MARCH 2021

General Weather Discussions and Analysis
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tireman4
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This has the potential to be bad. I remember the long-track tornado that moved from Tuscaloosa to Birmingham...watching on the Weather Channel...just amazed. A TORCON of 9. Goodness.
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tireman4
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Meanwhile, back in our area...

Special Weather Statement
Special Weather Statement
National Weather Service Houston/Galveston TX
1039 AM CDT Wed Mar 17 2021

TXZ213-227-237-171615-
Inland Brazoria TX-Inland Harris TX-Fort Bend TX-
1039 AM CDT Wed Mar 17 2021

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL FORT BEND...NORTHERN
BRAZORIA AND SOUTH CENTRAL HARRIS COUNTIES UNTIL 1115 AM CDT...

At 1038 AM CDT, Doppler radar was tracking a strong thunderstorm over
Pleak, or near Rosenberg, moving northeast at 35 mph.

Pea size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Pearland, Sugar Land, Missouri City, Rosenberg, Stafford, Bellaire,
West University Place, Richmond, northwestern Manvel, Hunters Creek
Village, Bunker Hill Village, Piney Point Village, Midtown Houston,
Greenway / Upper Kirby Area, Fresno, Neartown / Montrose, Town West,
Pecan Grove, Memorial Park and University Place.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 2939 9580 2952 9592 2982 9541 2953 9528
TIME...MOT...LOC 1538Z 245DEG 32KT 2951 9577

$$



Special Weather Statement
Special Weather Statement
National Weather Service Houston/Galveston TX
1030 AM CDT Wed Mar 17 2021

TXZ212-213-227-171615-
Waller TX-Inland Harris TX-Fort Bend TX-
1030 AM CDT Wed Mar 17 2021

...SPECIAL WEATHER STATEMENT...

At 1030 AM CDT, Doppler radar was tracking a strong thunderstorm near
Orchard, or near Rosenberg, moving northeast at 50 mph.

Pea size hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Sugar Land, Rosenberg, Stafford, Bellaire, West University Place,
Katy, Richmond, Jersey Village, Hunters Creek Village, Bunker Hill
Village, Piney Point Village, Greenway / Upper Kirby Area, Spring
Branch North, Greater Heights, Mission Bend, Neartown / Montrose,
Town West, Near Northside Houston, Pecan Grove and Memorial Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 2943 9584 2955 9604 3004 9576 2979 9533
TIME...MOT...LOC 1530Z 222DEG 42KT 2959 9589

$$
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Mesoscale Discussion 0200
NWS Storm Prediction Center Norman OK
1056 AM CDT Wed Mar 17 2021

Areas affected...Central MS...Central AL

Concerning...Severe potential...Tornado Watch likely

Valid 171556Z - 171800Z

Probability of Watch Issuance...95 percent

SUMMARY...The environment is becoming increasingly favorable for
tornadic supercells and a PDS tornado watch will likely be needed
within the next hour or two.

DISCUSSION...Regional radar and satellite imagery continues to show
deepening convection within the broad and robust warm-air advection
regime across much of MS and AL. Some modest clearing occurred
briefly ahead of the leading showers over MS and temperatures across
much of central and southern MS are now in the mid 70s. Slightly
cooler surface temperatures exist across central/southern AL.
Dewpoints exhibit a similar trend, with upper 60s/low 70s across
much of central/southern MS and mid to upper 60s across
central/southern AL. These thermodynamic conditions have eroded much
of the convective inhibition across the region, although forecast
soundings do suggests some minimal (i.e. MLCIN of -25 J/kg or more)
likely remains in place at the top of the boundary layer. Continued
moistening of the low-level profile coupled with slight cooling
aloft should result in a removal of all convective inhibition.

