[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 060536
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT AUG 06 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA... GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN
COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES..
THE CENTER OF TROPICAL STORM HARVEY AT 06/0300 UTC WAS NEAR
32.4N 57.0W MOVING E 5 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1000 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 45 KT
WITH GUSTS TO 55 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC OR MIATCPAT3/WTNT33 KNHC
FOR MORE DETAILS.  THE CENTER OF HARVEY REMAINS EXPOSED WITH THE
CLOSEST TSTMS ABOUT THREE-QUARTERS OF A DEGREE AWAY FROM THE
CENTER IN THE NE QUADRANT.  WLY SHEAR AND DRY AIR IN THE
MID/UPPER LEVELS HAVE BEEN HINDERING THE DEVELOPMENT OF THE
CYCLONE AND LITTLE CHANGE IS EXPECTED BEFORE HARVEY IS PICKED UP
BY A MID-LATITUDE TROUGH IN A COUPLE DAYS.  SCATTERED MODERATE
CONVECTION WITHIN 60 NM OF 34N56W.

THE CENTER OF TROPICAL DEPRESSION NINE AT 06/0300 UTC WAS NEAR
17.6N 40.6W MOVING WNW 17 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1010 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 25 KT
WITH GUSTS TO 35 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC OR MIATCPAT4/ WTNT34
KNHC FOR MORE DETAILS.  THE LOW-LEVEL CENTER IS WELL-DEFINED ON
SATELLITE PICTURES... STRANGELY ABSENT OF ANY SIGNIFICANT DEEP
CONVECTION.  THE CLOSEST TSTMS ARE OVER 90 NM FROM THE CENTER
WITH SOME ISOLATED TSTMS WITHIN 75 NM OF 16N40W.  CIRRUS CLOUDS
CAN BE SEEN ON SATELLITE MOVING W TO E... A SIGN THAT WLY SHEAR
IS IN PLACE.  COMPUTER MODELS SUGGEST THAT CONDITIONS WILL
REMAIN HOSTILE FOR DEVELOPMENT FOR AT LEAST THE NEXT COUPLE OF
DAYS.. WHEN THEREAFTER SLIGHTLY LOWER SHEAR AND WARMER WATER
COULD AID IN THE ORGANIZATION OF THE DEPRESSION.

...TROPICAL WAVES...

FAR E ATLC WAVE ADDED JUST W OF DAKAR ALONG 18W S OF 17N MOVING
W 10 KT.  THE DAKAR SOUNDING SHOWED SE WINDS AT 850 MB UP
THROUGH 700 MB... AND TIMESECTIONS AS WELL AS SATELLITE PICTURES
INDICATE A WAVE HAS PASSED THE WAVE.  THE NIGHT VISIBLE
SATELLITE SHOWS A BROAD AREA OF TURNING IN THE ITCZ ALONG WITH A
FEW TSTMS WITH WIDELY SCATTERED MODERATE WITHIN 90 NM OF THE
WAVE AXIS BETWEEN 8N-13N.

CENTRAL ATLC TROPICAL WAVE WILL BE ADDED TO THE 0600 UTC
ANALYSIS AND AT 0000 UTC WAS AT 48W S OF 17N MOVING W 10-15 KT.
LONG-TERM SATELLITE IMAGES SHOWS THAT THIS IS THE WAVE THAT
SPAWNED TD #9 AND HAS CONTINUED MOVING AHEAD OF THE DEPRESSION.
THE GFS MODEL ALSO SUPPORTS THIS WAVE POSITION.  WIDELY
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF LINE 10N46W
10N50W AND 9N44W 6.5N48W.  MOISTURE ASSOCIATED WITH THIS WAVE
SHOULD MOVE INTO THE LESSER ANTILLES LATE SUN WITH THE THRUST OF
THE MOISTURE INTO THE WINDWARD ISLANDS.

CARIBBEAN SEA TROPICAL WAVE IS ALONG 84W S OF 19N MOVING W 10-15
KT.  A FEW SHOWERS/TSTMS ARE MOVING INTO NE NICARAGUA WITH
ANOTHER FEW TSTMS NEAR 19N85W... THE WAVE IS LIKELY IN BETWEEN
THIS ACTIVITY BUT FAST-FLOW IN THE LOW-LEVELS IS TOTALLY MASKING
ANY WAVE SIGNATURE.

TROPICAL WAVE OVER SOUTHERN MEXICO IS NOW OUT OF THE AREA.

...ITCZ...

ITCZ IS CENTERED ALONG 11N16W 9N22W 11N31W 10N38W 11N45W
9N60W.   THE ITCZ IS NOT WELL-DEFINED BETWEEN 35W AND 45W.
ISOLATED MODERATE CONVECTION FROM 8N-12N BETWEEN 30W-52W.
WIDELY SCATTERED MODERATE FROM 8N-10N BETWEEN 26W-30W WITH A FEW
TSTMS WITHIN 60 NM OF 8N21W.

