[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041751
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE....

TROPICAL STORM BERTHA CENTERED NEAR 14.9N 29.7W AT 1500 UTC OR
ABOUT 335 NM W OF THE CAPE VERDE ISLANDS MOVING WNW AT 14 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED
WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT42 KNHC
FOR MORE DETAILS. BERTHA HAS MOVED W OF THE CAPE VERDE ISLANDS.
A BURST OF ISOLATED STRONG CONVECTION IS LOCATED N OF THE
CIRCULATION CENTER BETWEEN 29W-31W...WITH SCATTERED MODERATE
CONVECTION WITHIN 180 NM N AND 90 NM S OF THE CENTER. BERTHA
WILL BE PASSING OVER SLIGHTLY COOLER WATERS DURING THE NEXT 24
HOURS IN WHICH IT WILL MAINTAIN ITS INTENSITY WITH GRADUAL
STRENGTHENING FORECAST THEREAFTER AS ATMOSPHERIC CONDITIONS
APPEAR MORE FAVORABLE AND OCEANIC CONDITIONS REMAIN MARGINAL.

...TROPICAL WAVES...

TROPICAL WAVE IS TILTED ALONG 54W/55W S OF 22N MOVING W 20-25
KT. DESPITE THE HIGH AMPLIFICATION NOTED IN SATELLITE IMAGERY
AND AN EARLIER QUIKSCAT PASS...THERE IS MINIMAL ASSOCIATED
CONVECTION. SHALLOW SCATTERED SHOWERS ARE WITHIN 250 NM EITHER
SIDE OF THE AXIS.

TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN ALONG 71W S OF 19N
MOVING W 15-20 KT. SATELLITE IMAGERY SHOWS CLASSIC INVERTED-V
CURVATURE SIGNATURE ALONG WAVE AXIS NORTH OF 14N WITH SCATTERED
SHOWERS AND TSTMS FROM 15N-18N BETWEEN 66W-73W IN AN AREA MAINLY
SOUTH OF HISPANIOLA.

TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN ALONG 82W/83W S OF
15N MOVING W 10-15 KT. THIS WAVE LIES IN AN UPPER DIFFLUENT ZONE
ON THE S SIDE OF AN UPPER HIGH. THESE TWO FEATURES TOGETHER ARE
PRODUCING WIDESPREAD SHOWERS AND SCATTERED STRONG TSTMS FROM
11N-16N BETWEEN 81W-85W WHICH INCLUDES FAR ERN HONDURAS AND
NICARAGUA.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 13N21W 8N31W 6N34W 5N52W.
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 5N-11N
BETWEEN 14W-20W. SIMILAR CONVECTION IS FROM 6N-9N BETWEEN
27W-34W. ISOLATED MODERATE CONVECTION IS WITHIN 120 NM SOUTH OF
THE AXIS BETWEEN 36W-42W AND BETWEEN 46W-51W.

...DISCUSSION...

THE GULF OF MEXICO...
THE LARGE SCALE PATTERN ACROSS THE GULF CONSISTS OF AN ELONGATED
UPPER TROUGH EXTENDING FROM OFFSHORE OF THE ERN CONUS SW ACROSS
NRN FLORIDA AND INTO THE ERN GULF WATERS..AND AN UPPER LOW
SPINNING OVER SOUTHEAST TEXAS. BROAD RIDGING IS ACROSS CENTRAL
MEXICO EXTENDING INTO THE WEST CENTRAL GULF WATERS. THIS PATTERN
IS PRODUCING A FAIR AMOUNT OF MOISTURE OVER THE ENTIRE GULF.
HOWEVER...LIGHTNING DATA INDICATES THAT ONLY THE MID TO UPPER
LEVEL DIFFLUENCE E OF THE UPPER LOW ACROSS SE TEXAS IS
SUSTAINING SCATTERED SHOWER AND TSTM ACTIVITY ACROSS THE WRN
GULF SKIRTING COASTAL TEXAS AND MEXICO SWD INTO THE WRN BAY OF
CAMPECHE. MOST OF THIS ACTIVITY REMAINS W OF 94W. AT THE
SURFACE...RIDGE OF HIGH PRESSURE EXTENDING FROM THE W ATLC
COVERS MUCH OF THE NE GULF KEEPING WINDS LIGHT AND VARIABLE N OF
25N AND E OF 90W. ELSEWHERE...WINDS REMAIN EAST TO SOUTHEASTERLY
FROM 10-20 KT ACROSS THE WRN AND SRN GULF.

THE CARIBBEAN SEA...
A PAIR OF TROPICAL WAVES ARE PROPAGATING ACROSS THE SEA. THE
EASTERN ONE ALONG 71W IS WELL DEFINED WITH CLUSTERS OF SCATTERED
SHOWERS AND TSTMS N OF 15N TO THE SRN COAST OF HISPANIOLA
BETWEEN 66W-73W. THE OTHER WAVE ALONG 82W/83W IS AIDING IN
PRODUCING WIDESPREAD SHOWERS AND SCATTERED STRONG TSTMS ACROSS
THE WRN CARIBBEAN AND ERN HONDURAS/NICARAGUA AS IT TRACKS UNDER
AN UPPER DIFFLUENT AREA. THIS UPPER LEVEL DIFFLUENT AREA IS
ANCHORED BY AN UPPER HIGH CENTERED NEAR 15N80W WHICH HAS
CONTINUED TO CONCENTRATE HEAVY AMOUNTS OF RAINFALL ACROSS ERN
NICARAGUA WHERE POTENTIAL FOR FLOODING AND MUDSLIDES REMAIN.
ELSEWHERE...DEEP CONVECTION IS FAIRLY MINIMAL DUE TO NW FLOW AND
DRIER AIR ALOFT ACROSS ERN CUBA/JAMAICA...AND STRONG UPPER LEVEL
SUBSIDENCE/DRY AIR ACROSS THE FAR ERN CARIBBEAN AND LESSER
ANTILLES.

THE ATLANTIC OCEAN...
THE UPPER PATTERN REMAINS DIFFLUENT OVER THE W ATLC IN
ASSOCIATION WITH ELONGATED TROUGHING OVER THE ERN SEABOARD OF
THE U.S. AND A NARROW SLIGHTLY AMPLIFIED RIDGE E OF THE BAHAMAS
ALONG 70W. THIS PATTERN IS PRODUCING A LARGE SWATH OF CLOUDINESS
WHICH EXTENDS FROM NEAR WEST PALM BEACH FLORIDA TO 32N75W AND
NORTHEAST OF THE DISCUSSION AREA. SCATTERED SHOWERS WITH
EMBEDDED TSTMS ARE OBSERVED N OF 26N AND W OF 76W. FARTHER E...A
LARGE UPPER LOW IS SPINNING NEAR 33N54W WITH TROUGHING EXTENDING
S TOWARDS THE NE CARIBBEAN. LARGE SCALE RIDGING HOLDS E OF THERE
WITH AN UPPER HIGH POSITIONED NEAR 20N49W. OVERALL...THIS
PATTERN IS PRODUCING LITTLE SENSIBLE WEATHER.

AT THE SURFACE...A PAIR OF QUASI-STATIONARY HIGHS ARE OVER THE
CENTRAL ATLC...ONE ANALYZED 1027 MB NEAR 35N39W...THE OTHER 1026
MB HIGH NEAR 33N59W. A SURFACE TROUGH IS WEAKENING THE RIDGE
FROM 26N53W TO 33N47W. THIS TROUGH AND ASSOCIATED IMPULSE OF
MID-LEVEL ENERGY 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 150 NM OF THE AXIS.

$$
HUFFMAN




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