In addition to improving thermodynamics, the low-level wind fields
continue to increase. Recent VAD profiles from LIX and DGX show 50
kts within the 1-2 km layer. Latest VAD from DGX also sampled 0-3 km
storm-relative helicity over 350 m2/s2. These strengthening
low-level winds are expected to persist while gradually spreading
northward/northeastward into more of northern AL. Deep-layer
vertical shear is already in place over the region, with 0-6 km bulk
shear currently 50 kt over central MS/AL, increasing to 70 kt over
northern MS/AL.

In all, the overall environment is expected to becoming increasingly
favorable for discrete supercells capable of all severe hazards,
including intense tornadoes. These initial storms are forecast to
develop within the 17-19Z time frame. A prolonged threat for
tornadoes is anticipated across the region, with conditions
remaining favorable well into the evening.

..Mosier/Grams.. 03/17/2021

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

ATTN...WFO...BMX...HUN...MOB...MEG...JAN...

LAT...LON 32929083 34038838 33898610 32588612 31368837 31479076
32929083
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BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Houston/Galveston TX
1111 AM CDT Wed Mar 17 2021

The National Weather Service in League City has issued a

* Severe Thunderstorm Warning for...
Northeastern Fort Bend County in southeastern Texas...
Southeastern Montgomery County in southeastern Texas...
Northwestern Chambers County in southeastern Texas...
Southwestern Liberty County in southeastern Texas...
Central Harris County in southeastern Texas...

* Until 1145 AM CDT.

* At 1110 AM CDT, a severe thunderstorm was located over Afton Oaks /
River Oaks Area, moving northeast at 50 mph.

HAZARD...Quarter size hail.

SOURCE...Radar indicated.

IMPACT...Damage to vehicles is expected.

* Locations impacted include...
Northwestern Pasadena, northern Baytown, northern Missouri City,
Deer Park, Bellaire, Humble, West University Place, Galena Park,
Jacinto City, Jersey Village, Dayton, Hunters Creek Village, Bunker
Hill Village, Piney Point Village, Cloverleaf, Downtown Houston,
Greenway / Upper Kirby Area, Kingwood, Spring Branch North and
Second Ward.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Cloud to ground lightning is occurring with this storm. Move indoors
immediately. Lightning is one of nature's leading killers. Remember,
if you can hear thunder, you are close enough to be struck by
lightning.

&&

LAT...LON 2959 9547 2979 9567 3024 9509 2988 9473
TIME...MOT...LOC 1610Z 234DEG 49KT 2975 9543

HAIL...1.00IN
WIND...<50MPH

$$
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don
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First severe thunderstorm of the season. The rain is very heavy right now.
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Mesoscale Discussion 0201
NWS Storm Prediction Center Norman OK
1135 AM CDT Wed Mar 17 2021

Areas affected...Southeast Texas and western Louisiana

Concerning...Tornado Watch 28...

Valid 171635Z - 171800Z

The severe weather threat for Tornado Watch 28 continues.

SUMMARY...A new watch may be needed south of Watch 28 across
southeast Texas and western Louisiana.

DISCUSSION...The well-developed squall line has started to break up
and weaken across northern Louisiana and southern Arkansas where the
line has moved ahead of the front. However, stronger storms continue
farther south where storms are closer to the surface front in an
area of greater low-level convergence. These storms extend into
southeast Texas where no watch is currently in effect and thus a new
watch may need to be issued soon. The current tornado threat is
somewhat lower with southern extent as low-level wind fields are
quite unidirecitonal. However, the low-level jet is expected to
strengthen over the next few hours which may increase the tornado
threat. Damaging winds and large hail will be the primary threat in
the near term given around 1000 to 1500 J/kg MLCAPE and effective
shear around 50 knots.

..Bentley/Grams.. 03/17/2021

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

ATTN...WFO...LCH...SHV...HGX...

LAT...LON 32629374 32689292 32349220 31719225 30239289 29739311
29669383 29369449 28979509 28869532 29079582 29729573
32629374
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URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 29
NWS Storm Prediction Center Norman OK
1135 AM CDT Wed Mar 17 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
Western and central Alabama
Central to eastern Mississippi

* Effective this Wednesday morning and evening from 1135 AM until
700 PM CDT.

