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LU9DCE > ALERT 04.12.21 21:45z 317 Lines 14859 Bytes #999 (0) @ WW
BID : 8137_LU9DCE
Read: GUEST
Subj: STORM PREDICTION CENTER 04-DIC.21
Path: HB9ON<IW8PGT<IZ3LSV<I0OJJ<EA2RCF<LU9DCE
Sent: 211204/2130Z 8137@LU9DCE.TOR.BA.ARG.SOAM LinBPQ6.0.22
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ESTACION DE PACKET RADIO - BUENOS AIRES (GF05OM)
BOLETINES INFORMATIVOS PROGRAMADOS (BIP)
Copyright 2021 - Eduardo A. Castillo
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SPC Forecast Products Storm Prediction Center en-us None
spc.feedback@noaa.gov (spc.feedback@noaa.gov)
spc.feedback@noaa.gov (spc.feedback@noaa.gov) Sat, 04 Dec 2021
09:18:02 +0000 Sat, 04 Dec 2021 09:18:02 +0000 general 1
SPC Forecast Products
SPC - No watches are valid as of Sat Dec 4 09:18:02 UTC 2021 No
watches are valid as of Sat Dec 4 09:18:02 UTC 2021. Sat, 04
Dec 2021 09:17:10 +0000
SPC - No MDs are in effect as of Sat Dec 4 09:18:02 UTC 2021
No Mesoscale Discussions are in effect as of Sat Dec 4
09:18:02 UTC 2021. Sat, 04 Dec 2021 09:17:05 +0000
SPC Dec 4, 2021 0600 UTC Day 1 Convective Outlook SPC 1200Z Day
1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1120 PM
CST Fri Dec 03 2021
Valid 041200Z - 051200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms are expected from the Arklatex to the northern
Gulf States.
...Arklatex to northern Gulf States...
Weak short-wave trough over northeast TX is forecast to advance slowly
across the lower MS Valley later today before ejecting into the
central Gulf States overnight. In its wake, broad short-wave ridging
is forecast across TX ahead of the Baja Peninsula upper trough. This
flow regime will result in moist warm sector holding across much of
eastern TX/lower MS Valley. With the weak short-wave trough forecast
to advance across the lower MS Valley, low-level flow will veer a bit
and deep-layer flow is forecast to actually be seasonally weak, though
cool at mid levels. While large-scale forcing for ascent is not
expected to contribute appreciably, weak low-level warm advection
should be the primary forcing mechanism for elevated convection.
Forecast soundings suggest parcels lifted near 850mb across the
Arklatex could yield MUCAPE in excess of 1500 J/kg. However,
effective shear will be weak and NAM sounding at PRX around 20Z
suggests only 10kt at 500 mb. While some elevated convection is
expected across this region, weak shear and short-wave ridging will
not prove particularly favorable for large hail. Cool mid-level
temperatures may contribute to small hail in the strongest updrafts,
but the probability for severe appears too low to warrant a risk this
period.
..Darrow/Wendt.. 12/04/2021
Read more
Sat, 04 Dec 2021 05:25:17 +0000
SPC Dec 4, 2021 0700 UTC Day 2 Convective Outlook SPC 0700Z Day
2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM
CST Sat Dec 04 2021
Valid 051200Z - 061200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
COASTAL/EAST TEXAS TO THE MID-SOUTH AND LOWER OHIO VALLEY...
...SUMMARY...
Isolated strong to severe thunderstorms appear possible mainly Sunday
evening and overnight from parts of coastal/east Texas to the
Mid-South and lower Ohio River Valley.
...Synopsis...
An upper trough initially over the north-central CONUS will likely
undergo substantial amplification on Sunday as it digs
east-southeastward across much of the Midwest and Great Lakes. A weak
upper low over the Baja California vicinity is forecast to move little
through the period. Still, low-amplitude perturbations within the
southern branch of the mid-level westerlies downstream from the upper
low may also aid the amplification of the large-scale upper trough
over the lower/mid MS Valley by Sunday night. A surface low initially
over the Dakotas Sunday morning will develop eastward towards the
Upper Great Lakes by late Sunday night. An attendant cold front is
forecast to sweep east-southeastward over much of the Plains, Midwest,
and mid MS Valley through the period.
