Fall cold blast on our doorstep!

Those who are seriously ready for some "real fall" weather - with fire pits and crisp mornings - will like what we have in store. Those hoping for a few more warm days, enjoy today and stop reading. :-) The autumn weather roller coaster rolls on, but the valleys and peaks get a little lower after today! Enjoy the upper half of the 70s this afternoon as I don't see anything close to that for at least the next week.

Friday

Tomorrow starts mild as you wake up to temperatures near 60 degrees, a mild south breeze, and increasing clouds. But by mid-morning, a potent cold front sweeps through the region. A few showers are expected along the front, but most precipitation will occur behind the front. In addition to rain during the day tomorrow,  the wind shifts to the north and shoves MUCH cooler air over the Mid-South. Our high temperature (near 60°) occurs before the front arrives in the morning, then temperatures fall during the day, initially to around 50° by lunchtime and then into the upper half of the 40s during the afternoon. Yes, it'll be a good 15 degrees colder when the kids leave school in the afternoon than when they go in the morning! Plan accordingly. A brisk wind will make it feel colder. Welcome to fall.

Temperature predictions from the American GFS model (blue) and its ensemble members (variations on the same model - gray lines with the average in black) for the next 4 days. Note the precipitous drop during the day Friday and cold temperatures upcoming this weekend. (NOAA)

Friday Night

Lots of questions/concerns out there about Friday evening as many of us have fall/Halloween activities that are affected by what's going on outdoors, including football at multiple levels. At this point, it looks like scattered cold showers will hang on into the early evening, but probably not as steady as the afternoon hours. After 8pm or so, the showers should taper off, as temperatures continue to slowly fall towards 40°. Overall, just a raw, damp evening unfortunately! Total rainfall from this system looks to be in the neighborhood of 1/2".

Forecast accumulated rainfall through Saturday morning from the NWS. (WxBell)

Saturday

The front and its rain will be gone by Saturday morning and it appears the sun will return. A few afternoon clouds are expected, wrapping around low pressure to our north, but it will be dry. It'll also be our coolest day since mid-March as high temperatures only reach the mid 50s, despite sunshine. You can thank (sarcastically, if you want) a large trough over the Mississippi Valley that pushed the Friday front through.

Forecast upper-level (500 mb, or 18,000') wind and pressure pattern on Saturday from the GFS model. The "full-latitude" trough along the Mississippi River Valley will be responsible for our cold weather. (PivotalWx)

Sunday

Another chilly day is on tap. In fact, Sunday morning will be the coldest sunrise of the forecast period. Mid 30s temperatures and frost will be widespread, even within the Bluff City limits. Outlying areas could see a freeze. Plan ahead to protect any outdoor vegetation that you don't want cold damage done to. Highs again remain in the 50s. Maybe this airmass will finally start changing the color of the leaves!

Next week

An upwards trend in temperatures starts the week before another front, this one not quite as potent, arrives Tuesday. It will have a minor effect on our near-surface thermal layer, but we should still be able to get high temperatures above 60° for most of next week. It appears some post-frontal rain could affect the area on Wednesday so that day could be a little cooler. For trick-or-treating on Tuesday night, the early forecast calls for a slight chance of tricks and temperatures in the 50s. Not far from an "average" Halloween. We'll hope that the small rain chances stay just that - small - otherwise...

Be sure you have the MWN app for daily forecast updates (things can change fairly quickly around here this time of year!), current StormView Radar imagery, and more great MWN content, including our frequently-updated social media feeds. All the links you need are below!

Erik Proseus
MWN Meteorologist

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The fall weather roller coaster is leaving the station!

A gorgeous fall week is in the books and I know many of you are grateful for that! After a few "false starts" and a late end to the warm season, the pleasant days and cool mornings this week have been welcomed.

Friday Night

Now we're all ready for a beautiful fall weekend right? Well, perhaps Mother Nature can partially deliver... The weekend starts with Friday night though and it promises to be a nice one. Skies will be mainly overcast, but it will be dry with temperatures in the 70s and comfortable humidity levels for Friday Night Lights, the last free concert of the fall season at Levitt Shell (here's a plug for their awesome end-of-season benefit concerts in 2 weeks), and whatever else you might have planned.

Saturday

As we head into Saturday, I expect most of the day to be pretty decent, though clouds stick around and the south wind increases a bit ahead of our next weather-maker. Despite the chance of a few sprinkles or a brief light shower, it will be mainly dry with highs topping out near 80. Morning lows won't be as cool as this week - near 60 most likely, owing to increasing dewpoints on that south wind. Saturday evening should also be dry for most with a persistent south breeze at about 10 mph.

