92L still a threat to develop; Igor a hurricane; TD 12 forming near Africa
Tropical disturbance (92L) over the Central Caribbean, a few hundred miles south of the Dominican Republic, remains a threat to develop into a tropical depression. Satellite loops this morning show 92L may be starting to form a surface circulation, and an Air Force Hurricane Hunter aircraft will investigate 92L this afternoon to see if a tropical depression is forming.
The storm has only a modest area of heavy thunderstorm with limited low-level spiral banding and upper-level outflow, thanks to an infusion of dry air last night that disrupted the storm. Long range radar out of Puerto Rico shows that heavy rains are affecting that island, but there is no rotation to the radar echoes evident. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are hot, 29.5°C, and these warm waters extend to great depth. Water vapor satellite loops show a large area of dry air lies to the north and west of 92L, and this dry air could interfere with development at times over the next few days.
Figure 1. Morning satellite image of 92L.
Track forecast for 92L
The disturbance is moving west to west-northwest at 15 mph, and steering currents favor a continuation of this motion for the next three days. Model support for development is scattered. The GFS and NOGAPS models do not develop 92L. The GFDL and ECMWF models predict development, with a track taking 92L into Belize or Mexico's Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches today through Monday morning; southern Haiti can expect similar rains tonight through Monday night, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba can expect rains in the 2 - 4 inch range. Once 92L crosses the Yucatan, the ridge of high pressure steering it is expected to remain in place, forcing 92L to a second landfall in Mexico south of the Texas border.
Intensity forecast for 92L
NHC is putting the odds of 92L developing into a tropical depression by Tuesday at 50%; I'd put them higher, at 70%. However, time is running out for 92L to become a hurricane before hitting the Yucatan Peninsula on Wednesday. Given the current disorganized state of 92L, it would be difficult for it to intensify quickly enough to become a hurricane by then. The storm may also suffer another of its mysterious evening collapses, where it loses most of its heavy thunderstorm activity. However, the SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and water temperatures are certainly warm enough to support development. The main detriment to intensification is likely to be dry air, and 92L could wrap in some of the dry air to its northwest at times, slowing down development. There are a number of research flights being made into 92L this afternoon that should help long-term efforts to make better predictions in the future on whether or not disturbances like this will develop or not.
Figure 2. Morning satellite image of Igor.
Igor
Hurricane Igor appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is low, 5 - 10 knots, and is expected to drop below 5 knots for the next five days. Waters are warm, 28°C, and will warm to 29°C by Wednesday. Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. Igor is undergoing a period of rapid intensification today, and will probably be a Category 3 or 4 hurricane by Monday.
The track forecast for Igor remains unchanged. Igor will move west under the influence of a strong ridge of high pressure for the next 2 - 3 days, then turn more to the west-northwest then northwest in response to the steering influence of a broad trough of low pressure moving across the Western Atlantic on Tuesday and Wednesday. This should allow Igor to pass several hundred miles to the northeast of the Lesser Antilles. In the longer range, Igor may be a threat to Bermuda, and does have a small chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 15% of all tropical cyclones that have existed at Igor's current position have gone on to hit the U.S. East Coast; these odds are about 10% for Bermuda and 10% for Canada. The forecast steering pattern for the period 5 - 12 days from now from the ECMWF and GFS models shows a continuation of the pattern we've seen all hurricane season, with regular strong troughs of low pressure moving off the U.S. East Coast. This pattern favors Igor eventually recurving out to sea without affecting any land areas. Recent runs of the ECMWF model indicate that these troughs may not be as intense as previously thought, so it is possible Igor has a higher chance than usual to hit land than climatology suggests. One wild card may be the possible development of TD 12 behind Igor. If TD 12 develops into a hurricane, and moves close to Igor, as some of the models are suggesting, the two hurricanes could rotate around a common center, forcing Igor more towards the coast of the U.S. The long term fate of Igor is difficult to predict at this point.
Tropical Depression Twelve forms
Tropical Depression Twelve formed between the Cape Verdes Islands and coast of Africa this morning, and is already affecting the Cape Verdes with winds near tropical storm strength; sustained winds of 35 mph were recorded in the northwest Cape Verdes this morning. You can follow the progress of TD 12 through the Cape Verdes today using our wundermap.