...Coastal/East Texas to the Mid-South and Lower Ohio River
Valley... Modest low-level moisture emanating from the western Gulf
of Mexico should return northward through the day across much of the
southern Plains, lower MS Valley, Mid-South, and perhaps a small part
of the lower OH Valley ahead of the advancing cold front. Various
model forecast soundings across this region suggest this moisture will
likely remain fairly shallow away from the Gulf Coast. Residual
low-level capping will probably tend to inhibit robust convective
development through much of the day across the warm sector.
Still, thunderstorm initiation looks increasingly likely by Sunday
evening along or just ahead of the front from parts of eastern OK to
the Mid-South vicinity as ascent associated from the amplifying upper
trough overspreads these areas. Regardless, MLCAPE should remain
fairly weak, generally in the 250-1000 J/kg range, with mid to upper
50s and lower 60s surface dewpoints prevalent. But, both low-level and
deep-layer shear are forecast to strengthen quickly Sunday evening and
through the overnight hours with the approach of the upper trough.
This should foster some convective organization, and isolated strong
to damaging winds may occur with thunderstorms that form along the
front and quickly become linear while moving east-southeastward. Given
the expected strength of the boundary-layer flow and favorable
low-level shear as a southwesterly low-level jet strengthens through
the evening, a tornado or two also appears possible. The lack of
stronger forecast instability currently limits confidence in the
potential for a more robust severe threat.
There also appears to be some chance for open warm-sector development
from parts of east/coastal TX and southeastern OK into AR and western
LA Sunday evening/night. Steepened mid-level lapse rates and slightly
greater low-level moisture across these areas should support MUCAPE up
to 1000-2000 J/kg. Isolated severe hail may occur with any discrete
storms that can form given the strong effective bulk shear, in
addition to gusty downdraft winds and perhaps a tornado. The
convection that develops farther north along the front should outpace
the modest low-level moisture return late Sunday night into early
Monday morning, especially with eastward extent across the Mid-South
into the TN and OH Valleys. Accordingly, these thunderstorms should
gradually weaken in this time frame.
..Gleason.. 12/04/2021
Read more
Sat, 04 Dec 2021 06:29:49 +0000
SPC Dec 4, 2021 0830 UTC Day 3 Severe Thunderstorm Outlook SPC
0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM
CST Sat Dec 04 2021
Valid 061200Z - 071200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
COASTAL/EAST TEXAS INTO THE LOWER MISSISSIPPI VALLEY...
...SUMMARY...
Isolated strong to severe thunderstorms may occur mainly Monday
morning from parts of coastal/east Texas into the lower Mississippi
Valley.
...Synopsis...
A highly amplified, large-scale upper trough should move from the
central to eastern CONUS on Monday. An upper low in the southern
stream should shift eastward across northern Mexico through the day,
eventually reaching south TX late Monday into early Tuesday morning.
At the surface, a low over the Upper Great Lakes is forecast to
develop northeastward into Ontario/Quebec, with a trailing cold front
likely to continue sweeping east-southeastward over the East Coast,
Southeast, and southern Plains through the period.
...Coastal/East Texas into the Lower Mississippi Valley...
Thunderstorms should be ongoing early Monday morning along/ahead of
the front across parts of coastal/east TX into the lower MS Valley.
The primary forcing associated with the upper trough will remain
displaced to the north of this region. Still, the low-level ascent
associated with the surface cold front should be enough to support
continued convection through at least Monday morning. Generally low to
mid 60s surface dewpoints and modest diurnal heating should foster
weak instability across the warm sector. Even though the low/mid-level
wind field will likely veer and gradually weaken though the day as the
upper trough shifts farther east, there should be enough enhancement
to the mid-level westerlies to support sufficient deep-layer shear for
modest updraft organization. Isolated strong to severe storms posing
a threat for mainly damaging winds and perhaps marginally severe hail
appear possible mainly Monday morning. As convection develops
east-southeastward in tandem with the cold front, the deep-layer shear
should slowly diminish through the day. There should be a tendency for
these thunderstorms to gradually weaken with southward and eastward
extent by late Monday afternoon.
...Northeast...
Very strong low/mid-level flow is forecast to overspread much of the
Northeast on Monday as the upper trough progresses over the eastern
states. Latest guidance suggests that, at best, low 50s surface
dewpoints may attempt to move inland across parts of southern New
England ahead of the cold front. Weak MUCAPE extending through a
sufficiently deep layer could support charge separation and occasional
lightning flashes with elevated convection. At this point, the
potential for surface-based thunderstorms with any strong/gusty wind
threat appears limited due to the meager low-level moisture and
related lack of boundary-layer instability.
