Sample Atlantic Tropical Weather Discussion

AXNT20 KNHC 152356
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 
805 PM EDT TUE 15 JUL XXXX

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...SPECIAL FEATURE...

T.S. CLAUDETTE CENTERED NEAR 28.5N 98.2W OR 65 MILES S OF 
SAN ANTONIO TEXAS AT 16/0000 UTC MOVING W 11 KT. ESTIMATED 
MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED WIND 
SPEED IS 50 KT WITH HIGHER GUSTS. SEE LATEST NHC 
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER 
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. 
DESPITE HAVING MADE LANDFALL EARLIER THIS AFTERNOON... 
CLAUDETTE CONTINUES TO MAINTAIN AN IMPRESSIVELY TIGHT 
CIRCULATION THAT HAS ALMOST MOVED TOTALLY INLAND. THE EYE 
HAS FILLED IN WITH CLOUDS BUT RADAR IMAGERY STILL SHOWS A 
RAGGED YET WELL-DEFINED RAIN-FREE CENTER WITH CONVECTION 
ALMOST WRAPPING COMPLETELY AROUND IT. THE SYSTEM IS 
BECOMING MORE ASYMMETRIC WITH RESPECT TO THE RAIN COVERAGE 
AS MOST OF THE PRECIPITATION HAS MOVED TO THE NW SEMICIRCLE 
FROM SAN ANTONIO SWD WHILE AREAS ALONG THE COAST TRY TO DRY 
OUT. ONE LAST INTENSE BAND OF TSTMS HAS DEVELOPED JUST 
OFFSHORE AND WILL MOVE INLAND OVER NIGHT. NUMEROUS MODERATE 
TO STRONG CONVECTION FROM 27.5N-30N BETWEEN 97W-100W. 
NUMEROUS MODERATE TO STRONG IN A 10 NM-WIDE BAND EXTENDING 
FROM MATAGORDA BAY SWWD TO NEAR BROWNSVILLE TEXAS.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED 1440 NM E OF THE LESSER ANTILLES 
ALONG 37W S OF 18N MOVING W 15-20 KT. THE WAVE IS LOW 
AMPLITUDE IN SCOPE BUT STILL PRESENTS A FAIRLY WELL-DEFINED 
SIGNATURE ON SATELLITE IMAGERY. WIDELY SCATTERED MODERATE 
CONVECTION HAS RECENTLY BEGUN TO DEVELOP WITHIN 30 NM OF A 
LINE FROM 8.5N36W 8N42W.

TROPICAL WAVE LOCATED 300 NM E OF THE LESSER ANTILLES ALONG 
56W S OF 22N MOVING W 15-20 KT. THE WAVE PRESENTS EXCELLENT 
CIRCULATION IS SATELLITE IMAGERY WITH A BATCH OF LOW/MID 
LEVEL CLOUDS MOVING TOWARDS THE CNTRL LESSER ANTILLES. 
WINDS AT BUOY 41100 E OF THE ISLANDS HAVE BEEN VEERING OVER 
THE PAST SEVERAL HRS FROM NELY TO ELY INDICATING THAT THE 
WAVE AXIS IS NEARBY. IN ADDITION...THE REPORTED SURFACE 
PRESSURE HAS DROPPED BY 1 MB OVER THE PAST 4 HRS. DESPITE 
THE WELL-DEFINED STRUCTURE...WIDESPREAD MID/UPPER LEVEL DRY 
AIR HAS SUBDUED ANY CONVECTIVE DEVELOPMENT.

TROPICAL WAVE OVER THE EASTERN CARIBBEAN ALONG 64W S OF 19N 
MOVING W 15-20 KT. ALTHOUGH A PATCH OF LOW/MID LEVEL CLOUDS 
IS OBSERVED MOVING W THROUGH THE ERN CARIBBEAN...UPPER AIR 
TIME SECTIONS FROM BARBADOS AND GUADELOUPE HAVE SHOWN 
CONSISTENT NELY FLOW FROM THE SURFACE TO 500 MB OVER THE 
PAST 2 DAYS. IN ADDITION...ANY POSSIBLE LOW-LEVEL WIND 
PERTURBATION IS QUICKLY BECOMING OVERTAKEN BY THE MUCH 
STRONGER WAVE E OF THE ISLANDS. THEREFORE THE WAVE WILL 
PROBABLY BE DROPPED FROM THE NEXT SURFACE ANALYSIS AT 0000 
UTC.

