Extratropical Storm Igor Near Greenland

[srainhoutx]

Igor decided to make a come back after the demotion by the NHC...

[cisa]

Tropical systems will make a liar out of ya everytime. I keep thinking of Ike. How many times did the HPC change it's track on that storm before it found it's way here. I think that's whats so facinating...they're so unpredictable.

[biggerbyte]

That is what I have been saying. This year has been especially bad. It makes one not want to even comment, because as soon as you do, something drastic changes.

[srainhoutx]

000
WTNT31 KNHC 101454
TCPAT1
BULLETIN
TROPICAL STORM IGOR ADVISORY NUMBER 9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 AM AST FRI SEP 10 2010

...IGOR REGAINS TROPICAL STORM STATUS OVER THE FAR EASTERN
ATLANTIC OCEAN...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...16.4N 31.0W
ABOUT 465 MI...750 KM W OF THE CAPE VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/HR
PRESENT MOVEMENT...W OR 280 DEGREES AT 16 MPH...26 KM/HR
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES

[srainhoutx]

000
WTNT41 KNHC 110234
TCDAT1
TROPICAL STORM IGOR DISCUSSION NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST FRI SEP 10 2010

CONVENTIONAL SATELLITE IMAGES INDICATE THAT IGOR IS MAINTAINING A
BURSTING PATTERN...CHARACTERISTIC OF A SHEARED TROPICAL CYCLONE.
THE PARTIALLY EXPOSED LOW-LEVEL CENTER LIES NEAR THE NORTHEAST SIDE
OF A LARGE AND CIRCULAR CONVECTIVE MASS IN THIS IMAGERY...BUT
SEVERAL EARLIER MICROWAVE OVERPASSES INDICATED THE POSSIBILITY OF
THE LOW-LEVEL CENTER LYING UNDERNEATH THE CONVECTION. AN EXPANDING
UPPER-LEVEL OUTFLOW IS WELL ESTABLISHED IN ALL QUADRANTS EXCEPT TO
THE EAST. DVORAK INTENSITY ESTIMATES ARE AT 3.0/45 KT AND 3.5/55
KT FROM SAB AND TAFB...AND THE LATEST 3-HOURLY AVERAGED ADT VALUE
IS 3.3. GIVEN THE UNCERTAINTY WITH REGARD TO THE LOCATION OF THE
CENTER...THE ADVISORY INTENSITY IS INCREASED CONSERVATIVELY TO 45
KT.

THE INITIAL MOTION ESTIMATE OF 285/18 IS SOMEWHAT UNCERTAIN AND
REPRESENTS A LONGER-TERM AVERAGE...GIVEN DIFFERENCES BETWEEN
CONVENTIONAL AND MICROWAVE SATELLITE FIXES. THE FORECAST REASONING
REMAINS UNCHANGED. DYNAMICAL MODELS SHOW IGOR MOVING ON A WESTWARD
COURSE ON THE SOUTH SIDE OF A SUBTROPICAL RIDGE OVER THE EAST
CENTRAL ATLANTIC DURING THE NEXT 72 HOURS. DURING THIS
PERIOD...THE MODEL GUIDANCE IS IN GOOD AGREEMENT THAT IGOR SHOULD
SLOW ITS FORWARD SPEED AND THEN TURN WEST-NORTHWESTWARD BEYOND 72
HOURS IN RESPONSE TO A LARGE BREAK IN THE SUBTROPICAL RIDGE OVER
THE WESTERN AND CENTRAL ATLANTIC. THE OFFICIAL NHC TRACK LIES NEAR
THE MIDDLE OF THE GUIDANCE ENVELOPE...BUT IS A BIT NORTH OF THE
MULTI-MODEL CONSENSUS WHICH HAS TRENDED SLIGHTLY SOUTHWARD THIS
CYCLE.

UW-CIMSS ANALYSES STILL INDICATE AROUND 15 KT OF NORTHEASTERLY
VERTICAL WIND SHEAR OVER IGOR...A LESS THAN IDEAL ENVIRONMENT FOR
INTENSIFICATION. THE STATISTICAL-DYNAMICAL GUIDANCE INDICATES A
QUICK REDUCTION TO THE SHEAR DURING THE NEXT 24 HOURS...AND A LOW
SHEAR ENVIRONMENT OVER GRADUALLY WARMER WATERS ARE LIKELY TO LEAD
TO A STEADIER STRENGTHENING OVER THE NEXT COUPLE OF DAYS. THE
INTENSITY GUIDANCE PRESENTS A DILEMMA LATER IN THE FORECAST
PERIOD...HOWEVER. THE STATISTICAL MODEL OUTPUT INDICATES POSSIBLE
SOUTHWESTERLY SHEAR RELATED TO THE LONGWAVE TROUGH FORECAST OVER
THE WEST CENTRAL ATLANTIC...AS DO A FEW OF THE GLOBAL DYNAMICAL
MODELS. ON THE OTHER HAND...THE HWRF AND ECMWF SOLUTIONS A
CONTINUATION OF THE LOW SHEAR ENVIRONMENT AND A STRONGER IGOR. THE
OFFICIAL NHC INTENSITY FORECAST IS ABOUT THE SAME AS THE PREVIOUS
ONE...EXCEPT SLIGHTLY REDUCED LATE IN THE PERIOD IN DEFERENCE TO
THE STATISTICAL MODELS.


FORECAST POSITIONS AND MAX WINDS

INITIAL 11/0300Z 17.1N 34.9W 45 KT
12HR VT 11/1200Z 17.2N 37.2W 50 KT
24HR VT 12/0000Z 17.4N 40.1W 55 KT
36HR VT 12/1200Z 17.5N 42.8W 65 KT
48HR VT 13/0000Z 17.6N 45.3W 75 KT
72HR VT 14/0000Z 18.0N 49.5W 85 KT
96HR VT 15/0000Z 19.0N 53.0W 90 KT
120HR VT 16/0000Z 20.5N 56.0W 100 KT

$$
FORECASTER KIMBERLAIN

[srainhoutx]

Appears Igor has made Hurricane Status...

[srainhoutx]

000
WTNT41 KNHC 120233
TCDAT1
HURRICANE IGOR DISCUSSION NUMBER 15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST SAT SEP 11 2010

THE CLOUD PATTERN ASSOCIATED WITH IGOR HAS INCREASED IN ORGANIZATION
DURING THE PAST SEVERAL HOURS. A TIGHTLY-COILED BAND...WITH CLOUD
TOP TEMPERATURES TO -85C...WRAPS AROUND THE EASTERN SEMICIRCLE INTO
A DEVELOPING CENTRAL DENSE OVERCAST. AN EYE FEATURE HAS ALSO BEEN
BRIEFLY INTERMITTENT IN CONVENTIONAL SATELLITE IMAGERY...AND A
NUMBER OF MICROWAVE PASSES SEVERAL HOURS AGO REVEALED A DISTINCT
CONVECTIVE RING SURROUNDING THE CENTER. SUBJECTIVE DVORAK T-NUMBERS
AT 0000 UTC WERE A CONSENSUS 4.0 FROM BOTH SATELLITE AGENCIES...AND
3-HOURLY AVERAGED ADT VALUES FROM UW-CIMSS ARE 4.3. THE INITIAL
INTENSITY IS RAISED TO 65 KT THIS ADVISORY...MAKING IGOR THE FOURTH
HURRICANE OF THE 2010 ATLANTIC HURRICANE SEASON. THE UNDERLYING
OCEAN ONLY GETS WARMER ALONG THE FORECAST TRACK OF IGOR...PEAKING
AROUND 29C IN ABOUT 3 DAYS. THAT...COMBINED WITH A LIGHT SHEAR
ENVIRONMENT...WOULD FAVOR A STRENGTHENING TREND FOR THE NEXT FEW
DAYS...AND NEARLY ALL THE INTENSITY GUIDANCE MAKES IGOR A MAJOR
HURRICANE BY 72 HOURS. THEREAFTER...WHILE FLUCTUATIONS IN INTENSITY
MAY OCCUR...IGOR IS EXPECTED TO MAINTAIN MAJOR HURRICANE STATUS AND
BE A LARGE HURRICANE OVER THE CENTRAL NORTH ATLANTIC.

IGOR HAS MAINTAINED ROUGHLY THE SAME MOTION...275/15...THOUGH
PERHAPS A TAD SLOWER THAN EARLIER. SUBTROPICAL RIDGING NORTH OF
THE CYCLONE SHOULD BE THE DOMINANT STEERING FEATURE FOR THE NEXT 2
TO 3 DAYS...CARRYING IGOR ON A GENERAL WESTWARD TRACK. BEYOND THIS
TIME...DYNAMICAL MODELS SHOW IGOR SLOWING AND TURNING WEST-
NORTHWESTWARD AS IT APPROACHES AND THEN MOVES INTO A SUBSTANTIAL
BREAK IN THE SUBTROPICAL RIDGE. AS WAS THE CASE IN THE PREVIOUS
MODEL CYCLE...THERE CONTINUES TO BE CONSIDERABLE SPREAD IN THE
TRACK GUIDANCE...WITH THE GFDL/HWRF THE RIGHTMOST OF MODEL
SOLUTIONS AND THE UKMET/NOGAPS THE LEFTMOST. THESE DIFFERENCES
SEEM TO HINGE ON THE STRENGTH AND POSITION OF THE SUBTROPICAL
RIDGE...WITH THE FORMER MODELS FORECASTING A WEAKER RIDGE DISPLACED
TO THE EAST WHILE LATTER INDICATE A MORE ROBUST RIDGE EXTENDING
FARTHER WEST. THE OFFICIAL NHC FORECAST TRACK HAS BEEN ADJUSTED TO
THE RIGHT...FOLLOWING THE TREND IN THE GUIDANCE... BUT IS NOT AS
FAR RIGHT AS THE MULTI-MODEL CONSENSUS.


FORECAST POSITIONS AND MAX WINDS

INITIAL 12/0300Z 17.7N 42.5W 65 KT
12HR VT 12/1200Z 17.8N 44.8W 75 KT
24HR VT 13/0000Z 17.9N 47.4W 80 KT
36HR VT 13/1200Z 18.1N 49.7W 90 KT
48HR VT 14/0000Z 18.4N 51.9W 100 KT
72HR VT 15/0000Z 19.5N 55.0W 110 KT
96HR VT 16/0000Z 21.5N 58.0W 115 KT
120HR VT 17/0000Z 23.5N 61.0W 115 KT

$$
FORECASTER KIMBERLAIN

[Andrew]

GFS paints another fish:




The U.S. has been extremely lucky this year.

[srainhoutx]

Igor looks to be a Cat 2 Hurricane...

Code: Select all

   UW - CIMSS                     
              ADVANCED DVORAK TECHNIQUE       
                  ADT-Version 8.1.1                
         Tropical Cyclone Intensity Algorithm       

             ----- Current Analysis ----- 
     Date :  12 SEP 2010    Time :   114500 UTC
      Lat :   17:41:34 N     Lon :   44:38:51 W

     
                CI# /Pressure/ Vmax
                5.7 / 957.2mb/107.2kt

     
             Final T#  Adj T#  Raw T# 
                5.7     6.0     6.0

     Latitude bias adjustment to MSLP :  +2.0mb

 Estimated radius of max. wind based on IR : 28 km

 Center Temp :  +6.2C    Cloud Region Temp : -64.9C

 Scene Type : EYE  

 Positioning Method : RING/SPIRAL COMBINATION 

 Ocean Basin : ATLANTIC      
 Dvorak CI > MSLP Conversion Used : ATLANTIC  

 Tno/CI Rules : Constraint Limits : NO LIMIT 
                   Weakening Flag : OFF   
           Rapid Dissipation Flag : OFF   

[srainhoutx]

000
WTNT31 KNHC 121455
TCPAT1
BULLETIN
HURRICANE IGOR ADVISORY NUMBER 17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 AM AST SUN SEP 12 2010

...IGOR BECOMES A CATEGORY TWO HURRICANE...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.7N 45.7W
ABOUT 1145 MI...1840 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/HR
PRESENT MOVEMENT...W OR 270 DEGREES AT 13 MPH...20 KM/HR
MINIMUM CENTRAL PRESSURE...970 MB...28.64 INCHES

[Andrew]

WTNT31 KNHC 121806
TCPAT1
BULLETIN
HURRICANE IGOR SPECIAL ADVISORY NUMBER 18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
230 PM AST SUN SEP 12 2010

...IGOR RAPIDLY INTENSIFIES INTO A CATEGORY FOUR HURRICANE...


SUMMARY OF 230 PM AST...1830 UTC...INFORMATION
----------------------------------------------
LOCATION...17.7N 46.1W
ABOUT 1120 MI...1800 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...135 MPH...215 KM/HR
PRESENT MOVEMENT...W OR 270 DEGREES AT 14 MPH...22 KM/HR
MINIMUM CENTRAL PRESSURE...950 MB...28.05 INCHES


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


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 230 PM AST...1830 UTC...THE CENTER OF HURRICANE IGOR WAS LOCATED
NEAR LATITUDE 17.7 NORTH...LONGITUDE 46.1 WEST. IGOR IS MOVING
TOWARD THE WEST NEAR 14 MPH...22 KM/HR. A TURN TOWARD THE
WEST-NORTHWEST IS EXPECTED ON TUESDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 135 MPH...215 KM/HR...WITH HIGHER
GUSTS. IGOR IS A CATEGORY FOUR HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE. SOME ADDITIONAL STRENGTHENING IS FORECAST
DURING THE NEXT 48 HOURS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 40 MILES...65 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 160
MILES...260 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 950 MB...28.05 INCHES.


HAZARDS AFFECTING LAND
----------------------
NONE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 PM AST.

$$
FORECASTER ROBERTS/BRENNAN

[sau27]

Something interesting I noticed on the latest satellite image is small bursts of convection all around the edges of the storm. Something I have never seen before.

http://www.ssd.noaa.gov/goes/flt/t1/flash-vis.html

[Andrew]

Something interesting I noticed on the latest satellite image is small bursts of convection all around the edges of the storm. Something I have never seen before.

http://www.ssd.noaa.gov/goes/flt/t1/flash-vis.html

The reason you see that is because where Igor is located, the sun is getting close to sunset, and as a result you see the towering. It should become more noticeable as time goes on.

[Ptarmigan]

I am not surprised by it. I think Igor has a good shot at becoming a Category 5 hurricane.

[Andrew]

Also forgot to post projected path:

[texoz]

Igor is definitely going to boost up the ACE numbers for this season by the time he's done making his rounds of the Atlantic.

[srainhoutx]

000
WTNT31 KNHC 122037
TCPAT1
BULLETIN
HURRICANE IGOR ADVISORY NUMBER 19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
500 PM AST SUN SEP 12 2010

...LARGE AND POWERFUL IGOR MOVING WESTWARD OVER THE CENTRAL TROPICAL
ATLANTIC...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...17.7N 46.9W
ABOUT 1065 MI...1715 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...140 MPH...220 KM/HR
PRESENT MOVEMENT...W OR 270 DEGREES AT 14 MPH...22 KM/HR
MINIMUM CENTRAL PRESSURE...942 MB...27.82 INCHES

[Andrew]

Still intensifying:

[Andrew]

WSW movement is happening as of lately, and as you can see from the image above, this storm is just amazing. I am pretty much positive this will be the strongest storm of the year. This storm is a textbook screen-saver.

WOW!

[Andrew]

## ANNULAR HURRICANE INDEX (AHI) AL112010 IGOR 09/13/10 00 UTC ##
## PASSED SCREENING STEP, MIGHT BE ANNULAR, CALCULATE AHI FROM DISCRIMINANT ANALYSIS ##
## AHI= 1 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##
## ANNULAR INDEX RAN NORMALLY