The surface map for Saturday evening shows a cold front across the Plains, with most active weather (some severe storms) well to our west. There will be a low chance of a couple showers in the Mid-South tomorrow evening. (NWS)

Sunday

Things change early Sunday as a cold front nears and a fairly deep upper level trough , which is currently along the west coast, slides into the Plains. Precipitation chances increase precipitously (which they are wont to do) Sunday morning with a few non-severe thunderstorms thrown in for good measure. It will be mild as you head to church or brunch with temperatures in the 60s as rain becomes occasionally heavy. Look for the trend to continue throughout the day Sunday with temps not rising much above the lower 70s and rain continuing, producing up to 1-2" totals on Sunday. Though models differ a bit on the details, and any potential lulls, if you have outdoor plans Sunday, you'd be best served by having an alternate arrangement made.

An upper level trough is shown over the Plains on Sunday morning just behind a cold front that will be advancing into the region. Rain will arrive early Sunday in the metro with a few thunderstorms also possible. (PivotalWx)

Predicted rainfall totals through Sunday evening from the NWS - between 1-2" is a likely amount for the metro. (WxBell)

Monday

The forecast Monday is a little murky and unclear, mostly because the trough overhead is apt to form a "cut-off low" over the lower Mississippi Valley. Basically, this means a piece of the trough "cuts off" from the rest of the upper level flow and forms its own low pressure. That looks to prolong rain chances, at least in scattered form, into the day Monday. Again, details are still TBD, but for now I"m going with scattered showers and cooler temperatures (60s) Monday, as well as a steady north wind behind Sunday's cold front.

By Monday morning, the upper level trough has lifted north and left behind a cut-off low pressure system (shown over the Mississippi Delta), which will keep showers in the forecast on Monday. (PivotalWx)

Predicted rainfall totals through Monday evening from the NWS. We'll probably end up with widespread 2" rainfall amounts from this system. (WxBell

Tuesday and beyond

By Tuesday, the low moves east, high pressure builds back in, and in fact, another large trough develops over the eastern U.S. driving much cooler air into the Mid-South for mid-week. While it will be sunny out, this will likely be the coolest air of this early fall season with highs (maybe struggling) into the 60s and a few outlying areas probably seeing frost on Wednesday morning.

A massive upper level trough will be in place over the eastern U.S. by mid-week (shown on Wednesday morning), bringing the coolest weather of the fall to areas under its influence. (PivotalWx)

Looking out a bit further, another large-scale system quickly transits into the region as the progressive upper level pattern continues and we're probably looking at another rain event a week from now. Hang on tight - the autumn roller coaster has left the station!

Erik Proseus
MWN Meteorologist

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NOAA / NWS Winter Outlook released

The National Oceanic and Atmospheric Administration has released their 2017-2018 Winter Outlook, which is predicated on the emergence of a weak La Nina event in the eastern Pacific. NOAA indicates that La Nina is likely to be "weak and short-lived," but will still have an effect on the weather patterns over the United States. La Nina typically results in cool and wet conditions across the northern tier of the country and warm and dry conditions for the southern U.S. as compared to an average winter. The outlook graphics reflect that general thinking.

Temperature

The temperature outlook calls for a broad area across the southern United States with a high chance of above average temperatures. Specifically, the most likely areas for above average warmth are from the Four Corners region across Texas to the central Gulf Coast. North of those areas though, there is a good chance of seeing above normal temperatures across the rest of the southern U.S. and potentially the eastern U.S. Memphis and the Mid-South is also expected to average above normal this winter in the temperature department.

Precipitation

On the precipitation side, La Nina is well known for dry conditions across the southern tier of the U.S. and that is exactly what we see in the outlook graphic. The desert southwest, southern plains, Gulf Coast, and Mid-Atlantic are all forecast to end up drier than average. Areas that are likely to see above average precipitation include the norther Rockies, Ohio Valley, and central Great Lakes. The Mid-South is in an "equal chances" area, meaning there are no clear signals to indicate above or below precipitation.

