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LU9DCE > ALERT 17.07.21 19:51z 444 Lines 21885 Bytes #999 (0) @ WW
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Subj: STORM PREDICTION CENTER 17-JUL.21
Path: HB9ON<IW2OHX<IW0QNL<IZ3LSV<DB0ERF<DK0WUE<PE1RRR<KA1VSC<LU9DCE
Sent: 210717/1942Z 2363@LU9DCE.TOR.BA.ARG.SOAM LinBPQ6.0.21
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ESTACION DE PACKET RADIO - BUENOS AIRES (GF05OM)
BOLETINES INFORMATIVOS PROGRAMADOS (BIP)
Copyright 2021 Eduardo A. Castillo
+----------------------------------------------------------------------------+
Storm Prediction Center
en-us
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Sat, 17 Jul 2021 19:03:02 +0000
Sat, 17 Jul 2021 19:03:02 +0000
general
1
WW 382 SEVERE TSTM CT DC DE MA MD NJ NY PA VA WV CW 171710Z - 180300Z
0-CWZ000-180300-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 382
NWS Storm Prediction Center Norman OK
110 PM EDT Sat Jul 17 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Connecticut
District Of Columbia
Delaware
western Massachusetts
Maryland
New Jersey
southeast New York
central and eastern Pennsylvania
northern Virginia
northeast West Virginia
Coastal Waters
* Effective this Saturday afternoon and evening from 110 PM until
1100 PM EDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph likely
A tornado or two possible
SUMMARY...Storms will continue to develop and intensify within the
destabilizing warm sector across a portion of the Middle Atlantic
and Northeast States this afternoon and evening. Mostly multicells
and some marginal supercell structures are expected with storms
evolving into lines and bowing segments capable of mainly scattered
wind damage.
The severe thunderstorm watch area is approximately along and 125
statute miles east and west of a line from 30 miles east northeast
of Binghamton NY to 50 miles south southwest of Washington DC. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU2).
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.
&&
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
cumulonimbi with maximum tops to 500. Mean storm motion vector
26035.
...Dial
Read more
Sat, 17 Jul 2021 18:35:03 +0000
WW 0382 Status Updates
000-CWZ000-171940-
STATUS REPORT ON WW 382
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
..GLEASON..07/17/21
ATTN...WFO...OKX...BOX...ALY...LWX...PHI...BGM...CTP...
STATUS REPORT FOR WS 382
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
CTC001-003-005-007-009-013-171940-
CT
. CONNECTICUT COUNTIES INCLUDED ARE
FAIRFIELDHARTFORDLITCHFIELD
MIDDLESEXNEW HAVENTOLLAND
DEC001-003-005-171940-
DE
. DELAWARE COUNTIES INCLUDED ARE
KENTNEW CASTLE SUSSEX
DCC001-171940-
DC
. DISTRICT OF COLUMBIA COUNTIES INCLUDED ARE
DISTRICT OF COLUMBIA
Read more
Sat, 17 Jul 2021 18:35:03 +0000
MD 1307 CONCERNING SEVERE THUNDERSTORM WATCH 382... FOR PORTIONS OF NORTHERN VA...DC...CENTRAL/EASTERN MD...EASTERN PA...DE...NJ...AND SOUTHERN NY
Mesoscale Discussion 1307
NWS Storm Prediction Center Norman OK
0202 PM CDT Sat Jul 17 2021
Areas affected...Portions of northern VA...DC...central/eastern
MD...eastern PA...DE...NJ...and southern NY
Concerning...Severe Thunderstorm Watch 382...
Valid 171902Z - 172030Z
The severe weather threat for Severe Thunderstorm Watch 382
continues.
SUMMARY...The best chance for scattered damaging wind gusts in the
next couple of hours should focus across parts of northern Virginia
into central/eastern Maryland, eastern Pennsylvania, Delaware, New
Jersey, and far southern New York.
