Tuesday, August 27, 2019

TD Six becomes Tropical Storm Erin, remains a Threat to the Region

WTNT41 KNHC 280239

Tropical Storm Erin Discussion Number   6
NWS National Hurricane Center Miami FL       AL062019
1100 PM EDT Tue Aug 27 2019

Over the past several hours, the deep convection associated with the
cyclone has been developing progressively closer to the center of
circulation. And, at the time of this advisory the convection is now
covering a portion of the previously exposed low-level center. A
late morning scatterometer pass showed winds just over 30 kt over
the eastern semicircle of the cyclone. Since that time, the improved
convective pattern has resulted in an increase in the subjective
satellite intensity estimate from TAFB, indicating an initial
intensity of 35 kt.

Erin is still undergoing northerly shear, but possibly a little less
now than it had been battling for the past couple of days.  Little
change in environmental conditions are expected over the next 36
hours, so some slight strengthening could occur during that time.
After 24 hours, Erin will begin to interact with an approaching
mid-latitude trough over the northeastern United States. This should
cause the storm to gradually acquire extratropical characteristics,
and by 48 hours Erin is expected to have completed extratropical

Erin continues to meander, with an initial motion of 270/3 kt. The
approaching mid-latitude trough should begin to induce a northward
motion of Erin tonight and then accelerate the storm to the
northeast on Wednesday and Wednesday night. Model guidance is in
good agreement on this scenario and the official forecast is close
to the previous one, and near the corrected consensus HCCA. On this
track, Erin will remain well offshore of the United States coast.


INIT  28/0300Z 31.9N  72.1W   35 KT  40 MPH
 12H  28/1200Z 33.1N  72.4W   40 KT  45 MPH
 24H  29/0000Z 36.0N  71.6W   40 KT  45 MPH
 36H  29/1200Z 39.4N  68.9W   40 KT  45 MPH
 48H  30/0000Z 43.7N  65.1W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  31/0000Z...DISSIPATED

Forecaster Latto/Pasch

8:51 PM ADT Tuesday 27 August 2019
Tropical cyclone information statement for:

New Brunswick:

Fundy National Park
Grand Lake and Queens County
Grand Manan and Coastal Charlotte County
Kent County
Kouchibouguac National Park
Moncton and Southeast New Brunswick
Saint John and County
St. Stephen and Northern Charlotte County
Sussex - Kennebecasis Valley and Kings County
Nova Scotia

Prince Edward Island

For Tropical Depression Six.

The next information statement will be issued by 03:00 a.m. ADT.

Tropical Depression Six currently meandering off the Carolina coast. Will begin tracking northeastward toward Atlantic Canada on Wednesday, and will interact with existing weather system bringing heavy rain and gusty winds to the Maritimes late Thursday or Friday.

1. Summary of basic information at 09:00 p.m. ADT.

Location: Near 32.1 North 71.9 West.

About distance 485 kilometres southeast of Cape Hatteras NC.

Maximum sustained winds: 56 kilometres per hour.

Present movement: Northwest at 11 kilometres per hour.

Minimum central pressure: 1008 millibars.

2. Public weather impacts and warnings summary.

With Tropical Depression Six still nearly 1500 km and a few days away from the region, details on impacts for Atlantic Canada can only be generalised at this time. As the system begins to interact with a trough of low pressure approaching from the Great Lakes on Thursday, some of its moisture will likely feed into this trough and enhance the rainfall across the region. What is left of T.D. Six beyond Thursday will likely become absorbed in this trough before it reaches Newfoundland.

a. Wind.

While some gusty winds will likely accompany the system, it is unlikely that T.D. Six will be a major wind event in the region. It is unlikely that winds will reach warning criteria (i.e. gusts to 90 km/h or higher), but could still be strong enough to cause isolated power outages and minor damage, especially given that trees are still in full leaf.

b. Rainfall.

