Monday, May 9, 2011

Early summer-like heat wave this week, and a peek at the Memphis in May Barbecue Fest forecast

The Mid-South, and in fact much of the central U.S., is experiencing the effects of an unusually strong ridge of high pressure at the upper levels that will build through tomorrow, then begin to weaken later in the week.  The ridge is bounded on the west and east by troughs of low pressure aloft (see graphic below).  Typically this means dry and warm weather under the ridge and cooler and possibly wetter weather under the troughs.  This time will be no exception.  The jet stream flows around the ridge at the level shown (about 35,000 feet up), so the storm track will also be well to the north while we are under the influence of the ridge.
A large ridge of high pressure aloft builds directly over the Mid-South on Tuesday
In addition, high temperatures will be well above normal with 90s common in many places, as shown by Weather Channel graphics for Tuesday and Wednesday below.  In fact, the ridge and trough over the U.S. (above) are easy to pick out based on the temperature trends for tomorrow and Wednesday in the maps below. Surface high pressure is off to our east, which means southerly wind and higher humidity values for the Mid-South. So not only do we have heat from high pressure aloft, but we are also getting a touch of early summer humidity from surface high pressure to the east!

Heading into late in the week, the computer models are having a difficult time determining how quickly the ridge of high pressure breaks down, which will affect the timing of our next cold front.  Currently, the best guess is that sometime between Thursday night and Friday night, that front will move through, accompanied by thunderstorm chances ahead of and along it.  With several days of moisture and strong heating ahead of it, depending on the timing of the front, some storms may be severe.  The MWN Storm Center will have the details on possible severe weather.

Behind the front, the upper-level low pressure system builds to our north and the pattern remains unsettled.  It appears that small chances of rain are possible through the weekend, depending on where exactly the low pressure system sets up.  This could have an effect on the weather for the Memphis in May Barbecue Festival at Tiger Lane.  At least participants won't have to contend with the mighty Mississippi lapping at their grills! As the slogan adopted by MIM goes, "Memphis is Cookin' Come Hell or High Water!" As the week goes on, the forecast will be come clearer.  Check with the MWN Forecast frequently for the details.

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