Sunday, December 17, 2023

Destructive Subtropical System Update Two










































000
FXUS61 KCAR 180317
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
1017 PM EST Sun Dec 17 2023

.SYNOPSIS...
Strong low pressure will track up the East Coast on Monday then
pass to our west and continue north into Canada Monday night
into Tuesday. High pressure will slowly build into the area from
the northwest Wednesday into Friday.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
1015pm update...Rain is overspreading the area at this time and
will pick up in intensity later tonight. Low level moisture
spreading north is causing some areas of fog...most notably in
higher terrain. Temperatures will continue to rise all night.
The ongoing forecast for the Sou`easter looks good and no
substantive changes were made. The three major threats remain in
place for Monday: winds, flooding rains, and coastal flooding.

Our initial 00Z analysis and review of guidance indicates the
forecast remains on track.

The High Wind Warning for Downeast and the Bangor area continues
to look like an unfortunate reality. The highest winds will be
in the afternoon and early evening. Guidance continues to
advertise a 925mb low level jet with a strength between 80 and
100 kt depending on the model. The max speeds will be on the
coast, but magnitudes of over 60 kt will reach Aroostook County.
Guidance has been consistent on the LLJ for many days now and
confidence is high. We are not dealing with the caveat of a
shifting low track like a week ago. Surface gusts along the
coast around 70 mph are likely to cause widespread power outages
Downeast. Gusts of 55 to 65 mph further inland are a
significant threat to produce scattered to widespread power
outages across the entire forecast area. The previous discussion
below reiterates the concerns and uncertainties.

In terms of rainfall, this is a warm core low with origins deep
in the Gulf of Mexico. Deep moisture is moving north along the
Atlantic Seaboard from the Caribbean and the system has been
producing flooding from Florida northward into North Carolina.
Flood Watches are in place from North Carolina to Maine as the
system moves north tonight and tomorrow. PWs will likely be at
or above record daily readings on Monday along with record high
temperatures. The current Flood Watch looks good with the
heaviest rain moving across the area from mid-morning into late
afternoon Monday. The heaviest rain continues to show up in the
upslope terrain of Piscataquis County north towards the Katahdin
region. Higher terrain locations could see nearly 4 inches of
rain...which is about the threshold associated with road
washouts last week. Did notice a slight uptick in PWs and
overall QPF in recent guidance, but not enough to make changes
in ongoing headlines. The previous discussion below provides
more pertinent details.

The third concern is the coastal flooding. The coastal flooding
section below succinctly lays out the issues for tomorrow
afternoon`s high tide between 230pm and 3pm and the latest
guidance is consistent with our previous forecasts.


Previous discussion...
Have been some glazed roads from freezing drizzle in the Central
Highlands early this afternoon, but generally, temps have risen
above freezing and will continue to rise, and any icy roads
will be ending fast.

Tonight will feature increasing light rain and rising
temperatures to downright balmy levels...with mid 40s to low 50s
around dawn. No flooding concerns through the night as the
heavier rain won`t have arrived yet. Also, winds tonight will be
increasing some, but not impactful yet through the night.

Monday into Monday evening looks very rough. Models are locked
in on the rain and winds, and confidence is quite high on our
forecast rain totals and wind gusts. A strong low pressure will
be tracking north, passing just west of us late Monday. This
puts us under a very anomalously moist, warm, and windy airmass.
Big concerns for heavy rain and strong winds. For the winds,
have converted the high wind watch to a warning and raised gusts
just a little to a max of 70 mph on the coast and 60 mph inland
toward Bangor. Very concerned about numerous to widespread power
outages resulting. Have compared the parameters to similar
storms in the past, and this setup is about as bad as it gets
for downing a lot of trees. Went with a wind advisory north of
Bangor for gusts to 55 mph. Looks pretty significant by Northern
Maine standards as well, and can`t rule out needing a high wind
warning but went with a high end wind advisory for now. At the
least, expect isolated to scattered power outages in the north,
and can`t rule out more. The highest winds come Monday afternoon
and evening before a cold front moves through from SW to NE and
shuts off the winds pretty fast.

