Sunday, January 13, 2019

A weather smorgasbord this week, with an eye towards an Arctic air intrusion

We had a few nice days this past week with mild temperatures and some sunshine that allowed the ground to dry out a bit. Of course, that was followed quickly by more rain and, today, cold weather and dreary cloud cover. Looking ahead, we'll get a mix of clouds, some sun, cold weather, warming temperatures, and rain - all in the next 5 days. By next weekend, a significant pattern change is on the horizon.

Sunday night - Monday clouds

Despite high pressure building in, as we sometimes experience in winter with low sun angles and lots of low-level moisture, clouds will stick around tonight into Monday. We stayed near 40 today with a cold wind, but decreasing dewpoints on that north wind means temperatures will drop to near or just above freezing tonight. The clouds will keep the mercury from rising much Monday with highs very near what they were today, but just a bit less wind.

Sunday afternoon visible satellite imagery shows the Mid-South locked under widespread cloud cover. The clouds will persist through Monday at least. (College of DuPage)

The cloud party should break up Monday night as high pressure moves overhead with calm conditions and lows near 30.

Tuesday - Wednesday sun

For now, we believe abundant sunshine is ahead on Tuesday with highs back into the upper 40s. The NAM model, which is typically-more-aggressive with low clouds, thinks otherwise, but I feel optimistic.

Despite some high clouds moving over on Wednesday, south wind should finally being our temperatures back above normal. Morning lows in the upper 30s will rise to the mid 50s Wednesday afternoon and conditions remain dry.

Thursday rain - Friday dry

Thursday appears to be our next wet day as a weak system moves by in fast westerly flow at the jetstream level. It will be above normal temperature-wise though with lows in the 40s and highs in the upper 50s. Rain should not be heavy on Thursday. Thursday night into Friday looks dry and mild as we sit between systems, keeping a wary eye to the west. A few showers may arrive Friday evening, but not before highs climb above 60 degrees on south wind.

Weekend pattern shift

The "wary eye" mentioned above is because we'll be seeing an Arctic airmass drop into the Plains late this week that pushes into the Mid-South on Saturday. Timing of that cold air arrival is still TBD, but for now, we project a fairly wet day Saturday with a chance of thunderstorms due to the strength of the front moving in and a fair amount of wind. Temperatures will drop precipitously behind the front, potentially during the day Saturday, but very likely by Saturday night.

The Sunday morning GFS model forecast of surface features and precipitation from this Thursday night through next Sunday shows next Saturday's storm system moving through with rain and a potential for some light snow. At this point, various models disagree on the timing of cold air and moisture departure, and thus snow chances. The nature of the system though doesn't lend itself to more than light snow, if anything. (WeatherModels)

Will all the precipitation be gone before the cold air arrives? Model solutions vary on that as well. We'll be monitoring. Needless to say, behind that front, a bitterly cold airmass arrives, sending temperatures well below freezing by Sunday morning. Even with sunshine on Sunday, we may not reach the freezing mark for highs! That will be some 20-30 degrees colder than Saturday.

The European Model ensemble system predicts about a 25% chance that Memphis will get above freezing next Sunday, based on 50 runs of the European model this morning. (WeatherBell)

Winter arrives!

The long-range outlook indicates that next Sunday is the beginning of an overall pattern shift that brings in a run of below normal temperatures, perhaps continuing into early February. It's a pattern that will make precipitation forecasting somewhat tricky with each front/low pressure system that affects the area after that. Winter is NOT over snow-lovers! Do not give up hope just yet!

The NOAA temperature outlook for the end of January and first week of February indicates more cold air is likely on the way for the eastern half of the U.S. Stay tuned!

As always, look to the web or our MWN mobile app for the latest forecast information and to our social media platforms for the most up-to-date current trends. All links are below.

Erik Proseus
MWN Meteorologist

Follow MWN on Facebook and Twitter for routine updates and the latest info!
Complete MWN Forecast: 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

Friday, January 11, 2019

Memphis, TN Annual Climate Summary for 2018

2018 Annual Recap

Overall, despite some periods of very hot and extreme cold temperatures, and some excessively wet spells and a few dry months, 2018 ended with very close to average temperatures and precipitation that was well above average.

