RSS Mesoscale Discussions from Storm Prediction Center
WW 390 SEVERE TSTM TX CW 170100Z - 170800Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 390
NWS Storm Prediction Center Norman OK
800 PM CDT Sun Jun 16 2019
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Central and south Texas
Coastal Waters
* Effective this Sunday night and Monday morning from 800 PM
until 300 AM CDT.
* Primary threats include...
Scattered damaging winds and isolated significant gusts to 75
mph likely
Isolated very large hail events to 2.5 inches in diameter
possible
A tornado or two possible
SUMMARY...Thunderstorms should pose a damaging-hail threat early in
their lifespans, with potential for upscale growth to a
southeastward-moving complex offering mainly severe wind with
isolated large hail across the coastal plain.
The severe thunderstorm watch area is approximately along and 70
statute miles north and south of a line from 55 miles south
southwest of San Angelo TX to 50 miles north northeast of Palacios
TX. For a complete depiction of the watch see the associated watch
outline update (WOUS64 KWNS WOU0).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 387...WW 388...WW 389...
AVIATION...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 600. Mean storm motion vector
29030.
...Edwards
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WW 0390 Status Updates
STATUS REPORT ON WW 390
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 ENE DRT
TO 40 SSE JCT TO 20 WNW BAZ TO 25 SSE AUS TO 35 NNW PSX TO 20 E
PSX.
FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1101
..DIAL..06/17/19
ATTN...WFO...EWX...HGX...CRP...SJT...
STATUS REPORT FOR WS 390
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
TXC007-013-019-025-029-055-057-091-123-175-177-187-239-255-259-
265-285-297-325-385-391-463-469-493-170740-
TX
. TEXAS COUNTIES INCLUDED ARE
ARANSAS ATASCOSA BANDERA
BEE BEXAR CALDWELL
CALHOUN COMAL DEWITT
GOLIAD GONZALES GUADALUPE
JACKSON KARNES KENDALL
KERR LAVACA LIVE OAK
MEDINA REAL REFUGIO
UVALDE VICTORIA WILSON
GMZ235-330-350-170740-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
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No Mesoscale Discussions are in effect as of Mon Jun 17 07:53:04 UTC 2019.
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Mon Jun 17 2019
Valid 171200Z - 181200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL
AND SOUTHERN HIGH PLAINS AND OVER PARTS OF THE MID ATLANTIC...
...SUMMARY...
Strong to severe storms capable of wind or hail are expected across
parts of the Mid Atlantic this afternoon, and across the central and
southern High Plains from late afternoon through evening.
...Synopsis...
A belt of moderate upper level winds will stretch from the northern
Plains across the Great Lakes and into the Northeast while generally
lax zonal flow remains over the central and southern Plains. At the
surface, a stationary front will remain from the mid MS Valley
eastward into southern New England, with ample moisture to the south
supporting scattered storms.
...Southeast TX...
Areas of storms will affect this region early in the day, with an
outflow boundary near the middle TX Coast. Areas ahead of the
outflow may experience strong wind gusts, and marginal/elevated hail
is possible behind the boundary. In general, the severe threat will
decrease during the day.
...Northeast CO into central NE...
A weak area of low pressure will develop over northeast CO this
afternoon, with easterly surface winds across NE near a stationary
front. Strong heating beneath 500 mb temperatures near -10 C will
create steep lapse rates and MLCAPE up to 2000 J/kg. This will favor
large hail and damaging outflow winds as storms develop near the low
and along the boundary. Winds aloft will be weak, thus the threat
area will not expand very far east during the evening.
...Eastern NM into west TX...
Mid 60s F dewpoints will spread into far west TX as a boundary
stalls and eventually returns north. Strong heating will lead to
substantial instability along with light but veering winds with
height. This will support scattered cellular development with large
hail likely by late afternoon, with merging outflows supporting a
wind threat as storms move into TX. An isolated storm with very
large hail cannot be ruled out over the Davis mountains.
...Eastern KY and TN to the Delmarva...
In the wake of early day activity, destabilization will again occur
along and south of an east-west boundary roughly from the OH River
into far southern PA. Despite generally rising heights aloft, a weak
disturbance will emerge across the OH Valley, enhancing lift.
However, the most unstable air mass will be farther east into VA, MD
and DE where MLCAPE up to 2500 J/kg is possible. Sporadic marginal
hail and localized damaging wind gusts are possible.
..Jewell/Karstens.. 06/17/2019
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SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Mon Jun 17 2019
Valid 181200Z - 191200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE SOUTHERN/CENTRAL PLAINS...
...SUMMARY...
Isolated severe thunderstorms should develop across parts of the
southern and central Plains on Tuesday, with large hail, damaging
winds, and perhaps a couple tornadoes possible. Other marginally
severe storms may occur from parts of the Southeast into the
Tennessee/Ohio Valleys and Mid Atlantic.
...Southern/Central Plains...
Although details regarding convective evolution remain somewhat
unclear for Tuesday across the southern/central Plains, concerns
about convection occurring over the High Plains on Monday (today)
and contaminating the airmass across much of this region have been
reduced. It appears that one or more subtle vorticity maxima will
move from the southern/central High Plains across KS/OK and the TX
Panhandle through the day. Mid-level west-northwesterly flow will
gradually increase across these regions in association with these
features. At the surface, a cold front should move southward across
NE/KS, while a dryline mixes eastward across the southern High
Plains through the afternoon.