Commentary

It should be noted that above average temperatures for a season do not necessarily mean a lack of winter precipitation in the Mid-South. The Memphis area averages about four inches of sleet and snow each year, though it tends to vary each winter around that average, from an inch of two to 5-6" or more during the snowiest winters. Of course, one or two storms can produce those amounts, so it really comes down to having the right mix of moisture and cold air simultaneously. In addition, ice storms can also occur when a rain event runs into a shallow layer of cold air, either behind a cold front, or when high pressure north of the region filters cold air south into the region.

It's been several years since the area has seen "good" snowfall. The past six years have yielded a total of 7.1". The two previous years, 2009-10 and 2010-11, recorded 6.8" and 9.7" respectively, with big storms dumping even higher totals that affected portions of the metro but missed the airport. Maybe this will be our year for another heavy snow! As an aside, it should be noted that La Nina can sometimes produce severe weather episodes in the late wintertime as well, so we'll need to keep an eye out for that potential as well.

Erik Proseus
MWN Meteorologist

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Trending towards fall... after one more hot day

The past couple of day have provided some evidence that fall is indeed here, while the warmth this afternoon and Saturday remind us that "fall" is relative and includes peaks and valleys.

As opposed to last weekend when hot temperatures (90°+) were coupled with very muggy air, the hottest day (Saturday) before the next fall front arrives (Sunday) will feature dewpoints in the mid 60s instead of the low to mid 70s. So while it'll be quite warm for the Tigers tilt against a formidable-and-respected Navy opponent (forecast highs of 89° are within a degree of the record), a southerly breeze and only-somewhat-uncomfortable humidity levels should make for a bit more tolerable day. Just ignore the calendar and pretend it's early September! [As an aside, I suffered through the weather to revel in a win over UCLA and expect the level of suffering, at least from a weather perspective, to be a bit more muted. As for the outcome of the game... we can only hope that the heat of the day translates to a hot hand on the end of the right arm of one Riley Ferguson.]

The surface map for Saturday shows high pressure to our east ushering in warm air from the south, but a frontal system over the Plains is poised to dive south as a cold front by Sunday morning, bringing relief from the heat. (NWS)

Back to weather... As for what comes next - a return to the fall weather we expect in mid-October! A cold front moves through the Mid-South early Sunday. A warm start turns to off-and-on showers, a gusty north wind, and temperatures that don't move a lot from the morning lows in the upper 60s. Humidity falls on that north wind as temps only peak in the mid 70s. Don't expect a lot of sun, but I also don't expect prolonged rain.

Rainfall amounts associated with Sunday's front taper off from north to south with very small rain amounts expected in the Memphis area. (WxBell)

Precipitation earlier this week helped the dry ground that had developed, but don't expect enough Sunday to continue the trend. No drought indications are currently showing up in west TN or east AR, but parts of north MS have moved into the "abnormally dry" category on the most recent Drought Monitor.

The Drought Monitor shows D0 (abnormally dry) conditions over parts of north MS.

Looking ahead to next week, the first few days post-front look stunning, and the rest of the week doesn't look half bad! Sunny skies pervade as cooler high pressure builds in. Highs for most of the week will be in the 70s (though we might not quite make it there on Monday). Evenings will be cool with low humidity allowing temperatures to drop quickly once the sun sets - which is now getting closer to 6:00 than 7. Mornings will be crisp (I've been waiting to use that word!) with lows near 50° in the city and into the 40s in rural areas. Now THAT is fall!

The American GFS model forecasts temperatures to drop to autumnal levels next week behind Sunday's front. (WxBell)

A slow warming trend takes place  by week's end, though clouds will also start to increase as the next system approaches about a week from now. The good news is that the warmest days behind this weekend's front will be closer to 80° than 90°. Yet another sign that we're nearing Halloween. Enjoy this time of year - before you know it, we'll be complaining about it being too cold!

Keep tabs on the temperature swings and precipitation chances with the MWN mobile app and our social media feeds! Links are provided below.

Erik Proseus
MWN Meteorologist

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Humid weather and storm chances - then what?

I don't think many of us were pleased to see the return of summer over the weekend. We can thank the atmosphere surrounding Hurricane Nate for that, as it dragged humid Gulf air into the southern (and in fact, eastern) U.S. That airmass featured dewpoints in the lower 70s and high temperatures in the upper 80s. Which is just miserable for early October if you ask me, especially when most of us (except some lucky folks in Tipton and Fayette Counties) only got enough rain to make a mess of our vehicles.

