Severe WX Severe Weather Event 3/28/17-3/31/17 (2 Viewers)


Lori

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I guess the worse GA is going to deal is that interstate bridge collapse from the fire! Well I mean there is a severe thunderstorm warning (take heed) but so far no outbreak in Dixie Alley!!
 

Matt Grantham

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That's true, it could be out in lalaland like other models were for this event. Still, accurately handling a very complex event/setup like this one makes me feel that much more confident in it.
Unfortunately it was inadequate with the last event that produced so much hail.

I think your point is very valid though. I don't recall the HRRR ever falsely indicating a bust by way of coastal convection or a contaminated warm sector.
 

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MD 0385 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF SOUTH CAROLINA AND FAR SOUTHERN NORTH CAROLINA



Mesoscale Discussion 0385
NWS Storm Prediction Center Norman OK
1153 PM CDT Thu Mar 30 2017

Areas affected...Portions of South Carolina and far southern North
Carolina

Concerning...Severe potential...Watch possible

Valid 310453Z - 310700Z

Probability of Watch Issuance...40 percent

SUMMARY...Thunderstorms will gradually organize across coastal South
Carolina over the next 2-3 hours, with a potential threat for a few
damaging-wind gusts and perhaps a tornado or two.

DISCUSSION...As large-scale ascent related to the main
upper/mid-level trough overspreads the southeast U.S. coast tonight,
thunderstorms should increase in coverage over parts of
central/coastal South Carolina. Over the next several hours, a weak
frontal boundary, currently stretching from the SC/GA border
east/southeastward to the central SC coast, will slowly advance
northeast in tandem with a strengthening low-level mass response. To
the south of this boundary, modest surface moistening (e.g., dew
points rising into the mid/upper 60s) across eastern SC will combine
with cooling aloft to produce MLCAPE values upwards of 500-1000
J/kg. In addition, as the trough approaches from the west,
south/southwesterly low/mid-level flow will strengthen and veer with
height, enhancing effective storm-relative helicity, especially in
the vicinity of the front/confluence boundary. Considering the
relatively moist and weakly unstable nature of the environment, more
vigorous/organized convection late tonight may support spotty
damaging winds and/or a couple tornadoes. While uncertainty remains
with regards to the timing and overall coverage of stronger
convection, enough potential exists that trends will be monitored
for possible watch issuance within the next 2-3 hours.

..Picca/Edwards.. 03/31/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MHX...RAH...ILM...CHS...CAE...GSP...

LAT...LON 32897914 32697982 33008077 33678181 33918195 34368129
34938021 35027931 34807824 34357760 33747778 32897914


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MD 0386 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR EAST-CENTRAL AND EASTERN NC...SOUTHEAST VA



Mesoscale Discussion 0386
NWS Storm Prediction Center Norman OK
0857 AM CDT Fri Mar 31 2017

Areas affected...east-central and eastern NC...southeast VA

Concerning...Severe potential...Watch possible

Valid 311357Z - 311600Z

Probability of Watch Issuance...40 percent

SUMMARY...Storm organization is expected this morning. Isolated
damaging winds are becoming an increasing possibility along with a
low conditional risk for a weak tornado.

DISCUSSION...13z subjective surface mesoanalysis places a residual
frontal zone over the eastern shore of MD and arcing southwest into
south-central VA. The maritime air mass south of the front becomes
increasingly unstable with southward extent with surface
temperatures over southeast VA near 60 degrees F to the mid-upper
60s in eastern NC. Likewise, dewpoints correspondingly range from
the upper 50s over southeast VA and into the middle 60s within a
plume of richer moisture near and north of Cape Fear. Modifying the
12z MHX raob for 13z surface conditions within the moist axis yields
250-500 J/kg MLCAPE.

The KMHX VAD shows a veering wind profile with height and 200-300
m2/s2 0-1 km SRH and 40-kt effective shear. Given the low CAPE/high
shear setup, a conditional risk for isolated severe will probably
evolve as storms gradually intensify. Considerable cloudiness/rain
will limit greater destabilization and an overall greater severe
risk. Nonetheless, a couple of line segments (most likely over
southeast VA into far northeast NC) may pose an isolated damaging
wind hazard and a supercell or two (in addition to a line segment)
may yield a conditionally higher risk for isolated severe over
eastern NC.

..Smith/Hart.. 03/31/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...AKQ...MHX...RAH...ILM...

LAT...LON 34357874 36577822 37497743 37407654 36357560 35257555
33827795 34357874


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Kory

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I was camping out on Mt. Cheaha last night for a university sanctioned geology exercise. It got really crazy at about 7pm. We had winds gusting over 50mph. People's tents were going airborne. I lost my tent. A few trees came down. It was rough for about 30 minutes.
 

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MD 0387 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTHERN NC AND SOUTHERN VA



Mesoscale Discussion 0387
NWS Storm Prediction Center Norman OK
0108 PM CDT Fri Mar 31 2017

Areas affected...northern NC and southern VA

Concerning...Severe potential...Watch possible

Valid 311808Z - 311915Z

Probability of Watch Issuance...40 percent

SUMMARY...An isolated marginally severe hail and localized damaging
wind risk will probably develop.

DISCUSSION...Subjective surface analysis places a residual wedge
front/outflow boundary in a west-to-east orientation along the NC/VA
border. To the south of the boundary, temperatures have warmed into
the lower 70 degrees F with dewpoints in the lower 60s. As a
result, 0-3 km lapse rates are steepening and may aid in leading to
potential for localized damaging winds as storms develop and
intensify. Strong southwesterly low- to mid-level flow (40-55 kt at
500 mb) will serve to organize updrafts. Marginally severe hail and
gusty winds will be possible with the stronger cores as storms
develop eastward near/along the NC/VA border this afternoon.