Next post
I'll have a new post Monday morning, and perhaps late this afternoon if events warrant.
Jeff Masters
Reader Comments
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SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.6N 47.8W
ABOUT 1005 MI...1620 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...150 MPH...240 KM/HR
PRESENT MOVEMENT...W OR 270 DEGREES AT 13 MPH...20 KM/HR
MINIMUM CENTRAL PRESSURE...935 MB...27.61 INCHES
1 to 100. Igor is the most annular storm since Danielle, which also rated a 1 at one time.
WTNT31 KNHC 130246
TCPAT1
BULLETIN
HURRICANE IGOR ADVISORY NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST SUN SEP 12 2010
...IGOR STILL INTENSIFYING...
SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.6N 47.8W
ABOUT 1005 MI...1620 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...150 MPH...240 KM/HR
PRESENT MOVEMENT...W OR 270 DEGREES AT 13 MPH...20 KM/HR
MINIMUM CENTRAL PRESSURE...935 MB...27.61 INCHES
WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.
DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 PM AST...0300 UTC...THE EYE OF HURRICANE IGOR WAS LOCATED
NEAR LATITUDE 17.6 NORTH...LONGITUDE 47.8 WEST. IGOR IS MOVING
TOWARD THE WEST NEAR 13 MPH...20 KM/HR. A TURN TOWARD THE
WEST-NORTHWEST WITH SOME DECREASE IN FORWARD SPEED IS EXPECTED TO
BEGIN LATE MONDAY AND TUESDAY.
MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 150 MPH...240
KM/HR...WITH HIGHER GUSTS. IGOR IS A CATEGORY FOUR HURRICANE ON
THE SAFFIR-SIMPSON HURRICANE WIND SCALE. SOME FLUCTUATION IN
INTENSITY IS LIKELY DURING THE NEXT 48 HOURS...AND IGOR COULD
BECOME A CATEGORY FIVE HURRICANE ON MONDAY.
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 935 MB...27.61 INCHES.
HAZARDS AFFECTING LAND
----------------------
NONE.
NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 AM AST.
$$
FORECASTER BERG
no, but satellites can measure wave height, at least i think they can (:
TTAA00 KNHC DDHHMM
TROPICAL STORM JULIA DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122010
1100 PM AST SUN SEP 12 2010
INFRARED AND MICROWAVE SATELLITE IMAGERY SHOW THAT THE CENTER OF
THE CYCLONE IS LOCATED NEAR THE EASTERN EDGE OF A CURVED BAND OF
CONVECTION THAT WRAPS AROUND THE WESTERN SEMICIRCLE OF THE SYSTEM.
SUBJECTIVE DVORAK INTENSITY ESTIMATES ARE 35 KT FROM TAFB AND 30 KT
FROM SAB. OBJECTIVE DVORAK ESTIMATES FROM UW/CIMMS ARE SLIGHTLY
HIGHER. A BLEND OF THESE ESTIMATES SUPPORT AN UPGRADE OF THE
DEPRESSION TO A 35-KT TROPICAL STORM...THE TENTH OF THE 2010
ATLANTIC HURRICANE SEASON.
THE EASTERLY SHEAR IS EXPECTED TO WEAKEN DURING THE NEXT 12 HOURS
AND IS FORECAST TO REMAIN LIGHT OVER THE NEXT COUPLE OF DAYS.
DURING THAT TIME JULIA WILL BE TRAVERSING WARM WATER AND AS A
RESULT...STEADY STRENGTHENING IS ANTICIPATED. THE SHIPS...LGEM...
