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LU9DCE > ALERT 17.12.20 16:02z 298 Lines 13802 Bytes #999 (0) @ WW
BID : 43212_LU9DCE
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Subj: STORM PREDICTION CENTER 17 12
Path: HB9ON<IW8PGT<IZ3LSV<IK5FKA<IK5FKA<LU9HGS<LU3DVN<LU9DCE
Sent: 201217/1600Z 43212@LU9DCE.TOR.BA.ARG.SOAM BPQ6.0.20
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Storm Prediction Center
en-us
None
Thu, 17 Dec 2020 09:40:02 +0000
Thu, 17 Dec 2020 09:40:02 +0000
general
1
No watches are valid as of Thu Dec 17 09:40:03 UTC 2020.
Thu, 17 Dec 2020 09:39:19 +0000
MD 1857 CONCERNING HEAVY SNOW FOR CENTRAL NY...SOUTHERN VT/NH...FAR
NORTHWESTERN MA...FAR SOUTHERN MAINE
Mesoscale Discussion 1857
NWS Storm Prediction Center Norman OK
0333 AM CST Thu Dec 17 2020
Areas affected...central NY...southern VT/NH...far northwestern
MA...far southern Maine
Concerning...Heavy snow
Valid 170933Z - 171530Z
SUMMARY...Heavy snowfall rates ranging from 2-4 inches per hour are
expected to continue across central NY through 12z.These snowfall
rates have begun to develop over southern VT/NH as of 4am EST and
will develop into far southern Maine by 5am.
DISCUSSION...Radar mosaic as of 430am EST shows an impressive
frontogenetic snow band extending from near Binghamton, NY northeast
through Albany, NY and developing across southern VT/NH.Recent
measured reports from Binghamton have reached 5 inches per hour for
two hours earlier this morning and this band has yielded 2+ inches
per hour at observation sites farther east-northeast during the past
hour (3 inches at Albany, NY).The strong 700-650 mb frontogenesis
will continue to support the maintenance of an intense snow band in
central NY through 7am and into southern VT/NH.Co-located with the
frontogenetic snow band, model guidance has indicated the heaviest
rates (i.e., 4-5 inches per hour) have probably passed.However,
the strong lift favorably juxtaposed with the dendritic growth zone
will likely result in snowfall rates 2-4 inches per hour through 7am
from parts of central NY east into southern VT/NH, and persisting
across VT/NH and into southern Maine during the 7am-10am period with
rates in the 2-3 inches per hour range.
..Smith.. 12/17/2020
ATTN...WFO...GYX...BOX...BTV...ALY...BGM...
LAT...LON42327556 43417318 43857033 43876923 43377025 42827098
42787178 42537330 41977515 42327556
Read more
Thu, 17 Dec 2020 09:34:03 +0000
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1146 PM CST Wed Dec 16 2020
Valid 171200Z - 181200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated non-severe thunderstorms will be possible today in south
Florida and in California.
...DISCUSSION...
An upper-level trough will move eastward through the Gulf Coast
states today as a cold front advances southward across the Florida
Peninsula. A few thunderstorms may occur in southern Florida ahead
of the front. Another upper-level trough will move across
California. Thunderstorm development will be possible ahead of the
trough in eastern parts of the Sacramento Valley and in the
foothills of the Sierra Nevada, mainly this morning. No severe
thunderstorms are expected in the continental United States today or
tonight.
..Broyles.. 12/17/2020
Read more
Thu, 17 Dec 2020 05:55:32 +0000
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1110 PM CST Wed Dec 16 2020
Valid 181200Z - 191200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Aside from a corridor across parts of eastern Texas by daybreak
Saturday, the risk for thunderstorms appears neglible across much of
the U.S. Friday through Friday night.
...Synopsis...
Much of North America will remain under the influence of westerlies
branching downstream of a strong, zonal mid/upper jet across the
western through central southern mid-latitude/subtropical Pacific.
This regime will continue to include a number of modestly amplified,
progressive short wave troughs, including one accompanied by a
significant surface cyclone migrating away from the Atlantic
Seaboard Friday through Friday night.
