Thursday, August 27, 2009

Tropical Storm Danny #2


WOCN31 CWHX 271200
Tropical storm Danny information statement issued by the
Canadian hurricane centre of Environment Canada at 9.00 AM ADT
Thursday 27 August 2009.

The next statement will be issued by 3.00 PM ADT

... Danny still taking shape ...

1. Current position, strength, central pressure and motion

At 9.00 AM ADT... Tropical storm Danny was located near latitude
27.8 N and longitude 72.5 W... About 500 nautical miles or 925 km
east northeast of Cockburn . Maximum sustained winds are
Estimated at 50 knots... 93 km/h... And central pressure at 1006
MB. Danny is moving northwest at 7 knots... 13 km/h.

2. Forecast position, central pressure and strength

Date time lat lon MSLP Max wind
ADT MB kts kmh
Aug 27 9.00 AM 27.8N 72.5W 1006 50 93
Aug 27 9.00 PM 29.0N 73.5W 1004 50 93
Aug 28 9.00 AM 31.1N 74.0W 1002 55 102
Aug 28 9.00 PM 34.0N 73.4W 998 65 120
Aug 29 9.00 AM 37.7N 71.6W 987 65 120
Aug 29 9.00 PM 41.4N 68.8W 985 65 120
Aug 30 9.00 AM 45.7N 63.9W 990 55 102 post-tropical
Aug 30 9.00 PM 48.5N 58.6W 995 50 93 post-tropical
Aug 31 9.00 AM 50.8N 50.8W 998 45 83 post-tropical
Aug 31 9.00 PM 52.5N 44.1W 1000 40 74 post-tropical
Sep 01 9.00 AM 53.6N 34.9W 1002 35 65 post-tropical

3. Public weather impacts and warnings summary
Eventually Danny will produce rain over the weekend
But it is too early to determine amounts.

4. Marine weather impacts and warnings summary
Danny will weaken as it moves through canadian waters.
Though it may produce hurricane winds upon first entering
The marine district.. It will weaken once it moves over colder
waters.

5. Technical discussion for meteorologists

A. Analysis
Utilising ir satellite imagery has been difficult at this point
But once the visual imagery becomes avaiable.. The position
Should become clearer. Miami has had difficulty finding the
Centre of Danny as the wind field is asymetric as shown by
Quickscat plus the centre had reformed to the northeast.

B. Prognostic
Danny will present challenges to forecast centres as it is poorly
Formed. Yet.. The model guidance wants to develop
Danny into a marginal hurricance as it tracks northward
And passes the Carolina coast. Indications are
For Danny to undergo extra tropical transition once
It passes Cape Cod. How much hurricane force strength
Will be left in Danny beyond that point is questionable.

It must be emphasized that there is still a lot of uncertainty
With respect to the track and intensity of Danny once it
Reaches canadian waters. We are following the guidance from
Miami and will likely do so in the near future.

C. Public weather
Decaying tropical systems often produce heavy rain over the
Martimes and past experience indicates that locally higher
Amounts may be produced.

D. Marine weather

Predicted wind radii will be produced once there is more
Certainty in Danny's intensity.. Especially once it
Reaches canadian waters.

End campbell




WOCN31 CWHX 271200
TROPICAL STORM DANNY INFORMATION STATEMENT ISSUED BY THE
CANADIAN HURRICANE CENTRE OF ENVIRONMENT CANADA AT 9.00 AM ADT
THURSDAY 27 AUGUST 2009.

THE NEXT STATEMENT WILL BE ISSUED BY 3.00 PM ADT

... DANNY STILL TAKING SHAPE ...

1. CURRENT POSITION, STRENGTH, CENTRAL PRESSURE AND MOTION

AT 9.00 AM ADT... TROPICAL STORM DANNY WAS LOCATED NEAR LATITUDE
27.8 N AND LONGITUDE 72.5 W... ABOUT 500 NAUTICAL MILES OR 925 KM
EAST NORTHEAST OF COCKBURN . MAXIMUM SUSTAINED WINDS ARE
ESTIMATED AT 50 KNOTS... 93 KM/H... AND CENTRAL PRESSURE AT 1006
MB. DANNY IS MOVING NORTHWEST AT 7 KNOTS... 13 KM/H.