It is looking more and more like the interaction of T.D. Six and the fore-mentioned trough of low pressure will combine to produce significant rainfall across the region later Thursday and into Friday. Rainfall could meet or exceed warning criteria (50 mm or more in 24 hours) in parts of the Maritimes, with potential some isolated areas could see in excess of 100 mm. Details will become more clear in the coming days as the system becomes better defined and the expected trough interaction begins to take shape.

c. Surge/Waves.

At this time, given the expected intensity and track of the system, significant storm surge and coastal impacts from high waves are not very likely over the Maritimes. However, some higher than normal water levels and high surf are possible near and to the right of the track, and this will be monitored closely as the system evolves over the coming days.

3. Marine weather impacts and warnings summary.

Gale warnings will likely be required for waters near and adjacent to the track Erin takes through our region later on Thursday and Friday.

Forecaster(s): Borgel/Mercer

FXCN31 CWHX 280000
Tropical cyclone technical information statement issued by the
Canadian Hurricane Centre of Environment Canada at 8.53 PM ADT
Tuesday 27 August 2019.

The next statement will be issued by 3.00 AM ADT

1. Current position, strength, central pressure and motion

At 9.00 PM ADT, tropical depression six was located near latitude
32.1 N and longitude 71.9 W, about 262 nautical miles or 486 km
southeast of Cape Hatteras. Maximum sustained winds are estimated at
30 knots (56 km/h) and central pressure at 1008 MB. Six is moving
northwest at 6 knots (11 km/h).

2. Forecast position, central pressure and strength

Date     time     lat    lon   MSLP  Max wind
          ADT                    MB  kts  kmh
Aug 27  9.00 PM  32.1N  71.9W  1008   30   56
Aug 28  9.00 AM  33.7N  72.2W  1006   30   56
Aug 28  9.00 PM  35.9N  71.7W  1004   35   65
Aug 29  9.00 AM  39.0N  69.1W  1003   35   65
Aug 29  9.00 PM  42.1N  65.6W  1002   35   65 post-tropical
Aug 30  9.00 AM  45.0N  61.4W  1002   35   65 post-tropical
Aug 30  9.00 PM  47.7N  57.7W  1003   35   65 post-tropical
Aug 31  9.00 AM  51.2N  53.4W  1004   30   56 post-tropical

3. Technical discussion

A. Analysis

Tropical depression six is still struggling to strengthen, with the
circulation center clearly displaced from and north of the main area
of convection.  Intensity is mainatned at 30 knots, and after
meandering for most of the day the system has drifted slightly to the
northwest over the last few hours.

B. Prognostic

The strong westerly shear has held td six down all day, and there is
now some possibility it may not ever reach tropical storm strength as
the window for intensification will soon begin to close.  It will
remain over relatively warm water through this period, and should the
shear decrease somewhat as expected, some slight strenghthening is
expected over the next couple of days. Beyond Wednesday the system
will begin accerating northeastward as it starts interacting with a
baroclinic trough approaching from the Great Lakes. Phase space
guidance from most models indicate extra-tropical transition should
be fairly rapid and the system should be fully transitioned when it
moves into Canadian marine waters. Regardless, what is left of td six
should become absorbed into the fore-mentioned trough by the time it
reaches Newfoundland.

C. Predicted wind radii (NM)

Time          gales           storms            hurricane
         NE  SE  SW  NW    NE  SE  SW  NW    NE  SE  SW  NW
28/00Z    0   0   0   0     0   0   0   0     0   0   0   0
28/12Z    0   0   0   0     0   0   0   0     0   0   0   0
29/00Z   80 120  60   0     0   0   0   0     0   0   0   0
29/12Z   80 120  60   0     0   0   0   0     0   0   0   0
30/00Z   80 120  60   5     0   0   0   0     0   0   0   0
30/12Z   80 125  65  15     0   0   0   0     0   0   0   0
31/00Z   85 130  65  20     0   0   0   0     0   0   0   0
31/12Z    0   0   0   0     0   0   0   0     0   0   0   0


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