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LU9DCE > ALERT 16.11.20 15:09z 164 Lines 9075 Bytes #999 (0) @ WW
BID : 41206_LU9DCE
Read: GUEST
Subj: STORM PREDICTION CENTER 16 11
Path: HB9ON<IW8PGT<IZ3LSV<DB0ERF<DB0RES<ON0AR<YT7MPB<GB7CIP<N7HPX<LU9DCE
Sent: 201116/1501Z 41206@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 0116
AM CST Mon Nov 16 2020
Valid 171200Z - 181200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY... Organized severe thunderstorms are not expected
Tuesday or Tuesday night.
...Synopsis/Discussion... The upper-air pattern across the CONUS
will feature progressive, high-amplitude troughing in the East,
moving offshore from the Atlantic Coast late in the period,
and ridging moving from the Rockies across the Great Plains.
Height falls are forecast over much of the Pacific Coast in advance
of a series of shortwave troughs in cyclonic flow, south of a large
cyclone located west of Vancouver Island. Steep midlevel lapse
rates and cooling aloft with these perturbations -- atop a moist
marine layer -- should support isolated and sporadic lightning
amidst areas of mostly shallow towering cumuli and cumulonimbi
moving ashore from the Pacific.
In association with the eastern troughing, a cold front now located
from the eastern Carolinas to the north-central/northwestern Gulf
will progress southeastward down the FL Peninsula through day 1 and
decelerate/weaken into day 2. Modest but marginally sufficient
low/middle-level lapse rates are evident in forecast soundings
atop rich low-level moisture, within and south of the front,
in support of convective potential. The main question will be
strength of lift in support of sustaining convergence/convection deep
enough to generate lightning, given the subtlety of the wind shift
(northeasterly north of the front, easterly to east-northeasterly
to its south). For now, will maintain a low-end thunder line for
south FL, with the expectation that the bulk of lightning should be
over nearby Atlantic/Gulf waters where sea-air fluxes may provide
better thermodynamic support.
..Edwards.. 11/16/2020
SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0144
AM CST Mon Nov 16 2020
Valid 181200Z - 191200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY... Severe thunderstorms are not expected on Wednesday
or Wednesday night.
...Synopsis...
A somewhat amplified but progressive mid/upper-level pattern will
exist over the CONUS on Wednesday. The period will begin with
an amplified upper ridge oriented from the Upper Midwest to the
south-central states. Upper-level troughs will flank either side of
the ridge, oriented near the Pacific and Atlantic coasts. As the
Pacific trough shifts east, the upper ridge will deamplify as it
migrates eastward across the eastern U.S., and overall upper flow
pattern will become quasi-zonal.
Strong surface high pressure east of the Mississippi River will
maintain dry and stable conditions with little thunderstorm activity
expected. A weak surface lee trough will develop over the central
and southern Plains after 00z, resulting in modest Gulf return flow
across Texas and perhaps into Oklahoma, though instability will
be too meager and moisture too shallow to support any thunderstorm
activity in this weak WAA regime. Isolated thunderstorms are possible
near the Pacific Northwest coast from WA/OR into northeast CA ahead
of a weak front moving onshore early in the period. Cold temperatures
aloft will result in steep lapse rates and weak, albeit sufficient
instability supporting sporadic lightning flashes. As the upper
trough weakens and shifts east with time, thunderstorm activity
should diminish into the evening/overnight hours. Weak instability
and modest shear will preclude severe thunderstorm concerns.
..Leitman.. 11/16/2020
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK
0325 AM CST Mon Nov 16 2020
Valid 191200Z - 241200Z
...DISCUSSION... The period will begin with a positively tilted
trough over the U.S./Canadian West Coast -- a degraded remnant of the
substantial cyclone now over the northeastern Pacific. Downstream
and in low levels, a slow-moving cold front will extend from the
Great Lakes to the southern High Plains days 4-5/22nd-23rd, largely
parallel to and south of the faster flow aloft. Strong low-level
ridging over the Southeast and Gulf Coast will be slow to retreat,
precluding robust moisture return into this regime, with organized
severe potential too low for an outlook area days 4-6.
Though details differ some at shortwave scales, operational
GFS/ECMWF/CMC, and available ensemble guidance, generally agree that
the positively tilted synoptic trough will cross the western/central
CONUS and amplifying days 5-6, with the front sagging southeastward
through the Appalachians and western Gulf Coast States. Considerable
spread occurs at mid/upper levels from day 6 onward. Still, the
general pattern of front-parallel flow aloft suggests weak lapse
rates and abundant clouds/precip near the front that should keep
severe potential generally marginal and conditional.
One exception may be near the end of the period (days 7-8/23rd-24th)
in the upper Ohio Valley to Mid-Atlantic/Northeast, if a more
intensely amplified northern-stream cyclone, as forecast by
operational ECMWF (but not deterministic GFS/CMC nor several EC
ensemble members), verifies over the southern ON/lower Great Lakes
region. Such a scenario would strengthen frontal forcing under
intense flow aloft for potential low-topped convective band(s).
However, at such a long time range, predictability is very low for
such a solution.
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK
0126 AM CST Mon Nov 16 2020
Valid 161200Z - 171200Z
...Synopsis... A mid-level ridge and surface high pressure will
build across the Intermountain West into the Plains States through
the period. An overall quiescent surface wind field is expected to
develop across much of the southwest into the central U.S, limiting
wildfire-spread concerns. However, through the first half of the
day, surface high pressure across the Great Basin will support a
pressure gradient and dry offshore flow across southern California,
with modest wildfire-spread potential noted.
...Parts of southern California... 15-25 mph sustained offshore
flow and 15-25% RH are expected to be ongoing this morning across
portions of southern California, especially in the higher terrain of
the southern Transverse Ranges. An Elevated area has been maintained
for this scenario, however, surface winds are expected to gradually
veer to a more onshore component by late afternoon/early evening,
with RH recovery expected. As such, the Elevated area primarily
applies to the morning/early afternoon hours.
..Squitieri.. 11/16/2020
...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
0204 AM CST Mon Nov 16 2020
Valid 171200Z - 181200Z
...NO CRITICAL AREAS...
...Synopsis... An upper ridge will translate across the central
U.S while a mid-level trough moves ashore across the West Coast,
with surface high pressure prevailing beneath the upper ridge on
Day 2/Tuesday. Ahead of the upper trough, a strong southerly wind
field will develop across the western Great Basin. Farther east,
weak surface lee troughing will support modestly dry southerly
winds across the southern High Plains.
...Western Great Basin... By afternoon peak heating, 20+ mph
sustained southerly flow is expected across much of Nevada. While
some guidance members suggest that RH may dip to critical thresholds
by afternoon peak heating, other members suggest RH will be too
high to support widespread wildfire-spread potential. Highlights
have been withheld from the Great Basin, especially considering
the modestly receptive nature of fuels across the area.
..Southern High Plains... While fuels are somewhat receptive
to fire spread across portions of the central and southern High
Plains, questions remain regarding if widespread 15+ mph sustained
southerly winds can develop. While RH will likely dip into the 15-25%
range during the afternoon, the lack of upper support to sustain a
stronger wind field suggests that an Elevated area is not necessary
this outlook. However, should more model guidance members trend
stronger in surface wind speeds, an Elevated area may need to be
added in future outlooks.
..Squitieri.. 11/16/2020
...Please see www.spc.noaa.gov/fire for graphic product...
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