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April 5-6 Severe Threat

MattPetrulli

By MattPetrulli,
in Southeastern States

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weatherextreme

weatherextreme

Posted
Posted

Latest from Spann

 

Potentially Dangerous Situation Tomorrow

NO ISSUES TODAY: About the only problem today is dense fog this morning over parts of Central and South Alabama… that will dissipate by mid morning, and the day will be sunny and warm with a high in the low 80s.

Clouds move in tonight, and showers and storms are possible as early as 4:00 a.m. tomorrow as moist air rapidly moves northward. SPC has much of the state in a severe weather risk for this activity in their “Day One” outlook, which runs through 7am tomorrow. For North/Central Alabama, the main risk with the early morning storms will most likely come from hail and strong winds, highest tornado threat early tomorrow will be over Southwest Alabama.

TOMORROW: A surface low will be south of St. Louis, supported by a strong upper trough (the last in the series with this “wave train”) with strong wind fields. The large scale pattern is certainly favorable for severe weather across Alabama, but the small scale features will determine the magnitude of the event.

Instability values will rise rapidly during the day, and surface based CAPE values will be in the 3,000 to 4,000 j/kg range by afternoon, making for a “power keg” type atmosphere as the spring storm system approaches. Forecast shear profiles favor severe storms as well; SPC has now put parts of East and South Alabama in a “moderate” risk, with an “enhanced risk” for much of the rest of the state.

C8ljWkWXYAA3baq.jpg

 

It is important not to get too hung up in risk areas and lines on these maps; remember storms don’t know anything about those lines and terms. This is simply a guideline to let you know where the greatest risk will be. Could there be an upgrade to a high risk in later outlooks today? Yes, but it just isn’t that important. Just be ready one way or another.

PLACEMENT: While all of Alabama has a severe weather risk tomorrow, the highest tornado potential will come from roughly I-65 east, or over the eastern half of the state. This is where the best combination of lift, instability, and shear will be found. Understand a tornado is certainly possible over West Alabama, but the odds are a bit lower there.

TIMING: Best thing we can say for now is that we expect multiple waves of thunderstorms from 4:00 a.m. until 7:00 p.m. The highest threat of tornadoes will come during the afternoon/evening hours, during the peak of the daytime heating process. More than likely, there will be lull in the action during the midday hours, but even then a few severe storms will be possible. We will need to be vigilant through the entire day.

THREATS: All modes of severe weather will be possible tomorrow, including large hail, damaging straight line winds, and tornadoes. A few long track, strong/violent tornadoes are possible, especially in the “enhanced” and “moderate” risk areas defined by SPC on the map above.

RAIN: Rain amounts around one inch are likely; no flooding issues are expected.

CALL TO ACTION: Be sure you have a way of getting warnings; a NOAA Weather Radio is the baseline, and a good smart phone app is the other tier. Identify the safe place in your home, and be sure everyone knows where it is. And, in that safe place have helmets for everyone, along with hard sole shoes and preferably a portable airhorn in case you need help.

Be sure you have the ABC 33/40 app on your phone so you can watch our live severe weather coverage, if needed:

iOS version

Android verson

IMPORTANT: Long time readers know this is a “no hype” zone. You will hear lots of crazy things over the next 24 hours across social media platforms and other sources, but there is no need to be alarmed or overly anxious about this. This is spring in Alabama; we have severe weather threats. It is normal, and we are good at being prepared and ready. Just have a way of hearing warnings, have a plan, and we will get through this just fine. And, there is always the chance it will be a “bust”…. a day when storms aren’t as widespread or dangerous as forecast. Keep an eye on the blog for updates today.

 

 

 

 

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Superstorm93

Superstorm93

Posted
Posted
Just now, melonknee said:

That's the one. 

I checked that days outlook a few minutes ago, it seems Atlanta was just barely outside of the high risk!

I mean it was nine years ago (God I'm getting old) but yeah, the outlook wasn't very good for that one. Thankfully we've had tremendous advancements since then. 

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melonknee

melonknee

Posted
Posted
1 minute ago, Superstorm93 said:

I mean it was nine years ago (God I'm getting old) but yeah, the outlook wasn't very good for that one. Thankfully we've had tremendous advancements since then. 

I agree. One of the earliest high risks covered all of Alabama and Georgia if I'm remembering the placement correctly. 20 years brings a lot of advancements in forecasting!

I'm excited to see what the forecasts are going to look like in 5 years. 

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Natester

Natester

Posted
Posted

I've got bad news.  KMOB, KMXX, MEOX and KVAX radars are down.  Hoping that KMOB, KMXX and KEOX will be up by tomorrow.  KVAX, on the other hand,  will likely be down through tomorrow.  Worse than January 22, 2017.

 

EDIT: KVAX is out of commission for who knows how long.  Just like on January 22, 2017, we have a major radar hole. :|

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Dehrski

Dehrski

Posted
Posted
12 minutes ago, Natester said:

I've got bad news.  KMOB, KMXX, MEOX and KVAX radars are down.  Hoping that KMOB, KMXX and KEOX will be up by tomorrow.  KVAX, on the other hand,  will likely be down through tomorrow.  Worse than January 22, 2017.

http://radar2pub.ncep.noaa.gov/

If anyone wanted to check radar statuses, this is a good bookmark. Click on the radar site for more info! Definitely looks like KMOB, KMXX, and KEOX will be back up. 

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jshetley

jshetley

Posted
Posted

The GSP weather office is calling the NAM's cool stable air solution over our CWA an outlier, meaning they think things become unstable from noon onward. They think the storms start around 1pm from around Anderson to Chester to the south at first, but slowly spreading north.

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Jim Martin

Jim Martin

Posted
Posted

Here is a piece of the Area Forecast Discussion from the NWS in Birmingham...

Area Forecast Discussion
National Weather Service Birmingham AL
1249 PM CDT Tue Apr 4 2017

.UPDATE...
For 18Z Aviation.

&&

.SHORT TERM...

...Severe weather outbreak possible Wednesday...

A stalled front to our south will begin to return northward
tonight as a classic 500 mb trough takes shape over the Plains. A
surface low should intensify and track from eastern Oklahoma 
tonight toward the Ohio Valley on Wednesday, eventually putting 
Alabama in the warm sector. Before that occurs, a warm front will
move inland and accelerate northward early Wednesday morning across
the forecast area. Scattered storms are expected to develop 
around 4 AM as warm/moisture advection occurs near the warm 
front. Additional storms could also form along a trailing 
confluence band which may extend from central Alabama to the 
southwest. With MLCAPE possibly as high as 2500 J/kg in the warm 
sector and strong wind shear already in place through the entire 
column, any surface-based storms could produce long-track 
tornadoes. It is unclear how widespread this activity will be and 
if storms will become more organized. This is an important 
question we cannot answer at this time, but the morning activity 
will greatly impact what happens later in the day. 

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mackerel_sky

mackerel_sky

Posted
Posted
4 minutes ago, jshetley said:

The GSP weather office is calling the NAM's cool stable air solution over our CWA an outlier, meaning they think things become unstable from noon onward. They think the storms start around 1pm from around Anderson to Chester to the south at first, but slowly spreading north.

TWC just showed their " future radar" it had storms firing around 10-11 AM along the warm front along the Ga/SC border and then heading NE. They said even those could rotate. The rest of the day for our area, really doesn't look too scary, based on what that showed, plus the main line gets here at midnight to 2AM timeframe! Torcon of 5 though

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jshetley

jshetley

Posted
Posted
Just now, mackerel_sky said:

TWC just showed their " future radar" it had storms firing around 10-11 AM along the warm front along the Ga/SC border and then heading NE. They said even those could rotate. The rest of the day for our area, really doesn't look too scary, based on what that showed, plus the main line gets here at midnight to 2AM timeframe! Torcon of 5 though

I'm not sure if that timing will help a lot in this case though. This system is going to be strong and a 50KT low level jet during the passage of that line is hard to ignore.

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jojo762

jojo762

Posted
Posted 
Area Forecast Discussion
National Weather Service Peachtree City GA
352 PM EDT Tue Apr 4 2017


.SHORT TERM /Tonight through Wednesday Night/...
...Significant Severe Weather Outbreak Expected on Wednesday...

While today`s warm and sunny weather provided a brief respite from
the stormy weather, this break will be coming to an abrupt end
on Wednesday. A strong storm system currently over the Plains will
bring widespread thunderstorms to the CWA on Wednesday, many of
which will become severe.

By early Wednesday morning a warm front will be rapidly moving
northward into the area ushering in Gulf moisture. The first
thunderstorms of the day are expected to form along this northward-
advancing warm front during the morning hours. Any thunderstorms
that form during this time frame may become severe. Large hail will
be possible with any elevated activity north of the front while
damaging winds and tornadoes would be possible with thunderstorms
forming along and just south of the warm front in the warm sector.

As we approach midday into the early afternoon, additional
widespread thunderstorm development is expected across the CWA with
a strong upper jet and associated divergence aloft as well as ample
instability in place across the warm sector. Forecast
SBCAPE values in the 2000-3000 J/kg range are anticipated, which
if realized will provide plenty of fuel for these rapidly developing
thunderstorms. Impressive shear (for example, >50 knots of 0-6km
bulk shear) will also be in place. All of this is to say that an
appreciable severe thunderstorm outbreak is expected with tornadoes,
damaging winds, and large hail all increasingly likely. The
possibility for strong/long-track tornadoes will exist with any
discrete supercells that form.

With such a moist environment in place, heavy rainfall can also be
expected in these thunderstorms. At this point, expected rainfall
totals are not high enough to warrant widespread flooding
concerns, but localized issues will be possible. See the hydrology
section below for further details.

The threat for severe thunderstorms will continue ahead of the
approaching cold front through the evening. As the cold front
finally begins to clear parts of the area mid-to-late evening, the
severe threat will end from west to east.
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kayman

kayman

Posted
Posted
14 minutes ago, SmokeEater said:


Jesus, that monster in N AL goes right through Huntsville.

Oh, it's just south of Huntsville, which is more central portions of Madison County.  However, the some of the helicity tracks come very close to where my parents reside on the AL/GA stateline though...

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Tyler Penland

Tyler Penland

Posted
Posted
1 hour ago, jshetley said:

The GSP weather office is calling the NAM's cool stable air solution over our CWA an outlier, meaning they think things become unstable from noon onward. They think the storms start around 1pm from around Anderson to Chester to the south at first, but slowly spreading north.

Yeah I have to agree with them. It seems to be developing some sort of in-situ CAD which looks very odd given the overall set-up.

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Natester

Natester

Posted
Posted

Update on KMXX and KVAX:

  

NOUS64 KBMX 042033
FTMMXX
Message Date:  Apr 04 2017 20:33:48
KMXX will be down until Thursday, April 6th, as technicians wait for replacement
parts. Radar will return to service if parts arrive sooner.

  

NOUS62 KJAX 041930
FTMVAX
MESSAGE DATE:  APR 4 2017 19:29:40
KVAX 88D WEATHER RADAR REMAINS DOWN UNTIL FURTHER NOTICE. RETURN TO
SERVICE UNKNOWN AT THIS TIME.

 

EDIT: KEOX is back up.

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audioguy3107

audioguy3107

Posted
Posted
18 minutes ago, Superstorm93 said:

#1 Analog from last night 

Remember it well, that was the year of the Dunwoody, Ga tornado that tore through the northern part of metro Atlanta.  I toured the storm damage the next day and it was a real mess........F2 if I remember correctly.  That was a  11PM to 2 AM event for us in north Georgia.

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