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Author Topic: CATASTROPHIC FLOODING 4/30-5/2  (Read 159683 times)

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Offline dwagner88

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #30 on: April 28, 2010, 10:06:04 PM »
I would go saturday being that far east. You should also consider having to go shopping!! I don't think anyone really enjoys that it's just women's way to torment men.

Indeed. I usually just let her drop me off at fry's electronics. I could spend a week in there. That way we are both happy.
Winter 2009-10 Snowfall: 11.5 in. :)
Winter 2010-11 Snowfall: 15.5 in. :)
Winter 2011-12: Trace
Winter 2012-2013: 0.25 in.
Winter 2013-14: 10.6 (9.5 on 2/12)
Winter 2014-2015: 10.25 in.
Winters 2015-2019: basically nothing
Winter 2019-2020:
2/8/20: 4.25

Offline Thundersnow

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #31 on: April 29, 2010, 04:57:51 AM »
Day 3 (Saturday) shows Slight Risk, but notice the hatched area already:





Quote
   DAY 3 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0230 AM CDT THU APR 29 2010
   
   VALID 011200Z - 021200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE LOWER MS
   VALLEY...TN AND OH VALLEYS...
   
   ...SYNOPSIS...
   
   UPPER PATTERN WILL REMAIN CHARACTERIZED BY A BROAD DOUBLE VORTEX
   POSITIVE TILT UPPER TROUGH SATURDAY. A SIGNIFICANT IMPULSE WILL LIFT
   NEWD THROUGH THE GREAT LAKES EARLY SATURDAY. ANOTHER SHORTWAVE
   TROUGH INITIALLY OVER NRN MEXICO SATURDAY MORNING WILL EJECT NEWD
   REACHING THE MID MS VALLEY OVERNIGHT. FRONTAL BOUNDARY WILL LIKELY
   BECOME QUASI-STATIONARY FROM THE GREAT LAKES SWWD THROUGH ERN TX. A
   SURFACE WAVE IS FORECAST TO DEVELOP AND LIFT NEWD ALONG THE FRONT
   THROUGH THE LOWER AND MID MS VALLEYS IN ASSOCIATION WITH EJECTING
   SRN BRANCH JET STREAK. THIS WILL ACCELERATE EWD SRN PORTIONS OF THE
   FRONT INTO THE LOWER MS VALLEY OVERNIGHT.
   
   
   ...LOWER MS...TN AND OH VALLEYS...
   
   BOUNDARY LAYER WINDS WILL TEMPORARILY WEAKEN DURING THE DAY AS
   INITIAL LOW LEVEL JET LIFTS NWD INTO SRN ONTARIO IN ASSOCIATION WITH
   LEAD SHORTWAVE TROUGH. HOWEVER...MODERATE SLY FLOW WILL PERSIST OVER
   THE LOWER MS VALLEY MAINTAINING INFLUX OF RICH GULF MOISTURE.
   WIDESPREAD CLOUDS AND ONGOING CONVECTION WILL LIMIT DIABATIC WARMING
   OF THE BOUNDARY LAYER WITH MLCAPE GENERALLY BELOW 1000 J/KG EXCEPT
   OVER THE LOWER MS VALLEY REGION WHERE RICHER GULF MOISTURE WILL
   PERSIST. AT THIS POINT...UNCERTAINTY EXISTS REGARDING EVOLUTION OF
   ONGOING CONVECTION. HOWEVER...DEEP LAYER FLOW/VERTICAL SHEAR WILL
   REMAIN SUFFICIENT THROUGHOUT THE DAY FOR A THREAT OF ORGANIZED
   SEVERE STORMS. THE SEVERE THREAT MAY INCREASE FROM LATE AFTERNOON
   INTO THE OVERNIGHT INITIALLY OVER THE LOWER MS VALLEY AS THE LOW
   LEVEL JET STRENGTHENS IN RESPONSE TO EJECTING IMPULSE. STORMS WILL
   LIKELY REDEVELOP AHEAD OF EWD ADVANCING COLD FRONT. DEEP LAYER SHEAR
   AND HODOGRAPHS WILL BECOME SUPPORTIVE OF ORGANIZED STORMS WITH A
   THREAT OF DAMAGING WIND AND ISOLATED TORNADOES CONDITIONAL UPON
   SUFFICIENT SURFACE BASED INSTABILITY. THREAT WILL EXPAND NEWD ALONG
   MIGRATORY LOW-LEVEL JET TOWARD THE OH VALLEY OVERNIGHT.
   