For the rain, we aren`t looking at quite as much as parts of
Downeast saw with last week`s event. However, still expecting
2-3 inches over the southern 2/3 of the area, with a little less
in the far north which is left out of the flood watch but could
still have localized issues. Could be locally up to 4 inches in
the Central Highlands. Soil moisture is already extremely high
and creeks and rivers and running high. The heaviest rain rates
will during the day Monday and into early evening with up to
about a half inch an hour. Expanded the flood watch north to
Northern Penobscot due to forecast precip amounts being just as
high there as areas further SW that were already in the watch.
Rain tapers off from SW to NE early Monday evening, though the
flood threat lingers through the night. Will not be at all
surprised if there are quite a few roads closures and even some
damaged/destroyed roads like some areas Downeast saw last week.

Temperatures will be very mild in the 50s on Monday, and only
cool off a bit Monday night behind the cold front. No flash
freeze of roads expected on the back side of the system.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
A cold front will begin to cross the region during the day
Tuesday. Ahead of the front, it will still be another
unseasonably mild day with highs in the 40s. There will the
chance of showers with the front. As the colder air moves in
later Tuesday afternoon, there is a chance that any rain ends
in the form of a few snow showers across northern areas. Winds
shift to west/northwest in the wake of the front Tuesday night
ushering in much cooler air. This will allow Tuesday nights lows
to fall into the 20s under partly cloudy skies. High pressure
builds in for Wednesday with mainly dry conditions. Afternoon
highs will be just a few degrees above normal for this time of
year.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
High pressure remains in control through much of the period. This
brings generally fair weather through the weekend. A large
storm system will remain to the south of Nova Scotia through mid
week. Not totally out of the question that Downeast areas get
clipped with a few snow showers if the storm tracks far enough
west, but it appears that the system will remain far enough
east to have much of an impact on the region. It will be cooler
both Wednesday and Thursday with highs near seasonal levels both
days. There will also be a stiff north to northeast breeze on
Thursday, as the pressure gradient tightens up between high
pressure to our north and the strong low to the east. Fair
weather will persist Thursday night through next weekend as high
pressure remains in control. Expect mainly clear to partly
cloudy skies through the period. Afternoon high temperatures
will also be near normal through the period.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
NEAR TERM: MVFR through the rest of the day, with IFR beginning
to develop around or a little before 0z. High confidence in IFR
or worse areawide tonight, with rain developing as well. LLWS
at all sites, all times, generally increasing. For Monday,
generally IFR or low MVFR, and windy from the S with heavy rain.
Wind gusts 40-50 kts inland, and 50-60 kts near the coast. Winds
rapidly diminishing Monday night, with improvement to MVFR or
possibly VFR.


SHORT TERM: Tue...VFR/MVFR expected with scattered showers.
SW wind 10 to 15 kt becoming W to NW during the afternoon.

Tue Night through Saturday...Mainly VFR.

&&

.MARINE...
NEAR TERM: Seas and winds will ramp up through Monday, with
south winds storm force and seas building to near 30 ft late
Monday into Monday evening with a long period southerly swell.
Winds/seas beginning to ease late Monday night.


SHORT TERM: SCA conditions will persist through much of the mid
to late week period.

&&

.HYDROLOGY...
Another round of significantly warmer temperatures and heavy
rainfall poses another threat for small river, stream, creek and
urban flooding. Groundwater levels across Downeast and the
Central Highlands are in excess of the 95th percentile for this
time of year. Much of the partial frost that existed Downeast
has thawed along with the Central Highlands resulting in the
grounds being prone to additional water releases and very
little absorption. Much of the rivers across the Central
Highlands and Downeast are open and free of ice but some
isolated areas of ice do exist but expected to play a minimal
role in this event. Ice is present on portions of the northern
river basins, however the only significant ice is on the St.
John River. River ice is expected to break up and move in spots
on the Aroostook & St. John Rivers due to heavy rainfall and
very warm temperatures. Localized ice jams are possible on the
St. John River but expected to cause minimal impacts. Across the
Central Highlands and Downeast with excessive rainfall of 2-3
inches and very soaked thawed grounds poses the greatest risk of
flooding. Have opted to expand the flood watch to include all
of Downeast and Central Highlands including the Bangor region.