..Gleason.. 12/04/2021
Read more
Sat, 04 Dec 2021 08:18:28 +0000
SPC Dec 4, 2021 Day 4-8 Severe Weather Outlook Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0314
AM CST Sat Dec 04 2021
Valid 071200Z - 121200Z
...DISCUSSION...
Modest amplification of the mid-level westerlies may occur over
portions of the central/eastern CONUS on Day 4/Tuesday into Day
5/Wednesday. Regardless, a prior frontal passage into the northern
Gulf of Mexico should generally inhibit the inland advance of
substantial low-level moisture along most of the Gulf Coast in this
time frame. Parts of FL and southern GA may be an exception, but weak
forecast instability should limit the threat for organized severe
convection.
Latest medium-range guidance is starting to come into better agreement
with the prospect for another upper trough to amplify and move
eastward across the western/central CONUS around Day 6/Thursday into
Day 7/Friday. If this occurs, then the related low-level mass response
would encourage the inland return of rich low-level moisture from the
Gulf of Mexico into parts of the Southeast and perhaps even the OH
Valley. Of course, there are differences in the placement and
evolution of this upper trough and attendant surface features at this
extended time frame. Still, an increase in severe potential is evident
based on some of the latest models for parts of the lower MS Valley
and Southeast on Day 8/Saturday. While it is too soon to include a 15%
severe delineation due to model differences and inherent uncertainty,
this scenario will be closely monitored.
Read more
Sat, 04 Dec 2021 09:17:38 +0000
SPC Day 1 Fire Weather Outlook SPC Day 1 Fire Weather
Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1248
AM CST Sat Dec 04 2021
Valid 041200Z - 051200Z
...NO CRITICAL AREAS...
...Synopsis...
A strong jet stream across the Canadian border will begin to amplify
by the end of today. As this occurs, a surface trough will deepen and
slide eastward from the northern Rockies into the northern Plains.
High pressure will build into the Northwest and Great Basin.
...Eastern Wyoming...
Strong flow at mid-levels will shift southward over Wyoming during the
day. With the surface trough deepening in the High Plains, strong
westerly winds will develop by afternoon. Winds could reach 20-25 mph.
With the recent cold font, temperatures will be rather cool outside of
areas of downslope winds. Locally elevated conditions are possible in
the lee of the Big Horns and Laramie Range where RH is more likely to
drop to around 20%.
...Southern California...
A modest offshore pressure gradient is expected to develop by late
Saturday into early Sunday. Northerly/northeasterly winds aloft will
also strengthen through the period along the westerly flank of a
mid-level trough. RH reductions to near 15-20% may occur along with
winds of 15-20 mph. Models continue to trend slightly weaker with the
offshore gradient strength. Elevated conditions will be confined to
higher terrain and are not expected to become widespread.
..Wendt.. 12/04/2021
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
Sat, 04 Dec 2021 06:50:42 +0000
SPC Day 2 Fire Weather Outlook SPC Day 2 Fire Weather
Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1250
AM CST Sat Dec 04 2021
Valid 051200Z - 061200Z
...Synopsis...
An upper-level trough will continue to amplify as it moves into the
northern Plains and eventually the upper Midwest on Sunday. At the
surface, a stronger cold front will push quickly through the Plains
during the day. Across the western coast, northerly mid-level winds
will remain along with high surface pressure in the Great Basin.
...Southern High Plains...
Elevated to locally critical fire weather is expected to occur as the
surface pressure gradient tightens ahead of the advancing cold front.
Winds of 15-25 mph are possible. RH will generally fall to near 20%,
but some locations could see values as low as 15%.
...Southern California...
The modest offshore pressure gradient will likely peak on Sunday into
Monday morning. A few hours of locally elevated conditions are likely
within the higher terrain/foothills from Santa Barbara into Ventura
and Los Angeles Counties. RH near 15% is probable, but sustained winds
will not be overly strong away from wind-prone areas. A few stronger
gusts to 35-40 mph may occur given the favorable winds aloft.
...Central Plains...
Localized fire weather concerns are possible ahead of the front in
parts of eastern Colorado into western Kansas. RH of less than 20%
appears probable, but winds of 15-20 mph will likely only occur in
terrain-favored locations. Northerly winds of 20-30 mph behind the
cold front may briefly coincide with marginally reduced RH. RH
recovery behind the front will be swift, however.
..Wendt.. 12/04/2021
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
Sat, 04 Dec 2021 06:52:35 +0000
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