   ..DIAL.. 04/29/2010

Offline BRUCE

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #32 on: April 29, 2010, 05:04:40 AM »
yeah noticed that. i thought 30 percent waranted at least a moderate risk.
Come on severe wx season...

Offline Curt

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #33 on: April 29, 2010, 05:41:14 AM »
yeah noticed that. i thought 30 percent waranted at least a moderate risk.

SPC wont place a moderate on Day 3- too many factors at play, but potential is there. They will however hatch to make one aware of the potential threat. Just like last Sat, ongoing convection from Friday night could hamper Sat event. They are cautious at this point.

Offline toastido

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #34 on: April 29, 2010, 08:23:31 AM »
yeah noticed that. i thought 30 percent waranted at least a moderate risk.

There's only 15% probs on the day 3 at this point. Hatched means 10% or greater of significant severe. 
Don't knock the weather. If it didn't change once in a while, nine out of ten people couldn't start a conversation.
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(1868 - 1930)
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Adam: Girls come and go. Weather is constant
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Eric (Admin): there's no fornication in meteorology

Offline toastido

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #35 on: April 29, 2010, 09:04:57 AM »
From HUN - Doesn't look like they're too concerned over the Severe aspect of this system, more so the flooding threat:

Quote
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HUNTSVILLE AL
355 AM CDT THU APR 29 2010

ALZ001>010-016-TNZ076-096-097-291830-
LAUDERDALE-COLBERT-FRANKLIN AL-LAWRENCE-LIMESTONE-MADISON-MORGAN-
MARSHALL-JACKSON-DEKALB-CULLMAN-MOORE-LINCOLN-FRANKLIN TN-
355 AM CDT THU APR 29 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH ALABAMA AND PORTIONS
OF SOUTHERN MIDDLE TENNESSEE.

.DAY ONE...TODAY AND TONIGHT...

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY...

A SERIES OF UPPER LEVEL DISTURBANCES CROSSING THE AREA WILL
SUPPORT ISOLATED TO SCATTERED THUNDERSTORMS FRIDAY AFTERNOON
THROUGH SATURDAY. SOME OF THESE STORMS COULD BE STRONG TO
MARGINALLY SEVERE...ESPECIALLY WEST OF I-65 SATURDAY AFTERNOON
AND EVENING. DAMAGING WINDS...HAIL UP TO 1 INCH IN DIAMETER...
AND LOCALLY HEAVY RAIN ARE THE PRIMARY THREATS AT THIS TIME.

MORE ORGANIZED THUNDERSTORMS AND HEAVY RAINFALL CAN BE EXPECTED LATE
SUNDAY INTO MONDAY AS A SLOW-MOVING COLD FRONT CROSSES THE AREA. THE
PRESENCE OF A VERY WET AND UNSTABLE ENVIRONMENT WILL SUPPORT THE
POTENTIAL FOR HEAVY RAIN...ESPECIALLY SUNDAY NIGHT...WHERE UP TO 2
TO LOCALLY 4 INCHES OF RAINFALL CAN BE EXPECTED. HIGHER AMOUNTS ARE
POSSIBLE ACROSS NORTHWEST ALABAMA...BUT THE EXACT POSITIONING OF
THE HEAVIEST RAIN AREA REMAINS UNCERTAIN AT THIS TIME. RESIDENTS
SHOULD PREPARE FOR AN ELEVATED FLOOD THREAT THIS WEEKEND...ESPECIALLY
SUNDAY INTO MONDAY.

.SPOTTER CALL TO ACTION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL
IS NOT ANTICIPATED AT THIS TIME.

$$

DJN
Don't knock the weather. If it didn't change once in a while, nine out of ten people couldn't start a conversation.
Kin Hubbard
(1868 - 1930)
Quote
Adam: Girls come and go. Weather is constant
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Eric (Admin): there's no fornication in meteorology

Offline dwagner88

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #36 on: April 29, 2010, 10:21:27 AM »
So is it looking less likely that those gfs rainfall totals were the result of convective feedback? It had me in a bullseye of 7 + last time I checked it.
Winter 2009-10 Snowfall: 11.5 in. :)
Winter 2010-11 Snowfall: 15.5 in. :)
Winter 2011-12: Trace
Winter 2012-2013: 0.25 in.
Winter 2013-14: 10.6 (9.5 on 2/12)
Winter 2014-2015: 10.25 in.
Winters 2015-2019: basically nothing
Winter 2019-2020:
2/8/20: 4.25

Offline toastido

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #37 on: April 29, 2010, 10:23:07 AM »
So is it looking less likely that those gfs rainfall totals were the result of convective feedback? It had me in a bullseye of 7 + last time I checked it.

I think *SOME* of it may be feedback, but this system is going to have a LOT of precipitable water with it.  Maybe not 7+ inches, but probably a least a good 3-4+.
Don't knock the weather. If it didn't change once in a while, nine out of ten people couldn't start a conversation.
Kin Hubbard
(1868 - 1930)
Quote
Adam: Girls come and go. Weather is constant
Quote
Eric (Admin): there's no fornication in meteorology

Offline Curt

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #38 on: April 29, 2010, 10:52:07 AM »
Last night's GFS cranked out over 8 inches at KMEM. I am not sure this is accurate but models consistently are predicting 5-7 inches with each run. After KMEM's 3.3 inches last Saturday, April is going to be one wet month when its all said and done.

Severe looks to be more concentrated from West to West Mid TN/North MS/W KY for now.
« Last Edit: April 29, 2010, 11:03:16 AM by ctbpharmd »

Offline dwagner88

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #39 on: April 29, 2010, 11:13:17 AM »
Well mrx is paying attention. I'm not sure if I remember having one of these issued so far ahead of an event.
Quote
HYDROLOGIC OUTLOOK
NCC039-043-TNC001-007-009-011-013-019-025-029-057-059-063-065-067-
073-089-091-093-105-107-115-121-123-129-139-143-145-151-153-155-
163-171-173-179-VAC105-167-169-191-195-300900-

HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE MORRISTOWN TN
754 AM EDT THU APR 29 2010 /654 AM CDT THU APR 29 2010/

...PROLONGED RAINS THIS WEEKEND HAVE THE POTENTIAL TO CAUSE FLOODING...


A MAJOR SPRING RAIN SYSTEM IS APPROACHING THE TENNESSEE VALLEY AND
MAY BRING HUGE AMOUNTS OF GULF MOISTURE INTO THE REGION THIS
WEEKEND. DIFFERENT COMPUTER MODELS SHOW DIFFERENT TIMING AND
AMOUNTS AND SO IT WILL BE NECESSARY TO WATCH CLOSELY AND SEE
EXACTLY WHERE THE RAIN DEVELOPS AND HOW FAST IT MOVES.

RIVERS IN EAST TENNESSEE...EXTREME SOUTHWEST VIRGINIA...AND EXTREME
SOUTHWEST NORTH CAROLINA ARE ON THE LOW SIDE. ALSO...TOTAL RAIN
THIS YEAR HAS BEEN QUITE A BIT BELOW NORMAL. THIS WILL HELP TO
LESSEN THE LIKELIHOOD OF FLOODING. NEVERTHELESS...PLEASE KEEP AN
EYE OUT FOR THE POSSIBILITY OF A PROLONGED RAIN EVENT THIS WEEKEND.