TROPICAL WAVE OVER THE WESTERN CARIBBEAN ALONG 83W S OF 23N 
MOVING W 15 KT. A LINE OF TSTMS IS MOVING W ACROSS HONDURAS 
AND NICARAGUA WITH THE WAVE AXIS...BUT OTHER THAN THAT THE 
WAVE IS DIFFICULT TO LOCATE VIA THE LOW-LEVEL FLOW OR UPPER 
AIR SOUNDINGS FROM THE CNTRL/WRN CARIBBEAN. SCATTERED 
MODERATE CONVECTION FROM 10.5N-15N BETWEEN 84W-87W.

...ITCZ...

ITCZ AXIS ALONG 10N8W 12N16W 6N35W 8N50W 5N62W. SCATTERED 
MODERATE CONVECTION WITHIN 90 NM OF THE AXIS BETWEEN 12W-
21W AND 24W-27W.

...DISCUSSION...

GULF OF MEXICO...

CLAUDETTE HAS MADE LANDFALL OVER S TEXAS AND NOW THE GLFMEX 
IS GOING TO GET A BREATHER. THE UPPER LEVEL PATTERN WILL BE 
TAKING ON A MORE PROGRESSIVE STRUCTURE OVER THE NEXT 
SEVERAL DAYS AS A TRAIN OF ANTICYCLONES AND CYCLONES MOVES 
ACROSS THE ATLC BASIN FROM E TO W. THE UPPER LEVEL 
ANTICYCLONE THAT HAD BEEN PROVIDING SWLY SHEAR TO CLAUDETTE 
OVER THE WEEKEND IS STILL CAMPED OUT OVER THE BAY OF 
CAMPECHE...NOW CENTERED NEAR 22N92W AND FORECAST TO 
CONTINUE MOVING W TOWARDS CNTRL MEXICO THROUGH THURSDAY. A 
RIDGE AXIS EXTENDS NE OF THE ANTICYCLONE ACROSS S FLORIDA 
AND INTO THE WRN ATLC JUST AHEAD OF A WEAK UPPER LOW WHICH 
HAS DEVELOPED OVER CNTRL GEORGIA. THE LOW WILL QUICKLY DROP 
S THEN W...AND A SMALL AREA OF UPPER LEVEL DIVERGENCE MAY 
DEVELOP AHEAD OF THE LOW AND PRODUCE MORE WIDESPREAD 
SHOWERS/TSTMS OVER THE EXTREME NE GULF LATE WEDNESDAY INTO 
THURSDAY. OVER CLAUDETTE ITSELF...WATER VAPOR IMAGERY 
CONTINUES TO SHOW DIVERGENT UPPER LEVEL FLOW OVER E TEXAS 
WITH THE DRIEST AIR HAVING BEEN PUSHED WWD OVER THE MEXICAN 
PLATEAU. A WEAK 250 MB RIDGE AXIS HAS ALSO BEEN BUILDING 
JUST E OF THE STORM THROUGH LOUISIANA...AND THIS FEATURE 
WILL SOON SERVE AS THE CONNECTOR BETWEEN THE GLFMEX 
ANTICYCLONE AND A SECOND ANTICYCLONE OVER THE FOUR CORNERS 
AREA. IN THE MEANTIME...WIDELY SCATTERED MODERATE 
CONVECTION HAS FORMED ALONG A SURFACE CONVERGENCE LINE 
EXTENDING SE OF CLAUDETTE WITHIN 45 NM OF 30N94W 26N92.5W 
22N94W.

CARIBBEAN...

AS THE UPPER LOW OVER GEORGIA SINKS S...IT WILL BEGIN TO 
MERGE WITH A MUCH BROADER UPPER LOW NOW CENTERED OVER THE 
WRN CARIBBEAN. THIS LOW HAS BECOME STRETCHED...WITH THE 
TROUGH AXIS NOW STRETCHING FROM PANAMA ACROSS JAMAICA TO 
THE CNTRL BAHAMAS. AN AREA OF WEAK SUBSIDENCE IS ASSOCIATED 
WITH THE TROUGH AND IS LOCATED FROM 12N-21N BETWEEN 78W-83W 
BUT WIDELY SCATTERED SHOWERS/TSTMS HAVE STILL FORMED UP TO 
100 NM N OF PANAMA. THE TROUGH WILL CONTINUE TO SHIFT WWD 
AND WILL REACH THE GLFMEX WITHIN 48 HRS.

