Textbook severe weather case Easter Sunday

It may not rain constantly Easter Sunday but rain is likely, heavy at times.

This looks like a possibly historic severe weather outbreak in parts of Dixie, the data is showing all the parameters and ingredients coming together for heavy rain and numerous wind damage storms and some tornadoes, including the chance for a long-track strong tornado especially West and South of Atlanta.

From this distance that looks maximized in LA, MS, AL but other areas could be added in future updates. (The threat here in Metro Atlanta is real though).

It’s still 3-days out so too early for specifics but not too early to have your family shelter and safety plan in place just in case.

From this distance it looks like the greatest risk for damaging winds in our area will come late afternoon Easter OR overnight Sunday night, exiting first thing Monday morning.

(best estimate for now is 4pm Sunday to 2am Monday).

Check back for updates here and on-air WSB Radio through the weekend as the situation becomes more clear. Watches and warnings of some kind are likely.

One thing to keep in mind is there may be enough wind gusts for a tree to cause a power outage even without rain or a severe thunderstorm.

I've been covering the risk of severe weather Easter since Monday and illustrated the set-up in my blog back on Tuesday if you missed it here.

FACTORS I AM LOOKING AT WITH THE SYSTEM COMING OUR WAY:

*Southern California potent low pressure system ejects east and phases with another incoming northern jet stream trough of low pressure with incredible wind energy forming a large baroclinic cyclone surface and aloft.

*Strong short-wave trough becomes negatively-tilted with a rapidly deepening surface low that suddenly leaps Northeast whipping a cold front through the South and East states by Monday.

*Warmer than normal Gulf of Mexico water to feed moisture fuel.

*Strong low-level jet (~5,000FT).

*Intense upper-level jet stream (18,000-35,000FT) and possible dual jet stream couplet to maximize upward air motion.

*Jet stream overspreading surface warm sector of mature mid-latitude cyclone.

*Widespread parameters for near-surface helicity and wind-shear.

Bottom line... a prolific destructive and dangerous weather set-up for a widespread pretty broad area of the Southern States from Texas to the East Coast, BUT the details can not yet be pined down.

It is RARE for the NOAA Storm Prediction Center to issue a moderate risk 3 days in advance but they have, something reserved only for what they think may be prolific and impactful event.

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Five days of rain in a row in L-A and San Diego is very rare

The system now:

The weather in far off places plays a role here warmer than normal Pacific Ocean surface water energizes sub-tropical jet stream with upper-level low (ULL) in Southern jet stream and another from the polar jet stream from the Northwest merge:

WHAT HAPPENS NEXT:

SURFACE WEATHER MAP SEQUENCE:

Saturday surface chart:

Sunday morning surface chart:

Monday surface chart:

500MB LEVEL JET STREAM VORTICITY SUNDAY AFTERNOON:

500MB LEVEL JET STREAM VORTICITY EARLY MONDAY MORNING:

RAINFALL OUTLOOK:

SEVERE WEATHER GUIDANCE (greatest risk in brighter/darker colors):

WHAT THIS DOES *NOT* MEAN...

OMG we’re all gonna die.

Everyone will get storm damage.

There will be a thousand tornadoes and many will be the biggest and strongest and longest path ever seen in history on earth.

100% chance of rain means 100% of the day will be wet.

There’s no way the forecast can be a bust.

Again, none of the above are true.

Do I see some ways this can end up not being all that bad? Yes, just like snow or freeze predictions or any forecast there is a normal and expected margin of error.

We can get lucky in a variety of ways with this system, I won’t bore you with every one, to name a few... maybe the system ends up weaker than expected, the dynamics come close but don’t quite line up with the right timing (aka the phase-space it out of sync so best thermodynamics and kinematics are not together), heavy rain and storms near the Gulf sap the system of energy, rain and clouds are widespread enough to keep instability at a minimum and/or prevent surface rooted rotation, the system slows down enough that the storms weaken by the time any squall-line arrives locally and the air mass is less unstable than modeled etc.

Fingers crossed, as the Boy Scouts say: “Be prepared”. I’d rather be safe than sorry, plan for the worst hope for the best. Check back for updates through the weekend.

For more follow me on Twitter @MellishMeterWSB.

*******************************************************************************************************************************************

Do this know this NOW:

1) Figure out the safest place in your house

2) Keys: avoid windows, use interior room like bathroom, closet or pantry on the lowest floor

3) Mobile homes/manufactured homes are UNSAFE in a tornado and you must leave for better shelter.

4) Have multiple ways to get warnings but NOT social media or outdoor sirens:

5) RADIO/TV

6) Free APP