Tropicsweatherpr's WunderBlog

Is now pouch 13L.

Link

What 92L and Ex Florence are doing is cleaning the sal for this wave.

It looks like it will emerge sometime on Thursday. Let's see at what latitude it will do so because it will be important.

TAFB at 06z surface analysis has a 1007 mb low.

13-14N looks about right and indeed that's pretty much where currently the best rotation of the system and the strongest convection has been located today.

Motion at first maybe more to the WNW as an upper trough digs down way to the north near the Azores but once thats over it'll be westward for a time.

Quoting GeorgiaStormz:
The wave is decoupled it seems... maybe no TS right after shore but it might not take long..

Yes,it seems like a couple of vortices there. But as you said is a matter of time for it to get going.

It has been introduced at the TAFB 06Z analysis.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 10N11W TO 18N12W MOVING W AT 15 KT.
THIS WAVE HAS BEEN TRACKED ACROSS AFRICA THE PAST FEW DAYS AND
EXHIBITS VERY DISTINCT CYCLONIC CIRCULATION IN THE LOW-LEVELS.
WHILE THIS CIRCULATION IS NOTED IN GLOBAL MODEL DATA BETWEEN
600-850 MB...THE ONLY APPARENT SURFACE CIRCULATION IS LOCATED ON
THE NORTHERN EXTENT OF THE WAVE AS A 1005 MB LOW CENTERED NEAR
16N12W ACCORDING TO RECENT SURFACE OBSERVATIONS ACROSS W AFRICA.
WHILE CONVECTIVE TRENDS IN THE VICINITY OF THE WAVE AXIS HAVE
BEEN DOWNWARD INTENSITY WISE THE PAST 6 HOURS...A COMPLEX OF
SCATTERED MODERATE CONVECTION IS FROM 08N-12N BETWEEN 13W-19W...
WITH SCATTERED SHOWERS ELSEWHERE ACROSS PORTIONS OF INLAND W
AFRICA FROM 10N-16N BETWEEN 10W-16W.

Quoting MiamiSurvivor:
I've missed something (was on the road most of the day yesterday). Whats up with 92L being renumbered?

That was not a valid renumber.

A TROPICAL WAVE ACCOMPANIED BY AN AREA OF LOW PRESSURE IS
APPROACHING THE WEST COAST OF AFRICA WITH MINIMAL SHOWER AND
THUNDERSTORM ACTIVITY. SOME DEVELOPMENT OF THIS SYSTEM IS POSSIBLE
OVER THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD AT 10 TO 15 MPH.
THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

This will be a very interesting system to track down the road. Let's see what occurs in it's long journey.

WHXX01 KWBC 100017
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
0017 UTC FRI AUG 10 2012

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL932012) 20120810 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
120810 0000 120810 1200 120811 0000 120811 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 15.1N 17.1W 16.0N 20.4W 17.1N 23.9W 18.2N 27.6W
BAMD 15.1N 17.1W 16.3N 20.8W 17.7N 24.6W 19.1N 28.4W
BAMM 15.1N 17.1W 16.4N 20.9W 17.7N 24.9W 18.9N 29.1W
LBAR 15.1N 17.1W 16.3N 20.5W 18.1N 24.1W 19.9N 27.6W
SHIP 25KTS 32KTS 40KTS 46KTS
DSHP 25KTS 35KTS 42KTS 49KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
120812 0000 120813 0000 120814 0000 120815 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 19.3N 31.4W 21.4N 38.9W 23.5N 45.5W 25.8N 51.5W
BAMD 20.4N 32.3W 22.4N 39.3W 23.2N 45.7W 24.7N 51.1W
BAMM 20.0N 33.3W 21.3N 41.0W 21.6N 47.4W 22.3N 52.4W
LBAR 21.7N 31.0W 24.9N 36.2W 27.1N 38.0W 27.1N 37.0W
SHIP 50KTS 58KTS 67KTS 74KTS
DSHP 53KTS 61KTS 69KTS 77KTS

...INITIAL CONDITIONS...
LATCUR = 15.1N LONCUR = 17.1W DIRCUR = 285DEG SPDCUR = 16KT
LATM12 = 14.4N LONM12 = 14.0W DIRM12 = 283DEG SPDM12 = 16KT
LATM24 = 14.0N LONM24 = 9.7W
WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 20KT
CENPRS = 1004MB OUTPRS = 1008MB OUTRAD = 150NM SDEPTH = S
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

Observations at Cape Verde islands.