Larger rivers across portions of Central and Downeast Maine will
respond to the excessive runoff. Much of the rivers across
Central and Downeast Maine are running in the 76th-95th
percentile for daily flows while northern rivers are near
normal. Latest river ensembles (GEFS, HEFS & NAEFS) have a
35-50% chance the Piscataquis River at Dover-Foxcroft reaches
minor flood stage. The ensembles have the Mattawamkeag at
Mattawamkeag in a 25-50% chance of reaching minor flood stage.
Lastly, the Penobscot at Bangor will need to be monitored on
Monday at the time of high tide for potential flooding as noted
below in the tides and coastal flooding section.

&&

.TIDES/COASTAL FLOODING...
Confidence has increased in coastal flooding and wave runup
issues on Monday at the high tide near 245pm. While not a
particularly high astronomical tide, maximum storm surge and
large waves corresponds with the high tide. Surge is now
expected to be over 2 feet with potential to be close to 2.5
feet. Combined with seas 10 to 15 ft, minor to moderate coastal
flooding is likely...with wave runup being more of a concern
than raw water levels. At this time, the combined tide and
surge looks sufficient to cause minor issues on the Deer Isle
Causeway and in Machias along with other vulnerable locations.
With the strong southerly push, will also have to look for a 2
to 3 foot surge up the Penobscot River to Bangor at high tide.
The magnitude of the waves and the total water level at high
tide brings strong potential for significant splashover on
coastal roads such as Seawall Road and along the Schoodic
Peninsula. A Coastal Flood Warning has been hoisted for the
Downeast Coast from 1PM-5PM on Monday.

&&

.CLIMATE...
Record high temperatures are possible on Monday Dec 18th.

The current forecast high at Caribou is 55F. The record high is
54F in 2000.

The current forecast high at Bangor is 56F. The record high is
53F in 2000.

Record warm low temperatures are also possible on Monday at
these locations.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Wind Advisory from 7 AM Monday to 1 AM EST Tuesday for
     MEZ001>006-010-011-031-032.
     Flood Watch from 7 AM EST Monday through Tuesday morning for
     MEZ005-010-011-015>017-029>032.
     High Wind Warning from 7 AM Monday to 1 AM EST Tuesday for
     MEZ015>017-029-030.
     Coastal Flood Warning from 1 PM to 5 PM EST Monday for MEZ029-
     030.
MARINE...Storm Warning from 7 AM Monday to 1 AM EST Tuesday for
     ANZ050>052.

&&

$$

Near Term...Foisy/MCW
Short Term...Bloomer
Long Term...Bloomer
Aviation...Foisy/MCW/Bloomer
Marine...Foisy/MCW/Bloomer
Hydrology...
Tides/Coastal Flooding...
Climate...


10:28 PM AST Sunday 17 December 2023
High Storm Surge levels and very large waves are expected to impact the coast.

Impacts from storm surge are expected, including coastal flooding, beach erosion, minor infrastructure damage, spread of coastal debris, and localized coastal road washouts.

Locations: Atlantic coast of Nova Scotia, especially south-facing shorelines near Halifax and Eastern shore.

Maximum Water Levels: exceeding high astronomical tide, with water inundating vulnerable sections of coastline.

Maximum wave heights: 6 to 8 metres, breaking upon approach to shore.

Time span: Monday evening and Tuesday morning. Worst near high tide.

Remarks: Be sure to follow any instructions issued by local authorities.

High waves combined with the surge may cause damage along the coast. Coastal flooding is possible along the shoreline.