DISCUSSION...Storms have started to form into small clusters along
and ahead of a pre-frontal trough across the Mid-Atlantic. The
airmass downstream of these storms is moderately to strongly
unstable, with MLCAPE of 2000-3000 J/kg present. Steep low-level
lapse rates owing to strong diurnal heating of a very well mixed
boundary layer are promoting efficient downdraft accelerations. KEWR
(Newark NJ) measured a peak severe wind gust to 50 kt when a storm
moved through at 1849Z, while KOMH (Orange County Airport in
northern VA) similarly recorded a wind gust to 46 kt at 1815Z.
Modest but sufficient effective bulk shear around 20-30 kt will
likely continue fostering modest storm organization, with multicell
clusters the primary storm mode. Current expectations are for these
clusters to pose a scattered damaging wind threat for the next
couple of hours as they move eastward across northern VA, DC,
central/eastern MD, eastern PA, DE, NJ, and far southern NY,
including the NYC metro area.
..Gleason.. 07/17/2021
ATTN...WFO...OKX...PHI...CTP...LWX...
LAT...LON38167794 38717781 39317724 39647653 40637612 41107490
41147392 40917359 39927403 39507426 39127481 38797570
38307739 38167794
Read more
Sat, 17 Jul 2021 19:03:03 +0000
MD 1306 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL/WESTERN OKLAHOMA INTO THE OKLAHOMA AND TEXAS PANHANDLES
Mesoscale Discussion 1306
NWS Storm Prediction Center Norman OK
0142 PM CDT Sat Jul 17 2021
Areas affected...Central/Western Oklahoma into the Oklahoma and
Texas Panhandles
Concerning...Severe potential...Watch unlikely
Valid 171842Z - 172115Z
Probability of Watch Issuance...20 percent
SUMMARY...Thunderstorms are starting to increase in coverage and
intensity across northwestern Oklahoma.Although there is
significant uncertainty with regard to thunderstorm evolution this
afternoon, the lack of better shear will likely preclude the need
for a watch.
DISCUSSION...Elevated thunderstorms overnight and this morning over
southern Kansas have resulted in merging outflow boundaries across
northwestern Oklahoma.With strong insolation and low 70F
dewpoints, surface-based storms have begun to initiate along the
effective boundary in a moderately unstable environment (~2000 J/kg
MLCAPE per mesoanalysis). The midlevel west-northwesterly flow (~25
knots per the VNX VWP) is enhanced by a convectively-induced
midlevel perturbation moving southeastward across the region. When
coupled with 5-10 knot southerly low-level winds ahead of the
boundary, 25-35 knots of effective bulk shear is expected to support
some storm organization and associated severe weather threat (hail
and wind for the strongest cores) through the afternoon/early
evening across western/central Oklahoma and the Texas Panhandle.
Overall, the lack of stronger shear/flow is expected to limit the
coverage of severe weather, but convective trends will continue to
be monitored.
..Jirak/Dial.. 07/17/2021
ATTN...WFO...TSA...OUN...LUB...AMA...
LAT...LON36780227 36280105 35980021 35989949 36089876 36179848
36249806 36529664 36229636 35799626 35209652 34799694
34409768 34289859 34259974 34340054 34520119 35060192
35790239 36010254 36270273 36780227
Read more
Sat, 17 Jul 2021 18:43:03 +0000
MD 1305 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHERN VA AND WESTERN/CENTRAL NC
Mesoscale Discussion 1305
NWS Storm Prediction Center Norman OK
1215 PM CDT Sat Jul 17 2021
Areas affected...Portions of southern VA and western/central NC
Concerning...Severe potential...Watch unlikely
Valid 171715Z - 171945Z
Probability of Watch Issuance...20 percent
SUMMARY...A threat for occasional damaging wind gusts should
continue as storms move eastward this afternoon. The overall severe
threat will probably remain fairly isolated/marginal, and watch
issuance appears unlikely at this time.