THE NATIONAL WEATHER SERVICE IN MORRISTOWN TENNESSEE WILL ISSUE
UPDATES TO THIS NOTICE...AS NEEDED.



$$


BB



Winter 2009-10 Snowfall: 11.5 in. :)
Winter 2010-11 Snowfall: 15.5 in. :)
Winter 2011-12: Trace
Winter 2012-2013: 0.25 in.
Winter 2013-14: 10.6 (9.5 on 2/12)
Winter 2014-2015: 10.25 in.
Winters 2015-2019: basically nothing
Winter 2019-2020:
2/8/20: 4.25

Memphis Weather

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #40 on: April 29, 2010, 11:24:22 AM »
Just a few morning thoughts...

Overall not much change in thinking. A few concerns for Friday...but many parameters still appear to be coming together...especially over the state of AR...but this may spread into adjacent portions of TN/MS by late evening/early morning Saturday...and after the nocturnal LLJ further enhances low level shear...while surface CAPE remains around or over ~1000 j/kg. This could be a situation where the best tornado threat happens after the LLJ intensifies. Again...can't disagree at all with the current SPC Day 2...and it may be upgraded to Moderate Risk at some point...

My concern for Saturday is growing for an event that could be as substantial...maybe even moreso...than Friday...especially from about I-40 southward and again West TN more than any part of the state...though the threat could at least reach to I-65. Some CAPE parameters approaching 2000 j/kg with still high directional shear and favorable hodographs...I will add that Saturday still has a degree of uncertainty inherent in exact convective evolution from the previous night and so forth...but the potential at the very least is increasing...

The heavy rainfall/flooding threat remain...amounts 3-6"...locally higher...continue to look likely.
« Last Edit: April 29, 2010, 11:28:13 AM by Memphis Weather »

Memphis Weather

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #41 on: April 29, 2010, 11:54:02 AM »
My main issue I'm seeing with Friday at this point is with lapse rates. They're not very ideal...especially in the low levels...and while there is no significant capping inversion (there is a weak one) storms dealing with these more marginal lapse rates may have a tough time organizing...and especially producing tornadoes. The increase in the LLJ and its associated wind transport helps increase the lapse rates after sunset...and that is why I think the best threat may occur after then...especially from 9 PM onward. Still...this would be the one "fly in the ointment" if there ends up being one to cause Friday to go the way of a bust. Its not enough of an issue for me right now to back off...but this is what I'll probably be watching most closely over the next 24 hours. Saturday doesn't have as big of a problem with this as Friday...its more about ongoing convection/cloudcover...etc.

Memphis Weather

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #42 on: April 29, 2010, 01:00:21 PM »
MEG will be holding a teleconference for EM...Spotters...and Media Partners...etc...at 1:30 PM. If there is anything substantial from it I will pass it along...

Memphis Weather

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #43 on: April 29, 2010, 01:45:53 PM »
MEG confidence in severe is Low-Mod Friday...Mod Saturday...for flooding is Mod Friday...High Saturday...more substantial threat of severe weather/tornadoes looks to set up south of I-40 Saturday and West of the MS River Friday...severe threat may shift north of I-40 Saturday but not much confidence in that at this time...Flash flooding trumps all threats at this point in terms of potential signficance/widespread occurrence (4-8" with up to 10" locally) but severe threat is not to be downplayed...

Offline toastido

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Re: *SWM* SEVERE WEATHER: 4/30 - 5/2
« Reply #44 on: April 29, 2010, 01:51:12 PM »
MEG will be holding a teleconference for EM...Spotters...and Media Partners...etc...at 1:30 PM. If there is anything substantial from it I will pass it along...

HUN is doing a briefing at 2pm..  If anything stands out I'll pass it along, but I have a feeling it's going to be less about the severe threat (which looks marginal at best) and more about the flooding potential.
Don't knock the weather. If it didn't change once in a while, nine out of ten people couldn't start a conversation.
Kin Hubbard
(1868 - 1930)
Quote
Adam: Girls come and go. Weather is constant
Quote
Eric (Admin): there's no fornication in meteorology

 

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