Link

The 00z Best Track.

AL, 93, 2012081100, , BEST, 0, 175N, 230W, 25, 1008, LO

With the introduction into the Atlantic of the wet MJO,things may start to get more favorable.

93L continues to approach the warmer waters.

AL, 93, 2012081200, , BEST, 0, 202N, 314W, 25, 1011, LO

WHXX01 KWBC 121238
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1238 UTC SUN AUG 12 2012

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL932012) 20120812 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
120812 1200 120813 0000 120813 1200 120814 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 20.6N 35.5W 22.0N 39.2W 23.1N 42.7W 24.4N 45.9W
BAMD 20.6N 35.5W 21.9N 38.6W 22.8N 41.5W 23.6N 44.3W
BAMM 20.6N 35.5W 22.3N 39.1W 23.5N 42.5W 24.6N 45.7W
LBAR 20.6N 35.5W 21.7N 39.1W 22.8N 42.4W 23.7N 45.7W
SHIP 25KTS 25KTS 27KTS 31KTS
DSHP 25KTS 25KTS 27KTS 31KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
120814 1200 120815 1200 120816 1200 120817 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 25.7N 48.8W 29.2N 52.5W 33.0N 51.6W 35.0N 45.1W
BAMD 24.2N 47.0W 26.6N 51.3W 29.4N 52.7W 32.6N 50.3W
BAMM 25.7N 48.7W 29.0N 52.4W 32.4N 52.0W 34.9N 46.6W
LBAR 24.8N 48.7W 27.7N 52.8W 31.0N 53.0W 33.3N 47.9W
SHIP 38KTS 52KTS 58KTS 64KTS
DSHP 38KTS 52KTS 58KTS 64KTS

...INITIAL CONDITIONS...
LATCUR = 20.6N LONCUR = 35.5W DIRCUR = 280DEG SPDCUR = 20KT
LATM12 = 20.2N LONM12 = 31.4W DIRM12 = 285DEG SPDM12 = 21KT
LATM24 = 19.0N LONM24 = 27.3W
WNDCUR = 25KT RMAXWD = 50NM WNDM12 = 25KT
CENPRS = 1012MB OUTPRS = 1013MB OUTRAD = 100NM SDEPTH = S
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

12z Best Track.

93, 2012081312, , BEST, 0, 225N, 433W, 25, 1015, LO

Up to 30%.

A TROUGH OF LOW PRESSURE LOCATED OVER THE CENTRAL ATLANTIC ABOUT
1050 MILES SOUTHEAST OF BERMUDA IS PRODUCING A CONCENTRATED AREA
OF SHOWERS AND THUNDERSTORMS. SURFACE PRESSURES ARE HIGH AND NO
SIGNIFICANT DEVELOPMENT OF THIS DISTURBANCE IS EXPECTED TODAY.
HOWEVER...ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME MORE
CONDUCIVE OVER THE NEXT COUPLE OF DAYS. THIS SYSTEM HAS A MEDIUM
CHANCE... 30 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD TO NORTHWESTWARD AT
15 MPH.

Up to 50%.

A TROUGH OF LOW PRESSURE LOCATED OVER THE CENTRAL ATLANTIC ABOUT
900 MILES SOUTHEAST OF BERMUDA IS BECOMING BETTER DEFINED.
THUNDERSTORM ACTIVITY IS ALSO SHOWING SIGNS OF ORGANIZATION...AND
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR A
TROPICAL DEPRESSION TO FORM OVER THE NEXT COUPLE OF DAYS. THIS
SYSTEM HAS A MEDIUM CHANCE...50 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD
TO NORTHWESTWARD AT ABOUT 15 MPH.