Storm surge warnings are issued when water levels pose a threat to coastal regions.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to NSstorm@ec.gc.ca or tweet reports using #NSStorm.


10:27 PM AST Sunday 17 December 2023
Heavy rain is expected.

Locations: parts of mainland Nova Scotia.

Rainfall amounts: 50 to 70 mm, with potentially higher amounts locally.

Time span: Monday and ending Tuesday morning, except continuing for areas east of Halifax into mid-week.

Remarks:  A large area of rain will accompany the strong winds and will spread across the province Sunday night and Monday morning. Rainfall rates will likely peak Monday night. For eastern areas rain will continue well into Tuesday bringing additional amounts.

Localized flooding in low-lying areas is possible.

Rainfall warnings are issued when significant rainfall is expected.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to NSstorm@ec.gc.ca or tweet reports using #NSStorm.


10:26 PM AST Sunday 17 December 2023
Strong winds that may cause damage are expected or occurring.

Maximum wind gusts: southerly near 90 km/h.

Time span: beginning Monday afternoon and persisting into early Tuesday.

Locations: P.E.I.

High winds may toss loose objects or cause tree branches to break. Utility outages may occur.

Wind warnings are issued when there is a significant risk of damaging winds.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to PEstorm@ec.gc.ca or tweet reports using #PEStorm.


10:25 PM AST Sunday 17 December 2023
Very strong wind gusts that may cause damage are expected or occurring.

Maximum gusts: southerly 100 km/h.

Locations: Nova Scotia.

Time span: intensifying Monday morning and continuing Monday night.

Exterior seasonal decorations should be secured.

High winds may toss loose objects or cause tree branches to break. Utility outages may occur.

Wind warnings are issued when there is a significant risk of damaging winds.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to NSstorm@ec.gc.ca or tweet reports using #NSStorm.


8:38 PM AST Sunday 17 December 2023
Rainfall amounts: 30 to 50 mm, except locally near 80 mm in areas of heaviest rain.

Time span: Monday morning tapering to showers overnight Monday.

Locations: western, central, and southern New Brunswick.

Similar storms in the past have caused:
- localized flooding, especially in poor drainage areas
- the overflowing of creeks and rivers
- road shoulder erosion and washouts

Remarks: Rainfall rates will likely peak Monday evening. Highest rainfall totals will occur in areas of higher terrain.

Watch for possible washouts near rivers, creeks and culverts.

Rainfall warnings are issued when significant rainfall is expected.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to NBstorm@ec.gc.ca or tweet reports using #NBStorm.


8:06 PM AST Sunday 17 December 2023
Very strong wind gusts that may cause damage are expected or occurring.

Maximum gusts: southerly 90 - 100 km/h.

Locations: south-central New Brunswick.

Time span: Monday near noon ending overnight Monday.

Exterior seasonal decorations should be secured.

High winds may toss loose objects or cause tree branches to break. Utility outages may occur.

Wind warnings are issued when there is a significant risk of damaging winds.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to NBstorm@ec.gc.ca or tweet reports using #NBStorm.


Coastal Hazard Message
National Weather Service Caribou ME
250 PM EST Sun Dec 17 2023

MEZ029-030-181400-
/O.UPG.KCAR.CF.A.0002.231218T1800Z-231218T2300Z/
/O.NEW.KCAR.CF.W.0002.231218T1800Z-231218T2200Z/
Coastal Hancock-Coastal Washington-
250 PM EST Sun Dec 17 2023

...COASTAL FLOOD WARNING IN EFFECT FROM 1 PM TO 5 PM EST MONDAY...

* WHAT...Up to 2 feet of inundation above ground level expected in
  low-lying areas near shorelines. A powerful storm system will
  track west of Maine Monday and Monday night. Strong south to
  southeast winds and very large offshore seas will push a
  significant amount of water to the shoreline.

* WHERE...Coastal Hancock and Coastal Washington Counties.

