ATL: KATIA - Post Tropical - Discussion

[westwind]

Probably it is lower because some of the winds aren't transferring down to the surface.

Ok, so why would that happen? becouse she is now in the westerlies? She seams to have a well defined eyewall and none of the inner core problems Irene had... but i'm no pro. Just wondering if there is a reason why the winds wouldn't get to the serface.

[tropicana]

WARNINGS FROM UK MET OFFICE
Issued at - 09 Sep 2011, 17:06
Valid from - 12 Sep 2011, 00:00
Valid to - 12 Sep 2011, 23:59

The remains of Hurricane Katia are expected to come across the UK on Monday bringing a spell of very windy weather. There remains some uncertainty about its track and intensity, though with increasing indications that Scotland and Northern Ireland are most likely to bear the brunt the warning has been upgraded to amber here. The public should be aware of the risk of disruption to transport and of the possibility of damage to trees and structures.

The public are advised to take extra care.

STATEMENT FROM CANADIAN HURRICANE CENTRE
12 noon Fri Sep 9 2011

(excerpt)
Hurricane katia will remain well south of Nova Scotia and
Newfoundland. The cloud shield associated with katia has reached the
Atlantic coast of Nova Scotia and the cloud structure near the center
of the storm is becoming less organised. Leading precipitation band
almost reaching Sable Island and lightning currently detected over
slope waters south of Nova Scotia.

Gale- to storm-force winds will spread across the slope waters and
Laurentian Fan during the day and then the Grand Banks tonight.
Hurricane-force winds are possible over southernmost waters.

Current wave analysis indicates higher waves than predicted by the
models. 5 to 8 metre waves over southwestern marine district will
increase to possibly 10 or more. 2 metre waves along the coast of
Nova Scotia will increase during the afternoon. High waves are
expected to continue tonight and build along the southeast coast of
Newfoundland Saturday.

[CrazyC83]

Probably it is lower because some of the winds aren't transferring down to the surface.

Ok, so why would that happen? becouse she is now in the westerlies? She seams to have a well defined eyewall and none of the inner core problems Irene had... but i'm no pro. Just wondering if there is a reason why the winds wouldn't get to the serface.

Boundary layer differences at higher latitude and cooler waters keep winds higher aloft but lower at the surface.

[westwind]

Probably it is lower because some of the winds aren't transferring down to the surface.

Ok, so why would that happen? becouse she is now in the westerlies? She seams to have a well defined eyewall and none of the inner core problems Irene had... but i'm no pro. Just wondering if there is a reason why the winds wouldn't get to the serface.

Boundary layer differences at higher latitude and cooler waters keep winds higher aloft but lower at the surface.

Thanks I think that makes sense. Less vertical air movement from convection so less mixing of air layers and less wind at the surface.

[cycloneye]

POST-TROPICAL CYCLONE KATIA ADVISORY NUMBER 50
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 AM AST SAT SEP 10 2011

...KATIA LOSES TROPICAL CHARACTERISTICS OVER THE FAR NORTH
ATLANTIC...EXPECTED TO BRING STRONG WINDS TO THE BRITISH
ISLES AS A POWERFUL POST-TROPICAL CYCLONE ON MONDAY...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...44.7N 47.7W
ABOUT 295 MI...475 KM ESE OF CAPE RACE NEWFOUNDLAND
ABOUT 1960 MI...3160 KM WSW OF GLASGOW SCOTLAND
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...ENE OR 60 DEGREES AT 53 MPH...85 KM/H
MINIMUM CENTRAL PRESSURE...954 MB...28.17 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 AM AST...1500 UTC...THE CENTER OF POST-TROPICAL CYCLONE
KATIA WAS LOCATED NEAR LATITUDE 44.7 NORTH...LONGITUDE 47.7 WEST.
KATIA IS RACING TOWARD THE EAST-NORTHEAST NEAR 53 MPH...85 KM/H...
AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE
OF DAYS. ON THE FORECAST TRACK...THIS SYSTEM IS EXPECTED TO PASS
OVER OR NEAR THE NORTHERN BRITISH ISLES ON MONDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 80 MPH...130 KM/H...WITH HIGHER
GUSTS. KATIA IS EXPECTED TO REMAIN A STRONG EXTRATROPICAL CYCLONE
OVER THE NEXT 48 HOURS.

