Friday, October 5, 2012

The Big Kahuna front brings the coldest air of the season so far

All week, we've been talking on our social feeds about what we have called the "Big Kahuna" cold front that is due in tonight and how it's going to have a drastic affect on our weather.  It's time to provide some more detail, especially with regard to tonight and Saturday, as there are plenty of outdoor activities planned, including Live at the Garden with Bonnie Raitt, high school football games, the Bluff City Blues 100 bike events Saturday, and Memphis Tigers football game Saturday night.

Very warm air and sufficient Gulf moisture ahead of a potent Canadian cold front is the recipe for possible thunderstorms and the Storm Prediction Center has keyed onto the region.  A Slight Risk for severe weather, mainly due to possible hail or a wind gust, has been issued for roughly the southeast half of AR, including western portions of the metro (see below).  

Scattered thunderstorms will be possible to our west by the evening rush hour but are a little more likely along the front as it moves across the metro this evening. We expect the front to arrive in the city around 8pm.  Storms should not be as strong east of the Mississippi River as over AR, but everyone should still be weather aware, especially those outdoors tonight.


Besides possible showers and thunderstorms along the front, showers are also likely behind it as we head into the overnight hours. The graphic below shows a high-resolution computer model's "idea" of what the radar may look like at 8pm.  Remember this is a model and is not necessarily what will actually happen - but it gives a good idea of the possibility.  Expect rain to linger into the night as the front continues to move south.


The next graphic shows this computer model's interpretation of temperatures at 8pm tonight. Yellows and oranges are 70s to near 80. Light greens are 60s, dark greens 50s, and check out those 40s over southern Missouri! Temperatures will steadily fall behind the front with lows tonight near 50.


Rain should come to an end by early morning, probably by dawn, Saturday, though it will remain mostly cloudy and very cool with a north breeze throughout the day. Temperatures will only rise to the lower 60s (maybe), which would be some 20-25 degrees colder than this afternoon!

By late Saturday and into the evening hours, a disturbance behind the front will trigger additional showers, most of which should fall north of the metro.  However, a few showers will be possible for the Memphis Tigers football game on Saturday evening.  Combined with temperatures in the 50s, the sideline air conditioning units will NOT be needed tomorrow night!  We'll see temps drop to the mid 40s by Sunday morning with any rain ending by dawn.

Sunday should see clouds begin to move out, but again temperatures will struggle to reach 60.  The coldest night of this cool spell will be Sunday night.  Lower 40s are likely in the city and upper 30s (!!) will be likely in the coldest outlying areas.  Could some cold spots get their first frost of the year??  A warming trend commences Monday with 70s back in the forecast by Tuesday.

MemphisWeather.net will keep you updated on changing conditions, especially tonight, via our social media channels and mobile apps.  Find all the necessary links to stay informed below.

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Wednesday, October 3, 2012

September 2012 Climate Data and Forecast Accuracy


A break in the heat that has resulted in 2012 being (year-to-date) the warmest on record came after the first week of September when temperatures reached the upper half of the 90s for 7 days straight.  A cold front that dropped the high 20 degrees ended the run of 90s, probably for the year.  For the month, the average temperature was almost exactly average, while precipitation was well above normal and welcomed.

Through September 30th, the average temperature for 2012 of 69.9 degrees is 3.8 degrees above normal, beating the previous record though the end of September by about 1.5 degrees (2007, +2.4 degrees).  Drought conditions abated somewhat with local and upstream rainfall and 2012 is no longer among the top 10 driest years on record.  The Memphis metro, with the exception of northwest MS, is classified as being in a severe drought, down from extreme to start the month. Northwest MS remains in an extreme drought.


Memphis International Airport, Memphis, TN

The average temperature for the month of September was 75.3 degrees, or 0.1 degrees above normal. The average high temperature was 84.7 degrees and the average low was 65.9. The coolest temperature of the month was 53 degrees on the 19th and again on the 24th, while the highest temperature was 99 degrees on the 5th.  There were 7 days in which the high reached 90 degrees or higher (each day from the 1st through the 7th).  There were no temperatures records set or tied in September.

Precipitation for the month totaled 7.01", which was 3.92" above average. There were 12 calendar days with measurable rainfall, 3 of which saw totals of 1" or more (maximum 2.24" on the 1st-2nd). The peak wind gust was 47 mph from the northwest on the 7th as a thunderstorm moved overhead with an average wind speed for the month of 7.1 mph. Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions, Bartlett, TN

The average September temperature at Cirrus Weather Solutions was 72.3 degrees with a maximum of 98.7 degrees on the 5th and a minimum of 45.7 degrees on the 24th.  September precipitation measured 5.88" via the automated gauge and 6.38" in a manual gauge used for the CoCoRaHS program (including a small amount of rain that feel prior to 7am on October 1). The measured peak wind gust was 30 mph on the 1st. Average relative humidity was a muggy 76%. Click here for a daily recap on MemphisWeather.net.

MWN Forecast Accuracy

For the month of September, the average temperature error in all MWN temperature forecasts was 1.94 degrees, lower than all available computer model data and the National Weather Service. 69% of the MWN temperature forecasts for the month were within 2 degrees of the actual temperature. MWN's forecasts extend out five periods (2.5 days, or roughly 60 hours). For dewpoint accuracy, the MWN forecast averaged 2.54 degrees of error and fell within 2 degrees of the actual dewpoint 58% of the time. Historical accuracy statistics can be found here.

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Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps,  now with StormWatch+!
Nowcasting services available on our Facebook page and Twitter feed.