanksgiving holiday, with highs only cracking the low 50s in most spots, or about 10 degrees cooler than Tuesday. Sunny skies, however, will return as well. Those clear skies will continue Wednesday night, helping drop our temperatures near to below freezing, at around 30 degrees in the city and into the 20s outside the loop.

Much of the same conditions can be expected for your Thanksgiving holiday and continuing into Black Friday. The Memphis area can expect mostly sunny to clear skies with highs rising into the mid 50s for Thursday, and in the low 60s once again on Friday. Lows overnight will be chilly, with most in the mid 30s.

Highs for Thanksgiving across the metro will be in the mid 50s. (NWS)
The weekend following the Thanksgiving holiday will carry plenty of sunshine too, as high pressure builds into the Tennessee and Ohio Valleys, keeping fair weather in the long-term picture for now. Temperatures will moderate in the upper 50s to low 60s for highs on Saturday and Sunday, with lows mostly in the low to mid 40s. Looks like awesome weather Saturday for the Memphis Tigers (finally!) as they close out their regular season with Senior Day at the Liberty Bowl!

Travel Trouble? Where?

For those who may be traveling some greater distances for the extended holiday, be prepared for some travel headaches in spots. As the cold front that will help drop our temperatures in the Mid-South slides east, a few showers and storms will be possible Wednesday into Thursday, especially over Florida and coastal Georgia. Some rain also cannot be ruled out across New England.

The surface map for Thanksgiving morning shows that it could be a wet start to your Turkey Day over the Northeast, with more showers and storms possible during the day in Florida. The Pac Northwest will also be wet. (NWS)
The next system that will work its way across the nation will be entering the picture by Thanksgiving day in the Pacific Northwest. If your travels take you to Washington and Oregon, be prepared for what could be a wet holiday in the making.

As always, be sure to stay tuned to the weather by downloading the MWN app on your phone or mobile device. We'll be continually monitoring the weather throughout the holiday weekend with updated forecasts by our team of forecasters, as well as updates through social media on Facebook and Twitter.

From all of us at #TeamMWN, we wish you a safe and enjoyable Thanksgiving, full of family, friends, and food. We are certainly grateful for your continued support all year long!

Alex Herbst, Meteorologist
MWN Social Media Intern

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Friday, November 17, 2017

A cold front that means business and an early look at Turkey Day

The weekend before Thanksgiving brings lots of activities across the area, not the least of which is a Memphis Tiger football game with conference championship implications at 11am Saturday, as well as the downtown Memphis Christmas tree lighting event and a Christmas event in Arlington later in the day. So what's this big cold front we've been heading about? Let's get into the details.

Friday Night

You have to know that gusty south wind and temperatures in the lower 70s in mid-November, like we have today, are typically followed by a dose of reality just around the corner. That is certainly the case this time, as a cold front is getting ready to barrel across the region on Saturday. Today is "prep day" with that south wind pushing higher dewpoints (aka, more moisture) into the Mid-South. The wind will pick up even further tonight as the front makes progress in our direction with southerly gusts that will exceed 30 mph and could approach 40 mph! That will keep temperatures mild overnight (in the 60s), though precipitation chances are very low.

Surface low pressure will be located in southern Kansas and heading towards the Ohio Valley tonight into Saturday. Overnight into Saturday morning, the low combines with high pressure to our east to bring gusty southerly wind to the area. (PivotalWx)


As low pressure in the Plains moves east-northeast across the Midwest/Ohio Valley on Saturday, a cold front will sweep across the Mid-South. Current ETA for Memphis is 1-2pm, but that could vary an hour either way.  Ahead of the front, the strong southerly wind will continue with temperatures rising to 70° by noon. If you're tailgating, it'll be short sleeve weather with tie-downs for your tents a MUST. In addition, a few scattered showers are possible in the morning but they should be brief as the cloud-level wind will be pushing them at nearly highway speeds (for those that don't speed...).