2. FORECAST POSITION, CENTRAL PRESSURE AND STRENGTH

DATE TIME LAT LON MSLP MAX WIND
ADT MB KTS KMH
AUG 27 9.00 AM 27.8N 72.5W 1006 50 93
AUG 27 9.00 PM 29.0N 73.5W 1004 50 93
AUG 28 9.00 AM 31.1N 74.0W 1002 55 102
AUG 28 9.00 PM 34.0N 73.4W 998 65 120
AUG 29 9.00 AM 37.7N 71.6W 987 65 120
AUG 29 9.00 PM 41.4N 68.8W 985 65 120
AUG 30 9.00 AM 45.7N 63.9W 990 55 102 POST-TROPICAL
AUG 30 9.00 PM 48.5N 58.6W 995 50 93 POST-TROPICAL
AUG 31 9.00 AM 50.8N 50.8W 998 45 83 POST-TROPICAL
AUG 31 9.00 PM 52.5N 44.1W 1000 40 74 POST-TROPICAL
SEP 01 9.00 AM 53.6N 34.9W 1002 35 65 POST-TROPICAL

3. PUBLIC WEATHER IMPACTS AND WARNINGS SUMMARY
EVENTUALLY DANNY WILL PRODUCE RAIN OVER THE WEEKEND
BUT IT IS TOO EARLY TO DETERMINE AMOUNTS.

4. MARINE WEATHER IMPACTS AND WARNINGS SUMMARY
DANNY WILL WEAKEN AS IT MOVES THROUGH CANADIAN WATERS.
THOUGH IT MAY PRODUCE HURRICANE WINDS UPON FIRST ENTERING
THE MARINE DISTRICT.. IT WILL WEAKEN ONCE IT MOVES OVER COLDER
WATERS.

5. TECHNICAL DISCUSSION FOR METEOROLOGISTS

A. ANALYSIS
UTILISING IR SATELLITE IMAGERY HAS BEEN DIFFICULT AT THIS POINT
BUT ONCE THE VISUAL IMAGERY BECOMES AVAIABLE.. THE POSITION
SHOULD BECOME CLEARER. MIAMI HAS HAD DIFFICULTY FINDING THE
CENTRE OF DANNY AS THE WIND FIELD IS ASYMETRIC AS SHOWN BY
QUICKSCAT PLUS THE CENTRE HAD REFORMED TO THE NORTHEAST.

B. PROGNOSTIC
DANNY WILL PRESENT CHALLENGES TO FORECAST CENTRES AS IT IS POORLY
FORMED. YET.. THE MODEL GUIDANCE WANTS TO DEVELOP
DANNY INTO A MARGINAL HURRICANCE AS IT TRACKS NORTHWARD
AND PASSES THE CAROLINA COAST. INDICATIONS ARE
FOR DANNY TO UNDERGO EXTRA TROPICAL TRANSITION ONCE
IT PASSES CAPE COD. HOW MUCH HURRICANE FORCE STRENGTH
WILL BE LEFT IN DANNY BEYOND THAT POINT IS QUESTIONABLE.

IT MUST BE EMPHASIZED THAT THERE IS STILL A LOT OF UNCERTAINTY
WITH RESPECT TO THE TRACK AND INTENSITY OF DANNY ONCE IT
REACHES CANADIAN WATERS. WE ARE FOLLOWING THE GUIDANCE FROM
MIAMI AND WILL LIKELY DO SO IN THE NEAR FUTURE.

C. PUBLIC WEATHER
DECAYING TROPICAL SYSTEMS OFTEN PRODUCE HEAVY RAIN OVER THE
MARTIMES AND PAST EXPERIENCE INDICATES THAT LOCALLY HIGHER
AMOUNTS MAY BE PRODUCED.

D. MARINE WEATHER

PREDICTED WIND RADII WILL BE PRODUCED ONCE THERE IS MORE
CERTAINTY IN DANNY'S INTENSITY.. ESPECIALLY ONCE IT
REACHES CANADIAN WATERS.

END CAMPBELL

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