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2011 - Mid-Atlantic Severe Storm Thread


Kmlwx

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I wouldn't get that specific at this point, but 5-6pm seems to be where it wants to set up. Of course, with the model spread still somewhat significant we're realistically looking at a +/- 6 hours centered around 5-6pm with this storm.

I am hoping for the 5-6 time-frame give me some time to get home to get prepped for it if I have to chase to get the best lightning. This if it does occur could be a great Birthday Present, and Early one at that as Tuesday is my 32nd Birthday.

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I am hoping for the 5-6 time-frame give me some time to get home to get prepped for it if I have to chase to get the best lightning. This if it does occur could be a great Birthday Present, and Early one at that as Tuesday is my 32nd Birthday.

Your sig makes me epileptic :lol:

My gut says we'll see our first decent thunderstorms of the season in many parts of the area but I still question how severe they can actually get. Not sure we see any huge tornado threat or anything like that. (That'll be in May and June) lol

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My gut says we'll see our first decent thunderstorms of the season in many parts of the area but I still question how severe they can actually get. Not sure we see any huge tornado threat or anything like that. (That'll be in May and June) lol

Agreed... this event will be another nowcasting extravaganza due to the unceasingly-complicated storm evolutions we've had since December. I wouldn't put my money on anything in particular at this point, but I'm leaning towards a forced line of strong/severe storms (or just rain further N). Nearly all wind stuff, with an outside chance of hail. Tornadoes aren't that big of a concern right now as it looks like the winds will shear away that potential. Despite the speed shear, there is some really good veering modeled in the lower levels, so there is still a threat for tornadoes despite the strong winds aloft.

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Agreed... this event will be another nowcasting extravaganza due to the unceasingly-complicated storm evolutions we've had since December. I wouldn't put my money on anything in particular at this point, but I'm leaning towards a forced line of strong/severe storms (or just rain further N). Nearly all wind stuff, with an outside chance of hail. Tornadoes aren't that big of a concern right now as it looks like the winds will shear away that potential. Despite the speed shear, there is some really good veering modeled in the lower levels, so there is still a threat for tornadoes despite the strong winds aloft.

Isn't backing wind more favorable for tornadoes than veering wind? I've always heard this...like last event SPC has a discussion that mentioned how winds were veering but they still thought there was a decent threat (as if veering would decrease the chances).

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Isn't backing wind more favorable for tornadoes than veering wind? I've always heard this...like last event SPC has a discussion that mentioned how winds were veering but they still thought there was a decent threat (as if veering would decrease the chances).

Veering wind is just wind turning clockwise with height. An example would be southerly winds at the surface and westerly winds aloft. When they say things like "winds are expected to be more backed at the surface" they're implying that instead of something like a southerly surface wind direction it would be more southeasterly instead. It's kind of a backwards way of using the terminology, but it is what it is.

The "technical" definition of veering and backing: http://www.theweathe...m/habyhints/48/

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Veering wind is just wind turning clockwise with height. An example would be southerly winds at the surface and westerly winds aloft. When they say things like "winds are expected to be more backed at the surface" they're implying that instead of something like a southerly surface wind direction it would be more southeasterly instead. It's kind of a backwards way of using the terminology, but it is what it is.

The "technical" definition of veering and backing: http://www.theweathe...m/habyhints/48/

So technically both veering and backing can be conducive for tornadoes?

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So technically both veering and backing can be conducive for tornadoes?

Only if you're talking about winds veering with height and "more backed winds" at the SFC :arrowhead:

Think of the "more backed" thing just in terms of the SFC winds in my example, and not with winds backing with height. Like I said, the terminology is pretty backwards.

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Only if you're talking about winds veering with height and "more backed winds" at the SFC :arrowhead:

Think of the "more backed" thing just in terms of the SFC winds in my example, and not with winds backing with height. Like I said, the terminology is pretty backwards.

Confusing! But I get it now! :thumbsup:

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18z NAM looking incredibly sexy! Lock it in! :thumbsup:

DC and surrounding area:

- High temps in the upper 60s to lower 70s... in the mid/upper 60s when the precip. arrives.

- CAPE in the 500-1000 J/kg range

- LI of -1 to -4

- 0-3 km helicity of 450-600 m2/s2

That just made my afternoon.