AN AREA OF DISTURBED WEATHER...LOCATED OVER THE CENTRAL ATLANTIC
ABOUT 850 MILES SOUTHEAST OF BERMUDA...IS PRODUCING DISORGANIZED
SHOWERS AND A FEW THUNDERSTORMS. ALTHOUGH THERE IS NO EVIDENCE OF
A SURFACE CIRCULATION AND PRESSURES ARE HIGH...ENVIRONMENTAL
CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR DEVELOPMENT AND A
TROPICAL DEPRESSION COULD FORM OVER THE NEXT COUPLE OF DAYS. THIS
SYSTEM HAS A MEDIUM CHANCE...50 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES NORTHWESTWARD AND THEN
NORTHWARD AT ABOUT 15 MPH.

Up to 60%.

THE CIRCULATION ASSOCIATED WITH A DISTURBANCE LOCATED OVER THE
CENTRAL ATLANTIC ABOUT 775 MILES SOUTHEAST OF BERMUDA IS GRADUALLY
BECOMING BETTER DEFINED. ALTHOUGH THE ACCOMPANYING SHOWER AND
THUNDERSTORM ACTIVITY IS SOMEWHAT LIMITED...ENVIRONMENTAL
CONDITIONS ARE CONDUCIVE FOR A TROPICAL DEPRESSION TO FORM OVER THE
NEXT COUPLE OF DAYS. THIS SYSTEM HAS A HIGH CHANCE...60 PERCENT...
OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES
NORTH-NORTHWESTWARD AT 15 MPH TODAY AND TURNS NORTHEASTWARD BY
THURSDAY.

Up to 90%.

A WELL-DEFINED LOW PRESSURE SYSTEM IS LOCATED OVER THE CENTRAL
ATLANTIC ABOUT 630 MILES EAST-SOUTHEAST OF BERMUDA. SHOWER AND
THUNDERSTORM ACTIVITY CONTINUES TO SHOW SIGNS OF ORGANIZATION...
AND A TROPICAL DEPRESSION COULD FORM LATER TODAY. THIS SYSTEM
HAS A HIGH CHANCE...90 PERCENT...OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS AS IT MOVES NORTH-NORTHWESTWARD TO
NORTHWARD AT 15 MPH TODAY...AND TURNS NORTHEASTWARD TOMORROW.

BEGIN
NHC_ATCF
invest_RENUMBER_al932012_al082012.ren
FSTDA
R
U
040
010
0000
201208151933
NONE
NOTIFY=ATRP

Is now TS Gordon!

TROPICAL STORM GORDON DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012
500 AM AST THU AUG 16 2012

SATELLITE IMAGES INDICATE THAT A SMALL CENTRAL DENSE OVERCAST HAS
FORMED NEAR THE CENTER OF THE CYCLONE. MICROWAVE DATA ALSO SUGGEST
THAT THE CENTRAL FEATURES OF THE SYSTEM HAVE BECOME BETTER DEFINED.
THEREFORE...THE INITIAL INTENSITY IS INCREASED TO 35 KT...IN BEST
AGREEMENT WITH THE TAFB SATELLITE ESTIMATE. GORDON SHOULD BE
MOVING OVER RELATIVELY WARM WATER AND WITHIN A LIGHT-TO-MODERATE
SHEAR ENVIRONMENT FOR THE NEXT COUPLE OF DAYS. ALMOST ALL OF THE
GUIDANCE SHOWS THE STORM CLOSE TO OR BECOMING A HURRICANE WITHIN 72
HRS. THE NHC INTENSITY FORECAST IS SLIGHTLY INCREASED FROM THE
PREVIOUS ONE...BUT REMAINS BELOW THE INTENSITY CONSENSUS FROM 48-72
HR...AND IS NEAR A BLEND OF THE SHIPS/LGEM MODELS.

GORDON APPEARS TO HAVE RECURVED AND IS MOVING ABOUT 015/12 KT. THE
STORM IS EXPECTED TO BE STEERED NORTHEASTWARD THEN EASTWARD AROUND
THE NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE DURING THE NEXT
COUPLE OF DAYS. AFTER THAT TIME...GORDON SHOULD INTERACT MORE WITH
THE MID-LATITUDE WESTERLIES AND THEN TURN TOWARD THE NORTHEAST AHEAD
OF A TROUGH. WHILE THE MODELS ARE IN GOOD AGREEMENT...THERE HAS
BEEN A SOUTHWARD ADJUSTMENT TO THE TRACK IN THE MAJORITY OF THE
GUIDANCE...AND THE NHC FORECAST IS SHIFTED IN THAT DIRECTION.
WHILE GORDON IS EXPECTED TO BE NEAR THE AZORES IN ABOUT 4 DAYS...
MOST OF THE MODELS SUGGEST THAT IT WILL BE EXTRATROPICAL AT THAT
TIME.


