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LU9DCE > ALERT 23.11.20 15:13z 182 Lines 10334 Bytes #999 (0) @ WW
BID : 41597_LU9DCE
Read: GUEST
Subj: STORM PREDICTION CENTER 23 11
Path: HB9ON<IW8PGT<IZ3LSV<DB0ERF<DB0RES<ON0AR<GB7CIP<N7HPX<LU9DCE
Sent: 201123/1501Z 41597@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 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230
AM CST Mon Nov 23 2020
Valid 241200Z - 251200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS
OF THE SOUTHERN/CENTRAL PLAINS...OZARKS...MID-SOUTH...AND LOWER
MISSISSIPPI VALLEY...
...SUMMARY... Isolated strong to severe thunderstorms may occur
Tuesday into Tuesday night across portions of the southern/central
Plains, Ozarks, Mid-South, and lower Mississippi Valley. Damaging
winds should be the main threat, but a couple tornadoes and
marginally severe hail also appear possible.
...Southern/Central Plains into the Ozarks, Mid-South, and Lower
Mississippi Valley... An upper trough/low initially centered
over the Four Corners region will progress eastward across the
southern/central Plains by Tuesday evening, eventually reaching the
lower/mid MS Valley by the end of the period. A 40-50+ kt southerly
low-level jet will be present over much of the southern/central
Plains Tuesday morning, with this feature forecast to likewise shift
eastward through the day. Partially modified Gulf moisture will
be transported northward across the southern/central Plains ahead
of a developing surface low over KS and trailing cold front. A
dryline should also mix eastward through the day across parts of
western/central OK and north-central TX.
Modestly steepened mid-level lapse rates (around 7-7.5 C/km in the
700-500 mb layer) should overspread the warm sector across the
southern/central Plains as the upper trough/low moves eastward.
There remains some model disagreement regarding how quickly and
far north mid/upper 50s to low 60s surface dewpoints will reach by
late Tuesday afternoon. The degree of low-level moisture return
will have a large impact on how much surface-based instability
can be realized ahead of the cold front/dryline across southern
KS and central/eastern OK. Most guidance indicates that only weak
instability (MLCAPE generally less than 1000 J/kg) will develop
across these areas by peak afternoon heating. Still, a strong (60-70+
kt) southwesterly mid-level jet should overspread the warm sector
through the day, which will support more than enough deep-layer
shear for organized storms.
Convection may initiate by Tuesday afternoon in close proximity
to the upper low and left exit region of the mid-level jet in
southwestern/south-central KS. With cold mid-level temperatures
present, this activity should mainly pose an isolated threat for
marginally severe hail. Modest low-level moisture and instability
will probably limit a greater severe risk with northward extent in
KS. Additional storms may develop by early Tuesday evening along/east
of the dryline in central OK. All severe hazards appear possible
with this convection, but uncertainty regarding how unstable the
airmass across the warm sector will become currently precludes
greater severe probabilities across central/eastern OK and vicinity.
From Tuesday evening though early Wednesday morning, storms may grow
upscale into a line along or just ahead of the eastward-moving cold
front. Given the strength of the southwesterly low-level flow and
potential for weak surface-based instability ahead of this line,
isolated damaging winds may continue to be a threat through the end
of the period across parts of the Ozarks, Mid-South, and lower MS
Valley. An embedded tornado or two also cannot be ruled out with
very strong 0-1 km SRH forecast. This isolated/marginal severe
risk becomes more uncertain with northward extent into MO and the
Mid-South, where very strong low-level flow will be present, but
instability appears meager at best. Adjustments have been made to
the eastern extent of the Marginal risk area across the Mid-South
and lower MS Valley to account for the probable location of strong
to locally severe storms by the end of the period.
..Gleason.. 11/23/2020
SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226
AM CST Mon Nov 23 2020
Valid 251200Z - 261200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS
OF THE LOWER/MID MISSISSIPPI VALLEY...TENNESSEE VALLEY...AND
SOUTHEAST...
...SUMMARY... Isolated strong to severe thunderstorms may occur
Wednesday across parts of the lower/mid Mississippi Valley into
the Tennessee Valley and Southeast.