* WHEN...From 1 PM to 5 PM EST Monday.

* IMPACTS...Large breaking waves will cause overtopping of
  exposed coastal roadways, allowing large rocks to cause
  significant damage to vehicles. In addition, road debris and
  minor road damage could close some roadways. Major beach erosion
  with overtopping to dune structures is expected.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

&&
$$


URGENT - WEATHER MESSAGE
National Weather Service Caribou ME
242 PM EST Sun Dec 17 2023

MEZ001>006-010-011-031-032-181345-
/O.NEW.KCAR.WI.Y.0011.231218T1200Z-231219T0600Z/
Northwest Aroostook-Northeast Aroostook-Northern Somerset-
Northern Piscataquis-Northern Penobscot-Southeast Aroostook-
Central Piscataquis-Central Penobscot-Southern Piscataquis-
Northern Washington-
Including the cities of Allagash, Clayton Lake, Madawaska,
Fort Kent, Frenchville, Presque Isle, Caribou, Van Buren,
Mars Hill, Ashland, Baker Lake, Billy-Jack Depot, Baxter St Park,
Chamberlain Lake, Churchill Dam, Mount Katahdin, Millinocket,
East Millinocket, Patten, Medway, Houlton, Hodgdon, Sherman,
Smyrna Mills, Greenville, Monson, Blanchard, Lincoln, Howland,
Springfield, Dover-Foxcroft, Milo, Guilford, Danforth, Vanceboro,
and Topsfield
242 PM EST Sun Dec 17 2023

...WIND ADVISORY IN EFFECT FROM 7 AM MONDAY TO 1 AM EST TUESDAY...

* WHAT...Southeast winds 20 to 35 mph with gusts up to 55 mph
  expected.

* WHERE...Northwest Aroostook, Northeast Aroostook, Northern
  Somerset, Northern Piscataquis, Northern Penobscot, Southeast
  Aroostook, Central Piscataquis, Central Penobscot, Southern
  Piscataquis and Northern Washington Counties.

* WHEN...From 7 AM Monday to 1 AM EST Tuesday. Period of maximum
  winds is Monday afternoon and early evening.

* IMPACTS...Strong winds may blow down limbs, trees, and
  powerlines. Isolated to scattered power outages may result.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&
$$


URGENT - WEATHER MESSAGE
National Weather Service Caribou ME
242 PM EST Sun Dec 17 2023

MEZ015>017-029-030-181345-
/O.UPG.KCAR.HW.A.0004.231218T1200Z-231219T0600Z/
/O.NEW.KCAR.HW.W.0005.231218T1200Z-231219T0600Z/
Southern Penobscot-Interior Hancock-Central Washington-
Coastal Hancock-Coastal Washington-
Including the cities of Bangor, Brewer, Orono, Old Town, Amherst,
Aurora, Dedham, Eastbrook, Great Pond, Calais, Grand Lake Stream,
Wesley, Princeton, Ellsworth, Bar Harbor, Bucksport, Orland,
Castine, Eastport, Perry, Machias, and Cherryfield
242 PM EST Sun Dec 17 2023

...HIGH WIND WARNING IN EFFECT FROM 7 AM MONDAY TO 1 AM EST
TUESDAY...

* WHAT...South winds 35 to 45 mph with gusts up to 70 mph along
  the coast...and to 60 mph inland...expected.

* WHERE...Southern Penobscot, Interior Hancock, Central
  Washington, Coastal Hancock and Coastal Washington Counties.

* WHEN...From 7 AM Monday to 1 AM EST Tuesday. Period of maximum
  winds is Monday afternoon and early evening.

* IMPACTS...Damaging winds will blow down trees and powerlines.
  Numerous to widespread power outages are likely. Travel will
  be difficult, especially for high profile vehicles.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People should avoid being outside in forested areas and around
trees and branches. If possible, remain in the lower levels of
your home during the windstorm, and avoid windows. Use caution if
you must drive.

&&
$$

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