Tropical Storm Isaias Creeps Northward
WTNT44 KNHC 030243
TCDAT4
Tropical Storm Isaias Discussion Number 24
NWS National Hurricane Center Miami FL AL092020
1100 PM EDT Sun Aug 02 2020
Isais has not become better organized on satellite and radar imagery
at this time. The cyclone continues to produce vigorous deep
convection but this convection continues to be displaced to the
northeast of the center, and convective banding features are
ill-defined. Air Force Hurricane Hunter observations show that the
central pressure has not fallen since earlier today, and
flight-level and SFMR-observed surface wind measurements from the
aircraft indicate that the intensity remains near 60 kt. Although
Isais will be moving through an environment of fairly strong
southwesterly shear during the next day or so, it will also be
traversing the warm waters of the Gulf Stream with its high oceanic
heat content. The latter factor could result in the system becoming
a hurricane near landfall. The official forecast is close to the
intensity consensus, which keeps Isaias just below hurricane
strength.
It should be emphasized that there is little difference between a
strong tropical storm or a category 1 hurricane, in terms of
impacts.
After landfall, the interaction with land and strong shear should
result in steady weakening. Based on the global models, the
cyclone is likely to become an extratropical cyclone after it moves
into Canada and dissipate over the north Atlantic shortly
thereafter.
The motion continues to be slightly west of due north or 345/8 kt.
There has been no significant change to the track forecast
reasoning. Over the next couple of days, Isaias is expected to
accelerate north-northeastward on the east side of a large 500 mb
trough over the eastern United States and then turn northeastward
in 3 to 4 days as it moves through the mid-latitude westerlies.
The official track forecast is very close to the previous one and
similar to the latest corrected dynamical model consensus. This is
between the GFS, which shows a slightly faster motion and the ECMWF,
which is slightly slower.
Key Messages:
1. There is the danger of life-threatening storm surge inundation of
2 to 4 feet above ground level from Edisto Beach South Carolina to
Cape Fear North Carolina along the immediate coastline and adjacent
waterways. Life-threatening storm surge is possible along the
North Carolina coast from Cape Fear to Duck. Residents in these
areas should follow advice given by local emergency officials.
2. Tropical storm conditions will spread northward within the
Tropical Storm Warning area from Florida to Maryland through
early Tuesday. Isaias is expected to be near hurricane strength when
it reaches the coast of northern South Carolina and southern North
Carolina Monday night, and strong tropical storm force winds are
likely with hurricane conditions possible in the Hurricane Watch
area.
3. Heavy rainfall from Isaias will continue to result in potentially
life-threatening flash flooding in the Northwest Bahamas through
tonight. Flash and urban flooding, some of which may be significant
in the eastern Carolinas and the mid-Atlantic, is expected through
midweek along and near the path of Isaias across the East Coast of
the United States. Widespread minor to moderate river flooding is
possible across portions of the Carolinas and the mid-Atlantic.
4. Tropical storm conditions are forecast to spread northward
across the remainder of the U.S east coast on Tuesday and early
Wednesday. A tropical storm watch is in effect through Long Island
Sound and additional watches and warnings will likely be issued on
Monday.
FORECAST POSITIONS AND MAX WINDS
INIT 03/0300Z 28.5N 79.8W 60 KT 70 MPH
12H 03/1200Z 29.7N 80.0W 60 KT 70 MPH
24H 04/0000Z 32.2N 79.3W 60 KT 70 MPH
36H 04/1200Z 35.9N 77.3W 55 KT 65 MPH...INLAND
48H 05/0000Z 40.5N 74.0W 40 KT 45 MPH...INLAND
60H 05/1200Z 45.5N 70.0W 35 KT 40 MPH...INLAND
72H 06/0000Z 50.0N 65.5W 30 KT 35 MPH...POST-TROP/EXTRATROP
96H 07/0000Z 55.5N 56.5W 25 KT 30 MPH...POST-TROP/EXTRATROP
120H 08/0000Z...DISSIPATED
$$
Forecaster Pasch
000
FXUS61 KCAR 030114
AFDCAR
Area Forecast Discussion
National Weather Service Caribou ME
914 PM EDT Sun Aug 2 2020
.SYNOPSIS...
Low pressure will track northwest of the region through Monday.
A cold front will cross the area Monday night. Isaias will
track northeast across Maine Wednesday. An upper low will track
north of the region Thursday. High pressure will build across
the region Friday.
&&
.NEAR TERM /THROUGH MONDAY/...
9:14 pm update: Area radars show scattered showers across parts
of Aroostook County and into northern Piscataquis County.
Upstream there are showers and thunderstorms in Quebec to the
north of NY and VT. Some of this activity could work into
northern Maine after midnight, but it will likely weaken to just
scattered showers. There are plenty of mid level clouds across
the FA this evening, and still expect that low clouds will
develop in a mild and muggy air mass overnight along the coast
and work north overnight. Made some adjustments to the PoPs and
weather based on the latest radar trends. Otherwise, changes
were very minor and based on the latest observations and
expected forecast trends.