So what's on deck for the rest of the week? First, maybe some better rain chances. A high pressure airmass that promises some relief will draw closer to start the week, but first an upper level disturbance will trigger scattered showers and thunderstorms in the daytime heat today (and it will be hot - 90° this afternoon with that humidity baked on top). Chances of showers and a few thunderstorms continue overnight.

The morning run of the high-resolution NAM model indicates scattered storms should ignite after 2-3pm in the daytime heat, triggered by an upper-level disturbance. Loop runs from 1pm-10pm. (WxBell via NOAA - click here if it doesn't loop)

By Tuesday, the leading edge of the high pressure system will push a cold front through during the evening hours. Another chance of showers and thunderstorms accompanies the front Tuesday afternoon/evening in continued heat and humidity, as highs again reach near 90°. While severe thunderstorms are not expected today, there is a small chance of a few strong wind gusts on Tuesday. The Storm Prediction Center currently believes the highest risk (which is still fairly low, at "Marginal") is just north of the city. It's worth watching. Overall storm coverage will probably be in the 30-40% range.

The Storm Prediction Center outlook for Tuesday indicates a Marginal (category 1 of 5) Risk of a few severe storms, mainly capable of producing gusty wind, north of Memphis. This outlook could change, stay tuned.

Between today and tomorrow, I'm hoping most of us get some rain, because after that... there's no rain in sight. The cold front will do a good job of pushing the humid air out of the region as dewpoints fall from near 70° tomorrow afternoon to the mid 50s on Wednesday and look to remain there for the rest of the week. It will also be cooler on Wednesday as highs return to "normal" levels in the mid 70s. However, a return of warm temperatures occurs heading towards the weekend as sunny skies and increasingly anomalous pressure levels aloft result in afternoon highs back in the mid 80s after about two days reprieve.

The upper level (500 mb or 18,000') pressure pattern on Friday evening looks more like mid-summer than autumn as anomalously high pressure dominates the eastern 2/3 of the nation. The 594 "circle" over MS is where the high is centered, at a strength that in mid-summer would be capable of producing temperatures in the mid 90s to near 100. Fortunately, it's October... but still will be much warmer than average. (Pivotal Weather)

Looking out a bit further, another cooler airmass looks to arrive in about a week, preceded by a slight chance of rain on Sunday, which should again keep humidity at autumnal levels. However, the signals from the upper atmosphere indicate above normal pressure levels could put a damper on what otherwise would be cool fall weather. We'll have to see how that one plays out, but the last two times I've seen major cool-downs on the horizon (including the one that arrives tomorrow night), they've turned out to be short-lived... The Climate Prediction Center agrees, indicating that week 2 temperatures have a high probability of averaging above normal.

NOAA's Climate Prediction Center outlook for next week indicates a high probability of above normal temperatures. (NOAA/CPC)

Stay tuned to us via social media and our mobile app for the latest forecast information and radar updates. Links are below.

Erik Proseus
MWN Meteorologist

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September 2017 Climate Data for Memphis, TN

September Climate Recap

After a (relatively speaking) cool August, September continued the trend, as the first two weeks (actually 13 days) were the second coolest on record for that time of year. Every day from the 1st through the 14th registered at or below normal in the temperature department. However, it warmed up quickly during the second half of the month. The period September 15-30 saw no days with below normal temperatures and that period ended up 4th warmest on record. It definitely was a Jekyll and Hyde month!

The consistent part of the weather though was dryness. Less than 2" of rain fell during the month, as the remnants of former Hurricane Harvey moved out on August 31 and despite the remnants of former Hurricane Irma moving over on the 12th, resulting in a record cool day (high of 66°). Nearly 80% of the rain for the month (just over 1.25" at Memphis International Airport) fell on that day, otherwise it was a very dry month. There was no severe weather associated with Irma as there was Harvey in late August, and in fact, no severe weather for the month and no warnings issued.

Memphis International Airport, Memphis, TN

Temperature
Average temperature: 75.4 degrees (0.2 degrees above average)
Average high temperature: 84.8 degrees (0.3 degrees below average)
Average low temperature: 65.9 degrees (0.7 degrees above average)
Warmest temperature: 93 degrees (22nd)
Coolest temperature: 55 degrees (7th)
Heating Degrees Days: 3 (8 below average)
Cooling Degree Days: 321 (5 above average)
Records set or tied: Record cool maximum temperature set on the 12th (66 degrees)
Comments: Ten days recorded temperatures at or above 90 degrees. Year to date, the average temperature of 68.3° is tied for the fourth warmest on record.