FORECAST POSITIONS AND MAX WINDS

INIT 16/0900Z 32.2N 54.8W 35 KT 40 MPH
12H 16/1800Z 33.5N 53.4W 45 KT 50 MPH
24H 17/0600Z 34.6N 50.2W 50 KT 60 MPH
36H 17/1800Z 34.5N 46.3W 55 KT 65 MPH
48H 18/0600Z 34.4N 42.5W 65 KT 75 MPH
72H 19/0600Z 35.0N 34.5W 65 KT 75 MPH
96H 20/0600Z 36.8N 27.0W 55 KT 65 MPH...POST-TROP/EXTRATROP
120H 21/0600Z 39.5N 20.5W 45 KT 50 MPH...POST-TROP/EXTRATROP

$$
FORECASTER BLAKE

TROPICAL STORM GORDON DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012
1100 AM AST THU AUG 16 2012

VISIBLE SATELLITE IMAGERY INDICATES TIGHTLY CURVED CONVECTIVE BANDS
HAVE FORMED AROUND A SMALL CENTRAL DENSE OVERCAST...WHICH INDICATES
THAT GORDON IS STRENGTHENING. SATELLITE INTENSITY ESTIMATES ARE
T3.0 FROM TAFB...T2.5 FROM SAB...AND T2.7 ADT FROM UW-CIMSS. GIVEN
THE MID-LEVEL BANDED EYE FEATURE NOTED IN A 16/1143 UTC SSMIS
MICROWAVE IMAGE...THE INITIAL INTENSITY HAS BEEN INCREASED TO 45
KT...WHICH IS SUPPORTED BY THE 45-KT TAFB INTENSITY ESTIMATE.

GORDON IS RECURVING TO THE NORTHEAST...AND THE INITIAL MOTION IS NOW
045/14 KT. THE CYCLONE HAS ROUNDED THE SUBTROPICAL RIDGE AXIS AND
WILL BE MOVING INTO THE MID-LATITUDE WESTERLIES DURING THE NEXT
12-24 HOURS. AS A RESULT...GORDON SHOULD GRADUALLY TURN TOWARD THE
EAST THROUGH 72 HOURS. AFTER THAT TIME...THE CYCLONE IS EXPECTED TO
LIFT OUT TOWARD THE NORTHEAST AHEAD OF A DIGGING SHORTWAVE TROUGH
AND BE NEAR THE AZORES ISLANDS IN ABOUT 4 DAYS. THE NHC MODEL
GUIDANCE IS TIGHTLY PACKED AROUND THE PREVIOUS FORECAST TRACK...
SO ONLY MINOR TWEAKS WERE MADE FOR THIS ADVISORY.

SATELLITE IMAGERY INDICATES THAT UPPER-LEVEL OUTFLOW HAS BECOME WELL
ESTABLISHED IN ALL QUADRANTS...ESPECIALLY IN THE NORTHEASTERN
SEMICIRCLE. THE VERTICAL SHEAR IS FORECAST TO REMAIN FAVORABLE FOR
ABOUT THE NEXT 36 HOURS AND WARM SEA-SURFACE TEMPERATURES OF AT
LEAST 27C LIE AHEAD OF THE CYCLONE. AS A RESULT OF THESE FAVORABLE
CONDITIONS...STEADY INTENSIFICATION SEEMS REASONABLE ALTHOUGH DRY
MID-LEVEL AIR IS BEGINNING TO ENCROACH FROM THE WEST. BY 48
HOURS...WESTERLY WIND SHEAR AND DRY AIR ENTRAINMENT ARE EXPECTED TO
SHARPLY INCREASE...WHICH SHOULD ACT TO PUT A BRAKE ON THE
STRENGTHENING PROCESS. AS GORDON APPROACHES THE AZORES IN 4 DAYS...
THE SYSTEM COULD MERGE WITH A FRONTAL SYSTEM AND TRANSITION INTO A
STRONG EXTRATROPICAL CYCLONE. THE INTENSITY FORECAST IS IDENTICAL
TO THE PREVIOUS ADVISORY...AND IS CLOSE TO INTENSITY CONSENSUS
MODEL...IV15.