After lunchtime, and probably during the second half of the Tigers game, when Riley & Co. will be in the midst of raining touchdowns on SMU (Go Tigers!), the front will arrive at the speed of Tony Pollard's kickoff returns. You'll know when it hits, because it'll be marked by a sudden wind shift to the northwest, a brief period of potentially heavy rain, and possibly a rumble of thunder. The line of rain along the front looks to be narrow and fast-moving, so it may only last 10-15 minutes. Don the ponchos over the short-sleeve shirts, then be prepared to quickly add a sweatshirt layer once the rain ends! Once the quick-hitting rain ends, the wind turns cold and just as gusty (25-35 mph) and temperatures head down, tumbling quickly into the 50s.

The high-resolution NAM model from Friday morning shows scattered light showers Saturday morning (the beginning of the loop above) then a narrow line of heavy rain along the cold front by early afternoon. The latter half of the loop is Saturday afternoon into early evening and shows dry weather behind the front. (Tropical Tidbits)

The good news is that the rain threat ends once the front passes, mid to late afternoon and evening activities will be dry. Temperatures continue to fall into the upper 40s by tree lightning time downtown (5:30pm) and the blustery wind starts to let up, though will remain at 10-20 mph into the evening hours. If you have evening plans, think warm coats, not the shorts you had on in the morning!

As for a severe weather threat, the Storm Prediction Center currently has the metro on the edge of a "Marginal" (category 1 of 5) threat. There is meager instability ahead of the front and plenty of wind energy, so a brief wind gust to 60 mph is possible, though not likely, in the line that moves through along the front.

A Marginal Risk of a few severe wind gusts are predicted by the NWS for portions of the area in dark green. The thunderstorm threat, as well as severe threat, is very low (category 1 on the 5-point scale). (SPC)

The Tigers seemingly have been snake-bitten by weather events this year, but this event at least looks to be brief (outside of the sustained wind), so grab the poncho and #PackTheBowl for what promises to be a great football game! #StripeUp

The graph above shows temperature forecasts from several high-resolution models from tonight through Sunday. The black line is the model average. Note the very warm temps overnight, the large drop Sunday afternoon, and much cooler weather on Sunday, despite sunny skies. (NOAA)

Sunday and beyond

High pressure quickly builds in, making for a return to November-esque weather with highs generally in the 50s for Thanksgiving week and lows that could threaten freezing outside the city on Monday morning. A reinforcing shot of cool air arrives Tuesday night with freezing temperatures again possible Thanksgiving morning. Highs on Turkey Day will be cool - in the lower 50s most likely. Weather looks dry next week though, as any flies in the ointment that might bring precipitation stay well to our south in the Gulf.

Stay up to date with the latest conditions and forecast, as well as monitoring our Twitter and radar feeds, via the MWN mobile app. We appreciate your support of MWN in this small way, which pays big dividends for you!

Erik Proseus
MWN Meteorologist

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Thursday, November 9, 2017

Thoughts on the appearance of the sun and La Nina

Seven thoughts on a bright sunny day in Memphis...

1. It's been a while hasn't it? The sun came out in Memphis this morning, proof that it does still exist despite some folks expressing doubt over the past week!

Today is the first day since we went trick-or-treating that we've had an extended period of sunshine. Looking back through the hourly records from Memphis International Airport (link for weather geeks), there have been a few times after dark that skies have been clear since Halloween, but those don't count (no sunshine). During daylight hours, we've been partly cloudy for an hour or two here and there a couple times as well, but the overall character of each day since the calendar turned has been cloudy to mostly cloudy.

2. In fact, I had a feeling people wouldn't be ready for this rare event, so last night I issued a Bright Orb Warning. I hope it helped you adequately prepare!

3. It also occurred to me that tonight will be the first night we'll be able to fully experience a "Standard Time" sunset! It's gotten dark early this week, but at least today we'll have some daylight until the late, late hour of 5pm...