Precipitation
Monthly total: 1.61" (1.48" below average)
Days with measurable precipitation: 6
Wettest 24-hour period: 1.27" (12th)
Snowfall: None
Records set or tied: None
Comments:  Only one day recorded precipitation of more than one-half inch. Year to date, precipitation has totaled 38.27" or 99.5% of normal (average year-to-date: 38.47").

Miscellaneous
Peak wind: North/28 mph (10th)
Average wind: 6.2 mph
Average relative humidity: 67%
Average sky cover: 30%

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

Cirrus Weather Solutions / MemphisWeather.net, Bartlett, TN

Temperature
Average temperature: 72.8 degrees
Average high temperature: 85.5 degrees
Average low temperature: 62.0 degrees
Warmest temperature: 93.5 degrees (21st)
Coolest temperature: 49.8 degrees (7th)
Comments: None

Precipitation
Monthly total: 1.45" (automated rain gauge), 1.58" (manual CoCoRaHS rain gauge)
Days with measurable precipitation: 5
Wettest date: 0.98" (12th) (via automated gauge)
Snowfall: None
Comments: None

Miscellaneous
Peak wind: Northwest/17 mph (1st)
Average relative humidity: 80%
Average barometric pressure: 30.01 in. Hg
Comments: None

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

MWN Forecast Accuracy

MWN average temperature error: 1.14 degrees
MWN forecast temperatures within 2 degrees of actual: 87%
MWN average dewpoint error: 1.70 degrees
MWN forecast dewpoints within 2 degrees of actual: 77%

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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Will Nate rain on Memphis? And we're still waiting on fall!

For the past 5 weeks or so, our highest rain chances have been with the remnants of tropical systems. First there was Harvey and then Irma. Now Nate is moving onto the radar. While just named as a tropical storm this morning and currently over Nicaragua, it is on a trajectory to take it into the southern Gulf of Mexico by early Saturday, then move quickly north towards an early Sunday landfall along the central Gulf Coast (NOLA? Gulf Shores? Both are possible...). Here's what I had to say earlier today:

Fall Break travelers

If you are planning a fall break trip to the Gulf Coast, particularly the MS, AL, or FL panhandle region, you'll want to keep a close eye on it. As mentioned above, the intensity forecast is problematic. The good news is that it will be fairly compact and moving along at a decent pace, so its impacts won't last long, though after-effects could be an issue (flooding, power outages, etc.). Follow us on Facebook or Twitter for the latest and check out our MWN Tropical page for the latest graphics and NHC bulletins.

Meanwhile, back home...

Locally, we are looking at one more day of warm (mid 80s) but dry weather with low humidity on Friday. By Saturday, southerly flow ahead of an approaching trough will drag moisture from the Gulf of Mexico back into the area and it will be humid again. In addition, the trough and additional moisture will trigger the possibility of scattered showers and a few thunderstorms just about anytime during the day. Temperatures remain warm (mid 80s again), so it'll feel pretty sticky. Keep that in mind if you're heading to the Mempho music festival or other outdoor events like Levitt Shell! Rain chances increase Saturday night and Sunday as Nate's moisture feeds in on the southerly flow. The additional clouds and rain will keep Sunday's temperatures down to near 80.

The European model shows Nate moving from the central Gulf of Mexico on Saturday morning into southeast LA, Mississippi, then the Tennessee Valley by Monday evening. Rainfall is expected across the Mid-South on this track, but wind effects will be minimal. Graphic courtesy WxBell.

Nate's remnants look like they will move east of the Memphis area on Sunday night with continued rain chances, but likely not much of a wind effect. Scattered showers and thunderstorms remain possible Monday with highs back into the mid 80s.

Where's fall??

Earlier this week, I had been fairly confident that we would get a fall front to move through early next week that would knock highs back down into the 70s and deliver some nice fall weather. Well... the large high pressure that would bring that fall weather MAY move by just to our north. While I still expect some relief from the mid 80s and humid weather, we may not get quite as cool as previously advertised and that cooler weather now will be delayed by at least another day or so - to Thursday of next week.

We'll continue to keep our eyes peeled for signs of REAL fall weather, but for now we may have to just be happy that when the humidity creeps up, at least it's not 90 degrees out! Stay tuned to our social feeds for the latest on Nate and its effects on the Gulf coast and our area, as well as the MWN Forecast. And let's hope that this storm is the last one with any impact on the U.S. in what has been a very busy tropical season!

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