[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 040530
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI JUL 04 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 FEATURE....

TROPICAL STORM BERTHA CENTERED NEAR 13.4N 27.0W AT 0300 UTC OR
ABOUT 160 NM WSW OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING W
AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM
SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT42
KNHC FOR MORE DETAILS. BERTHA IS PULLING AWAY FROM THE CAPE
VERDE ISLANDS. LITTLE IMPACT WAS AFFECTED NEAR SAL ON THU AS SFC
REPORTS SHOW MAX WINDS JUST OVER 20 KT...A PRESSURE OF 1012 MB
AND VERY LITTLE RAINFALL. MORE OF AN IMPACT WAS LIKELY FELT OVER
THE SOUTHERN ISLANDS CLOSER TO THE CORE OF COMPACT BERTHA.
BERTHA MAINTAINS A WELL DEFINED CIRCULATION WITH A TIGHT AREA OF
NUMEROUS MODERATE TO STRONG CONVECTION MAINLY LOCATED WITHIN 90
NM N/NE OF THE CENTER. STRENGTHENING IS FORECAST IN THE SHORT
TERM AS ATMOSPHERIC CONDITIONS APPEAR FAVORABLE AND OCEANIC
CONDITIONS ARE MARGINAL.

...TROPICAL WAVES...

TROPICAL WAVE IS TILTED ALONG 50W/51W S OF 20N MOVING W 20 KT.
DESPITE THE HIGH AMPLIFICATION OBSERVED IN SATELLITE IMAGERY AND
SCATTEROMETER DATA...THERE IS MINIMAL ASSOCIATED CONVECTION.
SHALLOW SCATTERED SHOWERS ARE WITHIN 240 NM EITHER SIDE OF THE
AXIS.

THE LOW AMPLITUDE TROPICAL WAVE PREVIOUSLY ANALYZED NEAR 60W HAS
BEEN DROPPED FROM THE SFC ANALYSIS. THERE HAS BEEN LITTLE
EVIDENCE OF THIS FEATURE OVER THE PAST SEVERAL DAYS AND IT
APPEARS THAT MUCH OF ITS MOISTURE/ENERGY HAS BEEN DRAWN INTO THE
ITCZ...DUE TO THE ENHANCED NE FLOW ON THE W SIDE OF THE LARGE
WAVE TO ITS E.

TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN ALONG 69W S OF 18N
MOVING W 15-20 KT. A VORTICITY MAXIMUM REMAINS LOCATED ALONG THE
AXIS NEAR 15N. DISORGANIZED SCATTERED SHOWERS AND TSTMS ARE NEAR
THIS ENHANCED AREA OF CYCLONIC TURNING FROM 14N-16N BETWEEN
67W-69W. UPPER WINDS ARE NOT CONDUCIVE FOR FURTHER DEVELOPMENT.

TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN ALONG 81W S OF 15N
MOVING W 15 KT. THIS WAVE LIES IN AN UPPER DIFFLUENT ZONE ON THE
S SIDE OF AN UPPER HIGH...TRIGGERING SCATTERED SHOWERS AND TSTMS
FROM 12N-16N BETWEEN 79W-84W.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 16N17W 15N23W 10N29W 8N40W 5N48W
7N59W. SCATTERED MODERATE CONVECTION IS FROM 6N-10N BETWEEN
27W-32W AND FROM 4N-6N BETWEEN 36W-40W. SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 7N-11N E OF 16W.

...DISCUSSION...