HURRICANE-FORCE WINDS EXTEND OUTWARD UP TO 80 MILES...130 KM...FROM
THE CENTER...AND TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 310
MILES...500 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE BASED ON RECENT REPORTS FROM
CANADIAN BUOY 44140 NEAR THE CENTER OF KATIA IS 954 MB...28.17
INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...GALE- TO STORM-FORCE WINDS ARE EXPECTED TO AFFECT MUCH OF
THE BRITISH ISLES ON MONDAY...AND COULD CAUSE DAMAGE TO TREES AND
DISRUPT TRANSPORTATION AND OTHER PUBLIC SERVICES. INTERESTS IN
AND AROUND THE BRITISH ISLES AND NORTHERN EUROPE SHOULD MONITOR
PRODUCTS ISSUED BY THE UK MET OFFICE AT
http://WWW.METOFFICE.GOV.UK/WEATHER/.

SURF...LARGE SWELLS GENERATED BY KATIA WILL CONTINUE TO AFFECT U.S.
NEW ENGLAND AREAS...ATLANTIC CANADA...AND BERMUDA TODAY....AND
SPREAD EASTWARD INTO THE BRITISH ISLES SUNDAY AND MONDAY. THESE
SWELLS ARE LIKELY TO CAUSE LIFE-THREATENING SURF AND RIP CURRENT
CONDITIONS. PLEASE CONSULT PRODUCTS FROM YOUR LOCAL WEATHER SERVICE
OFFICE FOR ADDITIONAL INFORMATION.

RAINFALL...TOTAL RAIN ACCUMULATIONS OF 50 TO 100 MILLIMETERS...
2 TO 4 INCHES...ARE EXPECTED OVER THE WESTERN MOUNTAINS OF SCOTLAND
THROUGH MONDAY.


NEXT ADVISORY
-------------
THIS IS THE LAST PUBLIC ADVISORY ISSUED BY THE NATIONAL HURRICANE
CENTER ON KATIA. ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND
IN HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...
UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.

$$
FORECASTER STEWART

NNNN

[cycloneye]

Adios Katia.

POST-TROPICAL CYCLONE KATIA ADVISORY NUMBER 50
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 AM AST SAT SEP 10 2011

...KATIA LOSES TROPICAL CHARACTERISTICS OVER THE FAR NORTH
ATLANTIC...EXPECTED TO BRING STRONG WINDS TO THE BRITISH
ISLES AS A POWERFUL POST-TROPICAL CYCLONE ON MONDAY...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...44.7N 47.7W
ABOUT 295 MI...475 KM ESE OF CAPE RACE NEWFOUNDLAND
ABOUT 1960 MI...3160 KM WSW OF GLASGOW SCOTLAND
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...ENE OR 60 DEGREES AT 53 MPH...85 KM/H
MINIMUM CENTRAL PRESSURE...954 MB...28.17 INCHES

[CrazyC83]

954mb - wow, that could be really bad for northern Europe. Don't underestimate this!

[Chacor]

ABOUT 1960 MI...3160 KM WSW OF GLASGOW SCOTLAND

How often do you see that in an NHC advisory then!
I move to London on Tuesday - have to admit I'm a bit disappointed at possibly missing a chance to experience some high winds...

[CrazyC83]

ABOUT 1960 MI...3160 KM WSW OF GLASGOW SCOTLAND

How often do you see that in an NHC advisory then!
I move to London on Tuesday - have to admit I'm a bit disappointed at possibly missing a chance to experience some high winds...

The main impact would likely be well to the north, but with such a fast moving system, the margin of error is huge.

[Chacor]

12 Sep 2011, 00:00
Amber Alert of Wind
Issued at - 10 Sep 2011, 11:38
Valid from - 12 Sep 2011, 00:00
Valid to - 12 Sep 2011, 23:59

The remains of Hurricane Katia are expected to come across the UK on Monday bringing a spell of wet and very windy weather. There remains some uncertainty about its track and intensity, although Scotland and Northern Ireland are most likely to bear the brunt of the winds,

The public should be prepared for the risk of disruption to transport and of the possibility of damage to trees and structures.

The public are advised to take extra care, further information and advice can be found here: http://www.metoffice.gov.uk/weather/uk/links.html

[Cryomaniac]

From the latest discussion:
NO 96-HOUR POINT IS BEING GIVEN BECAUSE FORECAST POINTS IN THE
EASTERN HEMISPHERE BREAK A LOT OF SOFTWARE.

That is just... weird.