January started the year on a temperature roller coaster with warm spells in the 60s interrupted by extreme cold, including two separate periods that dropped as low as 10 degrees, one to start the year and another mid-month. The lowest temperature of the year occurred on the 17th (7 degrees) following a five-day period in which snow was recorded on four days and totaled 2.5". February was marked by excessive rainfall totaling 13.43" (the wettest February on record by over 2") and 19 rain days. Despite all the rain, temperatures were also well above average. March was fairly typical for springtime in the Mid-South with temperatures right at average despite some fairly pronounced swings. The month ended drier than average, and perhaps well below average considering that over two-thirds of the month's rain occurred on two days.

April was remarkably cool overall, ending as the 3rd coolest on record, but that was followed by the warmest May on record - quite the dichotomy! April was also quite wet, but the excess rainfall was completely swallowed up by a large deficit in May. June continued the hot/dry trend with multiple days reaching the mid 90s. It seemed summer started early in 2018!

July was fairly typical (a.k.a. HOT with multiple days in the mid 90s) with slightly above normal rainfall at Memphis International Airport, though it varied fairly widely due to the scattered nature of summertime thunderstorms. The dog days of summer continued in August with temperatures that averaged just slightly below normal and precipitation that was below the average for a normally dry month. Summer finally broke after the Labor Day, as the 90s departed and pleasant weather appeared. Overall, September was a bit warmer than usual with precipitation near average.

However, as October arrived, summer made one last return with multiple days near or just above 90 degrees for the first week of the month. Once again, the rest of the month was a reprieve as fall kicked in for good. November finally saw the Mid-South atmosphere turn cool with nine days that dropped to freezing or below and the earliest snow of more than 0.5" in over 25 years on the 14th. The month ended in the top 10% coolest on record. Finally, the year ended with temperatures that were above normal in December by a couple degrees and precipitation that would have been just below average if over 3" of rain didn't fall on the last two days of 2018. The two-day total ended up being just about what the departure from normal was for the month. For the year, the precipitation total was more than 10" above average and ranked #16 in the wettest years in recorded history.

Severe weather

Severe weather was fairly limited in 2018. Fortunately, the Mid-South recorded just 17 tornadoes, most weak. There was a single EF-2 tornado (in Clay County, AR and Dunklin County, MO on April 24) with the rest rated EF-0 or EF-1. Over half of the year's tornadoes occurred on that evening of February 24 (nine) and all but three occurred north of I-40. None occurred in the eight-county Memphis metropolitan area.

Tracks of all 17 tornadoes in the Mid-South in 2018.
The following represents a statistical recap of the weather for 2018 in Memphis. Another recap of  weather across the Mid-South for 2018, produced by the National Weather Service in Memphis, will be published soon.

Memphis International Airport, Memphis, TN

Average temperature: 63.2 degrees (0.1 degrees above average)
Average high temperature: 72.3 degrees (0.2 degrees below average)
Average low temperature: 54.2 degrees (0.6 degrees above average)
Warmest temperature: 97 degrees (July 5, 11, and 13)
Coolest temperature: 7 degrees (January 17)

Heating degree days: 3121 (156 above average)
Cooling degree days: 2568 (310 above average)
Days at or above 90 degrees: 89 (24.7 days above average)
Days at or below 32 degrees: 48 (5.2 days above average)
Last freeze/first freeze: April 8-November 10 (216 day growing season)

Records set or tied: April was the third coolest on record, while May was the warmest on record. The period May-July ranked third warmest on record. Eight daily warm weather records and two daily cold weather records were set in 2018. These included:

  • February 15 (65°, record high minimum)
  • February 18 (77°, record high)
  • February 20 (66°, record high minimum)
  • May 10 (90°, record high)
  • May 14 (93°, record high)
  • May 15 (93°, record high)
  • October 4 (92°, record high tied)
  • October 16 (50°, record low maximum)
  • November 14 (30°, record low maximum)
  • November 30 (64°, record high minimum)

Comments: After the previous two years ranked in the top 6 warmest on record in Memphis, 2018 was just a bit warmer than the 30-year climate average for temperature, and ranked in the top 25% warmest (tied for 34th) in the 145-year historical record at Memphis. 89 days saw high temperatures at or above 90 degrees (12th most on record). 48 days experienced freezing or sub-freezing temperatures.