AND GFDL MODELS ALL BRING JULIA TO HURRICANE STATUS WITHIN TWO DAYS
AND THE NHC FORECAST IS IN GOOD AGREEMENT. THEREAFTER...JULIA WILL
BE MOVING OVER SLIGHTLY COOLER SEA SURFACE TEMPERATURES AND INTO AN
AREA OF INCREASING SOUTHWESTERLY SHEAR TO THE EAST OF AN
UPPER-LEVEL LOW/TROUGH BETWEEN 30W AND 40W. IT IS A BIT SURPRISING
GIVEN THESE NEGATIVE FACTORS THAT THE INTENSITY GUIDANCE SHOWS
LITTLE...IF ANY...WEAKENING. BECAUSE OF THAT...THE OFFICIAL
FORECAST WILL KEEP JULIA AT 65 KT AT DAYS 3-5 FOR NOW.
THE CENTER OF JULIA WAS RELOCATED A LITTLE EAST OF THE PREVIOUS
ADVISORY POSITION BASED ON THE EARLIER MICROWAVE DATA. THE INITIAL
MOTION ESTIMATE IS 285/10. THE TRACK FORECAST REASONING REMAINS
THE SAME AS THE PREVIOUS ADVISORY. JULIA IS FORECAST TO MOVE
WEST-NORTHWESTWARD AROUND THE SOUTHWESTERN SIDE OF A MID-LEVEL
RIDGE THAT EXTENDS FROM AFRICA WESTWARD INTO THE EASTERN ATLANTIC.
IN A COUPLE OF DAYS...THE CYCLONE IS FORECAST TO TURN NORTHWESTWARD
TOWARD A WEAKNESS IN THE RIDGE. MOST OF THE GUIDANCE INDICATES A
TURN BACK TOWARD THE WEST-NORTHWEST LATE IN THE PERIOD AS JULIA
MOVES AROUND THE NORTH SIDE OF AN UPPER-LEVEL LOW THAT CUTS OFF
NEAR 40W. THE OFFICIAL FORECAST TRACK IS GOOD AGREEMENT WITH THE
PREVIOUS ADVISORY AND A BLEND OF THE LATEST RUNS OF THE GFS...
UKMET...GFDL...HWRF...AND ECMWF MODELS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 13/0300Z 13.5N 23.5W 35 KT
12HR VT 13/1200Z 14.0N 25.3W 45 KT
24HR VT 14/0000Z 14.9N 27.6W 50 KT
36HR VT 14/1200Z 15.9N 29.5W 55 KT
48HR VT 15/0000Z 17.1N 31.1W 65 KT
72HR VT 16/0000Z 20.9N 35.1W 65 KT
96HR VT 17/0000Z 24.5N 41.0W 65 KT
120HR VT 18/0000Z 27.5N 46.5W 65 KT
$$
FORECASTER BROWN
NNNN
Forecast to be cat 5.
But Here's Julia!... and Igor at 150mph...
TCDAT2
TROPICAL STORM JULIA DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122010
1100 PM AST SUN SEP 12 2010
INFRARED AND MICROWAVE SATELLITE IMAGERY SHOW THAT THE CENTER OF
THE CYCLONE IS LOCATED NEAR THE EASTERN EDGE OF A CURVED BAND OF
CONVECTION THAT WRAPS AROUND THE WESTERN SEMICIRCLE OF THE SYSTEM.
SUBJECTIVE DVORAK INTENSITY ESTIMATES ARE 35 KT FROM TAFB AND 30 KT
FROM SAB. OBJECTIVE DVORAK ESTIMATES FROM UW/CIMMS ARE SLIGHTLY
HIGHER. A BLEND OF THESE ESTIMATES SUPPORT AN UPGRADE OF THE
DEPRESSION TO A 35-KT TROPICAL STORM...THE TENTH OF THE 2010
ATLANTIC HURRICANE SEASON.
THE EASTERLY SHEAR IS EXPECTED TO WEAKEN DURING THE NEXT 12 HOURS
AND IS FORECAST TO REMAIN LIGHT OVER THE NEXT COUPLE OF DAYS.
DURING THAT TIME JULIA WILL BE TRAVERSING WARM WATER AND AS A
RESULT...STEADY STRENGTHENING IS ANTICIPATED. THE SHIPS...LGEM...