Just a random point connected to this, it might partly explain why they don't say anything about the alleged TCs in the Mediterranean, since they are likely to be East of Greenwich. Obviously that isn't likely to be the only reason (namely that I think the official position is that they are polar lows).

ABOUT 1960 MI...3160 KM WSW OF GLASGOW SCOTLAND

How often do you see that in an NHC advisory then!
I move to London on Tuesday - have to admit I'm a bit disappointed at possibly missing a chance to experience some high winds...

I think the last advisory for Grace in 09 was something like "X MILES SW OF CARDIFF, WALES".

[artist]

NHC hurricane plots

[AdamFirst]

from the UK Meteorological Service

Also, issued by the Ireland Meteorological Service

Issued at 10 September 2011 - 11:09
Severe Weather Warning
Stormy weather is likely to develop late Sunday night and continue much of Monday with coastal counties of Connaught and Ulster most at risk.
Southwest winds could gust between 100 and 130 km/hr (60-80 MPH) in exposed areas. Very high waves expected on west, northwest and north coasts on Monday with wave heights between 6 and 10 metres.

http://www.met.ie/forecasts/warnings.asp

[artist]

that's crazy to see originating over here, huh?

[tropicana]

Last advisory by the Canadian Hurricane Centre on KATIA

TROPICAL CYCLONE TECHNICAL INFORMATION STATEMENT ISSUED BY THE
CANADIAN HURRICANE CENTRE OF ENVIRONMENT CANADA AT 3.02 PM ADT
SATURDAY 10 SEPTEMBER 2011.

THIS IS THE FINAL FORECAST MESSAGE FOR THIS STORM.

1. CURRENT POSITION, STRENGTH, CENTRAL PRESSURE AND MOTION

AT 3.00 PM ADT , POST-TROPICAL STORM KATIA WAS LOCATED NEAR
LATITUDE 44.8 N AND LONGITUDE 41.5 W , ABOUT 495 NAUTICAL MILES
OR 920 KM ( 570 miles) EAST SOUTHEAST OF ST JOHNS . MAXIMUM SUSTAINED WINDS
ARE ESTIMATED AT 70 KNOTS ( 130 KM/H ) ( 80mph) AND CENTRAL PRESSURE AT
958 MB. KATIA IS MOVING NORTHEAST AT 60 KNOTS ( 106 KM/H ) ( 65mph).

2. FORECAST POSITION, CENTRAL PRESSURE AND STRENGTH

DATE TIME LAT LON MSLP MAX WIND
ADT MB KTS KMH
SEP 10 3.00 PM 44.8N 41.5W 958 70 130 POST-TROPICAL
SEP 10 9.00 PM 48.1N 34.8W 960 65 120 POST-TROPICAL
SEP 11 3.00 AM 51.1N 28.1W 961 65 120 POST-TROPICAL

3. TECHNICAL DISCUSSION

A. ANALYSIS
THE SYSTEM HAD COMPLETED TRANSITION TO POST-TROPICAL, WITH A CLASSIC
CLOUD PATTERN, AND IS DEVELOPING A GOOD BAROCLINIC SIGNATURE. IT IS
RACING EAST AND AWAY FROM ATLANTIC CANADA WITHIN A BAND OF VERY
STRONG WESTERLIES. BEHIND THE SYSTEM IS A SHARP AND INTENSE
NORTHWESTERLY JET WHICH IS CURRENTLY DEVELOPING WINDS APPROACHING
HURRICANE FORCE, AND GIVING FAIRLY IMPRESSIVE WAVE ACTIVITY ACROSS
THE SOUTHERN GRAND BANKS.AT 11 UTC BUOY 44140 INDICATED A PRESSURE
MEASURMENT OF 957 MB AS KATIA PASSED NORTH OF IT. THIS COMBINED
WITH GUSTS TO NEAR STORM FORCE CAUSED US TO REDUCED THE MINIMAL
CENTRAL PRESSURE TO 955 MB.

