Possible heavy severe weather in the US Southeast this Tuesday-Wednesday

I haven’t been following any of the discussion groups but noticed some concern expressed on the Storm Prediction Center‘s outlooks.

Tuesday, April 9

These outlooks are always done in caps. You don’t usually see hash marks on day 3, I believe:

Day 3 image

SPC AC 070729

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT SUN APR 07 2013

VALID 091200Z – 101200Z

…THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MO VALLEY TO THE
SRN PLAINS…

…SYNOPSIS…
HIGHLY AMPLIFIED UPPER-LEVEL TROUGH OVER THE WEST SHOULD EVOLVE INTO
TWO DISTINCT SHORTWAVE IMPULSES…ONE MOVING NEWD TOWARDS THE
NRN/CNTRL PLAINS AND THE OTHER REMAINING IN THE BASE OF THE TROUGH
OVER NWRN MEXICO. MID-LEVEL SWLYS WILL INCREASE ACROSS THE
WARM/MOIST SECTOR IN RESPONSE TO THE LEAD IMPULSE. AT THE
SURFACE…CYCLONE IN THE LEE OF THE SRN ROCKIES SHOULD DEVELOP NEWD
AND REACH THE LOWER MO VALLEY BY TUE NIGHT. THE SRN PLAINS DRYLINE
WILL BE PROGRESSIVELY OVERTAKEN BY A COLD FRONT WHICH SHOULD REACH
CNTRL TX BY EARLY WED.

…LOWER MO VALLEY TO THE SRN PLAINS…
A BROAD CORRIDOR OF ORGANIZED SEVERE POTENTIAL WITH ALL HAZARD TYPES
IS ANTICIPATED TUE AFTERNOON INTO WED MORNING. AN UPGRADE TO
MODERATE RISK WILL CONTINUE TO BE CONSIDERED IN LATER OUTLOOKS.

LOW CONFIDENCE EXISTS IN THE SYNOPTIC PATTERN GIVEN RELATIVELY LARGE
SPREAD IN GUIDANCE WITH THE HANDLING OF THE LEAD SHORTWAVE IMPULSE
EJECTING FROM THE WRN CONUS TROUGH. NCEP GUIDANCE REMAINS FASTER
THAN THE ECMWF/UKMET WITH THE PROGRESSION OF THE IMPULSE WHICH
AFFECTS POSITIONING OF THE DRYLINE/COLD FRONT…AND MORE BULLISH
WITH THE AMPLITUDE OF KINEMATICS OVER THE WARM/MOIST SECTOR. THIS
BREEDS SUBSTANTIAL UNCERTAINTY OVER WHERE TO PLACE HIGHER SEVERE
PROBABILITIES OR EVEN WHETHER THEY ARE NEEDED BEYOND AN ENHANCED
SLIGHT RISK.

REGARDLESS OF THE PATTERN DIFFERENCES…GIVEN STRENGTHENING RETURN
FLOW IN THE WRN GULF…A MODERATELY UNSTABLE AIR MASS WILL BECOME
MORE WIDESPREAD IN THE S-CNTRL CONUS. WITH STEEP MID-LEVEL LAPSE
RATES AND FORCING FOR ASCENT INCREASING THROUGH THE
PERIOD…SUPERCELLS AND ORGANIZED CLUSTERS SHOULD COMMENCE TUE
AFTERNOON IN PARTS OF KS AND DEVELOP S/EWD INTO THE SRN PLAINS AND
TOWARDS THE MID-MS VALLEY DURING THE EVENING/OVERNIGHT. LARGE HAIL
/SOME SIGNIFICANT/ AND TORNADOES WILL LIKELY BE THE PRIMARY HAZARDS.
WHILE THE THREAT FOR DAMAGING WINDS SHOULD INCREASE DURING THE
LATTER HALF OF THE PERIOD AS LOWER-LEVEL FLOW STRENGTHENS AND
CONVECTIVE MODE BECOMES MORE CLUSTER/LINEAR.

..GRAMS.. 04/07/2013

Right now the risk is given as “slight,” but note that they might upgrade it to “moderate.” This far out, that’s unusual, too, and again, a sign for concern if you live in the affected areas.

Wednesday, April 10

Day 4-8 is a fairly new thing at the SPC outlook page (new to me, anyway), but I noticed this morning that they have it labeled “severe” on their front page currently. That’s worrisome, too, this far out.

SPC/NOAA

SPC/NOAA

In this case, the color red is used to signify it’s a day 4 outlook, not for severity. I did a screen save to get the accompanying graph box – it shows Memphis, Little Rock, Shreveport, Jackson and Jonesboro in the risk zone – and text. You’ll probably have to click on the image to read the text.

day4 text and graph

Rest of the week

The event will also unfold eastward through the South after Wednesday, on throughout the week, as usual. They’re going with the most relevant models through the current day 4.

Resources

Of course, the best way to follow an unfolding severe weather event in your is via local TV or radio as it happens. Keep them tuned in, especially Tuesday and Wednesday.

The SPC has a number of online products to follow, if you’re so inclined, or you can enter your location (either town/state name or ZIPcode) at the SPC page to get your local NWS page, which has forecasts, watches, warnings, radar images and more.

While you’re at the SPC page, be sure to check out the Education and Outreach portion of the right sidebar, whether this is your first severe weather experience or if you’ve gotten way too much experience of such things (i.e., once or more). It’s a great resources, and their Tornado FAQ page is renowned and thorough.

Let’s not discount the threat of flooding with even regular weather in the South, let alone the extremes. The National Severe Storms Laboratory recently tweeted this image, along with the caption, “THIS is why you should turn around if there is water covering the road.”

flood

Sure, maybe the flooded portion of the highway ahead of you won’t be that bad, but if you can’t see beneath the water surface, why are you betting your life on getting through it?

And water is heavy, even before it starts moving in a flood – only a few inches can knock you off your feet as well as pick up and carry off your sedan, SUV or pickup.

Turn around – don’t drown!

And please stay away from overpasses, even if you’re being chased by a tornado! It’s a myth that they provide shelter.

Really, you don’t want to be on any limited access highway when there’s a tornado nearby. It can go where it likes – you can’t.

See?

That was near Dallas in April 2012.

Think ahead, even if it’s a work day and you’ve got a long commute.

For the longer term, and especially since the Atlantic hurricane season is also coming up soon, FEMA has a useful and free publication, Against the Wind: Protecting Your Home From Hurricane and Wind Damage.

Summary

It looks like a major severe weather event in the southeastern US may be coming up this week (yes, in other regions of the country, too – I’ve just lived in the South and have a feel for severe weather there, and it’s also close to my heart).

This is all based on computer models, of course, and the longer the models run, the more inaccuracies they can show. Hopefully, this won’t pan out, but it’s telling that the experts are indeed showing it, despite the long-term nature of these outlooks.

Stay safe out there, readers! I’m selfish and value each and every one of you.



Categories: Weather

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