AND GFDL MODELS ALL BRING JULIA TO HURRICANE STATUS WITHIN TWO DAYS
AND THE NHC FORECAST IS IN GOOD AGREEMENT. THEREAFTER...JULIA WILL
BE MOVING OVER SLIGHTLY COOLER SEA SURFACE TEMPERATURES AND INTO AN
AREA OF INCREASING SOUTHWESTERLY SHEAR TO THE EAST OF AN
UPPER-LEVEL LOW/TROUGH BETWEEN 30W AND 40W. IT IS A BIT SURPRISING
GIVEN THESE NEGATIVE FACTORS THAT THE INTENSITY GUIDANCE SHOWS
LITTLE...IF ANY...WEAKENING. BECAUSE OF THAT...THE OFFICIAL
FORECAST WILL KEEP JULIA AT 65 KT AT DAYS 3-5 FOR NOW.
THE CENTER OF JULIA WAS RELOCATED A LITTLE EAST OF THE PREVIOUS
ADVISORY POSITION BASED ON THE EARLIER MICROWAVE DATA. THE INITIAL
MOTION ESTIMATE IS 285/10. THE TRACK FORECAST REASONING REMAINS
THE SAME AS THE PREVIOUS ADVISORY. JULIA IS FORECAST TO MOVE
WEST-NORTHWESTWARD AROUND THE SOUTHWESTERN SIDE OF A MID-LEVEL
RIDGE THAT EXTENDS FROM AFRICA WESTWARD INTO THE EASTERN ATLANTIC.
IN A COUPLE OF DAYS...THE CYCLONE IS FORECAST TO TURN NORTHWESTWARD
TOWARD A WEAKNESS IN THE RIDGE. MOST OF THE GUIDANCE INDICATES A
TURN BACK TOWARD THE WEST-NORTHWEST LATE IN THE PERIOD AS JULIA
MOVES AROUND THE NORTH SIDE OF AN UPPER-LEVEL LOW THAT CUTS OFF
NEAR 40W. THE OFFICIAL FORECAST TRACK IS GOOD AGREEMENT WITH THE
PREVIOUS ADVISORY AND A BLEND OF THE LATEST RUNS OF THE GFS...
UKMET...GFDL...HWRF...AND ECMWF MODELS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 13/0300Z 13.5N 23.5W 35 KT
12HR VT 13/1200Z 14.0N 25.3W 45 KT
24HR VT 14/0000Z 14.9N 27.6W 50 KT
36HR VT 14/1200Z 15.9N 29.5W 55 KT
48HR VT 15/0000Z 17.1N 31.1W 65 KT
72HR VT 16/0000Z 20.9N 35.1W 65 KT
96HR VT 17/0000Z 24.5N 41.0W 65 KT
120HR VT 18/0000Z 27.5N 46.5W 65 KT
$$
FORECASTER BROWN
theres a complete article about it in wikipedia: here is the link if u wish to know more about them.
http://en.wikipedia.org/wiki/Annular_hurricane
I literally gasped in real life when I saw that.
According to RGB LOOP, yes. May only be a jog though and we'd need to see if that motion maintains. It could, however, be instrumental movement, delaying the turn or making the turn less pronounced.
Keep watching! ;)
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST SUN SEP 12 2010
IGOR HAS CONTINUED TO INTENSIFY WITH VERY COLD CLOUD TOPS...LOWER
THAN -70C...WRAPPING AROUND THE SLOWLY-SHRINKING EYE DURING THE
PAST SEVERAL HOURS. ALTHOUGH THE TOPS HAVE RECENTLY WARMED A
LITTLE OVER THE SOUTHWEST QUADRANT...SUBJECTIVE DVORAK ESTIMATES
FROM TAFB AND SAB ARE T6.5/127 KT AND OBJECTIVE ESTIMATES FROM THE
ADT AND HIE ALGORITHMS ARE T6.6/130 KT AND T6.9/137 KT...
RESPECTIVELY. AS A COMPROMISE...THE INITIAL INTENSITY IS SET AT
130 KT. AN EXPERIMENTAL PRODUCT FROM UW-CIMSS RUN AT NHC INDICATES
THAT THERE IS A 42 PERCENT CHANCE OF SECONDARY EYEWALL FORMATION
WITHIN THE NEXT 12 HOURS...AND A 90 PERCENT CHANCE WITHIN 24 HOURS.
