Monday, June 18, 2018

Increasing rain chances temper temperatures

I think we'd just be happy with average temperatures at this point, right? I mean, in the past 49 days, we have had just TWO days with daily average temperatures that were below normal - and they were each just one degree shy of the daily average! The heat has been persistent, no doubt. Well, if you think like I do, I might have some...


But first we have Tuesday, which will be very similar to Monday. Another day with high temperatures in the lower 90s, heat indices near 100 degrees, and scattered clouds and isolated thunderstorms. Most of us stay dry at least one more day, but then the pattern changes as a ridge of high pressure aloft break down.

The GFS forecast upper level (18,000', or 500mb) pattern from Monday night through Saturday night (each frame is 12 hours apart). See below for explanation and impacts of the "bowling ball" closed low pressure that moves by to our north late this week.(PivotalWeather)

Upper level weather pattern in control

The forecast upper level pattern (at roughly 18,000' above ground level) from Monday night through Saturday night is shown above. Notice the "hill" (or ridge) produced by the black lines over the Mississippi Valley at the beginning of the loop is replaced by a "bowling ball" of concentric circles as the loop progresses, then flattens out at the end of the loop. What happens is that the high pressure ridge is squashed by a fairly strong upper level low pressure system (the bowling ball) that moves by to our north.

The proximity of the low pressure center means a fairly marked uptick in cloud cover and rain chances as it approaches and passes by. With southerly wind at the surface, the energy associated with that low will tap into a good amount of Gulf moisture, triggering the likelihood of showers and thunderstorms from mid to late week. In addition, a semi-tropical system that will bring torrential rain to parts of the Texas coast the next few days will also contribute moisture to this system. We are left with a very different weather pattern for Wednesday-Friday than we have seen in some time - one that features abundant cloud cover and high rain chances, thereby resulting in cooler (though still humid) conditions. I think we'll take some mid/upper 80s and clouds versus the low/mid 90s and sunshine of late (at least for a couple days)!

Severe weather impacts

We'll need to closely monitor the potential for severe weather, as thunderstorms are expected at times during this period. I believe those chances will be fairly minimal though due to the cloud cover which will limit instability a great deal. A few strong wind gusts or hail could be possible at times in stronger storms though. The flash flooding threat will also be monitored, though I expect that also to be fairly low. All of these threats will be refined on a daily basis and communicated through our social media channels, so be sure you are following MWN on Facebook and Twitter and have downloaded our mobile app for the latest details.

Takeaways:


  • One more hot day Tuesday with a couple storms possible
  • Increase in clouds and precip chances Wednesday
  • Best chances of showers and thunderstorms Thursday-Friday
  • Cooler temperatures mid- to late-week, but still humid
  • An inch or more of rain for many in the Mid-South
  • Severe weather threats undetermined, but not a major concern


Approximate precipitation expected through Sunday morning across the south-central U.S. (NWS/WPC, WxBell)



Erik Proseus
MWN Meteorologist

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

Saturday, June 16, 2018

May 2018 Climate Data for Memphis, TN

May Climate Recap

After an April that will be remembered as the third coldest on record, averaging over six degrees below normal, May flipped the script and went into the record books as the warmest on record, nearly six degrees above the long-term average! The average temperature for the month was over 21 degrees warmer than April. Averaging the first five months of the year together, Memphis is right at "normal" year-to-date, which just goes to show you that there is no such thing as normal! Three May days saw high temperatures set or tie their daily records, while only a single day (the 5th) recorded a below average daily temperature, and that was by a single degree. The warmth began when the calendar turned to May and was persistent.


Officially, precipitation for the month was below average by nearly two inches, however scattered thunderstorms on several days resulted in a wide range of precipitation amounts. As an example, MWN in Bartlett recorded nearly 3" more rain than the airport from localized deluges under these storms. Severe weather was not widespread, though a few of the scattered "summertime" cells that formed in the May heat produced severe reports. Hail fell in Shelby County on the 19th and 20th and there were wind damage reports in Crittenden County (20th) and Tate County (31st). There were multiple Severe Thunderstorm and Flash Flood Warnings during the month in the metro, but no Tornado Warnings. Most Flash Flood Warnings were in Shelby County for urban flooding from localized heavy downpours.

Memphis International Airport, Memphis, TN


Temperature
Average temperature: 77.4 degrees (5.7 degrees above average)
Average high temperature: 87.0 degrees (5.8 degrees above  average)
Average low temperature: 67.8 degrees (5.6 degrees above average)
Warmest temperature: 93 degrees (14th, 15th)
Coolest temperature: 56 degrees (1st, 6th)
Heating Degrees Days: 0 (19 below average)
Cooling Degree Days: 390 (226 above average)
Records set or tied: The month was the warmest May on record. Record high temperatures were set on May 14 and 15 (both 93°). A record high temperature was tied on May 10 (90°).
Comments: Eight days recorded high temperatures at or above 90 degrees, which is 6 days above average. The May average temperature was more than 20 degrees warmer than the April average temperature.

Precipitation
Monthly total: 3.32" (1.93" below average)
Days with measurable precipitation: 11
Wettest 24-hour period: 1.06" (17th)
Snowfall: 0.0"
Records set or tied: None
Comments: Only a single day recorded more than 1.0".

Miscellaneous
Peak wind: Southwest/41 mph (19th)
Average wind: 7.0 mph
Average relative humidity: 70%
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: 76.1 degrees
Average high temperature: 87.7 degrees
Average low temperature: 66.2 degrees
Warmest temperature: 94.2 degrees (15th)
Coolest temperature: 50.8 degrees (1st)
Comments: None

Precipitation
Monthly total: 5.76" (automated rain gauge), 6.21" (manual CoCoRaHS rain gauge)
Days with measurable precipitation: 13
Wettest date: 1.60" (20th) (via automated gauge)
Snowfall: None
Comments: None

Miscellaneous
Peak wind: South/26 mph (20th)
Average relative humidity: 75%
Average barometric pressure: 29.96 in. Hg

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

MWN Forecast Accuracy

MWN average temperature error: 1.79 degrees
MWN forecast temperatures within 2 degrees of actual: 75%
MWN average dewpoint error: 1.87 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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Follow MWN on Facebook and Twitter for routine updates and the latest info!
Complete MWN Forecast: MemphisWeather.net on the mobile web or via the MWN mobile app
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder