HURRICANE IGOR

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[dkmac]

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11AM

00 WTNT41 KNHC 101455 TCDAT1 TROPICAL STORM IGOR DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010 1100 AM AST FRI SEP 10 2010 IGOR REMAINS A SHEARED TROPICAL CYCLONE. DURING THE PAST FEW HOURS...HOWEVER...THE SHEAR HAS BEGUN TO SHOW SIGNS OF ABATING AND THE LOW-LEVEL CENTER IS NOW FARTHER INTO THE EASTERN PORTION OF THE CENTRAL DEEP CONVECTION. THE UPGRADE TO STORM STATUS IS BASED ON A SATELLITE INTENSITY ESTIMATE OF 35 KT FROM TAFB AND A 47-KT UW-CIMSS 3-HR AVERAGE ADT. THE INITIAL MOTION IS 280/14. THE INITIAL POSITION AND MOTION ARE STILL SOMEWHAT UNCERTAIN DUE TO MULTIPLE CIRCULATIONS ROTATING AROUND THE CENTER OF A LARGER CYCLONIC GYRE. HOWEVER...THE MOTION IS EXPECTED TO BE BASICALLY WESTWARD FOR THE NEXT 96 HOURS OR SO ALONG THE SOUTHERN PERIPHERY OF A STRONG SUBTROPICAL RIDGE LOCATED TO THE NORTH OF THE CYCLONE. BY DAY 5...A SERIES OF WEAK SHORTWAVE TROUGHS MOVING THROUGH THE BASE OF A BROAD LONGWAVE TROUGH FORECAST TO BE OFF THE U.S. EAST COAST IS FORECAST BY ALL OF THE GLOBAL MODELS TO CREATE A WEAKNESS IN THE RIDGE BETWEEN 50W-60W LONGITUDE. THIS IS EXPECTED TO WEAKEN THE STEERING FLOW AND CAUSE IGOR TO SLOW DOWN AND ALSO TURN WEST-NORTHWESTWARD. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY AND THE TVCN MODEL CONSENSUS. CURRENT SHEAR ANALYSES FROM SHIPS AND UW-CIMSS...ALONG WITH WATER VAPOR WINDS...INDICATE THE VERTICAL SHEAR ACROSS IGOR HAS DECREASED FROM 20 KT DOWN TO 10 KT DURING THE PAST 24 HOURS. THIS DECEASING SHEAR TENDENCY IS EXPECTED TO CONTINUE THROUGHOUT THE FORECAST PERIOD AS IGOR MOVES OVER GRADUALLY INCREASING SSTS...ESPECIALLY AFTER 48 HOURS. THE RESULT SHOULD BE STEADY INTENSIFICATION WITH IGOR POSSIBLY REACHING HURRICANE STATUS ON SUNDAY AND MAJOR HURRICANE STATUS BY DAY 5...AS INDICATED BY THE SHIPS...GFDL...AND HWRF MODELS. THE OFFICIAL INTENSITY FORECAST IS A LITTLE BELOW THE GUIDANCE THROUGH 48 HOURS DUE TO UNCERTAINTY ABOUT WHEN IGOR WILL DEVELOP A CONSOLIDATED CENTER OF CIRCULATION...BUT IS CLOSE TO THE GUIDANCE THEREAFTER. FORECAST POSITIONS AND MAX WINDS INITIAL 10/1500Z 16.4N 31.0W 35 KT 12HR VT 11/0000Z 16.6N 33.2W 40 KT 24HR VT 11/1200Z 16.8N 36.2W 45 KT 36HR VT 12/0000Z 17.0N 39.2W 50 KT 48HR VT 12/1200Z 17.1N 41.7W 60 KT 72HR VT 13/1200Z 17.3N 46.2W 70 KT 96HR VT 14/1200Z 18.2N 50.3W 85 KT 120HR VT 15/1200Z 19.5N 53.5W 95 KT

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[dkmac]

StormW at WU:

Good day everyone!

TROPICAL STORM IGOR:

Tropical Storm Igor had weakened yesterday, and was downgraded to a tropical depression, but has recently become better organized, and has regained TS status.

Satellite imagery from yesterday through this morning indicated that Igor had been under some pretty good easterly shear, which pushed the bulk of his convection to the west of the LLC.

Current conditions, based on satellite loop imagery, and current wind shear products from CIMSS, indicate that conditions have become more favorable, and that the LLC is at least 90% under the convection.







The following was available from the 11:00 a.m. advisory:

11:00 AM AST Fri Sep 10
Location: 16.4°N 31.0°W
Max sustained: 40 mph
Moving: W at 16 mph
Min pressure: 1004 mb

Based on the current improvement, and forecast wind shear products, I believe Igor will become a Hurricane, and concur at the moment with the NHC intensity scheme, save any more dry air intrusion:

FORECAST POSITIONS AND MAX WINDS

INITIAL 10/1500Z 16.4N 31.0W 35 KT
12HR VT 11/0000Z 16.6N 33.2W 40 KT
24HR VT 11/1200Z 16.8N 36.2W 45 KT
36HR VT 12/0000Z 17.0N 39.2W 50 KT
48HR VT 12/1200Z 17.1N 41.7W 60 KT
72HR VT 13/1200Z 17.3N 46.2W 70 KT
96HR VT 14/1200Z 18.2N 50.3W 85 KT
120HR VT 15/1200Z 19.5N 53.5W 95 KT



Current and forecast steering layers maps, and various satellite loop imagery channels, indicate that Igor should travel to the W to WNW (slightly north of due west[280]), during the next 48 hours. Thereafter, he should begin to come under the influence of a deep layer trof, that will erode the western periphery of the subtropical ridge.

Exact track on Igor, however, will be depended upon:
1.) His forward speed
2.) The timing and movement of the trof
3.) The strength of the weakness.

In all probability, this turn to the NW will occur, but upon analysis of forecast steering, and an upcoming change in the pattern, I believe any significant turn will be a little further to the west of model guidance at the moment.

I do agree with the NHC forecast track at the moment, however, I do believe Igor is going to HAVE to make that turn at the point indicated, or not too further west of there.



The slim possibility could exist of another shift left after the initial turn, before a full re-curve takes affect.

I only mention this as, (I know it's been tossed out here already, that the GFS calls for the same steering pattern for the next 2 weeks), I have to somewhat disagree with the GFS forecast on the continued steering pattern. I believe that we will see a brief reprieve in that steering pattern, as I have analyzed some parameters that tell me different from the GFS. Igor SHOULD make a total re-curve, however, based on what I'm seeing, and mind you, with pretty good consistency over the past 72 hours. I'm not too sold on the second and third areas that will exit Africa, re-curving as previous systems.

At any rate, I will continue to monitor Igor throughout the week for any significant changes in track.

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Looks like a fish

Looks like your post just went poof

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HWRF

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Day 6 ECMWF...

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AL, 11, 2010091018, , BEST, 0, 166N, 323W, 40, 1002, TS

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5pm

SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...16.7N 33.3W ABOUT 620 MI...995 KM W OF THE CAPE VERDE ISLANDS MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/HR PRESENT MOVEMENT...W OR 280 DEGREES AT 21 MPH...33 KM/HR MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES

[richardginn]

Another Bermuda storm?????

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AL, 11, 2010091100, , BEST, 0, 170N, 342W, 45, 1000, TS,

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HWRF 18z

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Track and intensity.

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