[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 252346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUL 25 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM FRANKLIN IS CENTERED NEAR 30.7N 69.5W...OR ABOUT
250 NM WSW OF BERMUDA...AT 25/2100 UTC NEARLY STATIONARY.
MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT.  THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
FOR MORE DETAILS.  THE SYSTEM HAS BEEN DRIFTING EASTWARD DURING
THE DAY AND HAS BEEN MOVING ERRATICALLY WITH WEAK STEERING
CURRENTS.  TSTMS HAVE BEEN OVER A DEGREE AWAY FROM THE CENTER
OVER THE PAST 24 HOURS BUT HAVE RECENTLY FORMED A LITTLE CLOSER
TO THE CENTER WITHIN 45 NM.  RECENT SATELLITE PICTURES INDICATE
A WEAK LOW-LEVEL CIRCULATION ROTATING ON THE N SIDE OF
FRANKLIN.. HINTING THAT THERE MAY BE MORE THAN ONE CENTER OF IN
THIS DISORGANIZED SYSTEM.  UPPER WINDS DO NOT LOOK FAVORABLE FOR
MUCH STRENGTHENING NOW WITH AN UPPER LOW JUST TO THE W OF THE
CYCLONE PROVIDING WLY SHEAR.  SCATTERED MODERATE CONVECTION FROM
30N-32N BETWEEN 66W-68.5W.

TROPICAL DEPRESSION GERT HAS DISSIPATED AND IS NOW LONGER A
SPECIAL FEATURE.

...TROPICAL WAVES...

CENTRAL ATLC TROPICAL WAVE ALONG 32W/33W S OF 22N MOVING W 15-20
KT WITH A 1014 MB LOW ALONG THE WAVE NEAR 11N.  THE LAST VISIBLE
SATELLITE PICTURES SHOWED A LARGE CIRCULATION ASSOCIATED WITH
THE WAVE WITH NO WELL-DEFINED CENTER.  A RECENT QUIKSCAT
CONFIRMS THE LOCATION OF THE LOW THOUGH WINDS ASSOCIATED WITH
THE FEATURE ARE LESS THAN 20 KT.  THERE IS A BIT OF DRY AIR
ENTRAINED INTO THE NORTHERN PART OF THE WAVE THAT IS PROBABLY
INHIBITING DEVELOPMENT AS ANY TSTMS HAVE BEEN WEAK AND
SHORT-LIVED.  HOWEVER CONVECTION HAS BEEN INCREASING A LITTLE
TONIGHT NEAR THE CENTER WITH WIDELY SCATTERED MODERATE
CONVECTION FROM 8N-12N BETWEEN 33W-40W.  COMPUTER MODELS SUGGEST
VERTICAL WIND SHEAR WILL REMAIN LOW AS THE WAVE MOVES WESTWARD
AND THE WAVE MAY HAVE SOME POTENTIAL FOR DEVELOPMENT AFTER IT
ENTERS WARMER WATERS W OF 40W.

E CARIBBEAN WAVE ALONG 67W S OF 15N MOVING W 25 KT.  THIS WAVE
HAS BEEN REPOSITIONED AS THE SOUTHERN END OF THE WAVE HAS RACED
AHEAD OF THE NORTHERN PORTION... WHICH IS NOW A TROUGH FROM
14N55W TO 23N52W.  VERY LIGHT WINDS ARE ASSOCIATED WITH THE
TROUGH E OF THE LESSER ANTILLES ALONG WITH ISOLATED WEAK/
MODERATE CONVECTION WITHIN 60 NM OF THE TROUGH AXIS.  THE WAVE
WAS RESPONSIBLE FOR TSTMS NEAR THE ABC ISLANDS TODAY BUT THESE
TSTMS HAVE MOSTLY DISSIPATED SAVE A FEW CELLS NEAR ARUBA.  THE
WAVE IS MOVING INTO AN AREA WITH VERY FAST LOW/MID LEVEL FLOW
AND WILL PROBABLY BE DIFFICULT TO TRACK OVER THE NEXT COUPLE OF
DAYS.  ANY INCREASE IN MOISTURE FROM THE TROUGH OVER THE LESSER
ANTILLES SHOULD BE NEGLIGIBLE.

W CARIBBEAN TROPICAL WAVE ALONG 88W S OF 20N MOVING W 15-20 KT.
A FEW SHOWERS ARE IN THE GULF OF HONDURAS OTHERWISE A LARGER
AREA OF TSTMS OVER CENTRAL HONDURAS IS LIKELY ASSOCIATED WITH
THE WAVE.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 12N16W 13N27W 7N35W 12N48W.  THE
ITCZ IS NOT WELL-DEFINED W OF 48W.  WIDELY SCATTERED MODERATE
CONVECTION IS FROM 4N-10N BETWEEN 35W-44W.  SIMILAR CONVECTION
IS WITHIN 45 NM OF LINE 11N22W 13N26W.

...DISCUSSION...

