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LU9DCE > ALERT 14.11.20 15:30z 239 Lines 13539 Bytes #999 (0) @ WW
BID : 41044_LU9DCE
Read: GUEST
Subj: STORM PREDICTION CENTER 14 11
Path: HB9ON<IW8PGT<LU4ECL<VK2RZ<W0ARP<AL0Y<K5DAT<N7HPX<GB7YEW<LU9DCE
Sent: 201114/1501Z 41044@LU9DCE.TOR.BA.ARG.SOAM LinBPQ6.0.20
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ESTACION DE PACKET RADIO - BUENOS AIRES (GF05OM)
BOLETINES INFORMATIVOS PROGRAMADOS (BIP)
CASTILLOEDUARDO@OUTLOOK.COM.AR
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SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1154
PM CST Fri Nov 13 2020
Valid 141200Z - 151200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN PLAINS...OZARKS AND ARKLATEX...
...SUMMARY... Severe thunderstorms associated with wind damage and
perhaps a tornado or two may occur across eastern Oklahoma and the
Ozarks late this afternoon and evening.
...Eastern Oklahoma/Northwest Arkansas/Southern and Central
Missouri... Southwest mid-level flow will be in place today from the
southern Plains eastward into the Mississippi Valley ahead of the an
upper-level trough moving through the High Plains. At the surface,
a low will deepen across the central Plains as moisture advection
occurs in the southern Plains. The surface low will move eastward
into the lower Missouri Valley this afternoon with a cold front
advancing southeastward across the central Plains and southern High
Plains. Ahead of this front, surface dewpoints will increase into
the lower to mid 60s F from northeast Texas into eastern Oklahoma
and western Arkansas. In response, a pocket of moderate instability
is forecast to develop across eastern Oklahoma by late afternoon.
SBCAPE values are forecast to peak around 1500 J/kg.
Increasing low-level convergence just ahead of the front will
likely result in convective initiation along the northern end of the
stronger instability late this afternoon. Discrete cell formation
appears most likely during the one to two hours after initiation.
This will be the most probable time for supercell development.
Strong deep-layer shear, aided by the exit region of the mid-level
jet, and ample low-level shear should be favorable for an isolated
tornado threat with supercells. The tornado threat appears likely
to be greatest along the western edge of the low-level jet from
south-central Missouri southwestward into northwest Arkansas and
far eastern Oklahoma. Due to a band of focused large-scale ascent,
a squall-line is expected to organize and move east-southward across
the Ozarks extending south-southwestward into the Arklatex. This is
expected in the early to mid evening as the low-level jet markedly
strengthens. Wind damage will be the primary threat along the leading
edge of this line of strong to severe storms. The severe threat
could continue into parts of eastern Missouri and east-central
Arkansas late this evening.
..Squitieri/Broyles.. 11/14/2020
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1128
PM CST Fri Nov 13 2020
Valid 151200Z - 161200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY... The threat for thunderstorms is expected to remain low
across the Ohio Valley and southern New England Sunday into Sunday
night, though gusty winds will be possible with shallow convection.
...OH Valley to southern New England... A midlevel shortwave trough
will reach peak amplitude and will move quickly eastward over the
OH Valley Sunday and New England Sunday night. A deep, associated
surface cyclone over the upper Great Lakes at the beginning of the
period will develop northeastward across parts of ON/QC, while a
trailing cold front moves quickly eastward. This front will focus
shallow convection and some low-end potential for lightning flashes.
Low-level moisture return into the OH Valley will be substantially
more limited compared to areas farther southwest on Saturday.
Boundary-layer dewpoints should be confined to the mid-upper 40s
by midday across the upper OH Valley, immediately in advance of
the front. Shallow buoyancy is expected along the cold front as
low-level lapse rates steepen with modest surface heating and
cooling above the surface. The depth of the buoyancy will be
questionable for charge separation and lightning production with
bands of shallow convection focused in the zone of ascent along
the front during the day across OH/PA/NY. A corridor of low-level
moistening from the Mid-Atlantic into southern New England should
help maintain weak buoyancy rooted near or just above the ground
into early Sunday night across southern New England. Though the
potential for lightning will remain limited, there is a small chance
of strong/damaging gusts driven by the shallow convection given
SBCAPE of 100-200 J/kg and 50-60 kt flow in the lowest 2 km above
ground level. Thus, will maintain a general thunderstorm area and
will continue to re-evaluate the potential for strong convective
gusts with shallow convection in later updates.
...Elsewhere... Pre-frontal destabilization will be sufficient
for isolated thunderstorms along a cold front during the afternoon
across deep South TX. Rain showers will be possible across central
FL, though any convection here will be limited by a pronounced
midlevel inversion.
..Thompson.. 11/14/2020
SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0153
AM CST Sat Nov 14 2020
Valid 161200Z - 171200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY... Severe thunderstorms are not expected Monday and
Monday night.
...Synopsis...
An amplified but semi-progressive mid/upper level pattern will exist
across the CONUS on Monday. An upper trough over the western states
will shift eastward across the Rockies as a shortwave trough develops
southeastward into the Pacific Northwest by Tuesday morning. Further
east, a mid/upper shortwave trough over the northern Plains will
intensify as it ejects eastward across the Upper Midwest and Great
Lakes. Surface high pressure will persist across much of the West and
southeastern states, but low pressure will develop across the Upper
Midwest and Great Lakes in association with the deepening mid/upper
shortwave trough. This will bring a reinforcing cold front and shot
of cooler weather across this region. Convection with this frontal
system appear unlikely given a dearth of boundary-layer moisture
will be left behind in the wake of a cold frontal passage in the
Days 1/2-Sat/Sun period.