DISCUSSION...Storms have recently formed along/east of the Blue
Ridge Mountains in southern VA and western NC. Additional storms may
develop this afternoon along a pre-frontal trough across
south-central VA into central NC. Visible satellite imagery shows
mostly clear skies ahead of this activity, and robust diurnal
heating has already warmed surface temperatures into the upper 80s
and lower 90s as of 17Z. MLCAPE of 1500-3000 J/kg will be present
across the warm sector, even with mid-level lapse rates remaining
poor. Steepening low-level lapse rates should support some potential
for strong/gusty downdraft winds with any loosely organized clusters
that can form. However, deep-layer shear is expected to remain quite
weak across this region (25 kt or less), with the stronger mid-level
southwesterly flow displaced well to the north. This should keep
overall storm organization modest at best, and the threat for
damaging wind gusts fairly isolated. At this point, it appears that
Severe Thunderstorm Watch issuance will probably not be needed due
to the limited storm organization expected.
..Gleason/Dial.. 07/17/2021
ATTN...WFO...AKQ...RAH...RNK...GSP...
LAT...LON35528102 35938140 36438120 37058005 37487884 37777832
37737756 37027740 36167768 35497850 35367964 35528102
Read more
Sat, 17 Jul 2021 17:16:03 +0000
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1124 AM CDT Sat Jul 17 2021
Valid 171630Z - 181200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
THE NORTHEAST STATES AND MIDDLE ATLANTIC AS WELL AS THE NORTHERN
THROUGH CENTRAL HIGH PLAINS...
...SUMMARY...
Thunderstorms with damaging wind are expected over a portion of the
Northeast/Mid-Atlantic today. Other storms with damaging wind and
large hail are possible this afternoon/evening across parts of the
northern through central High Plains.
...Northeast through Middle Atlantic...
Surface analysis as of mid-day shows a warm front from MA westward
through southern NY to a weak surface low over Lake Erie. A cold
front extends southwest from the low through OH. The warm sector
south of these boundaries is very moist with 70F dewpoints, and
mostly clear to partly sunny skies are already occurring from the
Middle Atlantic area into much of PA, southern New England into MD,
VA where MLCAPE between 1500 and 2500 J/kg is likely this afternoon.
A positive-tilt upper trough is currently moving through the
southern Great Lakes and OH. A couple of MCVs are embedded within
the flow just downstream of this feature including one over
northeast OH and another moving into western NY. A belt of 35-40 kt
southwesterly winds in the 800-500 mb layer accompanying the upper
trough will spread east through the northern portion of the warm
sector contributing to up to 30-35 kt effective bulk shear. Storms
developing within pre-frontal convergence bands and over the higher
terrain will gradually intensify as they continue east through a
destabilizing boundary layer. Though the stronger winds aloft will
remain north of the warm sector, sufficient vertical shear will
exist to support some organized structures. Some storms may evolve
into line and bowing segments capable of producing mainly damaging
wind during the afternoon into the early evening. See swomcd 1304
for more information.
...Northern High Plains this afternoon into early tonight...
Gradual background height rises will occur over the northern High
Plains as the midlevel ridge expands northeastward from the central
Rockies.Despite the height rises, subtle speed maxima will crest
the ridge and move southeastward over the Dakotas.Strong surface
heating along a lee trough will support widely scattered, high-based
storms this afternoon from northeast CO across eastern WY to eastern
MT.The storms will spread southeastward this evening into richer
low-level moisture from northwest KS northward across the Dakotas,
but also into increasing convective inhibition with cooling surface
temperatures toward sunset.Effective bulk shear of 30-40 kt could
be sufficiently strong for some supercell structures, but low-level
shear will generally remain weak where storms are more probable
through this evening.
Overall, the scenario appears supportive of a few severe outflow
gusts and isolated large hail this evening, and some of the storms
could persist as a cluster or two into tonight across NE/KS as warm
advection strengthens.
...Southern Plains through late evening...
A couple of remnant MCVs are moving slowly southeastward over KS/NE,
and these features may persist through the day.Boundary-layer
dewpoints in the upper 60s to mid 70s will support strong buoyancy
this afternoon (MLCAPE of 2000-3000 J/kg) along and south of a
stalled front and the mesoscale outflows associated with ongoing
morning convection (driven by warm advection).Though vertical
shear will remain modest at best, weak but veering winds with height
should support a few clusters of southeastward-moving storms capable
of producing isolated strong/damaging outflow gusts.