B. PROGNOSTIC
THE VIGH MODEL CONSENSUS IS TIGHTLY PACKED INDICATING A STRAIGHT
LINE COURSE ACROSS THE ATLANTIC TO NORTH OF OR NEAR THE UNITED
KINGDOM WITHING 2-3 DAYS. KATIA WILL BE WELL EAST OF CANADIAN WATERS BY
LATE THIS AFTERNOON. DESPITE ITS TRANSITION TO POST-TROPICAL
STATUS, DYNAMICAL MODELS SHOW KATIA WILL NOT LOSE MUCH STRENGTH
AS IT HEADS INTO THE NORTH ATLANTIC. THE GEM-REGIONAL MODEL
CONTINUES TO SHOW CENTRAL PRESSURES IN THE 960 MB RANGE AND A
LARGE AND VERY STRONG WIND FIELD ALONG WITH IT AFTER IT LEAVES
CANADIAN WATERS.

[Extratropical94]

Just a question:
If Katia is moving towards the NE at 65 mph and her sustained winds are 80 mph, does that mean that if you are in the SE quad, you feel 145 mph winds, and only 15 mph winds in the NW quad?

[Cryomaniac]

Just a question:
If Katia is moving towards the NE at 65 mph and her sustained winds are 80 mph, does that mean that if you are in the SE quad, you feel 145 mph winds, and only 15 mph winds in the NW quad?

I don't think it's quite that simple, but I'm not an expert.

[AJC3]

Just a question:
If Katia is moving towards the NE at 65 mph and her sustained winds are 80 mph, does that mean that if you are in the SE quad, you feel 145 mph winds, and only 15 mph winds in the NW quad?

Nope. 80 MPH MSW are ground relative, not storm relative.

[AJC3]

ABOUT 1960 MI...3160 KM WSW OF GLASGOW SCOTLAND

How often do you see that in an NHC advisory then!
I move to London on Tuesday - have to admit I'm a bit disappointed at possibly missing a chance to experience some high winds...

I forget which storm it was a few years ago but the final advisory had the position relative to Reykjavik, Iceland.

Edit: It was 2008's Bertha.

00
WTNT32 KNHC 201501
TCPAT2
BULLETIN
TROPICAL STORM BERTHA ADVISORY NUMBER 70
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
1100 AM AST SUN JUL 20 2008

...BERTHA BECOMES EXTRATROPICAL OVER THE FAR NORTH ATLANTIC...

AT 1100 AM AST...1500Z...THE CENTER OF TROPICAL STORM BERTHA WAS
LOCATED NEAR LATITUDE 51.3 NORTH...LONGITUDE 35.7 WEST OR ABOUT 850
MILES...1365 KM...EAST-NORTHEAST OF CAPE RACE NEWFOUNDLAND AND ABOUT
1020 MILES...1640 KM...SOUTHWEST OF REYKJAVIC ICELAND.

[AJC3]

ABOUT 1960 MI...3160 KM WSW OF GLASGOW SCOTLAND

How often do you see that in an NHC advisory then!
I move to London on Tuesday - have to admit I'm a bit disappointed at possibly missing a chance to experience some high winds...

I forget which storm it was a few years ago but the final advisory had the position relative to Reykjavik, Iceland.

Edit: It was 2008's Bertha.

00
WTNT32 KNHC 201501
TCPAT2
BULLETIN
TROPICAL STORM BERTHA ADVISORY NUMBER 70
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
1100 AM AST SUN JUL 20 2008

...BERTHA BECOMES EXTRATROPICAL OVER THE FAR NORTH ATLANTIC...

AT 1100 AM AST...1500Z...THE CENTER OF TROPICAL STORM BERTHA WAS
LOCATED NEAR LATITUDE 51.3 NORTH...LONGITUDE 35.7 WEST OR ABOUT 850
MILES...1365 KM...EAST-NORTHEAST OF CAPE RACE NEWFOUNDLAND AND ABOUT
1020 MILES...1640 KM...SOUTHWEST OF REYKJAVIC ICELAND.

And you actually posted this about 2000's Alberto in the same thread in 2008.

viewtopic.php?f=68&t=101591&p=1744162&hilit=#p1744162

Happened with Alberto 2000.

TROPICAL STORM ALBERTO ADVISORY NUMBER 78
NATIONAL WEATHER SERVICE MIAMI FL
11 AM AST WED AUG 23 2000

...ALBERTO...BECOMES EXTRATROPICAL AS IT HEADS FOR ICELAND...

AT 11 AM AST...1500Z...THE CENTER OF THE EXTRATROPICAL STORM THAT
WAS ALBERTO WAS LOCATED NEAR LATITUDE 54.6 NORTH...LONGITUDE 34.1
WEST OR ABOUT 780 MILES...1255 KM...SOUTH-SOUTHWEST OF REYKJAVIK
ICELAND.