18z NAM has FROPA around midnight... probably too slow still.

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18z NAM looking incredibly sexy! Lock it in! :thumbsup:

DC and surrounding area:

- High temps in the upper 60s to lower 70s... in the mid/upper 60s when the precip. arrives.

- CAPE in the 500-1000 J/kg range

- LI of -1 to -4

- 0-3 km helicity of 450-600 m2/s2

That just made my afternoon.

18z NAM has FROPA around midnight... probably too slow still.

So NAM suggests a tornado threat is there?

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So NAM suggests a tornado threat is there?

The tornado threat is certainly a bit higher given the better thermal instability (if you take the NAM verbatim), but we'll still have the issues with the strong wind speeds shearing away some of the storms' rotation.

But to keep things in perspective for everyone, this is just one run of the NAM. It's certainly got some uplifting things in it and is a step in the right direction, but I wouldn't realistically get my hopes up yet.

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18z NAM looking incredibly sexy! Lock it in! :thumbsup:

DC and surrounding area:

- High temps in the upper 60s to lower 70s... in the mid/upper 60s when the precip. arrives.

- CAPE in the 500-1000 J/kg range

- LI of -1 to -4

- 0-3 km helicity of 450-600 m2/s2

That just made my afternoon.

18z NAM has FROPA around midnight... probably too slow still.

Oh man! When is a severe weather threat good? Only when weather weenies of the world unite! LOL! I mean we would hate it to hit our homes, but love the adrenaline! BTW Ellinwood, I mean nothing negative and I am not calling you a weenie, just made me chuckle at the excitement for something potentially bad!

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Oh man! When is a severe weather threat good? Only when weather weenies of the world unite! LOL! I mean we would hate it to hit our homes, but love the adrenaline! BTW Ellinwood, I mean nothing negative and I am not calling you a weenie, just made me chuckle at the excitement for something potentially bad!

Don't worry about it... I'm definitely a severe weather weenie (though a weenie with knowledge and some restraint :P). I think of wishing for severe weather no different than people who want a foot or more of snow... both are meteorologically fascinating, though they should be kept in perspective when pertaining to its actual impact towards life and property.

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Don't worry about it... I'm definitely a severe weather weenie (though a weenie with knowledge and some restraint :P). I think of wishing for severe weather no different than people who want a foot or more of snow... both are meteorologically fascinating, though they should be kept in perspective when pertaining to its actual impact towards life and property.

Agreed!

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00Z NAM starting to catch on to the right idea... FROPA for Monday night is a couple hours earlier around 10pm now. Some shifts in the placement of the instability, but the general idea is still the same.

My thoughts are leaning towards a high-end slight risk for our area. Not that confident considering the spread in possible solutions, but somewhere in the region could hit low-end Moderate Risk before all is said and done. Upgrade to Moderate Risk would most likely occur in a nowcasting/Day 1 situation.

I'll go 5 Tor / 30 Wind / 5 Hail with this update for the DC area.

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00Z NAM starting to catch on to the right idea... FROPA for Monday night is a couple hours earlier around 10pm now. Some shifts in the placement of the instability, but the general idea is still the same.

My thoughts are leaning towards a high-end slight risk for our area. Not that confident considering the spread in possible solutions, but somewhere in the region could hit low-end Moderate Risk before all is said and done. Upgrade to Moderate Risk would most likely occur in a nowcasting/Day 1 situation.

I'll go 5 Tor / 30 Wind / 5 Hail with this update for the DC area.

awfully bullish dude :hug::whistle:

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day2probotlk_20110227_0700_any_prt.gif

...LOWER-MID MS VALLEY TO CAROLINAS/MID-ATLANTIC REGION...

SVR EVENT DISCUSSED IN DAY-1 OUTLOOK WILL BE ONGOING INTO THIS

PERIOD ACROSS WRN PORTIONS OUTLOOK AREA...AND MAY FAN OUT TO AFFECT

BROAD SWATH OF ERN STATES THROUGH AFTERNOON/EVENING. DAMAGING WIND

WILL BE MAIN THREAT...WITH AT LEAST A FEW TORNADOES POSSIBLE.

CORRIDOR OF GREATER RISK AND MORE ENHANCED PROBABILITIES IS POSSIBLE

WITHIN THIS SWATH...BUT TOO DEPENDENT ON MESOSCALE PROCESSES TO

NARROW DOWN SPECIFICALLY ATTM.