GULF OF MEXICO...
MOSTLY CLEAR SKIES DOMINATE THE AREA WITH A FEW HIGH CLOUDS OVER
THE OPEN WATERS.  DIURNAL TSTMS HAVE EXPLODED OVER YUCATAN ON
THE FAVORABLE EASTERN SIDE OF AN INVERTED TROUGH EXTENDING FROM
THE BAY OF CAMPECHE TO 25N92W.  ANY CIRCULATION FROM GERT SEEMS
TO HAVE DISSIPATED THOUGH REMNANT BANDS ARE PRODUCING SCATTERED
MODERATE CONVECTION WITHIN 75 NM OF 24N98W.  FARTHER E... A
SUBTLE SFC TROF EXTENDING AWAY FROM T.S. FRANKLIN STRETCHES
ACROSS FAR S FLORIDA AND THEN OVER THE E GULF WATERS TO 27N90W
WITH VISIBLE IMAGES INDICATING A WEAK 1015 MB LOW PRES NEAR
26N84W.  THE TROUGH HAS CAUSED EXTREMELY WEAK FLOW OVER THE NE
GULF AND SERVED AS A FOCUSING MECHANISM FOR WIDELY SCATTERED
TSTMS... NOW DISSIPATED... OVER S FLORIDA.  THE ATMOSPHERE WILL
REMAIN RELATIVELY DRY OVER THE NEXT FEW DAYS WITH A LOW CHANCE
OF SHOWERS/TSTMS OVER THE WATER.  THE BULK OF THE MUCH-HERALDED
AFRICAN DUST IS REMAINING EITHER TO THE S OVER THE CARIBBEAN OR
IS GETTING SUCKED INTO THE CIRCULATION OF FRANKLIN...SO LITTLE
EFFECTS ARE EXPECTED OVER THE GULF REGION SAVE THE FAR S
PORTIONS NEAR THE YUCATAN.  SOME INCREASE IN DUST IS POSSIBLE BY
LATE SAT AS LOW/MID LEVEL WINDS TURN MORE ELY OVER THE SE GULF
INTO S FLORIDA.

CARIBBEAN...
THE SAHARAN DUST SURGE HAS JUST ABOUT SPREAD ACROSS THE ENTIRE
CARIBBEAN BASIN WITH ONLY ISOLATED SHOWERS NOTED ON PUERTO RICO
RADAR. THE PLUME CONCENTRATIONS HAVE THINNED OUT CONSIDERABLY
OVER THE PAST FEW DAYS...AND NOW VISIBLE IMAGERY SUGGESTS ONLY
HAZY SKIES OVER THE AREA.  DRY AIR HAS WIPED OUT MOST CONVECTION
SAVE FOR WIDELY SCATTERED MODERATE ACTIVITY INLAND OVER
NICARAGUA AND HONDURAS.  ELY WINDS ALOFT OVER THE NW CARIBBEAN W
OF JAMAICA.. WITH THE MID-OCEANIC TROUGH RUNNING FROM A WEAK
MID/UPPER LOW NEAR NE DOMINICAN REPUBLIC SW TO 14N83W IN NE
NICARAGUA.  VERY DRY AIR IN THE MID/UPPER LEVELS CONTROLS THE
CARIBBEAN E OF THE TROUGH AXIS.  WEAK UPPER RIDGING HAS BUILT
INTO THE SE CARIBBEAN FROM NEAR MARTINIQUE THRU THE ABC ISLANDS
TO N COSTA RICA THOUGH ANY SIGNIFICANT SHOWERS ARE MOSTLY OVER S
AMERICA.  THE TRADEWINDS ACROSS THE REGION ARE AS STRONG AS THEY
HAVE BEEN DURING THE PAST FEW MONTHS WITH WINDS UP TO 30 KT
POSSIBLE IN THE TYPICAL ENHANCED REGION NW OF COLOMBIA.

ATLANTIC...
COMPLEX UPPER PATTERN IN THE W ATLC WITH A MID/UPPER HIGH OVER
THE CAROLINAS AND ONE NEAR 26N67W WITH A SHARP MID/UPPER LEVEL
TROF ALIGNED OVER T.S. FRANKLIN IN BETWEEN FROM ABOUT BERMUDA TO
26N76W.  DIFFLUENCE BETWEEN THE RIDGE AND THE CYCLONE ARE
CAUSING AN ABUNDANCE OF SHOWERS TO FORM WELL TO THE S OF
FRANKLIN WITH ISOLATED MODERATE CONVECTION FROM 24N-27N BETWEEN
64W-70W.   FARTHER E...ANOTHER SHARP UPPER TROF IS ALONG 29N53W
19N55W BUT APPEARS TO BE LIFTING TO THE N IN WATER VAPOR
IMAGERY.  THE S END OF THE UPPER TROUGH IS ENHANCING SHOWERS
WITHIN 90 NM OF 18N55W NEAR A SURFACE TROUGH.  STRONG UPPER
RIDGING LIES ACROSS THE E/CNTRL ATLC ALONG 16N WHICH IS
SUPPORTING DEEP EASTERLY FLOW OVER A LARGE AREA TO ITS S.
HOWEVER...MOISTURE IS MOSTLY LIMITED AND STABLE CONDITIONS N OF
THE ITCZ ARE LIMITING CONVECTION TO TWO MAIN AREAS...S OF THE
TRPCL WAVE ALONG 32W/33W AND BETWEEN SENEGAL AND THE CAPE VERDE
ISLANDS.  VERY DRY AIR COVERS THE TROPICAL ATLC N OF 10N W OF
36W.  FARTHER N...A DEEP TROUGH.... MUCH DEEPER THAN AVERAGE FOR
THE MIDDLE OF THE SUMMER... EXTENDS FROM JUST E OF THE AZORES TO
29N33W THOUGH ANY WEATHER IS N OF THE AREA.  A 1024 MB HIGH IS
NEAR 30N40W RIDGING ESE TO 25N18W AND WSW TO 26N55W THEN
24N66W.  WITH A RATHER NEGATIVE NAO AND ACTIVE MID-LATITUDE
PATTERN...PRESSURES ARE EXTREMELY LOW IN THE SUBTROPICAL RIDGE
WITH CORRESPONDINGLY LIGHT TRADES IN THE TROPICAL ATLC.

$$
BLAKE

WWWW
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