The year started on a roller coaster with brutal cold around New Year's Day and another very cold spell at mid-month, both which saw lows drop to 10° or colder. However, between and just after these spells, temperatures reached the mid 60s. Moving into spring, April was the third coldest on record, but the switch flipped in May, which ended as the warmest May on record, and remained hot into early summer. The period May-July was 3rd warmest on record. (June was the 12th warmest on record.) September also ranked in the top 25 warmest on record, while November was very cool, ranking 13 coolest.

Temperatures for the year (lows/highs) are plotted in dark blue against the normals (brown), record highs (red) and record lows (light blue).  Where the dark blue extends above or below the brown indicates temperatures above or below normal, respectively.

Monthly total: 64.15" (10.47" above average)
Days with measurable precipitation: 137 (29.3 days above average)
Days with 1"+ precipitation: 19 (1.6 days above average)
Wettest day: 3.12" (February 28)

Total Snowfall: 3.1" (0.7" below average)
Days with a trace or more snowfall: 9
Greatest snow depth (6am CST): 2" (January 16)

Records set or tied: The month of February (13.43") was the wettest on record. Snowfall of 0.6" on November 14 was the most that early in the year since 1991. Daily record included:

  • February 28 (3.12")
  • April 14 (3.02" - tie)

Comments: Overall, 2018 ended well above average for precipitation, the 16th wettest year in the 147-year record, or just outside the top 10%. Nineteen days had an inch or more of liquid precipitation; six days had more than 2" (nine is the record).

The year was led by February, which ranked #1 for that month. April was also wet, ranking in the top 25. Summer was a see-saw precipitation-wise with June and August ranked in the top 50 driest and July and September in the top 35 wettest. Fall was generally near normal, while December was wet, particularly the end of the month, ending 16th wettest in the 147-year record. Snowfall totaled just over 3" with perhaps the most notable snow being the 0.6" that occurred on November 14, the most snow that early in the season in over 25 years. The other 2.5" occurred in a very cold five-day period in mid-January, with four of the five days recording snowfall.

Precipitation accumulation for 2018 is plotted as the dark green line, compared with a normal year in brown. Precipitation was near normal until a very wet spell in the latter half of February (two of the three wettest days of the year were in the last week of February). From then on, precipitation remained well above average. The surplus was reduced a bit in the summer months, but continued wet spells in fall and early winter resulted the year ending more than 10" above average.

Peak wind gust: West/61 mph (May 27)
Average wind: 8.1 mph
Average relative humidity: 68%

Click here for monthly/daily statistical recaps for Memphis International Airport.

Cirrus Weather Solutions /, Bartlett, TN

Average temperature: 61.9 degrees
Average high temperature: 72.7 degrees
Average low temperature: 51.8 degrees
Warmest temperature: 97.2 degrees (June 28)
Coolest temperature: 1.9 degrees (January 17)

Heating degree days: 3490
Cooling degree days: 2363

Annual total: 65.91" (automated rain gauge), 72.04" (manual CoCoRaHS rain gauge)
Wettest date: 2.49" (June 21) (CoCoRaHS)

Total Snowfall: 3.3"
Days with a trace or more snowfall: 3
Greatest snow depth: 3.0" (January 17)

Peak wind: South/33 mph (June 1)
Average relative humidity: 77%
Average barometric pressure: 30.07" Hg

Click here for monthly/daily statistical recaps for Bartlett, TN.

MWN Forecast Accuracy

Number of MWN forecasts produced and verified in 2018: 531
MWN average temperature error: 2.03 degrees
MWN forecast temperatures within 2 degrees of actual: 69.0%
MWN average dewpoint error: 2.23 degrees
MWN forecast dewpoints within 2 degrees of actual: 65.0%

MWN's forecasts extend out five periods (2.5 days, or roughly 60 hours) and the numbers above represent the error/accuracy of the entire 2.5 day period. Historical accuracy statistics can be found here.

Erik Proseus
MWN Meteorologist

Follow MWN on Facebook and Twitter for routine updates and the latest info!
Complete MWN Forecast: 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