Stable conditions will generally prevail east of the Rockies (in
addition to much of the west) in the wake of this system, with
little change forecast across most areas through this period.
However, boundary-layer moistening and northward return flow may be
ongoing by Friday morning across parts of the southwestern Gulf of
Mexico, on the southwestern flank of elongated surface ridging
encompassing much of eastern North America and the Gulf of Mexico.
Models do suggest that the Eastern surface ridge axis will gradually
shift toward the Atlantic coast during this period, coincident with
the progression of mid-level troughing east of both the Canadian
Prairies and the southern U.S. Rockies.It appears that this will
be accompanied by surface troughing into the Upper Midwest, lower
Missouri Valley and southeastern Great Plains Friday night, preceded
by weak to modest southerly return flow.As this occurs, modest
low-level moisture emanating from the southwestern Gulf of Mexico
may reach upper Texas coastal areas by 12Z Saturday.
...Eastern Texas...
Latest model runs, most notably the NAM, appear a bit slower with
the low-level moisture return to the northwest Gulf coast vicinity,
in addition to farther south and slower with the mid-level short
wave digging to lee of the southern Rockies, before turning
eastward.However, it does still appear that moisture return above
a residual surface-based stable layer will contribute to the
development of at least very weak CAPE by late Friday night.As
weak mid-level cooling begins to overspread the Ark-La-Tex southward
toward the upper Texas coastal plain, convection capable of
producing lightning appears possible by around 12Z Saturday.
..Kerr.. 12/17/2020
Read more
Thu, 17 Dec 2020 06:01:26 +0000
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0155 AM CST Thu Dec 17 2020
Valid 191200Z - 201200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
The risk for severe thunderstorms appears negligible across the
U.S., Saturday through Saturday night.
...Discussion...
Much of North America will remain under the influence of branching
westerlies emanating from the mid-latitude and subtropical Pacific,
but broad mid/upper ridging developing within this regime may spread
inland of the Pacific coast during this period.Downstream, as one
short wave trough digs across the southern Rockies and another
southeast of the Canadian Prairies, it appears that a short wave
trough, initially over the southern Great Plains at 12Z Saturday,
will pivot east-northeastward through the lower Ohio and Tennessee
Valleys by late Saturday night.
A significant surface cyclone, initially developing to the lee of
the Canadian Rockies, is forecast to accompany the northern
perturbation into northwestern Ontario by the end of the period.
Models indicate that this will trail an initially more significant
cyclone over Hudson Bay, with a developing cold front within weak
surface troughing trailing southward across the upper Great Lakes
into the southeastern Great Plains.However, they suggest little in
the way of substantive wave development along this boundary as it
continues to shift east of the Mississippi Valley.
Modest moisture return emanating from the southwestern Gulf of
Mexico may reach northwestern Gulf coastal areas by 12Z Saturday.
While this may spread inland across upper Texas coastal areas,
mostly above a residual surface based stable layer, it appears that
it will only contribute to very weak CAPE as far north as the lower
Mississippi Valley.
...Southeastern Great Plains into Gulf States...
Weak destabilization associated with pre-cold frontal elevated
moisture return may support increasing convection capable of
producing lightning in a corridor across northeastern Texas through
central Arkansas early Saturday.This likely will be aided by
forcing for ascent ahead of the approaching short wave trough.
As the short wave impulse turns east-northeast of the southern Great
Plains, models suggest that one tightening low-level thermal
gradient ahead of the cold front (roughly in the 925-850 mb layer),
near its intersection, may provide a focus for continuing weak
thunderstorm activity.Due to spread among the various model
output, how far east remains a little unclear, but low probabilities
for thunderstorms may extend as far east as north central Georgia by
late Saturday night.
Models suggest that another corridor of favorable ascent may support
thunderstorm development southeastward into better low-level
moisture and instability across southeast Texas and southern
Louisiana.However, any intensification into more vigorous
thunderstorms capable of posing an appreciable severe threat
probably will be confined to northwestern into north central Gulf of
Mexico.