..Dial/Jirak.. 07/17/2021
Read more
Sat, 17 Jul 2021 16:31:06 +0000
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1211 PM CDT Sat Jul 17 2021
Valid 181200Z - 191200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL PLAINS...
...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
central Plains on Sunday.
...Synopsis...
The only changes to the outlook with the Day 2 Update are to general
thunderstorm areas. The Plains Marginal risk remains unchanged due
to large spread in forecast guidance and low confidence.
Large-scale upper ridging will encompass much of the western states
into the Plains. A couple of shortwave troughs embedded in
larger-scale troughing from the Northeast into the Mid-MS Valley
will gradually pivot east/northeast through the period. Scattered
thunderstorms are expected from the southeastern U.S. northward
along the Atlantic coast. Weak vertical shear will limit organized
storms and severe potential will remain limited. High PW values
could result in sporadic, locally damaging gusts, but the threat for
any substantial, organized severe threat is low.
...Central Plains...
Deep layer flow will remain weak on the eastern periphery of the
upper ridge. However, a seasonally moist and unstable airmass will
be in place. South/southeasterly low level flow beneath modest
northwesterly flow aloft will result in sufficient vertical shear
for a few organized, stronger storms. Forecast guidance varies quite
a bit regarding convective evolution with some CAMs indicating
storms ongoing across NE Sunday morning and shifting southward
through the day. Other guidance suggests thunderstorms will develop
during the afternoon into the nighttime hours through diurnal
processes and along residual thunderstorm outflows. While convective
evolution remains uncertain, at least a marginal threat for locally
damaging gusts and perhaps some hail will exist given the
instability/shear parameter space.
..Leitman.. 07/17/2021
Read more
Sat, 17 Jul 2021 17:16:50 +0000
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1133 AM CDT Sat Jul 17 2021
Valid 171700Z - 181200Z
...Portions of the Great Basin into the northern Rockies...
Morning RAOBs across the Southwest indicate a mid-level moisture
plume is moving northward with precipitable water values increasing
by 0.12" at VEF - Las Vegas, NV over the last 12 hours. Meanwhile,
mid-level moisture is limited across much of the remainder of the
Great Basin and into the northern Rockies (e.g., 0.42" precipitable
water at LKN - Elko, NV RAOB). Thunderstorms are expected to develop
this afternoon across northeast Nevada, southeast Idaho, northwest
Utah, and northwest Colorado, as strong diurnal heating promotes
upslope flow along the higher terrain. While high-resolution
ensemble guidance suggests mid-level height rises may limit storm
longevity/coverage, isolated to widely scattered storms are possible
through mid-evening. Confidence in widely scattered coverage is
greatest over northeast Nevada (near/east of Elko, NV). New fire
ignitions are possible with any thunderstorm (especially away from
the storm core) as fuels across this region are extremely dry with
ERC percentiles at or above 92% (in many cases exceeding 98%).
...Southeast Oregon, far northeast California, northwest Nevada...
The forecast for Elevated fire weather conditions remains on track
across this area. A minor southward expansion was made into Alpine
County, California to near/south of the Tamarack fire, as the latest
high-resolution guidance suggests several hours of sustained surface
winds near 15 mph amidst 15% minimum RH values this afternoon.
Locally elevated conditions will likely extend farther south in the
vicinity of Mono and Inyo counties, California.
..Elliott.. 07/17/2021
.PREV DISCUSSION... /ISSUED 0154 AM CDT Sat Jul 17 2021/
...Synopsis...
Upper-ridging will persist across the Inter-mountain West as
mid-level troughing continues over the Pacific Northwest. Beneath
modest mid-level flow, in proximity to the Cascades, boundary layer
mixing and downslope flow will support dry and breezy conditions.
Meanwhile, a mid-level moisture plume will continue to pivot around
the periphery of the upper-ridge, promoting thunderstorm
development, with dry strikes possible in the northern Rockies.
...Portions of the Northern Rockies...
