[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 092330
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU AUG 09 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...

TROPICAL WAVE IS ADDED TO THE SFC MAP ALONG 25W S OF 16N
ESTIMATED TO BE MOVING W 10 KT. MET-9 SATELLITE HOVMOLLER
DIAGRAMS WERE THE MAIN SOURCE USED TO TRACK THIS FEATURE BACK
OVER AFRICA. A LONG-TERM SATELLITE LOOP SHOWED THE BREAKING OF
THIS ONCE LARGER WAVE NEAR THE AFRICAN COAST A DAY OR TWO AGO.
THE MORE CONVECTIVE PART...THE NRN BRANCH...WAS SWEPT NEWD BY A
STRONG UPPER LOW/TROUGH. THE SRN PORTION APPEARED TO CONTINUE
TRACKING W...WHICH IS THE FEATURE THAT WAS JUST ADDED TO THE
ANALYSIS. CURRENTLY...THIS WEAK SYSTEM IS NEAR THE WRN EDGE OF A
LARGE CYCLONIC GYRE OVER W AFRICA. WHILE LOW-LEVEL TURNING IS
APPARENT ON SATELLITE IMAGERY NEAR THIS LOW AMPLITUDE
WAVE...CONVECTION IS MINIMAL.

TROPICAL WAVE IS ALONG 39W S OF 14N MOVING W 10 KT. THIS LOW
AMPLITUDE WAVE REMAINS WEAK ONLY CAUSING A SLIGHT PERTURBATION
IN THE ITCZ. LITTLE SHOWER ACTIVITY IS ASSOCIATED WITH THIS
FEATURE.

HIGHER AMPLITUDE TROPICAL WAVE IS ALONG 59W/60W MOVING W NEAR 15
KT. THIS WAVE HAS BEEN EASY TO TRACK SINCE EMERGING OFF THE
AFRICAN COAST ABOUT A WEEK AGO. THE UW-CIMSS TPW PRODUCT DEPICTS
THIS WAVE NICELY AS A NARROW SURGE OF MOISTURE. SIGNIFICANTLY
DRIER AIR/DUST IS BEING ADVECTED W BEHIND IT. THIS WAVE HAS
PICKED SOME DEEP MOISTURE TODAY DUE TO THE DIFFLUENT ZONE ALOFT
ALONG AND E OF THE WAVE. SCATTERED SHOWERS AND TSTMS ARE
WEAKENING WITHIN 120 NM EITHER SIDE OF THE AXIS.

TROPICAL WAVE IS ALONG 70W S OF 19N MOVING W NEAR 15 KT.
SCATTERED TO NUMEROUS SHOWERS AND TSTMS ARE SHEARED OFF TO THE E
OF THE AXIS FROM 13N-16N BETWEEN 64W-69W. MORE ACTIVITY HAS
DEEPENED FURTHER W...BUT THIS APPEARS MORE ASSOCIATED WITH A SFC
TROUGH AND A LARGE UPPER DIFFLUENT ZONE. MORE ON THIS ACTIVE
WEATHER IN THE CARIB DISCUSSION SECTION.

TROPICAL WAVE IS ALONG 84W S OF 20N MOVING W 10-15 KT. THIS WAVE
LIES UNDERNEATH AN UPPER LOW WHICH IS HELPING TO GENERATE
SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 90 NM OF THE AXIS.
LITTLE LOW-LEVEL TURNING OR WAVE-TYPE SIGNATURE IS EVIDENT.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N16W 12N26W 10N38W 8N47W 11N58W.
THE AXIS REMAINS QUIET THIS EVENING WITH ONLY SCATTERED MODERATE
CONVECTION WITHIN 150 NM S OF THE AXIS BETWEEN 50W-54W. STRONG
CONVECTIVE BLOW-UP IS OVER AFRICA APPROACHING THE COAST
ASSOCIATED WITH THE NEXT TROPICAL WAVE.