Isolated to scattered storms will probably form both along the front
in KS and on the dryline across the TX/OK Panhandles into northwest
TX. Although relatively greater low-level moisture may remain
displaced to the south of these regions, steep mid-level lapse rates
will advect eastward through the day, and at least moderate to
perhaps very strong instability is forecast to develop across the
warm sector by late afternoon. Although effective bulk shear of
30-35 kt may be on the lower margins to support supercells, initial
convection along the dryline will likely pose a large hail threat,
and significant hail (2" in diameter or greater) may occur given the
very strong instability forecast. Farther north along the cold front
in KS, storms may have a tendency to grow upscale into a bowing
cluster and move southward into northern/eastern OK through the
evening. Damaging winds may eventually become the primary threat
with these storms.
The potential for a MCS to develop farther south into
central/southern OK and parts of north TX remains uncertain. But,
both the 00Z GFS and 12Z ECMWF show this as a possibility Tuesday
evening, and the airmass should remain unstable across these
regions. Damaging winds would be a concern with these storms if this
scenario were to occur. Isolated tornadoes may also occur across
parts of northwest TX and southwestern OK early Tuesday evening if
storms can remain relatively discrete as a low-level jet gradually
strengthens across this region.
...Southeast into the TN/OH Valleys and Mid Atlantic...
Yet another low-amplitude shortwave trough should move from parts of
the Southeast into the lower OH/TN Valleys and Mid Atlantic on
Tuesday. Around 30-40 kt of mid-level west-southwesterly flow should
be present ahead of this feature. At the surface, a weak boundary
should remain situated from southwest to northeast across parts of
the OH Valley into PA/NY. Thunderstorms that form ahead of the
shortwave trough and to the south of the front may pose an isolated
severe risk as they move eastward, with moderate buoyancy combining
with modest shear to support occasionally organized updrafts.
Isolated damaging winds should be the main threat where low-level
lapse rates can steepen due to diurnal heating. Some marginally
severe hail may also occur with the strongest cores.
...MAXIMUM RISK BY HAZARD...
Tornado: 5% - Slight
Wind: 15% - Slight
Hail: 15% SIG - Slight
..Gleason.. 06/17/2019
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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0231 AM CDT Mon Jun 17 2019
Valid 191200Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS TO THE MID MS VALLEY...
...SUMMARY...
Organized severe thunderstorms may occur Wednesday from parts of the
southern Plains into the mid Mississippi Valley, and potentially as
far north as the Midwest.
...Southern Plains into the Mid MS Valley and Midwest...
A shortwave trough initially over the southern/central Plains should
amplify Wednesday as it moves over the lower/mid MS Valley.
Seasonably strong mid-level flow will be present across these
regions, and a moist low-level airmass is also expected. As a
surface low develops northeastward across the Midwest, a cold front
will move southeastward over the mid MS Valley and parts of the
southern Plains. Storms should develop along the front by the
afternoon, with moderate to strong instability supporting robust
updrafts. Shear should be strong enough to support supercells, but
storms may have a tendency to grow upscale into one or more bowing
complexes given the linear forcing of the front. Regardless, the
forecast combination of instability and shear will likely support
organized severe thunderstorms through at least Wednesday evening.
Uncertainty exists regarding the potential for morning convection to
contaminate the warm sector, and the northward extent of
surface-based thunderstorms. For now, have not extended the Slight
Risk farther northward into IL/IN based on these uncertainties.
...Northern Plains...
Isolated severe storms may occur Wednesday afternoon along a surface
lee trough across parts of the northern Plains. Low-level moisture
should remain somewhat limited across this region, but increasing
westerly winds aloft associated with a mid-level jet overspreading
this region may support some thunderstorm organization through the
early evening.
..Gleason.. 06/17/2019
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0101 AM CDT Mon Jun 17 2019
Valid 171200Z - 181200Z
...NO CRITICAL AREAS...
...Synopsis...
A quasi-zonal flow pattern will remain in place today across much of
the CONUS, with a weak mid-level trough retrograding from the Great
Basin into portions of Southern California. In general, mid-level
flow will remain rather weak. At the surface, dry conditions will
persist across southern portions of the Desert Southwest, from
southern New Mexico/Arizona into southern Nevada/California. There
is some indication among the latest high-resolution guidance for
perhaps a brief period of locally elevated fire-weather conditions
to develop across south-central New Mexico, however, fuels here are
generally non-receptive given recent precipitation. Otherwise, given
the lack of any appreciable mid-level flow or forcing mechanisms,
surface winds should generally remain light, precluding the need for
any fire-weather highlights at this time.
..Karstens.. 06/17/2019
...Please see www.spc.noaa.gov/fire for graphic product...
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SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0102 AM CDT Mon Jun 17 2019
Valid 181200Z - 191200Z
...Synopsis...
The stagnant quasi-zonal flow pattern will begin to break down on
Tuesday as marginally enhanced mid-level westerly flow (35-45 kt)
associated with an upper-level jet streak enters the Pacific
Northwest. At the surface, an area of low pressure will develop,
beneath the right-exit/diffluence region of the upper-level jet,
across southern Canada and track into north-central Montana.
Otherwise, dry conditions will persist across southern portions of
the Desert Southwest where winds will generally remain light.
...Columbia Basin Vicinity...
Diurnal heating and vertical mixing of the marginally enhanced
mid-level flow will allow afternoon sustained westerly winds of
15-20 mph to develop as RH values fall into the 20-25% range amidst
fuels that are at least marginally receptive to large-fire spread.
Thus, an elevated fire-weather designation has been introduced for
the region, with perhaps some potential for locally critical
conditions, particularly in terrain-favored locations that can act
to locally enhance wind speeds.
..Karstens.. 06/17/2019
...Please see www.spc.noaa.gov/fire for graphic product...
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