While upper ridging will continue to slowly amplify through the
period, widespread strong diurnal heating/boundary-layer mixing and
associated upslope flow along the higher terrain will support
thunderstorm development by afternoon. Weak low and mid-level flow
suggests that storms will be relatively slow moving overall, and
isolated on the large-scale given the presence of the upper ridge.
Nonetheless, enough coverage warranting a broader isolated dry
thunderstorm delineation is expected across northern parts of the
Great Basin into the Northern Rockies. These high-based storms will
develop atop a deep sub-cloud layer, with around 0.75 inch
precipitable water values. In addition, critically to extremely
critically dry fuels will be in place, with record high ERCs and
100/1000 hr fuel dryness noted in spots.
...Southern parts of the Pacific Northwest/Northwest Great Basin...
Modest mid-level flow will overspread the Northwest given the
presence of an upper trough. Beneath the modest mid-level flow will
reside a deep, dry boundary layer, where downslope flow to the lee
of the southern Cascades/northern Sierra will promote widespread 15
mph sustained westerly surface winds with 15-20% RH. Elevated
highlights have been introduced for the dry and breezy conditions
within proximity/to the lee of the higher terrain.
Read more
Sat, 17 Jul 2021 16:34:35 +0000
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0124 PM CDT Sat Jul 17 2021
Valid 181200Z - 191200Z
Primary change with this forecast update was to extend the isolated
dry thunderstorm area farther west to the California coast from
Santa Barbara County northward to Sonoma County. The latest
high-resolution guidance continues to suggest isolated to widely
scattered thunderstorms spreading/developing northward from late
morning into the afternoon/evening tomorrow along the northern
periphery of the mid-level moisture surge across southern/central
California, Nevada, and Idaho. While a mix of wet/dry thunderstorm
modes is expected, extremely dry fuels over the area suggest that
new lightning ignitions are likely -- with the greatest threats
along/near the foothills and across the higher terrain. Thunderstorm
activity is expected to be lower across Montana, though an isolated
thunderstorm over dry fuels remains possible.
An upper-level disturbance will bring a secondary surge of mid-level
moisture northward late Sunday night into Monday morning with
another round of isolated to widely scattered dry thunderstorms
possible across central California into western Nevada.
..Elliott.. 07/17/2021
.PREV DISCUSSION... /ISSUED 0218 AM CDT Sat Jul 17 2021/
...Synopsis...
Similar to Day 1, upper ridging will continue to very gradually
amplify across the Interior West as upper troughing is maintained
across the Pacific Northwest. Modest southwesterly flow aloft will
overspread the Cascades and northern Sierra, promoting dry downslope
flow favorable for supporting some wildfire-spread threat. Mid-level
monsoonal moisture will also continue to pivot around the periphery
of the upper ridge, with isolated thunderstorm development likely
from the Sierra to the Montana/Canadian border.
...Far northeast California, southeast Oregon, extreme northwest
Nevada...
By afternoon peak heating, downslope flow across the northern Sierra
and southern Cascades will promote 15 mph sustained westerly surface
winds and 15-20% RH for several hours. These Elevated surface
conditions will begin in the higher terrain and develop eastward
into the Harney Basin and extreme northwest Nevada, as also
supported by the latest guidance consensus.
...Lee of the Sierra to northern Montana...
With afternoon heating and the development of adequate buoyancy in
the -20 to -30C layer, at least isolated thunderstorm development is
expected in the higher terrain areas of the Sierra into northern
Montana. While winds aloft are expected to be weak overall, the
storms are expected to be high-based, occurring atop critically to
record dry fuels. Some of the latest guidance shows a low-level
impulse emanating from southern California, and moving northwestward
through the day. This low-level feature may potentially foster
greater thunderstorm coverage. Given the very receptive fuels in
place, conditions will be monitored for isolated dry thunderstorm
highlight expansions and possibly the introduction of a scattered
dry thunderstorm area for parts of far east-northeast California
into central Nevada in future outlooks.
Read more
Sat, 17 Jul 2021 18:26:38 +0000
+--------------------------- POWERSHELL SLACKWARE ---------------------------+
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