...Lower/Mid Mississippi Valley into the Tennessee Valley and
Southeast... A closed upper low with associated southwesterly
mid-level jet should continue to advance from the lower/mid MS
Valley to the Mid-Atlantic vicinity on Wednesday. A surface low
initially over northern MO is forecast to develop northeastward
across the Midwest/OH Valley and lower Great Lakes while slowly
filling through the period. A cold front extending southward from
this low should progress generally eastward across parts of the
lower/mid MS Valley, TN Valley, and Southeast through the day.
A broken line of showers/storms may be ongoing at the start of
the period across these regions along/ahead of the cold front
with a isolated/marginal severe threat. Substantial low-level
moisture return will probably make only a limited northward advance
ahead of the front. Still, diurnal heating and cooling mid-level
temperatures with the approach of the upper trough/low may promote
weak instability through Wednesday evening across the narrow
warm sector. Given strong flow aloft attendant to the previously
mentioned mid-level jet, there should be more than enough deep-layer
shear to support organized storms. Isolated strong to damaging winds
appear to be the main threat with any storms that can either persist
along the front or develop ahead of it. A brief tornado or two also
cannot be ruled out mainly early in the period, before low-level
winds veer more west-southwesterly as the primary low-level jet
shifts north of the surface warm sector and into the OH Valley by
Wednesday evening. Eventually, the cold front should outpace the
modest low-level moisture return across the TN Valley and Southeast,
with a gradual reduction in the already isolated/marginal severe
threat by late Wednesday evening as the system occludes.
..Gleason.. 11/23/2020
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK
0336 AM CST Mon Nov 23 2020
Valid 261200Z - 011200Z
...DISCUSSION... A positively tilted large-scale upper trough
should develop eastward across the western/central states on Day
4/Thursday. In the wake of a prior frontal intrusion, low-level
moisture may return northward across parts of TX and the lower
MS Valley from Day 4/Thursday into Day 5/Friday. Depending on the
evolution of this upper trough and whether it closes off over the
Southwest, it appears possible that at least an isolated/marginal
severe threat may develop across parts of the southern Plains, lower
MS Valley, and Southeast, mainly from Day 5/Friday into the upcoming
weekend. Regardless, too much uncertainty currently exists regarding
the placement/amplitude of the upper trough/low and related surface
features to include any 15% severe probabilities at this time.
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK
0147 AM CST Mon Nov 23 2020
Valid 231200Z - 241200Z
...Synopsis... An upper-level trough evident on satellite imagery
this morning has moved across northern California. This trough
is forecast to deepen as it moves eastward throughout the day.
At the surface, low pressure is forecast to develop in the lee of
the central Rockies while high pressure builds into the Pacific
Northwest and northern Intermountain West.
...Southern California... In the wake of the departing upper-level
trough, strong northerly winds aloft will move across the area today.
This will result in sustained northerly surface winds of 15-25 mph
(with stronger gusts) across terrain-favored (i.e., downslope)
locations of Santa Barbara, Ventura, and Los Angeles Counties.
While RH values are expected to remain above critical thresholds,
the strong, gusty winds will elevate fire weather conditions.
...Southeastern Arizona/Southwestern New Mexico... Despite the
arrival of the strongest midlevel winds after peak heating,
southwesterly flow aloft will increase throughout the day, leading
to sustained surface winds of 20 mph (with stronger gusts) as
the boundary layer deepens. With afternoon RH values approaching
critical thresholds (15%), elevated fire weather conditions are
likely across the region today.
..Jirak.. 11/23/2020
...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
0151 AM CST Mon Nov 23 2020
Valid 241200Z - 251200Z
...Synopsis... A strong shortwave trough, with an associated
midlevel speed max around 100 knots, is forecast to eject
northeastward across the southern/central Plains on Tuesday. At the
surface, a low pressure system will deepen near the Texas/Oklahoma
Panhandles and lift northeastward toward the mid-Mississippi Valley.
...Southern New Mexico and Western Texas... Boundary layer
heating and mixing in the presence of enhanced flow aloft will
lead to sustained westerly surface winds of 20-30 mph across the
region on Tuesday. While afternoon RH values may approach critical
thresholds (15%), especially across West Texas, the spatial overlap
of critical winds and RH is forecast to be limited at this time.
Thus, elevated to locally critical fire weather conditions are
expected across the region on Tuesday.
..Jirak.. 11/23/2020
...Please see www.spc.noaa.gov/fire for graphic product...
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Politicians are the same all over. They promise to build a bridge even
where there is no river.
-- Nikita Khrushchev
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