DISCUSSION...
GULF OF MEXICO...
THE COMBINATION OF A STRONG UPPER HIGH OVER THE SRN U.S. AND AN
UPPER LOW ABOVE THE NW CARIB IS PRODUCING STRONG UPPER ELY FLOW
ACROSS THE GULF. SCATTERED TSTMS FIRED UP THIS AFTERNOON ACROSS
THE FLORIDA PANHANDLE WITH SOME WEAKENING DEBRIS ACTIVITY OVER
THE COASTAL WATERS. BESIDES FOR THAT...THE REGION REMAINS QUIET
WITH ONLY PATCHES OF MID-HIGH LEVEL CLOUDS. AT THE SFC...THE
PATTERN REMAINS WEAK WITH A QUASI-STATIONARY 1016 MB HIGH CENTER
NEAR 28N93W. THIS WEAK PRES GRAD IS EXPECTED TO CONTINUE FOR A
FEW MORE DAYS ALLOWING WINDS AND SEAS TO REMAIN LIGHT/LOW.
MOISTURE IS EXPECTED TO INCREASE ACROSS THE SE PORTION OF THE
REGION THIS WEEKEND AS THE SFC TROUGH IN THE ATLC/N CARIB PUSHES
INTO THE REGION.

CARIBBEAN SEA...
SEVERAL LOW-LEVEL FEATURES ALONG WITH A LARGE AREA OF UPPER
DIFFLUENCE IS PRODUCING A CONSIDERABLE AMOUNT OF MOISTURE OVER
THE CARIB. THE DIFFLUENT UPPER PATTERN CONSISTS OF AN UPPER LOW
APPROACHING THE YUCATAN PENINSULA...TWO UPPER HIGHS NEAR 16N78W
AND 15N65W AND ANOTHER UPPER LOW TO THE N OF THE REGION JUST E
OF THE BAHAMAS. WITHIN THIS MOIST ENVIRONMENT THERE ARE TWO
AREAS WHERE CONVECTION IS FOCUSED. THE MOST PRONOUNCED IS THE N
CENTRAL/W CARIB...INCLUDING JAMAICA AND ERN CUBA N OF 15N
BETWEEN 74W-79W. THIS SCATTERED MODERATE CONVECTION IS BEING
TRIGGERED BY A SFC TROUGH WHICH IS ANALYZED ACROSS THE CENTRAL
BAHAMAS TO THE CENTRAL CARIB SEA ALONG 25N76W 21N78W 15N76W.
SLIGHTLY WEAKER CONVECTION IS OVER THE ERN CARIB FROM 13N-16N
BETWEEN 64W-69W. THIS ACTIVITY IS ASSOCIATED WITH A TROPICAL
WAVE NEAR 70W...REFER TO THE SECTION ABOVE FOR MORE INFO.
SCATTERED SHOWERS ARE POSSIBLE JUST ABOUT ANYWHERE ELSE IN THE
BASIN DUE TO THE MOIST ENVIRONMENT IN PLACE.

ATLANTIC OCEAN...
THE NRN HALF OF A SFC TROUGH EXTENDS NNE FROM ERN CUBA ACROSS
THE CENTRAL BAHAMAS ALONG 22N78W 26N76W 30N72W. THIS PART OF THE
TROUGH AXIS IS QUITE A BIT QUIETER...IN TERMS OF CONVECTION...AS
COMPARED TO THE PORTION IN THE CARIB. A MID-HIGH LEVEL CLOUD
DECK COVERS MOST OF THE REGION BETWEEN 50W-75W ASSOCIATED WITH
THIS TROUGH AND DIFFLUENCE ALOFT BETWEEN AN UPPER LOW NEAR
25N69W AND OTHER UPPER FEATURES BOTH TO THE N AND S OF THE
REGION. THE UPPER PATTERN THEN FOLDS INTO A LARGE SCALE HIGHLY
ELONGATED TROUGH EXTENDING SW ALONG 32N31W 24N51W 12N58W.
RIDGING TAKES OVER E OF THERE STRETCHING W FROM AN ANTICYCLONE
OVER AFRICA ALONG 23N4W 20N23W 15N46W. ABUNDANT DRY AIR ALOFT
COVERS THE NE PORTION OF THE AREA ROUGHLY N OF 20N E OF 30W.

ELSEWHERE AT THE SFC...THE MAIN FEATURE IS A 1027 MB HIGH
CENTERED NEAR 37N36W. THIS HIGH IS PRODUCING LIGHT TO MODERATE
TRADES ACROSS THE BULK OF THE ATLC DISCUSSION AREA. A QSCAT PASS
NEAR 20Z SHOWS A SMALL AREA OF SLIGHTLY STRONGER WINDS NEAR THE
COAST OF NW AFRICA...BUT THESE WINDS ARE MUCH WEAKER THAN THE
PAST FEW DAYS.

$$
CANGIALOSI


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