[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 090116
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI JUN 08 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE ALONG 33W S OF 12N MOVING W 10-15 KT. THIS WAVE
HAS LOST A GREAT DEAL OF ITS STRUCTURE AND CONVECTION SINCE
YESTERDAY AND MAINLY CONSISTS OF WEAK TURNING IN LOW CLOUDS.
THE PSN OF THE WAVE FOLLOWS CONTINUITY AND IS PLACED ON THE
UPSHEAR SIDE OF ASSOCIATED SCATTERED SHOWERS AND ISOLATED TSTMS
WITHIN 240 NM W OF THE AXIS.

A TROPICAL WAVE IS ALONG 56W S OF 11N MOVING W NEAR 10 KT. WAVE
PASSAGE WAS EVIDENT IN THE RAOBS AT CAYENNE FRENCH GUIANA
BETWEEN 07/1100 UTC AND 07/2300 UTC. EARLIER CONVECTION NOTED
WITH THE WAVE HAS DECREASED MARKEDLY OVER THE PAST SEVERAL HOURS
WITH ONLY ISOLATED MODERATE CONVECTION NOTED FROM 8N TO 10N
WITHIN 90-120 NM E OF THE WAVE AXIS.

A TROPICAL WAVE SLIGHTLY RELOCATED ACROSS THE SRN CARIB ALONG
69W/70W S OF 15N IS MOVING W NEAR 15 KT. THE UPPER AIR TIME
SECTION FROM TRINIDAD SHOWED A CLEAR WAVE PASSAGE EARLY IN THE
DAY YESTERDAY. THIS WAVE REMAINS LARGELY VOID OF DEEP CONVECTION
AS THE FEATURE PRESSES WESTWARD IN A STRONGLY SUBSIDENT
ENVIRONMENT. HOWEVER...24-H PRES TENDENCIES IN THE SE CARIB SHOW
A RATHER PRONOUNCED 2-3 MB DROP SHOWING THE STRENGTH OF THIS
FEATURE.

A TROPICAL WAVE OVER THE EPAC ALONG 90W S OF 13N MOVING W 10-15
KT. THIS WAVE WAS CHALLENGING TO TRACK OVER THE PAST FEW DAYS
WITH LITTLE WAVE SIGNATURE NOTED IN SFC OBS OR SATELLITE IMAGES.
HOWEVER...THIS MORNING'S VIS PICTURES SHOWS A FAIR AMOUNT OF LOW
TO MID LEVEL CYCLONIC TURNING NEAR 10N90W...LEADING TO THE
SHIFTED PSN. FOR MORE DETAILS REFER TO THE EAST PACIFIC
TWD...MIATWDEP.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N9W 5N31W 6N35W 4N44W 6N53W.
CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN
240 NM N OF THE AXIS E OF 15W. THIS ACTIVITY IS OCCURRING AHEAD
OF WHAT APPEARS TO BE A TROPICAL LARGE WAVE OF LARGE AMPLITUDE
THAT IS STILL INLAND OVER AFRICA ROUGHLY ALONG 8W. TONIGHTS TIME
SECTIONS SHOULD PROVIDE BETTER DETAIL ON THIS SYSTEM WHICH MAY
BE ADDED TO THE TROPICAL SURFACE ANALYSIS WITHIN THE NEXT DAY OR
TWO AS IT PUSHES OFF THE AFRICAN COAST. ELSEWHERE ALONG THE
ITCZ...ONLY ISOLATED TO SCATTERED MODERATE CONVECTION WAS
NOTED WITHIN 180 NM N OF THE AXIS BETWEEN 20W AND 30W.

...DISCUSSION...