THE GULF OF MEXICO...
THE LARGE SCALE PATTERN CONSISTS OF AN ELONGATED UPPER TROUGH
EXTENDING SW ACROSS THE EAST AND CENTRAL WATERS...AN UPPER LOW
SPINNING OVER SOUTH TEXAS AND BROAD RIDGING LIES OVER CENTRAL
MEXICO. THIS PATTERN IS KEEPING A FAIR AMOUNT OF MOISTURE OVER
THE REGION. HOWEVER...LIGHTNING DATA INDICATES THAT LITTLE OF
THIS IS LEADING TO SIGNIFICANT TSTM ACTIVITY OVER THE CENTRAL
AND EASTERN WATERS. THERE IS SCATTERED SHOWERS AND TSTMS NEAR
THE COAST OF MEXICO AND SOUTH TEXAS S OF 27N W OF 96W MAINLY
ASSOCIATED WITH THE DIFFLUENT PATTERN MENTIONED ABOVE. AT THE
SFC...ATLC RIDGING EXTENDS ACROSS THE ALONG 28N ALLOWING WINDS
TO BE LIGHT ACROSS THE N WATERS AND MODERATE TO FRESH OVER THE S
WATERS.

THE CARIBBEAN SEA...
A PAIR OF TROPICAL WAVES ARE PROPAGATING ACROSS THE SEA. THE
EASTERN ONE (APPROACHING 70W) HAS BEEN FAIRLY WELL DEFINED OVER
THE PAST COUPLE OF DAYS...HOWEVER...IT APPEARS LESS ORGANIZED
TONIGHT AS ONLY A SMALL AREA OF SCATTERED SHOWERS/TSTMS EXIST
FROM 14N-16N BETWEEN 67W-69W. THE OTHER WAVE ALONG 81W HAS BEEN
FAIRLY INACTIVE OVER THE PAST COUPLE OF DAYS BUT IT HAS GAINED
CONVECTION TONIGHT AS IT TRACKED INTO AN UPPER DIFFLUENT AREA.
REFER TO THE TROPICAL WAVE SECTION ABOVE FOR MORE DETAILS.
ELSEWHERE...DEEP CONVECTION IS FAIRLY MINIMAL AT THE MOMENT
DESPITE A MOIST ENVIRONMENT ALOFT. HOWEVER...ITS QUITE A
DIFFERENT STORY OVER EL SALVADOR...GUATEMALA...WRN HONDURAS AND
BELIZE...WHERE NUMEROUS SHOWERS AND TSTMS ARE OCCURRING IN
ASSOCIATED WITH THE UPPER DIFFLUENT ZONE AND SOME INFLUENCE
FROM A DISTURBANCE IN THE EAST PACIFIC NEAR 11N95W.

THE ATLANTIC OCEAN...
THE UPPER PATTERN REMAINS DIFFLUENT OVER THE W ATLC BETWEEN
ELONGATED TROUGHING OVER THE EASTERN SEABOARD OF THE U.S. AND A
NARROW RIDGE E OF THE BAHAMAS ALONG 70W. THIS PATTERN IS
PRODUCING ABUNDANT CLOUDINESS AND EMBEDDED SCATTERED SHOWERS AND
TSTMS OVER THE NW BAHAMAS AND NEARBY WATERS N OF 25N W OF 77W.
FARTHER E...A LARGE UPPER LOW IS SPINNING NEAR 32N53W WITH
TROUGHING EXTENDING S TOWARDS THE NE CARIBBEAN. LARGE SCALE
RIDGING HOLDS E OF THERE WITH AN UPPER HIGH POSITIONED NEAR
20N44W. OVERALL...THIS PATTERN IS PRODUCING LITTLE SENSIBLE
WEATHER BESIDES FOR SCATTERED SHOWERS AND TSTMS NEAR THE UPPER
LOW N OF 29N BETWEEN 43W-59W.

AT THE SFC...A PAIR OF QUASI-STATIONARY HIGHS ARE OVER THE
CENTRAL ATLC...ONE ANALYZED 1028 MB NEAR 34N41W...THE OTHER 1026
MB HIGH NEAR 34N61W. A SFC TROUGH IS WEAKENING THE RIDGE FROM
23N50W TO 31N46W. THIS TROUGH APPEARS TO BE PARTLY ASSOCIATED
WITH THE LARGE TROPICAL WAVE TO THE S AND THE UPPER LOW CENTERED
TO THE NW. SCATTERED LOW-LEVEL SHOWERS ARE WITHIN 180 NM OF THE
AXIS.

$$
CANGIALOSI




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