FORECAST POSITIONS AND MAX WINDS

INIT 16/1500Z 33.3N 53.8W 45 KT 50 MPH
12H 17/0000Z 34.3N 51.8W 50 KT 60 MPH
24H 17/1200Z 34.9N 48.3W 55 KT 65 MPH
36H 18/0000Z 34.9N 44.5W 60 KT 70 MPH
48H 18/1200Z 34.8N 40.6W 65 KT 75 MPH
72H 19/1200Z 35.6N 32.7W 60 KT 70 MPH
96H 20/1200Z 37.9N 25.5W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 21/1200Z 40.4N 19.0W 45 KT 50 MPH...POST-TROP/EXTRATROP

$$
FORECASTER STEWART

TROPICAL STORM GORDON DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012
500 PM AST THU AUG 16 2012

GORDON HAS BEEN STRENGTHENING OVER THE PAST 12 HOURS. VISIBLE
SATELLITE IMAGERY CONTINUES TO SHOW TIGHTLY COILED CONVECTIVE CLOUD
BANDS SPIRALING INTO A SMALL CENTRAL DENSE OVERCAST FEATURE.
SATELLITE INTENSITY ESTIMATES ARE T3.5/55 KT FROM TAFB...T3.0/45 KT
FROM SAB...AND T2.7/39 KT ADT FROM UW-CIMSS. AN 1143 UTC SSMIS
IMAGE INDICATED A CLOSED MID-LEVEL EYE FEATURE AND A 1311 UTC ASCAT
OVERPASS REVEALED 39-KT SURFACE WINDS...WHICH WHEN ADJUSTED FOR THE
KNOWN LOW BIAS OF THE SCATTEROMETER DATA YIELDS ABOUT 44 KT. GIVEN
THE MUCH IMPROVED BANDING STRUCTURE SINCE THOSE MICROWAVE DATA WERE
ACQUIRED...THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KT.

GORDON IS NOW MOVING TOWARD THE EAST-NORTHEAST...OR 055/15 KT...AND
IS ON THE PREVIOUS FORECAST TRACK. THE CYCLONE IS MOVING ALONG THE
NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE AND WILL BE MOVING INTO
THE MID-LATITUDE WESTERLIES DURING THE NEXT 12-18 HOURS. GORDON
SHOULD GRADUALLY TURN EASTWARD AND CONTINUE THAT MOTION THROUGH AT
LEAST THE 48-HOUR FORECAST PERIOD. BY 72 HOURS...THE CYCLONE IS
FORECAST TO BEGIN LIFTING OUT TOWARD THE NORTHEAST AHEAD OF A
SHORTWAVE TROUGH...AND BE NEAR THE AZORES ISLANDS BETWEEN DAYS 3
AND 4. THE NHC TRACK GUIDANCE REMAINS TIGHTLY PACKED AROUND THE
PREVIOUS FORECAST TRACK...SO NO SIGNIFICANT CHANGES WERE MADE TO
THIS FORECAST PACKAGE.

UPPER-LEVEL OUTFLOW REMAINS WELL ESTABLISHED IN ALL QUADRANTS...AND
DRY MID-LEVEL AIR HAS MANAGED THUS FAR TO REMAIN AWAY FROM THE
INNER CORE REGION. WEAK VERTICAL SHEAR COUPLED WITH SSTS GREATER
THAN 27C SHOULD ALLOW FOR SOME ADDITIONAL INTENSIFICATION TO OCCUR
DURING THE NEXT 24-36 HOURS. BY 48 HOURS...HOWEVER...ENTRAINMENT OF
DRY MID-LEVEL AIR FROM THE WEST ALONG WITH INCREASING VERTICAL WIND
SHEAR IN EXCESS OF 30 KT SHOULD INDUCE STEADY WEAKENING. AS GORDON
NEARS THE AZORES ISLANDS IN 3 TO 4 DAYS...THE CYCLONE IS FORECAST
BY MOST OF THE GLOBAL MODELS TO MERGE WITH A FRONTAL SYSTEM AND
BECOME A STRONG EXTRATROPICAL CYCLONE. THE INTENSITY FORECAST IS
ONLY SLIGHTLY HIGHER THAN THE PREVIOUS ADVISORY...AND REMAINS CLOSE
TO IV15 INTENSITY CONSENSUS MODEL.