THE GULF OF MEXICO...
THE WRN EXTENSION OF A W ATLC SFC RIDGE STRETCHES ACROSS FLORIDA
INTO THE GULF ALONG 29N. THIS RIDGE IS PRODUCING MODERATE TO
FRESH SELY RETURN FLOW IN THE MID AND W GULF...WITH LIGHTER
WINDS IN THE E GULF CLOSER TO THE HIGH PRES CENTER. ALOFT...THE
PATTERN IS CONFLUENT BETWEEN AN UPPER HIGH CENTERED OVER S
MEXICO NEAR 18N100W AND AN UPPER LOW OVER SE FLORIDA. THIS
PATTERN IS LEADING TO A DRY STABLE AIRMASS ACROSS THE MAJORITY
OF THE REGION AIDING IN THE WIDESPREAD FAIR WEATHER. HOWEVER...
INSTABILITY NEAR THE UPPER LOW IS FUELING SCATTERED SHOWERS AND
TSTMS ACROSS THE SRN THIRD OF THE FLORIDA PENINSULA...RADAR
DATA FROM MIAMI INDICATED CYCLONIC TURNING IN THE REFLECTIVITY
OVER ERN MIAMI-DADE COUNTY MOVING SW TOWARD THE UPPER KEYS.
ADDITIONAL STORMS WITH FREQUENT LIGHTNING STRIKES WERE NOTED
OVER THE FLORIDA STRAITS. THE WEEKEND LOOKS TRANQUIL OVER THE
GULF WITH SFC WINDS ANTICIPATED TO RELAX AS WEAK HIGH PRES
DEVELOPS AND SETTLES IN THE N CENTRAL GULF.

THE CARIBBEAN SEA...
THE MOST ACTIVE WEATHER IN THE REGION REMAINS OVER PANAMA...
COSTA RICA AND THE EXTREME SW CARIB WHERE SATELLITE IMAGERY AND
LIGHTNING DATA DEPICT SCATTERED MODERATE/STRONG CONVECTION S OF
11N W OF 77W. THIS ACTIVITY APPEARS MOSTLY TIED TO THE ITCZ WITH
SOME ENHANCEMENT FROM DIFFLUENCE ALOFT. OTHERWISE...TROPICAL
WAVES ARE THE MAIN ISSUE OVER THE REGION WITH ONE IN THE SE
CARIB AND THE OTHER APPROACHING THE WINDWARD ISLANDS. THE LATTER
IS AIDING IN SCATTERED SHOWERS AND TSTMS ACROSS THE LESSER
ANTILLES. FOR MORE DETAILS REFER TO THE TROPICAL WAVES SECTION
ABOVE. OTHERWISE...MODERATE TO FRESH TRADES AND FAIR WEATHER
DOMINATE AS A LARGE AREA OF DRY SINKING AIR LIES ALOFT
ASSOCIATED WITH WEAK UPPER RIDGING.

ATLANTIC OCEAN...
INSTABILITY ASSOCIATED WITH A WELL DEFINED UPPER LOW SPINNING
OVER S FLA IS FUELING SCATTERED SHOWERS AND TSTMS OVER THE
BAHAMAS...S FLORIDA AND THE FLORIDA STRAITS MAINLY IN AN AREA
S OF 26N W OF 74W. THE STRONGEST ACTIVITY IS NOW LOCATED S OF
THE UPPER LOW MAINLY ACROSS THE FLORIDA STRAITS AND ANDROS
ISLAND. OTHERWISE...SFC HIGH PRES RIDGE RULES WITH A 1021 MB
CENTER NEAR 31N72W. FARTHER NE...A LARGE VERTICALLY STACKED LOW
PRES AREA IS LOCATED NEAR 38N60W. THIS SYSTEM IS PROVIDING
LIMITED SUPPORT FOR A WEAKENING COLD FRONT WHICH EXTENDS FROM
32N55W TO 26N63W. SCATTERED SHOWERS ARE WITHIN 120 NM E OF THE
FRONT AND N OF 24N BETWEEN 47W-52W IN AN ASSOCIATED UPPER
DIFFLUENT ZONE.

MUCH OF THE CENTRAL AND EASTERN ATLC DISCUSSION AREA IS UNDER
THE INFLUENCE OF WEAK SFC HIGH PRES RIDGING RESULTING IN LIGHT
WINDS. UPPER LOW WITH MEAN CENTER NEAR 29N42W IS BECOMING
ELONGATED AND MAY OPEN UP INTO A TROUGH. THIS FEATURE APPEARS TO
BE GENERATING ISOLATED TSTMS NEAR 28N43W AND AN AREA OF
CIRRUS CLOUDS WITHIN A DIFFLUENT AXIS. A S-SWLY JET ORIGINATES
NEAR THE BASE OF THE ASSOCIATED TROUGH NEAR 14N49W AND CONTINUES
NE ALONG 22N40W 31N37W THEN TURNS EWD TO THE S OF A LARGE DEEP
LAYERED OCCLUDED LOW PRES SYSTEM E OF THE AZORES NEAR 40N21W.

$$
COBB




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