..Smith/Hart.. 03/31/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...AKQ...MHX...RAH...RNK...GSP...

LAT...LON 36967973 36887843 36957715 36477680 36017730 35847830
35748058 35938077 36967973


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Tornado OTG near Norfolk, Va

kakq_20170331_2150_SRV_0.4.png

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 600 PM EDT FOR ...THE
NORTHWESTERN CITY OF CHESAPEAKE AND THE SOUTHEASTERN CITY OF
SUFFOLK...

At 541 PM EDT, a confirmed large and extremely dangerous tornado was
located near Downtown Suffolk, moving east at 25 mph.

This is a PARTICULARLY DANGEROUS SITUATION. TAKE COVER NOW!

HAZARD...Damaging tornado.

SOURCE...Radar confirmed tornado.

IMPACT...You are in a life-threatening situation. Flying debris may
be deadly to those caught without shelter. Mobile homes
will be destroyed. Considerable damage to homes,
businesses, and vehicles is likely and complete destruction
is possible.

The tornado will be near...
Bowers Hill around 555 PM EDT.
Chesapeake around 600 PM EDT.

Other locations impacted by this tornadic thunderstorm include
Suffolk Airport, Saunders, Magnolia, Nurney, Chesapeake Airport and
Kilby.
 

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MD 0388 CONCERNING TORNADO WATCH 105... FOR PORTIONS OF COASTAL VIRGINIA/NORTH CAROLINA



Mesoscale Discussion 0388
NWS Storm Prediction Center Norman OK
0511 PM CDT Fri Mar 31 2017

Areas affected...Portions of coastal Virginia/North Carolina

Concerning...Tornado Watch 105...

Valid 312211Z - 312345Z

The severe weather threat for Tornado Watch 105 continues.

SUMMARY...The threat for a couple tornadoes, isolated instances of
large hail, and a few damaging-wind gusts continues.

DISCUSSION...Multiple supercells, as well as a small linear segment
with an embedded mesovortex, continue eastward across Watch 105 this
evening. One tornado was already evident via a dual-pol debris
signature (around 2135Z) near Suffolk, VA. Occasional ZDR arc
signatures with this supercell, as well as two to the
west/southwest, suggest a near-storm environment characterized by
favorable low-level storm-relative flow veering with height.
Interaction with a weak warm front lingering over the area and/or
recent outflow boundaries may further yield an uptick in tornado
potential, as localized backing of near-surface winds occurs.
Sufficient buoyancy/effective shear overlap (especially with
southward extent) will also encourage a few instances of severe
hail.

As mid-level ascent increases with the approach of the main
vorticity maximum to the west, these cells should persist as they
head toward the coast. Indeed, this ascent is likely aiding a linear
segment currently near Greenville County, VA. As it pushes east, an
attendant threat for damaging wind and an embedded tornado or two
will likely exist with this line, with the overall threat ending
following its passage.

..Picca.. 03/31/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...AKQ...RAH...

LAT...LON 36097630 35927676 36067722 36567752 37177766 37217667
36927591 36327560 36117609 36097630


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Lori

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Several minutes ago, TWC was showing an impressive correlation coefficient and now they are saying law enforcement confirmed a tornado....storm is headed to VA Beach...
 

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MD 0389 CONCERNING WINTER MIXED PRECIPITATION FOR PORTIONS OF NEW ENGLAND



Mesoscale Discussion 0389
NWS Storm Prediction Center Norman OK
0717 PM CDT Fri Mar 31 2017

Areas affected...Portions of New England

Concerning...Winter mixed precipitation

Valid 010017Z - 010615Z

SUMMARY...Pockets of freezing rain up to 0.05 inches per hour will
continue/expand this evening into the overnight hours across parts
of southern/central New England (especially over higher elevations).
Freezing rain may mix with sleet at times as well. Farther north,
snowfall rates up to 1 inch per hour will be possible across
southern New Hampshire and vicinity later this evening into tonight.

DISCUSSION...Recent surface analysis depicts pressure falls of
around 1-1.5 mb/hr along and offshore the New Jersey and Long Island
coasts this evening. In turn, a surface cyclone currently near the
Mid-Atlantic coast will advance northeast towards the New York Bight
as it deepens. Concurrently, enhanced 850-700-mb flow and related
warm advection/isentropic ascent will spread eastward towards
southern New England, maintaining a broad shield of precipitation
over the region.

Surface observations indicate a mixture of sleet and freezing rain
occurring at several sites across Massachusetts and northern
Connecticut presently, and forecast soundings suggest winter
precipitation is likely more prominent in locations above 500-700 ft
in elevation. As the offshore low further deepens and shifts
northeast, backing near-surface winds will allow near/sub-freezing
temperatures to expand across parts of northern Connecticut
northward into Massachusetts. Thus, pockets of freezing rain upwards
of 0.05 inches per hour should persist/expand through the overnight,
while occasionally mixing with/changing to sleet.

Farther north, KBOX dual-pol data illustrate the northeastern extent
of the melting layer extending from far southern New Hampshire
southeastward to Cape Cod. While the low-level jet/warm advection
will further amplify, diabatic cooling effects from melting
hydrometeors and adiabatic cooling from broad ascent should preclude
much movement of this transition zone tonight. In turn, north of
this boundary, snowfall rates may increase up to 1 inch per hour
late this evening.

..Picca.. 04/01/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...GYX...BOX...BTV...ALY...

LAT...LON 42367138 41997204 41717313 41677344 42687332 43347308
43827183 43837109 43627079 43277075 42727074 42367138


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WesL

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I'm ordering TWBot to stand down for this event and moving this event out of the pinned event list. Thanks everyone. See you on Monday.
 

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