...THIS IS A PARTICULARLY DANGEROUS SITUATION...

* Primary threats include...
Numerous tornadoes expected with a few intense tornadoes likely
Scattered damaging winds and isolated significant gusts to 80
mph likely
Scattered large hail and isolated very large hail events to 3
inches in diameter likely

SUMMARY...Numerous discrete supercells are expected to develop this
afternoon capable of producing strong to intense tornadoes.

The tornado watch area is approximately along and 80 statute miles
east and west of a line from 70 miles northwest of Gadsden AL to 35
miles southeast of Pine Belt MS. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU9).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 26...WW 27...WW 28...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 3 inches. Extreme turbulence and surface wind
gusts to 70 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 24030.

...Grams
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jasons2k
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It was a dud here. Only 0.02”
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don
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We could have a higher potential for severe weather and heavy rain next week as a trough dips down over the plains.
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It's gonna be an angry spring
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URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 30
NWS Storm Prediction Center Norman OK
1155 AM CDT Wed Mar 17 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of
Southwest Louisiana
Far southeast Texas
Coastal Waters

* Effective this Wednesday morning and evening from 1155 AM until
600 PM CDT.

* Primary threats include...
A few tornadoes likely with a couple intense tornadoes possible
Scattered damaging winds and isolated significant gusts to 75
mph possible
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible

SUMMARY...A few discrete supercells should develop along and just
ahead of the cold front pushing east from southeast Texas. The
greatest tornado threat is expected towards central Louisiana during
the late afternoon.

The tornado watch area is approximately along and 70 statute miles
east and west of a line from 30 miles northeast of Fort Polk LA to
50 miles south southwest of Lake Charles LA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU0).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 26...WW 27...WW 28...WW
29...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2.5 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 550. Mean
storm motion vector 24035.

...Grams
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Mesoscale Discussion 0202
NWS Storm Prediction Center Norman OK
1202 PM CDT Wed Mar 17 2021

Areas affected...Portions of southeast Mississippi and southwest
Alabama

Concerning...Tornado Watch 29...

Valid 171702Z - 171800Z

The severe weather threat for Tornado Watch 29 continues.

SUMMARY...A strong tornado threat will increase from Wayne county,
Mississippi to Marengo and Wilcox counties in Alabama over the next
1-2 hours.

DISCUSSION...Shower activity through the morning has continued to
deepen and a strong storm has developed in Jones County, MS. This
storm has quickly exhibited low-level rotation which is indicative
of the favorable low-level shear profile in this region. SPC
mesoanalysis shows an area of 300 to 400 m2/s2 of 0-3km SRH in this
region which is a result of southeasterly surface winds in local
observations in this area and a 50 knot south-southwesterly
low-level jet around 1.5km to 2km sampled by the KMOB and KDGX VWP.
The ongoing storm in this region in addition to any subsequent
development could pose a significant tornado threat given the
aforementioned favorable low-level shear profile and STP values
around 2 to 3.

..Bentley/Grams.. 03/17/2021

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

ATTN...WFO...BMX...MOB...JAN...

LAT...LON 31808915 32228864 32538795 32418740 32128729 31668749
31588799 31458874 31478910 31538924 31808915
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Belmer
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The WMO (World Meteorological Organization) Hurricane Committee has retired Dorian from 2019 and Laura, Eta and Iota (2020) from the rotating list of Atlantic names due to the damage and death associated with them.

Also interesting of note in the article, "It also decided that the Greek alphabet will not be used in future because it creates a distraction from the communication of hazard and storm warnings and is potentially confusing."

More here: https://public.wmo.int/en/media/press-r ... e-of-greek
Blake
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Mesoscale Discussion 0209
NWS Storm Prediction Center Norman OK
0224 PM CDT Wed Mar 17 2021

Areas affected...Central AL

Concerning...Tornado Watch 29...33...

Valid 171924Z - 172100Z

The severe weather threat for Tornado Watch 29, 33 continues.