FORECAST POSITIONS AND MAX WINDS

INIT 16/2100Z 34.2N 52.1W 55 KT 65 MPH
12H 17/0600Z 34.7N 49.9W 60 KT 70 MPH
24H 17/1800Z 34.9N 46.2W 65 KT 75 MPH
36H 18/0600Z 34.7N 42.5W 70 KT 80 MPH
48H 18/1800Z 34.7N 38.6W 60 KT 70 MPH
72H 19/1800Z 36.1N 30.8W 55 KT 65 MPH
96H 20/1800Z 38.8N 23.2W 45 KT 50 MPH...POST-TROP/EXTRATROP
120H 21/1800Z 41.2N 15.8W 40 KT 45 MPH...POST-TROP/EXTRATROP

$$
FORECASTER STEWART

TROPICAL STORM GORDON DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012
1100 PM AST THU AUG 16 2012

ALTHOUGH THE CONVECTION IS NOT VERY DEEP...SATELLITE IMAGES SHOW
THAT THE CLOUD PATTERN HAS BECOME SYMMETRIC WITH THE CENTER OF THE
CYCLONE EMBEDDED WITHIN A CIRCULAR AREA OF THE STRONGEST CONVECTION.
A WELL-DEFINED CYCLONICALLY-CURVED BAND IS WRAPPING AROUND THE
NORTH AND EAST SIDES OF THE CIRCULATION. T-NUMBERS FROM BOTH
TAFB AND SAB ARE 4.0 AND 3.0 RESPECTIVELY. AN AVERAGE OF THESE TWO
ESTIMATES SUGGESTS AN INITIAL INTENSITY OF 60 KNOTS. GORDON ONLY
HAS A DAY OR SO TO BECOME A HURRICANE BEFORE IT MOVES OVER COOLER
WATERS AND ENCOUNTERS STRONG SHEAR. A GRADUAL WEAKENING SHOULD THEN
BEGIN...BUT GORDON IS FORECAST TO REMAIN A TROPICAL STORM BY THE
TIME IT MOVES THROUGH THE AZORES IN 3 DAYS. ONCE GORDON MOVE EAST OF
THE AZORES...IT SHOULD ACQUIRE EXTRATROPICAL CHARACTERISTICS.

GORDON IS MOVING TOWARD THE EAST OR 085 DEGREES AT 15 KNOTS...WELL
EMBEDDED WITHIN THE MID-LATITUDE WESTERLIES. SINCE THE STEERING
CURRENTS ARE FORECAST BY THE GLOBAL MODELS TO REMAIN WELL
ESTABLISHED...GORDON SHOULD CONTINUE TO MOVE EASTWARD FOR THE NEXT
THREE DAYS WITH NO SIGNIFICANT CHANGE IN FORWARD SPEED. TRACK
MODELS ARE IN REMARKABLY GOOD AGREEMENT IN BRINGING THE CYCLONE
EASTWARD THROUGH THE AZORES. MODELS ALSO SHOW A GRADUAL TURN TOWARD
THE NORTHEAST BY 72 HOURS AS A SHORTWAVE TROUGH AMPLIFIES TO THE
WEST OF THE CYCLONE. THE OFFICIAL FORECAST IS IN THE MIDDLE OF THE
GUIDANCE ENVELOPE AND BRINGS GORDON THROUGH THE AZORES IN ABOUT 3
DAYS.