THE PERIOD OF RAPID INTENSIFICATION IS LIKELY TO END SOON...BUT THE
OFFICIAL FORECAST FOLLOWS THE SHIPS/LGEM MODELS BY SHOWING IGOR
REACHING THE THRESHOLD OF CATEGORY 5 STRENGTH BEFORE THAT HAPPENS.
SOME WEAKENING IS THEN INDICATED AFTER EYEWALL REPLACEMENT
OCCURS...BUT IGOR IS EXPECTED TO REMAIN A POWERFUL HURRICANE FOR
SEVERAL DAYS. AS IS ALWAYS THE CASE WITH STRONG HURRICANES LIKE
IGOR...FLUCTUATIONS IN INTENSITY ARE LIKELY BUT ARE ALSO DIFFICULT
TO FORECAST.
THE MEAN MOTION IS 270/11...BUT IGOR HAS BEEN WOBBLING A LITTLE TO
THE SOUTH OF THAT VECTOR. IGOR IS MOVING INTO AN ENVIRONMENT WHERE
THE STEERING FLOW IS BECOMING INCREASINGLY DICTATED BY A LARGE
LONGWAVE TROUGH OVER THE WESTERN ATLANTIC...AND THE HURRICANE IS
EXPECTED TO RESPOND BY TURNING TOWARD THE WEST-NORTHWEST WITHIN THE
NEXT 24-48 HOURS. SOME OF THE GLOBAL MODELS INDICATE THAT THE
TROUGH COULD FLATTEN A LITTLE BY DAY 3 AND ALLOW THE SUBTROPICAL
RIDGE TO BUILD WESTWARD...BUT AT THIS TIME THERE IS TOO MUCH
DISAGREEMENT TO INDICATE A WESTWARD TURN IN THE FORECAST. THE
TRACK GUIDANCE HAS SHIFTED A LITTLE TO THE NORTH...BUT THE NEW
OFFICIAL FORECAST STILL LIES ON THE SOUTHERN SIDE OF THE GUIDANCE
ENVELOPE UNTIL IT BECOMES CLEAR THAT IGOR IS READY TO TURN. THIS
SOLUTION ALSO GIVES CREDENCE TO THE MORE SOUTHERN ECMWF AND UKMET
MODELS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 13/0300Z 17.6N 47.8W 130 KT
12HR VT 13/1200Z 17.8N 49.5W 140 KT
24HR VT 14/0000Z 18.2N 51.3W 135 KT
36HR VT 14/1200Z 18.9N 53.0W 130 KT
48HR VT 15/0000Z 19.8N 54.6W 125 KT
72HR VT 16/0000Z 22.0N 57.5W 125 KT
96HR VT 17/0000Z 24.0N 60.0W 120 KT
120HR VT 18/0000Z 27.0N 63.0W 110 KT
$$
FORECASTER BERG
WTNT41 KNHC 130248
TCDAT1
HURRICANE IGOR DISCUSSION NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST SUN SEP 12 2010
IGOR HAS CONTINUED TO INTENSIFY WITH VERY COLD CLOUD TOPS...LOWER
THAN -70C...WRAPPING AROUND THE SLOWLY-SHRINKING EYE DURING THE
PAST SEVERAL HOURS. ALTHOUGH THE TOPS HAVE RECENTLY WARMED A
LITTLE OVER THE SOUTHWEST QUADRANT...SUBJECTIVE DVORAK ESTIMATES
FROM TAFB AND SAB ARE T6.5/127 KT AND OBJECTIVE ESTIMATES FROM THE
ADT AND HIE ALGORITHMS ARE T6.6/130 KT AND T6.9/137 KT...
RESPECTIVELY. AS A COMPROMISE...THE INITIAL INTENSITY IS SET AT
130 KT. AN EXPERIMENTAL PRODUCT FROM UW-CIMSS RUN AT NHC INDICATES
THAT THERE IS A 42 PERCENT CHANCE OF SECONDARY EYEWALL FORMATION
WITHIN THE NEXT 12 HOURS...AND A 90 PERCENT CHANCE WITHIN 24 HOURS.
