Monday, April 27, 2015

April showers to end the month, then a beautiful start to May!

We've experienced a cool, breezy day today with high cloudiness covering the region. The clouds and breeze can be traced to the atmosphere battling between high pressure to our north over the Plains and Midwest and low pressure to our south from old Mexico into the Gulf Coast region. Despite the last few days of cooler weather, the month of April is about 3 degrees above normal temperature-wise.

High pressure to our north and multiple areas of low pressure to our south mean cloud cover and a northeast breeze in the Mid-South as the storm track stays to our south into this evening.

The string of low pressure systems has been responsible for severe weather from TX to LA last night into this early afternoon. Below is a graphic that shows lightning density (number of strokes per square kilometer) from 1:30am-1:30pm today. It's easy to pick out the storm track!

Lightning density plotted between 1:30am-1:30pm CDT today (cumulative) clearly show where storms have occurred in the past 12 hours or so. Image courtesy WxBell.

The storms in Texas last night dropped tornadoes and softball size hail. By mid-day today, the same system was responsible for torrential rain, copious lightning, and extreme wind (strong enough to blow several empty train cars from a rail bridge in New Orleans, watch the amazing video from WGNO-TV below).



As the main area of low pressure moves across the Gulf Coast over the next 48 hours, our cloudiness will turn into periods of showers as we head into Tuesday, with lingering clouds and possibly light rain or drizzle on Wednesday. This will help reduce our rainfall deficit for the month of April a bit as we head into May. Temperatures will stay below normal through mid-week thanks to the clouds and rain.

Total precip expected by the GFS (American) computer model through Wednesday evening as low pressure tracks to our south. Most areas in the metro are forecast to receive about 1/2" of rain with the Tuesday/Wednesday system.

However, as we head towards week's end and the first weekend in May, we'll return to more seasonal weather with afternoon temperatures slowly climbing back towards 80° though mornings will remain pleasantly cool as humidity values stay fairly low. In addition to pleasant temps, sunshine will be ABUNDANT for the kickoff of Memphis in May and Beale Street Music Fest! At least for this weekend, it won't be "Memphis in Mud" and the biggest concern will be possible sunburn prior to dusk!


Erik Proseus
MWN Meteorologist

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Thursday, April 23, 2015

Weekend weather marked a period of rain, possibly severe storms

As we head towards a busy late April weekend with plenty of outdoor activities to choose from, weather may play a role in the outcome of some of them. I'll cover the expectations and potential hazards for the next few days as another developing Plains low moves east through the Mid-Mississippi Valley.

Friday

The low takes shape and begins to strengthen in western Kansas as high pressure now to our north shifts east off the Atlantic seaboard and a warm front starts slowly moving north from the Gulf Coast. Showers become increasingly likely during the day in the Mid-South as moisture overrides the warm front with very low chances of thunder. Rainfall should not be excessive during the day but chances increase from a low probability in the morning to higher probabilities (likely in fact) by late in the afternoon. Temperatures should reach 70 by afternoon.

Friday evening (7pm) surface map shows a warm front lifting north towards the Mid-South as rain falls ahead of it (dark green). Map courtesy NOAA/NWS.

Friday Night

This will be the wettest period of the forecast as the warm front lifts through the Mid-South and the low continues shifting east. Periods of heavy rain are possible and thunderstorms are expected. Rainfall could reach an inch during the overnight in some places within the metro. It will also remain mild with temps in the 60s and a gusty south wind.

Saturday morning (7am) surface map with the low moving east across MO, a warm front to our north, and rain chances dwindling. Map courtesy NOAA/NWS.

While the severe weather threat is low Friday night, it is not nil. Most of the metro, as of mid-day Thursday, is in a Slight Risk zone (category 2 of 5), with the best chances of severe storms to our west. Some storms may be capable of producing strong wind gusts or hail. This forecast bears watching but overall I'm not impressed with the chance of significant hazards or damaging weather. If you plan to be out Friday night, keep an eye on your favorite weather source.

Friday's severe weather outlook from SPC shows the best chance of severe storms to our west with a Marginal to Slight Risk during the overnight hours in the metro.

Saturday

By early Saturday morning, most of the rain should be east of the metro from Friday night. The low pressure system will be scooting by to our north and most models give us a fairly dry day with some sunshine, especially in the afternoon, very gusty southwest wind (to 30+ mph), and temperatures that soar into the 80s!

The key words above are fairly dry, as there will be some impressive ingredients in place for severe storms capable of producing hail and strong wind, as well as a very low tornado threat. The last remaining ingredients seem to be a trigger to get those storms to form (which should be a cold front that sweeps through the area) and additional moisture in the low levels that looks to be less-than-optimal for storms. Thus, while the precipitation chance is low (30% at this writing), any storms that manage to fire could get strong quickly. The best chance of storms forming appears to be around lunchtime through the mid-afternoon hours and locations to our east probably have a better chance of severe storms than here in the metro.

Saturday's severe weather outlook from SPC indicating a chance that any storms that form could become severe.

If you plan on being out on Saturday, the weather factors to consider are: protection from the sun with temps in the mid 80s, a very strong southwest wind, and the possibility of a few strong to severe storms forming. Keep one eye to the sky and follow us on Twitter or the MWN mobile app for the latest updates.

Sunday

A beautiful spring day! Wind will have died down, humidity will be lower, sunshine will abound, and temperatures will be in the 70s. A GREAT day for outdoor activities before rain chances move back in next week! It'll make you want to dance...


Go Grizzlies!

Erik Proseus
MWN Meteorologist

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Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
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