FORECAST POSITIONS AND MAX WINDS

INIT 17/0300Z 34.6N 50.3W 60 KT 70 MPH
12H 17/1200Z 34.9N 47.7W 65 KT 75 MPH
24H 18/0000Z 34.8N 43.5W 70 KT 80 MPH
36H 18/1200Z 34.5N 39.5W 65 KT 75 MPH
48H 19/0000Z 34.5N 35.9W 60 KT 70 MPH
72H 20/0000Z 36.5N 28.5W 50 KT 60 MPH
96H 21/0000Z 39.0N 21.0W 45 KT 50 MPH...POST-TROP/EXTRATROP
120H 22/0000Z 41.0N 15.0W 40 KT 45 MPH...POST-TROP/EXTRATROP

$$
FORECASTER AVILA

TROPICAL STORM GORDON DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012
500 AM AST FRI AUG 17 2012

THE CLOUD PATTERN OF GORDON HAS DETERIORATED OVER THE PAST SEVERAL
HOURS WITH CENTRAL CONVECTION BECOMING LESS SYMMETRIC. MICROWAVE
IMAGES SUGGEST THAT THE LOW-LEVEL CENTER IS LOCATED SOMEWHAT TO THE
SOUTHWEST OF THE MID-LEVEL CIRCULATION...PROBABLY A REFLECTION OF
WESTERLY SHEAR. SATELLITE ESTIMATES HAVE COME DOWN A BIT...SO THE
INITIAL WIND SPEED IS REDUCED TO 55 KT. A SMALL TROUGH SEEN TO THE
NORTHWEST OF GORDON IN WATER VAPOR IMAGES COULD HAVE HELPED CAUSED
THE RECENT INCREASE IN SHEAR. MOST OF THE GLOBAL MODELS SHOW THIS
TROUGH WEAKENING...WHICH MIGHT ALLOW THE SHEAR TO DECREASE AGAIN.
THE BULK OF THE GUIDANCE STILL PREDICT GORDON WILL BECOME A
HURRICANE BEFORE MOVING OVER COOLER WATERS IN A COUPLE OF
DAYS...THOUGH THE SHIPS AND LGEM MODELS HAVE BACKED OFF ON THIS
SOLUTION. THE NHC FORECAST IS LOWERED FROM THE PREVIOUS ONE...BUT
STILL SHOWS GORDON BRIEFLY AS A HURRICANE. THE NEW FORECAST IS
GENERALLY BELOW THE MODEL CONSENSUS...SHADED TOWARD THE SHIPS/LGEM
GUIDANCE.

GORDON IS MOVING EASTWARD AT ABOUT 16 KT. THE STORM IS BEING
STEERED TO THE SOUTH OF A LARGE TROUGH OVER THE NORTHEASTERN
ATLANTIC OCEAN...WHICH SHOULD CAUSE THE TROPICAL CYCLONE TO MOVE A
LITTLE SOUTH OF EAST FOR THE NEXT DAY OR SO. AFTER THAT
TIME...GORDON WILL LIKELY BEGIN TO GAIN SOME LATITUDE AS A
SHORTWAVE MOVES DOWN THE WESTERN SIDE OF THE TROUGH. MODELS
CONTINUE TO BE IN VERY GOOD AGREEMENT...AND ONLY A SMALL SOUTHWARD
CHANGE WAS MADE TO THE OFFICIAL FORECAST. WHILE GORDON IS
EXPECTED TO MOVE NEAR THE AZORES IN ABOUT 3 DAYS...A COMBINATION OF
COLD WATER...INCREASING SHEAR...AND A NEARBY BAROCLINIC ZONE SHOULD
PROMOTE EXTRATROPICAL TRANSITION OF THE SYSTEM NEAR OR BEFORE IT
REACHES THOSE ISLANDS.