4. How long does the sun stick around? The MWN Forecast shows more sun than clouds through Saturday morning before some dense cirrus cloud cover arrives. We'll see a weak system move through Sunday that brings a chance of rain, but the sun should return Monday for a couple days. Another cold front arrives next Wednesday with slightly higher rain chances. Overall, we should be able to get used to seeing sunshine more days than not over the coming week.

5. How about temperatures? We'll call them "seasonal," which is pretty decent. Normal highs are in the mid 60s this time of year with lows in the mid 40s. After a reinforcing shot of cool air tomorrow, we should see numbers fairly close to that for the upcoming week. Friday will be chilly with highs only in the mid 50s and if you're up early Saturday morning, you'll need a coat if you head to the patio for coffee. Rural areas will be near freezing and everyone will be in the 30s. Layer up if you're running the Greenline Half or 5K at Shelby Farms!

6. Meanwhile, to our west, the National Weather Service (NWS) has officially declared that La Nina has begun (again) in the Pacific. We had a weak La Nina last winter, which then turned "neutral" earlier this year. The NWS calls this return to La Nina a "double dip." It will have effects on the winter ahead.

Red areas are places where the forecast odds favor a much warmer than usual winter, while blue colors favor cooler than usual winter. The darker the color, the higher the probability of that outcome (not a larger departure from average). NOAA map, based on data from NOAA CPC.

Brown areas are places where the forecast odds favor a much drier than usual winter, while blue-green colors favor wetter than usual winter. The darker the color, the higher the probability of that outcome (not a larger departure from average). NOAA map, based on data from NOAA CPC

7. Though I don't have an official "winter forecast" published, locally I expect we'll see a warmer than average winter season, but it could actually start cooler than average (late November into December). Mid to late-winter will likely be above average overall. While areas to our south (closer to the Gulf coast) will be drier than usual, I expect we will see a storm track that could favor some storminess as we sit in a "battleground" between warmer air in the south and pushes of cold air to our north. This setup could favor a winter weather scenario or two. I'm leaning more towards ice than snow, but that can't be predicted in this area more than a few days out, so why listen to me in November??

Enjoy the sunshine!

Erik Proseus
MWN Meteorologist

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Saturday, November 4, 2017

October 2017 Climate Data for Memphis, TN

October Climate Recap

Temperatures ended up slightly above average for the month, though the first half of the month featured more above average days, while the second half of the month saw more below average temperatures. In the early half of October, there were several days in the upper 80s and one day reached 92 degrees, which set a record for the date (9th). The tide turned at mid-month with more 60s and 70s, and even a couple of days with highs in the 50s and lows in the 30s. According to the National Weather Service, the low of 31 degrees on the 29th was the first sub-freezing low temperature in the month of October in 24 years!

Except for two days of the month, October was also dry. However that was offset by a 2.50" rain event on the 10th and another one inch-plus soaker on the 27th. Those two days totals over 90% of the monthly precipitation. The rain on the 10th was also not evenly distributed, as MWN's Bartlett weather station only recorded 0.41", thus ending the month well below normal. There was no severe weather for the month and no warnings issued.

Memphis International Airport, Memphis, TN

Average temperature: 65.2 degrees (1.1 degrees above average)
Average high temperature: 75.8 degrees (1.4 degrees above average)
Average low temperature: 54.6 degrees (0.8 degrees above average)
Warmest temperature: 92 degrees (9th)
Coolest temperature: 31 degrees (29th)
Heating Degrees Days: 128 (8 above average)
Cooling Degree Days: 143 (51 above average)
Records set or tied: Record warm minimum temperature tied on the 8th (72 degrees). Record high temperature set on the 9th (92 degrees).
Comments: Year to date, the average temperature of 68.0° is tied for the fourth warmest on record.

Monthly total: 4.04" (0.06" above average)
Days with measurable precipitation: 7
Wettest 24-hour period: 2.50" (10th)
Snowfall: None
Records set or tied: 2.50" of rain on the 10th was the second wettest October 10th on record.
Comments:  Only two days recorded precipitation of more than one-half inch, however those dates accounted for 91% of the rain total for the month. Year to date, precipitation has totaled 42.31" or 99.7% of normal (average year-to-date: 42.45").