..Kerr.. 12/17/2020
Read more
Thu, 17 Dec 2020 07:59:30 +0000
Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CST Thu Dec 17 2020
Valid 201200Z - 251200Z
...DISCUSSION...
Models indicate that an initially intense, zonal mid/upper jet
across western and central portions of the southern mid-latitude
Pacific will undergo considerable amplification through the extended
period.This is expected to lead to amplification within the
branching downstream flow, with guidance indicating greatest
certainty concerning the evolution of a prominent ridge across the
northeastern Pacific into the northern U.S./Canadian Pacific coast
early next week.It appears that this ridge will build as far north
as the Arctic latitudes of Alaska/northwestern Canada, before
large-scale downstream mid/upper trough amplification proceeds, from
the lee of the Canadian/northern U.S. Rockies through much of the
eastern U.S. by early Christmas Day.
There is sizable spread concerning the short wave perturbations
contributing to this large-scale trough evolution.However, model
output has been indicating the potential for strong cyclogenesis,
either with an initial low developing east-northeast of the middle
Missouri Valley though the Great Lakes region by mid week, or with a
secondary low developing to its southeast by late week.
Associated strengthening of deep-layer wind fields within the
evolving warm sectors will pose a conditional risk for increasing
severe weather potential, given sufficient instability.However,
moisture to contribute to appreciable destabilization remains
unclear, as deep Gulf of Mexico boundary-layer moistening to support
a substantive inland return flow remains hampered, particularly with
another mid-level perturbation forecast to pivot across the
Southeast early this week.
Still, there may be at least some potential for one or two
low-topped convective lines to evolve, which could be accompanied by
an enhancement of risk for damaging wind gusts, across parts of the
Ohio Valley on Wednesday, and parts of the eastern Gulf/south
Atlantic Coast states on Christmas Eve.
Read more
Thu, 17 Dec 2020 09:39:46 +0000
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0112 AM CST Thu Dec 17 2020
Valid 171200Z - 181200Z
...NO CRITICAL AREAS...
...Synopsis...
Quiescent fire-weather conditions are expected to continue through
the day today.A relatively cool airmass has taken hold across much
of the central and eastern U.S. in the wake of a storm system
currently near the East Coast.This will keep RH values relatively
high and preclude fire-weather risk for most areas.Localized areas
of west Texas will experience 15-25% RH values during peak heating,
though wind speeds are expected to be too light for any large-scale
fire-weather risk.Finally, onshore flow is expected to take hold
across southern California and allow for moist air to migrate inland
atop relatively dry fuels, mitigating fire-weather concerns there.
..Cook.. 12/17/2020
Read more
Thu, 17 Dec 2020 07:14:11 +0000
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0116 AM CST Thu Dec 17 2020
Valid 181200Z - 191200Z
...Synopsis...
A mid-level wave will traverse the central and southern Rockies
Friday, spreading enhanced mid-level flow across portions of New
Mexico and west Texas during peak heating hours.Ahead of this
system, a surface low will organize near the New Mexico/Texas border
area and migrate slowly southeastward.Meanwhile, high pressure
across the Great Basin will promote offshore flow across southern
California that will gradually strengthen over time.
...Southern California...
The aforementioned offshore pressure gradient will persist
throughout the day and into the overnight hours, with dry low-level
air returning to regions where dry fuels are located.A few areas
will experience 15-25 mph easterly surface winds in tandem with the
dry air (characterized by areas of 12-25% RH values during peak
heating).Elevated to locally critical fire-weather conditions are
expected as result - especially in locations where terrain-related
enhancement of surface winds can occur.
...Southern New Mexico and west Texas...
Low-level drying will occur in many areas during the day in response
to a sharpening surface trough/low expected to be in west Texas by
00Z.RH values are expected to fall into the 12-25% range during
peak heating. Meanwhile, sustained surface winds will reach 30 mph
in several areas along with a few higher gusts.Where fuels are
dry, an elevated fire-weather threat will exist.
..Cook.. 12/17/2020
Read more
Thu, 17 Dec 2020 07:18:21 +0000
+------------------------- POWERSHELL WINDOWS ----------------------------+
Don't look back, the lemmings are gaining on you.
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