FORECAST POSITIONS AND MAX WINDS

INIT 17/0900Z 34.6N 48.1W 55 KT 65 MPH
12H 17/1800Z 34.5N 45.3W 55 KT 65 MPH
24H 18/0600Z 34.2N 41.4W 60 KT 70 MPH
36H 18/1800Z 34.2N 37.5W 65 KT 75 MPH
48H 19/0600Z 34.7N 33.7W 55 KT 65 MPH
72H 20/0600Z 37.0N 26.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 21/0600Z 39.0N 19.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
120H 22/0600Z 40.0N 17.0W 30 KT 35 MPH...POST-TROP/EXTRATROP

$$
FORECASTER BLAKE

TROPICAL STORM GORDON DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082012
1100 AM AST FRI AUG 17 2012

THE SATELLITE APPEARANCE OF GORDON REMAINS RATHER UNIMPRESSIVE...
WITH CLOUD TOP TEMPERATURES WARMING OVER THE PAST FEW HOURS AND THE
COLDEST CLOUD TOPS DISPLACED NORTH AND WEST OF THE CENTER. UW-CIMSS
SATELLITE ANALYSIS AND SHIPS DIAGNOSTICS SHOW AROUND 15 KT OF
WEST-NORTHWESTERLY SHEAR OVER THE CYCLONE...WHILE MET-9 AIRMASS
IMAGERY AND MICROWAVE IMAGERY SHOW SOME DRY AIR WRAPPING INTO THE
CIRCULATION FROM THE SOUTHWEST. THE INITIAL INTENSITY IS HELD AT 55
KT BASED ON A BLEND OF THE LATEST DVORAK FINAL-T AND CI-NUMBERS
FROM TAFB AND SAB. THE CENTRAL PRESSURE OF 997 MB IS BASED ON AN
OBSERVATION OF 999 MB FROM A DRIFTING BUOY THAT THE CENTER PASSED
JUST NORTH OF AROUND 1000 UTC.

THE SHEAR IS FORECAST TO DECREASE A LITTLE IN THE SHORT TERM...WHICH
SHOULD ALLOW GORDON TO STRENGTHEN A BIT BEFORE THE CYCLONE REACHES
SUB-26C WATERS AND THE SHEAR INCREASES IN 36 TO 48 HOURS. THE NHC
FORECAST SHOWS THE CYCLONE PEAKING AT 60 KT IN 24 TO 36 HOURS AND
IS CLOSE TO A BLEND OF THE SHIPS AND LGEM MODELS UNTIL
EXTRATROPICAL TRANSITION OCCURS.

THE INITIAL MOTION ESTIMATE IS A LITTLE SOUTH OF DUE EAST...095/16.
GORDON WILL BE STEERED GENERALLY EASTWARD FOR THE NEXT DAY OR SO TO
THE SOUTH OF A LARGE MID/UPPER-LEVEL TROUGH OVER THE NORTHEASTERN
ATLANTIC. BY 48 HOURS...A SHORTWAVE TROUGH IS EXPECTED TO APPROACH
THE CYCLONE FROM THE WEST AND INDUCE AN EAST-NORTHEASTWARD TURN AS
THE CYCLONE BECOMES EXTRATROPICAL IN ABOUT 3 DAYS. A SLOW EAST-
NORTHEASTWARD MOTION IS EXPECTED AT DAYS 4 AND 5 AS THE CYCLONE
WEAKENS. OVERALL THE TRACK MODEL GUIDANCE REMAINS IN GOOD AGREEMENT
ON THIS SCENARIO. THE NEW NHC FORECAST IS LARGELY AN UPDATE OF THE
PREVIOUS ONE AND IS CLOSE TO A CONSENSUS OF THE GFS AND ECMWF.

THE 34-KT WIND RADII WERE ADJUSTED OUTWARD BASED ON A PARTIAL ASCAT
PASS FROM AROUND 1250 UTC.

FORECAST POSITIONS AND MAX WINDS

INIT 17/1500Z 34.5N 46.3W 55 KT 65 MPH
12H 18/0000Z 34.2N 43.4W 55 KT 65 MPH
24H 18/1200Z 34.1N 39.6W 60 KT 70 MPH
36H 19/0000Z 34.4N 35.6W 60 KT 70 MPH
48H 19/1200Z 35.2N 31.8W 55 KT 65 MPH
72H 20/1200Z 38.0N 24.0W 45 KT 50 MPH...POST-TROP/EXTRATROP
96H 21/1200Z 39.0N 19.5W 40 KT 45 MPH...POST-TROP/EXTRATROP
120H 22/1200Z 39.5N 16.5W 35 KT 40 MPH...POST-TROP/EXTRATROP

$$
FORECASTER BRENNAN