SUMMARY...A corridor more favorable for the development of strong
tornadoes may be evolving across central AL.

DISCUSSION...Radar imagery from BMX, GWX, and MOB continues to show
a cluster of supercells over west-central AL. The downstream air
mass is characterized by temperatures in the low/mid 70s and
dewpoints in the upper 60s. As noted in the recent BMX sounding,
this air mass is less buoyant than farther west (along the central
MS/AL border) where this cluster initially developed. However, in
contrast to the slightly less favorable thermodynamics, surface
winds here are more southeasterly, veering to southerly in the
low-levels, and then southwesterly farther aloft. This is resulting
in considerable low-level vertical shear. Recent VAD profile from
BMX sampled 350+ m2/s2 of 0-1 km storm-relative helicity. Given the
already organized character of these storms, potential exists for
the development of strong tornadoes if a more discrete nature can be
maintained.

..Mosier.. 03/17/2021

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

ATTN...WFO...BMX...MOB...
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Radar scan just south/southeast of Tuscaloosa...

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Mesoscale Discussion 0210
NWS Storm Prediction Center Norman OK
0256 PM CDT Wed Mar 17 2021

Areas affected...Northeast Louisiana...southeast Arkansas and much
of Mississippi.

Concerning...Tornado Watch 32...

Valid 171956Z - 172130Z

The severe weather threat for Tornado Watch 32 continues.

SUMMARY...The tornado threat is expected to increase late this
afternoon/evening.

DISCUSSION...Most of Mississippi is in a relative lull for
convective coverage/intensity with more intense convection to the
east with the stronger low-level jet and to the west near the
surface trough. Within this area, significant clearing has allowed
temperatures to warm into the low 80s with dewpoints in the upper
60s yielding MLCAPE of 1500 to 2000 J/kg per SPC mesoanalysis. This
strong surface heating has led to deep boundary layer mixing (as
evident on the 18Z JAN RAOB) and as a result, surface flow has
veered southwesterly across much of Mississippi which has reduced
low-level directional shear significantly. However, despite this
veered low-level flow, a widespread and potentially intense tornado
threat is still expected late this afternoon/evening as the surface
trough approaches.

Low-level flow in proximity to this surface trough has started to
back across southeast Arkansas and Louisiana. Expect this trend to
continue as the boundary tightens in response to the ejecting upper
trough. Evidence of this ejecting trough and the corresponding
increase to the flow field can be seen on the KLCH VWP where 1km
flow has strengthened by 20 kts (to near 60 knots) within the last
hour. Expect this stronger low-level jet to overspread much of the
warm sector by 22-00Z which should elongate low-level hodographs
substantially.

Expect multiple supercells to develop along this surface boundary in
the next few hours and track northeastward through the late
afternoon and into the evening hours. In response to the
aforementioned instability and strengthening low-level shear, the
12Z HREF shows widespread 4+ STP across much of Mississippi this
afternoon/evening with some areas in excess of 6. This environment
will support the potential for intense/long-track tornadoes through
the late afternoon and evening hours.

..Bentley.. 03/17/2021

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

ATTN...WFO...HUN...MEG...JAN...LIX...LZK...LCH...SHV...
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Belmer wrote: Wed Mar 17, 2021 2:20 pm The WMO (World Meteorological Organization) Hurricane Committee has retired Dorian from 2019 and Laura, Eta and Iota (2020) from the rotating list of Atlantic names due to the damage and death associated with them.

Also interesting of note in the article, "It also decided that the Greek alphabet will not be used in future because it creates a distraction from the communication of hazard and storm warnings and is potentially confusing."

More here: https://public.wmo.int/en/media/press-r ... e-of-greek
Dexter replaces Dorian and Leah replaces Laura.

Alternative lists of names instead of Greeks for Atlantic and Pacific....

https://public.wmo.int/en/media/news/su ... names-raiv
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don
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Looking at the models today for right now I would be more concerned with heavy rain, than severe weather for us next week as instability may be lacking.But of course that could change.
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