WESTERN AND CENTRAL ATLANTIC...

A FLATTENED MID/UPPER LEVEL ANTICYCLONE IS CENTERED OVER 
THE LEEWARD ISLANDS NEAR 19N63W WITH MODERATE TO STRONG 
SUBSIDENCE MOVING WWD ACROSS THE TRPCL ATLC AND ERN 
CARIBBEAN FROM 7N-20N BETWEEN 43W-73W ON ITS SRN PERIPHERY. 
THE ANTICYCLONE IS HELPING TO PRODUCE MOSTLY CONVECTION-
FREE WEATHER OVER THE CARIBBEAN...DEPRIVING AT LEAST TWO 
TRPCL WAVES MOVING THROUGH THE AREA OF AN IMPORTANT 
MOISTURE SOURCE. TO THE NE...AN UPPER LEVEL TROUGH AXIS IS 
BEGINNING TO NUDGE ITS WAY SWD INTO THE DISCUSSION AREA NW 
OF 29N56W AND THIS FEATURE WILL CONTINUE TO BROADEN AND SAG 
SWD...PUSHING THE ANTICYCLONE WWD TOWARDS THE BAHAMAS. THE 
TROUGH ITSELF IS IMPORTANT BECAUSE IT IS PRODUCING AN AREA 
OF UPPER LEVEL DIVERGENCE TO ITS E...GENERALLY N OF 28N 
BETWEEN 48W-54W. A WEAK MID/UPPER LEVEL ANTICYCLONE 
CENTERED NEAR 28N46W IS ALSO HELPING TO STRENGTHEN THIS 
FLOW PATTERN. CONVECTION HAS DEVELOPED WITHIN THE AREA OF 
DIVERGENCE THROUGHOUT THE DAY AND OUTFLOW CONTINUES TO 
IMPROVE AS THE RIDGE BUILDS TO THE NW. IN EFFECT...A 1020 
MB SURFACE LOW HAS FORMED AT THE SURFACE NEAR 28N51W MOVING 
NW 10 KT. THE LOW DEVELOPED FROM A TROUGH WHICH BROKE OFF 
FROM THE NRN END OF THE TRPCL WAVE NOW LOCATED AT 56W. 
VISIBLE IMAGERY THROUGHOUT THE DAY HAS INDICATED THE 
FEATURE HAS GAINED A CONSIDERABLE AMOUNT OF ORGANIZATION 
AND RECENTLY A LARGE AREA OF SCATTERED TSTMS HAS BEEN 
DEVELOPING UP TO 250 NM E OF THE CENTER. TROPICAL CYCLONE 
DEVELOPMENT IS POSSIBLE WITH THIS SYSTEM WITHIN THE NEXT 24 
HRS AS IT MOVES NW AROUND THE LARGE SUBTROPICAL SURFACE 
HIGH.

EASTERN ATLANTIC...

THE SUBTROPICAL 250 MB RIDGE EXTENDS WWD FROM THE COAST OF 
AFRICA ALONG 22N17W 24N40W AND THEN CONNECTS TO THE 
DEVELOPING UPPER LEVEL ANTICYCLONE OVER THE CNTRL ATLC NEAR 
28N46W. DEEP ELY FLOW IS LOCATED TO THE S OF THE RIDGE AXIS 
WITH GENERALLY ABUNDANT MOISTURE BETWEEN AFRICA AND 40W. A 
BROADENING UPPER LEVEL TROUGH IS SKIRTING THE NE CORNER OF 
THE DISCUSSION AREA N OF 24.5N E OF 25W AND UPPER LEVEL 
CONVERGENCE AT THE BASE OF THE TROUGH IS PRODUCING A NARROW 
BAND OF MODERATE SUBSIDENCE WITHIN 90 NM OF A LINE FROM 
26N34W 25N25W 31N10W.

$$
BERG