SFC ANALYSIS SHOWS 60S F SFC ISODROSOTHERM ALREADY INLAND TO RED

RIVER VALLEY REGION OF S-CENTRAL/SE OK AND N-CENTRAL/NE TX AS OF

27/05Z...WITH MID-60S CENTRAL TX AND COASTAL PLAIN. RELATED MOIST

PLUME IS FCST TO ADVECT NEWD ACROSS OZARKS AND LOWER-MID MS VALLEY

DAY-1...LEADING EDGE OF WHICH MAY BE SUPPORTING AT LEAST MRGL SVR

HAIL POTENTIAL IN TSTMS ROOTED ABOVE SFC OVER PORTIONS NRN

INDIANA/OH BY 28/12Z. FARTHER S ACROSS WARM SECTOR...MORNING

BOUNDARY LAYER WILL CONTAIN CHARACTERISTIC TEMPORAL MAX IN STATIC

STABILITY IN SHALLOW/NEAR-SFC LAYER. HOWEVER...THETAE ADVECTION

WILL HELP TO OFFSET THIS TENDENCY ENOUGH TO YIELD SVR THREAT FROM

QLCS AND/OR EMBEDDED SUPERCELL MODES. FCST MORNING SOUNDINGS SHOW

MAGNITUDE/DEPTH OF STABLE LAYER TOO SMALL TO PRECLUDE EFFECTIVE

LIFTED PARCELS FROM BEING SFC-BASED...OR VERY NEARLY SO. MAIN

UNCERTAINTIES FOR EARLY IN PERIOD INVOLVE WHETHER ANY

EMBEDDED/PRECURSORY SUPERCELLS WILL BE PRESENT IN ADDITION TO

DOMINANT LINEAR CONVECTIVE MODE...AND HOW FAR SWD INITIAL BAND OF

MAY BACKBUILD INTO MORE STRONGLY CAPPED...ELEVATED MIXED-LAYER AIR.

ADDITIONAL DEVELOPMENT AND/OR BACKBUILDING OF INITIAL/MORNING

ACTIVITY IS EXPECTED DURING DAY ACROSS PORTIONS TN VALLEY REGION AND

AL INTO SRN APPALACHIANS...WHILE ACTIVITY ALONG/AHEAD OF COLD FRONT

FARTHER N MOVES EWD-ENEWD UP OH VALLEY AND INTO CENTRAL

APPALACHIANS. BROAD AREA OF FAVORABLE DEEP-LAYER SHEAR IS EXPECTED

ACROSS AT LEAST MRGLLY UNSTABLE WARM SECTOR...WITH MID-UPPER FLOW

STRENGTHENING JUST AHEAD OF COLD FRONT AS SHORTWAVE TROUGH APCHS.

STRONGEST ISALLOBARIC FORCING WILL BE SHIFTING NEWD ACROSS ST.

LAWRENCE VALLEY AND NY/NEW ENGLAND...AHEAD OF WARM

SECTOR...RESULTING IN SWLY SFC WINDS OVER MOST OF OUTLOOK AREA.

HOWEVER...FCST SOUNDINGS SUGGEST SLGT VEERING WITH HEIGHT IN LOWEST

1-2 KM...COMBINED WITH STG SPEED SHEAR...WILL PRODUCE FAVORABLY

ENLARGED HODOGRAPHS FOR BOWS...AS WELL AS SUPERCELLS EITHER EMBEDDED

WITHIN OR AHEAD OF CONVECTIVE BANDS. BROAD SWATHS OF DAMAGING WIND

APPEAR QUITE POSSIBLE...HENCE LARGE SIZE OF AOA 30% SVR

PROBABILITIES.

INSTABILITY WILL BE WEAKER WITH NWD EXTENT...BUT WITH AT LEAST

NEUTRAL TO WEAKLY POSITIVE BUOYANCY AS FAR N AS OH/PA IN SUPPORT OF

SVR THREAT. SRN EXTENT OF ORGANIZED SVR POTENTIAL REMAINS RATHER

UNCERTAIN ATTM...THEREFORE PROBABILITIES ARE TAPERED SWD TOWARD GULF

AND SEWD TOWARD COASTAL CAROLINAS.

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