...DISCUSSION...

GULF OF MEXICO...
WEAK 1014 MB LOW REMAINS S OF PENSACOLA NEAR 29N87W.  THERE IS
LITTLE ORGANIZATION TO THE LOW AND SURFACE PRESSURES ARE NOT
FALLING.  COMPUTER MODELS SUGGEST THE LOW WILL REMAIN NEAR THE
COAST FOR THE NEXT SEVERAL DAYS... ADDING TO DIURNAL CONVECTION
E OF MISSISSIPPI THRU THE FLORIDA PANHANDLE.  A MID/UPPER LOW IS
SITTING BETWEEN BIRMINGHAM AND JACKSON AND SHOULD AGAIN HELP
FIRE DAILY TSTMS FROM THE NE GULF THRU SE GEORGIA.  OTHERWISE A
WEAK INVERTED MID/UPPER TROUGH IS OVER THE SE GULF AND STRONG NW
WINDS ARE OVER THE SW GULF WITH WEAK UPPER TROUGHING EXTENDING
FROM 24N90W TO SE TEXAS.  A FEW TSTMS ARE IN THE BAY OF
CAMPECHE... LEFTOVERS FROM DIURNAL ACTIVITY OVER YUCATAN ALONG
WITH ISOLATED MODERATE CONVECTION WITHIN 90 NM OF 21N95W.

CARIBBEAN SEA...
FOR THE FIRST TIME IN RECENT MEMORY... CYCLONIC WINDS ALOFT
COVER THE CARIBBEAN.  GONE ARE THE ELY WINDS THAT HELPED PRODUCE
MAJOR HURRICANES IN THE CARIBBEAN IN JULY... REPLACED WITH A
MID/UPPER LOW JUST S OF DOMINICAN REPUBLIC NEAR 16N68W AND A
TROUGH EXTENDING WNW TO THE CAYMAN ISLANDS.  THIS TROUGH IS
LEADING TO WNW TO NW WINDS ALOFT IN THE W CARIBBEAN WITH SOME
UPPER DIVERGENCE IN THE EXTREME SW CARIBBEAN PRODUCING A FEW
TSTMS.  MODERATE/STRONG SUBSIDENCE COVERS THE CARIBBEAN WATERS.
HIGH PRESSURE ALOFT SHOULD REBUILD INTO THE E CARIBBEAN BY MON
BUT THE W CARIBBEAN LOOKS TO BE UNDER THE INFLUENCE OF UPPER
TROUGHING FOR THE FORESEEABLE FUTURE.

ATLANTIC OCEAN...
MID/UPPER RIDGING COVERS THE NW PART OF THE AREA.... FROM 30N62W
S OF BERMUDA TO NE FLORIDA.  A WEAK SURFACE TROUGH EXTENDS FROM
27N72W TO JUST N OF CAPE CANAVERAL WITH ISOLATED TSTMS WITHIN 90
NM OF 29N79W.  RELATIVELY DRY ELY FLOW IS S OF THE RIDGE AXIS E
OF THE CENTRAL BAHAMAS AROUND THE NORTHERN SIDE OF THE COLD LOW
IN THE CARIBBEAN.  FARTHER E... MID/UPPER HIGH IS NEAR 25N52W
WITH LOTS OF SUBSIDENCE N OF 20N BETWEEN 48W-58W.  A CUT-OFF LOW
CONTINUES TO SPIN NEAR 27N42W WITH A FEW TSTMS NEAR THE COLD AIR
INSTABILITY IN THE CENTER WITHIN 60 NM OF THE LOW.  THIS LOW IS
THE SYSTEM THAT IS SHEARING TD #9 FOR AT LEAST THE NEXT DAY OR
TWO.  VERY DRY AIR ALOFT CONTROLS THE REST OF THE AREA E OF 35W
N OF 20N WITH SUBSIDENCE BETWEEN AN UPPER TROUGH NW OF THE
CANARY ISLANDS AND UPPER RIDGING IN THE DEEP TROPICS.  ELY UPPER
WINDS DOMINATE MOST OF THE DEEP TROPICS... SAVE AN INVERTED
TROUGH PASSING THRU THE CAPE VERDES ISLANDS AND THE SOUTHERN
EXTENT OF THE COLD LOW IN THE CENTRAL ATLC WITH A TROUGH S TO
18N44W.  THE UPPER RIDGE AXIS LIES AT ABOUT 17N NEAR THE
DEPRESSION... WHICH IS N OF THE RIDGE AND IS EXPERIENCING WLY
SHEAR ALONG WITH LOTS OF DRY AIR IN THE MID/UPPER LEVELS.

$$
BLAKE

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