The stalled remains of the cold front from the Days 1/2 will be
draped across the FL Peninsula on Monday. Dewpoints in the upper
60s and low 70s a modest heating will result in weak instability
and isolated thunderstorms are possible as the front slowly sags
southward through the period. Weak overall thermodynamic and
kinematic fields will preclude any organized severe threat.
..Leitman.. 11/14/2020
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK
0324 AM CST Sat Nov 14 2020
Valid 171200Z - 221200Z
...DISCUSSION... Severe thunderstorm potential appears low during
the Day 4-8 period. An amplified mid/upper level pattern, with
a ridge in the west and a trough in the east, will de-amplify with
time. The western upper ridge will shift eastward, weakening over the
Great Lakes and New England through Day 6/Thu. In the wake of this
feature, the upper flow regime will become more quasi-zonal. Surface
high pressure is expected to persist over much of the eastern half
of the CONUS, resulting in dry and quiescent conditions for much
of the weak. Some weak Gulf return flow is possible across parts of
the south-central states around Days 7-8/Fri-Sat. Forecast guidance
suggests at least a weak shortwave mid/upper trough may eject across
the Rockies and into the northern/central Plains during that time,
resulting in a lee surface low and southerly low level return flow
ahead of another cold front. Details in timing and location of this
feature vary, but some shower or thunderstorm activity could return
to parts of the south-central U.S. by next weekend.
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK
0145 AM CST Sat Nov 14 2020
Valid 141200Z - 151200Z
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE CENTRAL AND
SOUTHERN HIGH PLAINS...
...Synopsis... A progressive mid-level trough will traverse
the Central Plains during the day, with 80+ knot 500 mb flow
overspreading the area by afternoon peak heating. Strong lee
troughing will take place across the Plains as a surface low develops
across the Upper Mississippi Valley. With surface high pressure
situated across the Intermountain West, a well-defined pressure
gradient will contribute to strong downslope flow, while a deep and
dry boundary layer will allow for downward momentum transport of
the strong mid-level flow. As such, very windy and dry conditions
are expected across western parts of the Plains states, where
wildfire-spread potential will be of concern. Fortifying surface
high pressure across the western CONUS will also contribute to a
developing pressure gradient and weak offshore flow across portions
of southern California towards the end of the period.
...Portions of the central and southern High Plains... By afternoon
peak heating, widespread 20-30 mph sustained west-northwesterly
surface winds are expected to develop, along with 15-25% RH. Latest
model guidance differs somewhat regarding how RH will drop by
afternoon peak heating, with some members showing 20% minimum RH,
with others depicting 15%. An Elevated highlight was maintained
across the central and southern High Plains to include a broader
region of dry/windy conditions atop at least marginally receptive
fuels. A Critical highlight is in place where confidence is highest
in RH dropping to 15%. Winds may occasionally gust well over 30
mph across portions of the Critical area, and very brief/localized
Extremely Critical conditions cannot be completely ruled out.
...Parts of the southern California Transverse Ranges... As a
surface pressure gradient begins to develop across southern
California towards the end of the period (late Saturday night
into early Sunday morning), modest offshore flow is expected.
Nonetheless, the latest high-resolution model guidance suggests
that sustained offshore winds exceeding 15 mph and RH dropping
to 15-20% will likely be confined to the higher terrain of the
southern Transverse Ranges. As such, the localized coverage of
winds/RH supporting wildfire spread preclude any highlights for
this outlook, though locally Elevated conditions are possible.
..Squitieri.. 11/14/2020
...Please see www.spc.noaa.gov/fire for graphic product...
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK
0222 AM CST Sat Nov 14 2020
Valid 151200Z - 161200Z
...Synopsis... Widespread 50+ knot mid-level flow is expected to
persist across the central Plains states through the Day 2/Sunday
period, as a trough aloft progresses across the eastern CONUS. The
stronger flow aloft will continue to overspread a dry boundary
layer, which will foster downward momentum transport as surface
heating commences. With downslope flow expected along the lee of
the Rockies, dry and windy conditions fostering wildfire-spread
potential are likely across portions of the central/southern High
Plains. Meanwhile, surface high pressure will remain in place across
the Intermountain West, with a surface pressure gradient promoting
continued dry offshore flow across portions of southern California.
...Parts of the central and southern High Plains... With strong
mid-level westerly winds and a well-mixed boundary layer remaining
in place across the central/southern High Plains Sunday afternoon,
widespread 15-25 mph sustained westerly surface winds coinciding
with 15-25% RH are expected. An Elevated area was introduced
where model guidance consensus depicted the most favorable wind/RH
overlapping. In addition, some guidance hints at Critical conditions
developing along the NM/TX border by afternoon peak heating. However,
the modest receptiveness of fuels and lack of more substantial
model agreement in Critical conditions occurring precludes Critical
highlights at this time.
Farther southeast, Elevated conditions are also possible with the
passage of a cold front east of the Edwards Plateau. However, the
lack of receptive fuels suggests that an Elevated highlight is not
currently warranted.
...Parts of southern California... Modest offshore flow in
association with a surface pressure gradient will continue
across southern California, especially towards the end of the
period (late Sunday into early Monday morning). Nonetheless,
upper ridging will be in place. As such, the lack of more
substantial upper support suggests that Elevated wind/RH should
remain constrained to terrain-favoring areas, as also depicted
by the latest high-resolution model guidance. An Elevated area
has been withheld for now, though conditions will continue to be
monitored for the need of an Elevated area, should guidance trend
more favorably to more widespread dry/windy conditions.
..Squitieri.. 11/14/2020
...Please see www.spc.noaa.gov/fire for graphic product...
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Cabbage, n.:
A familiar kitchen-garden vegetable about as large and wise as
a man's head.
-- Ambrose Bierce, "The Devil's Dictionary"
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