THE PERIOD OF RAPID INTENSIFICATION IS LIKELY TO END SOON...BUT THE
OFFICIAL FORECAST FOLLOWS THE SHIPS/LGEM MODELS BY SHOWING IGOR
REACHING THE THRESHOLD OF CATEGORY 5 STRENGTH BEFORE THAT HAPPENS.
SOME WEAKENING IS THEN INDICATED AFTER EYEWALL REPLACEMENT
OCCURS...BUT IGOR IS EXPECTED TO REMAIN A POWERFUL HURRICANE FOR
SEVERAL DAYS. AS IS ALWAYS THE CASE WITH STRONG HURRICANES LIKE
IGOR...FLUCTUATIONS IN INTENSITY ARE LIKELY BUT ARE ALSO DIFFICULT
TO FORECAST.
THE MEAN MOTION IS 270/11...BUT IGOR HAS BEEN WOBBLING A LITTLE TO
THE SOUTH OF THAT VECTOR. IGOR IS MOVING INTO AN ENVIRONMENT WHERE
THE STEERING FLOW IS BECOMING INCREASINGLY DICTATED BY A LARGE
LONGWAVE TROUGH OVER THE WESTERN ATLANTIC...AND THE HURRICANE IS
EXPECTED TO RESPOND BY TURNING TOWARD THE WEST-NORTHWEST WITHIN THE
NEXT 24-48 HOURS. SOME OF THE GLOBAL MODELS INDICATE THAT THE
TROUGH COULD FLATTEN A LITTLE BY DAY 3 AND ALLOW THE SUBTROPICAL
RIDGE TO BUILD WESTWARD...BUT AT THIS TIME THERE IS TOO MUCH
DISAGREEMENT TO INDICATE A WESTWARD TURN IN THE FORECAST. THE
TRACK GUIDANCE HAS SHIFTED A LITTLE TO THE NORTH...BUT THE NEW
OFFICIAL FORECAST STILL LIES ON THE SOUTHERN SIDE OF THE GUIDANCE
ENVELOPE UNTIL IT BECOMES CLEAR THAT IGOR IS READY TO TURN. THIS
SOLUTION ALSO GIVES CREDENCE TO THE MORE SOUTHERN ECMWF AND UKMET
MODELS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 13/0300Z 17.6N 47.8W 130 KT
12HR VT 13/1200Z 17.8N 49.5W 140 KT
24HR VT 14/0000Z 18.2N 51.3W 135 KT
36HR VT 14/1200Z 18.9N 53.0W 130 KT
48HR VT 15/0000Z 19.8N 54.6W 125 KT
72HR VT 16/0000Z 22.0N 57.5W 125 KT
96HR VT 17/0000Z 24.0N 60.0W 120 KT
120HR VT 18/0000Z 27.0N 63.0W 110 KT
$$
FORECASTER BERG
Potential energy is a property of a system and not of an individual body or particle. It depends only on its initial and final configurations; it is independent of the path the object travels. The value of potential energy is arbitrary and relative to the choice of reference point. Gravitational potential energy near the Earth's surface may be computed by multiplying the weight of an object by its distance above the reference point.
Potential energy may be converted into energy of motion, called kinetic energy. Traditionally potential energy is included with kinetic energy as a form of mechanical energy so that the total energy in gravitational systems can be calculated as a constant.
WTNT41 KNHC 130248
TCDAT1
HURRICANE IGOR DISCUSSION NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST SUN SEP 12 2010
IGOR HAS CONTINUED TO INTENSIFY WITH VERY COLD CLOUD TOPS...LOWER
THAN -70C...WRAPPING AROUND THE SLOWLY-SHRINKING EYE DURING THE
PAST SEVERAL HOURS. ALTHOUGH THE TOPS HAVE RECENTLY WARMED A
LITTLE OVER THE SOUTHWEST QUADRANT...SUBJECTIVE DVORAK ESTIMATES
FROM TAFB AND SAB ARE T6.5/127 KT AND OBJECTIVE ESTIMATES FROM THE
ADT AND HIE ALGORITHMS ARE T6.6/130 KT AND T6.9/137 KT...