Previous discussion:
High pressure will slide southeast of the region tonight as a low
lifting north of the eastern Great Lakes pulls a warm front across
the area. Some showers are possible with this front, mainly across
northern areas this evening. Otherwise, an increasing gradient
between high pressure to the southeast and the low lifting up to our
west will bring an increasing southerly breeze and increasing
humidity overnight. The humid air lifting north over the waters will
likely bring some fog along the coast. Low pressure will lift north
of the region Monday as a corridor of drier air lifts across our
area. A few showers and perhaps an isolated thunderstorm may be
across the north. Otherwise, Monday will turn out partly cloudy and
humid. A weak cold front will slide across the area late Monday into
Monday evening ushering in just slightly drier air. High
pressure will follow later Monday night bringing a tranquil
night. Moisture running north well ahead of tropical storm
Isaias will bring increasing clouds late at night. Showers will
likely increase on Tuesday along a corridor of lift supported by
divergence aloft between the subtropical high to the east and
an upper trough approaching from the west. The best chance for
showers will be central and western areas where bands of
steadier rain may develop late in the day as the low center of
tropical storm Isaias tracks into southern New England.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
Isaias will approach Tuesday night then cross the region
Wednesday. Models are in better agreement tracking the storm
northeast across Maine Wednesday while starting to transition
from a tropical to an extratropical system. However, uncertainty
still exists regarding the exact timing of the storm across
Maine. Winds, along with rainfall, will be dependent on both the
eventual track and intensity of the storm. Current indications
are that Isaias will have an over land trajectory while
approaching southern Maine Tuesday night, then remain over land
while tracking northeast across Maine Wednesday. Expect rain,
along with a chance of thunderstorms, to expand across the
region Tuesday night then persist with the system Wednesday. The
rain could be heavy at times later Tuesday night through
Wednesday. An upper trof approaching from the west could help
enhance rainfall with the system. Rainfall totals will also be
enhanced across the favored upslope terrain areas. Windy/very
windy conditions are also expected Wednesday. Temperatures will
be at near normal levels Wednesday.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The storm will exit across the Maritimes Wednesday night. Rainfall
will diminish later Wednesday into Wednesday night in the wake of
the storm. An upper low will track north of Maine Thursday,
while surface high pressure builds across the region. Could have
the slight chance of afternoon showers across mostly the north
and mountains Thursday. Otherwise, expect generally partly
cloudy skies Thursday. High pressure will cross the region
Friday, with mostly clear skies. An upper level trof will cross
the region Saturday with partly cloudy skies along with a
slight chance of showers across mostly the north and mountains.
An isolated shower is possible Sunday. Otherwise, expect mostly
clear/partly cloudy skies Sunday. Near normal level
temperatures are expected Thursday, with slightly above normal
level temperatures Friday through Sunday.
Hazardous Weather Outlook
National Weather Service Caribou ME
820 PM EDT Sun Aug 2 2020
MEZ001>006-010-011-015>017-031-032-040030-
Northwest Aroostook-Northeast Aroostook-Northern Somerset-
Northern Piscataquis-Northern Penobscot-Southeast Aroostook-
Central Piscataquis-Central Penobscot-Southern Penobscot-
Interior Hancock-Central Washington-Southern Piscataquis-
Northern Washington-
820 PM EDT Sun Aug 2 2020
This Hazardous Weather Outlook is for Central Highlands Maine, Far
Eastern Maine, Far Northern Maine, Interior DownEast Maine, North
Woods Maine and Penobscot Valley Maine.
.DAY ONE...Tonight.
Hazardous weather is not expected at this time.
.DAYS TWO THROUGH SEVEN...Monday through Saturday.
Isaias is forecast to track across Maine by mid-week. Confidence is
increasing on the track of Isaias but some uncertainties remain in
timing. The exact track will determine the impacts, but gusty winds
and heavy rain will be possible.
.SPOTTER INFORMATION STATEMENT...
Weather spotters are encouraged to report significant weather
conditions according to Standard Operating Procedures.
$$
8:59 AM ADT Sunday 02 August 2020
Tropical cyclone information statement for:
New Brunswick
For Tropical Storm Isaias.
The next information statement will be issued by 09:00 a.m. ADT Monday.
Current indications show Tropical Storm Isaias will approach Eastern Canada around mid-week, and could bring locally heavy rainfall and gusty winds to parts of the region Wednesday or Thursday.
The Canadian Hurricane Centre is closely monitoring the progress of Tropical Storm Isaias (pronounced ees-ah-EE-ahs), which is currently located just off of the south Florida coast. Isaias is expected to approach Eastern Canada from the New England region later Wednesday or Thursday. The most likely impacts for Canada will be potential for heavy rainfall and gusty winds.
There is still a wide range of potential track and intensity scenarios that are possible over the next several days for Isaias, thus details on impacts are difficult to determine at this time. Interests in Eastern Canada should closely monitor forecasts for early to midweek as this situation continues to evolve.
The Canadian Hurricane Centre will begin issuing regular updates on Isaias beginning 09:00am Monday.
Forecaster(s): Borgel/CHC
Please continue to monitor alerts issued by the Canadian Hurricane Centre and forecasts issued by Environment Canada.
posted by Advackia at 9:06 PM
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