Peak wind: Northwest/32 mph (24th)
Average wind: 7.9 mph
Average relative humidity: 64%
Average sky cover: 40%

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

Cirrus Weather Solutions /, Bartlett, TN

Average temperature: 62.9 degrees
Average high temperature: 76.5 degrees
Average low temperature: 50.5 degrees
Warmest temperature: 91.9 degrees (9th)
Coolest temperature: 27.2 degrees (29th)
Comments: None

Monthly total: 1.74" (automated rain gauge), 1.69" (manual CoCoRaHS rain gauge)
Days with measurable precipitation: 8
Wettest date: 0.74" (27th) (via automated gauge)
Snowfall: None
Comments: None

Peak wind: Northwest/22 mph (15th)
Average relative humidity: 76%
Average barometric pressure: 30.07 in. Hg
Comments: None

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

MWN Forecast Accuracy

MWN average temperature error: 1.89 degrees
MWN forecast temperatures within 2 degrees of actual: 70%
MWN average dewpoint error: 1.79 degrees
MWN forecast dewpoints within 2 degrees of actual: 73%

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

Wednesday, November 1, 2017

It's November? Where did fall go?

We've had a nice little run of fall weather lately with a mix of cool and warm temperatures that seem to average out to about what most people expect this time of year. Yeah well... you can forget about all that for the next several days!

High pressure aloft will strengthen over the Gulf of Mexico and far southern U.S. into Mexico, forcing the jet stream well to our north. At the surface, high pressure will build into the southeastern U.S. from the Atlantic, setting up a good fetch of warm air from the Gulf into the Mid-South. While a front will attempt to move into the Mid-South from the north on Friday, it will stall to our north, blocked by the edge of the high pressure area over our region. Combined, the result is well above normal temperatures for several days.

The Wednesday mid-day run of the American GFS model valid Thursday evening shows surface high pressure drawing warm air into the Mid-South from the Gulf as the cooler air remains well to our north. (PivotalWx)

The warm weather started to creep back today as a warm front lifted to our north, shifting the wind to the south, escorting in moister air (higher dewpoints in the lower 60s versus 30s and 40s of late), and thus warmer temperatures. Even despite cloud cover all day and a few light showers around, the mercury still rose to the upper 60s.

Dewpoints will remain in the 60s for the next few days according to the GFS model. That is a lot of moisture in the air for early November! (PivotalWx)

We'll have low chances of showers daily for the next few days with the best chances being Thursday night into Friday, though still only 40-50%, as minor waves in the upper levels move through and trigger possible showers. An isolated thunderstorm can't be ruled out Friday as well. By Saturday, the surface high establishes itself a bit more and rain chances dwindle to just a slight (20%) chance. That trend continues into early next week. 

A loop of forecast precipitation from the GFS model through Monday shows scattered chances several times between now and then. The primary rain chances will be Thursday night into Friday with a drying trend this weekend.

As for temperatures, if you really like cool, crisp fall air, look away! The highs, and especially the lows, will be far from that. Normally we average upper 60s for high temperatures this time of year and upper 40s for lows. You can add about 10° to those average highs as we will likely reach 80° at least once if not a couple times in the next 4-5 days (starting Thursday). Overnight lows will be very mild as well, owing to the warm moist air and cloud cover. Look for wake-up temperatures in the mid 60s each day into early next week.

GFS forecast temperatures over the next week show the warm air in place through the middle of next week. (Temperatures are for trend purposes only and are not exact.) (PivotalWx)

Looking ahead, the high should begin to break down, allowing a cold front to finally move through the Mid-South by Tuesday or Wednesday of next week. That would push us back toward the "normal" range for temperatures and bring our next best chance of widespread rainfall of the measurable variety. Hopefully then we can get back to more "fall-like" weather!

Check for the latest updates to the MWN Forecast anytime using your MWN mobile app and follow us on social media for the latest info! Pertinent links can be found below.

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