RESPECTIVELY. AS A COMPROMISE...THE INITIAL INTENSITY IS SET AT
130 KT. AN EXPERIMENTAL PRODUCT FROM UW-CIMSS RUN AT NHC INDICATES
THAT THERE IS A 42 PERCENT CHANCE OF SECONDARY EYEWALL FORMATION
WITHIN THE NEXT 12 HOURS...AND A 90 PERCENT CHANCE WITHIN 24 HOURS.
THE PERIOD OF RAPID INTENSIFICATION IS LIKELY TO END SOON...BUT THE
OFFICIAL FORECAST FOLLOWS THE SHIPS/LGEM MODELS BY SHOWING IGOR
REACHING THE THRESHOLD OF CATEGORY 5 STRENGTH BEFORE THAT HAPPENS.
SOME WEAKENING IS THEN INDICATED AFTER EYEWALL REPLACEMENT
OCCURS...BUT IGOR IS EXPECTED TO REMAIN A POWERFUL HURRICANE FOR
SEVERAL DAYS. AS IS ALWAYS THE CASE WITH STRONG HURRICANES LIKE
IGOR...FLUCTUATIONS IN INTENSITY ARE LIKELY BUT ARE ALSO DIFFICULT
TO FORECAST.
THE MEAN MOTION IS 270/11...BUT IGOR HAS BEEN WOBBLING A LITTLE TO
THE SOUTH OF THAT VECTOR. IGOR IS MOVING INTO AN ENVIRONMENT WHERE
THE STEERING FLOW IS BECOMING INCREASINGLY DICTATED BY A LARGE
LONGWAVE TROUGH OVER THE WESTERN ATLANTIC...AND THE HURRICANE IS
EXPECTED TO RESPOND BY TURNING TOWARD THE WEST-NORTHWEST WITHIN THE
NEXT 24-48 HOURS. SOME OF THE GLOBAL MODELS INDICATE THAT THE
TROUGH COULD FLATTEN A LITTLE BY DAY 3 AND ALLOW THE SUBTROPICAL
RIDGE TO BUILD WESTWARD...BUT AT THIS TIME THERE IS TOO MUCH
DISAGREEMENT TO INDICATE A WESTWARD TURN IN THE FORECAST. THE
TRACK GUIDANCE HAS SHIFTED A LITTLE TO THE NORTH...BUT THE NEW
OFFICIAL FORECAST STILL LIES ON THE SOUTHERN SIDE OF THE GUIDANCE
ENVELOPE UNTIL IT BECOMES CLEAR THAT IGOR IS READY TO TURN. THIS
SOLUTION ALSO GIVES CREDENCE TO THE MORE SOUTHERN ECMWF AND UKMET
MODELS.
It has moved ever so slightly WSW
Actually did some research on it and they have one at 19/38 and another at 21/58 ... But nothing in between... So I guess they do have bouys in the area...
Both arguments are valid. Here's why: John is in Seattle. Sue is in St. Louis. Bill is in Miami. John finds the halfway point between him and Bill. Sue finds the halfway point between her and Bill. In both cases, Bill is in the same place. However, the center between John and Bill is more to the Northwest than the center between Sue and Bill.
As the northern part of the eyewall contracts, the center of the eye effectively moves WSW, even though the system as a whole is still moving west.
And unless it starts back nw I think it is significant and will not make the next forecast point (unless of course that point is moved).
But then again my eyes are failing due to advanced age! And I know nothing about nautical bearings. So I guess it all means nothing.
The discussion says he was going a little south.
read dr. masters latest. hasn't been wrong yet.
MARK
17.70N/47.70W
SOME OF THE GLOBAL MODELS INDICATE THAT THE
TROUGH COULD FLATTEN A LITTLE BY DAY 3 AND ALLOW THE SUBTROPICAL
RIDGE TO BUILD WESTWARD...BUT AT THIS TIME THERE IS TOO MUCH
DISAGREEMENT TO INDICATE A WESTWARD TURN IN THE FORECAST.
Viewing: 3151 - 3201
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