[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 180556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI JUL 18 2008

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 INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

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

...SPECIAL FEATURES...

TROPICAL STORM BERTHA IS CENTERED NEAR 33.9N 55.4W AT 18/0300
UTC MOVING EAST AT 15 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
997 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60
KT. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER
MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. BERTHA IS MAINTAINING
TROPICAL STORM STRENGTH AND ITS STRUCTURE AS A TROPICAL STORM
WITH DEFINED BANDING FEATURES AND OUTFLOW ALOFT. SCATTERED
MODERATE CONVECTION IS FROM 33N-36N BETWEEN 53W-56W IN THE
NORTHEASTERN QUADRANT.

TROPICAL WAVE IS ALONG 67W/68W S OF 18N WITH A 1009 MB LOW ALONG
THE WAVE AXIS NEAR 13N MOVING W NEAR 15-20 KT. EARLIER AN AIR
FORCE RECONNAISSANCE AIRCRAFT INVESTIGATED THE SYSTEM AND FOUND
ONLY A BROAD CLOSED CIRCULATION CENTER. ENVIRONMENTAL CONDITIONS
ARE EXPECTED TO GRADUALLY BECOME MORE FAVORABLE OVER THE NEXT
DAY OR SO AS THE SYSTEM MOVE WESTWARD INTO AN AREA OF BETTER
UPPER LEVEL DIFFLUENCE. HEAVY RAINS AND GUSTY WINDS ARE POSSIBLE
OVER NORTHERN VENEZUELA AND ADJACENT ISLANDS TONIGHT AND
TOMORROW. SCATTERED MODERATE CONVECTION REMAINS FROM 13N-16N
BETWEEN 68W-71W TO THE NORTHEAST OF THE LOW. ELSEWHERE...
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS COVER THE
REMAINDER OF THE AREA S OF 17N BETWEEN 63W-73W.

TROPICAL WAVE IS ALONG 83W S OF 22N WITH A 1010 MB LOW ALONG THE
WAVE NEAR 14N. THIS SYSTEM HAS SLOWED TO NEAR 10 KT GIVEN THE
LARGE EXPANSIVE AREAL COVERAGE OF THE OVERALL CIRCULATION.
ALTHOUGH THIS SYSTEM IS NOT EXPECTED TO BECOME A TROPICAL
DEPRESSION BEFORE MOVING INLAND ACROSS CENTRAL AMERICA TONIGHT
OR FRIDAY...SHOWERS AND GUSTY WINDS ARE EXPECTED TO CONTINUE
SPREADING OVER PORTIONS OF HONDURAS AND NICARAGUA. THIS ACTIVITY
COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUDSLIDES.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 12N-19N
BETWEEN 79W-89W.

A 1012 MB LOW IS OFF THE COAST OF JACKSONVILLE FLORIDA NEAR
30.5N80.5W WITH A SURFACE TROUGH EXTENDING SW ACROSS CENTRAL
FLORIDA. ENVIRONMENTAL CONDITIONS COULD ALLOW FOR SOME SLOW
DEVELOPMENT OF THIS SYSTEM DURING THE NEXT COUPLE OF DAYS AS THE
LOW DRIFTS TO THE NORTH OR NORTH-NORTHEAST AND REMAINS OVER THE
OPEN WATERS OF THE W ATLC. SCATTERED SHOWERS/THUNDERSTORMS
REMAIN IN THE W ATLC FROM 27N-32N BETWEEN 78W-80W. ANOTHER
SMALLER AREA OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
FROM 24N-27N BETWEEN 78W-80W AND MOVING NWD.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 46W S OF 19N MOVING W NEAR 15 KT. HIGH
AMPLITUDE INVERTED-V CURVATURE IS OBSERVED ON SATELLITE IMAGERY
WITH NO ASSOCIATED SHOWERS OR DEEP CONVECTION.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 15N16W 7N23W 7N43W 7N49W 9N63W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 75 NM OF
THE ITCZ BETWEEN 21W-28W. SCATTERED MODERATE CONVECTION IS
WITHIN 60 NM OF A LINE FROM 6N53W TO 10N57W.

...DISCUSSION...

GULF OF MEXICO...
MAIN AREA OF ADVERSE WEATHER IS OFF THE NE FLORIDA PENINSULA
AND INTO THE W ATLC DUE TO THE 1012 MB LOW OFF THE COAST OF
JACKSONVILLE FLORIDA. AN UPPER LOW IS OVER THE NW GULF NEAR
27N95W WITH AN UPPER RIDGE COVERING THE ERN GULF AND RIDGE AXIS
EXTENDING FROM THE FLORIDA PANHANDLE TO THE YUCATAN CHANNEL.
THESE UPPER FEATURES ARE RATHER BENIGN AS A 1017 MB SURFACE HIGH
PRESSURE CENTERED NEAR 29N93W IS MAINTAINING LIGHT WINDS AND
RELATIVE TRANQUIL WEATHER ACROSS THE GULF OF MEXICO.

CARIBBEAN SEA...
THE FOCUS ACROSS THE CARIBBEAN SEA IS TWO FOLD...THE TROPICAL
WAVE ALONG 83W AND THE ERN CARIBBEAN TROPICAL WAVE ALONG
66W/67W. SEE SPECIAL FEATURES ABOVE. THESE TWO SYSTEMS ENCOMPASS
MOST OF THE CARIBBEAN. UPPER LEVEL LOW LOCATED OVER THE SE
BAHAMAS EXTENDS TROUGHING ACROSS ERN CUBA AND JAMAICA. EAST OF
THE TROUGH AXIS WHICH IS ALONG 74W...UPPER DIFFLUENCE IS
GENERATING SCATTERED SHOWERS ACROSS THE WINDWARD PASSAGE AND WRN
HISPANIOLA. ELSEWHERE...UPPER LEVEL SUBSIDENCE AND DRY AIR IS
ACROSS THE LEEWARD/VIRGIN ISLANDS AND PUERTO RICO.

ATLANTIC OCEAN...
THE MAIN FOCUS FOR THE W ATLC IS THE 1012 MB LOW OFF THE NE
FLORIDA COAST NEAR JACKSONVILLE FLORIDA AND TROPICAL STORM
BERTHA WHICH REMAINS NORTH OF THE REGION. SEE SPECIAL FEATURES
ABOVE. A SMALL AREA OF HIGH PRESSURE IS LOCATED SW OF T.S.
BERTHA CENTERED BY A 1019 MB HIGH NEAR 27N67W. AN UPPER HIGH IS
LOCATED SE OF BERTHA AND KEEPING MOST OF THE WRN ATLC E OF 77W
AND CENTRAL ATLC DRY TONIGHT. A SMALL AREA OF SCATTERED SHOWERS
IS S-SE OF BERMUDA FROM 27N-29N BETWEEN 59W-65W DUE TO
DIFFLUENCE ALOFT. A SURFACE RIDGE COVERS THE ERN ATLC E OF 45W
ANCHORED BY 1033 MB HIGH NW OF THE AZORES.

$$
HUFFMAN




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